UNEP-GEF WIO-LaB PROJECT
NATIONAL REPORT ON STATUS OF MUNICIPAL WASTEWATER MANAGEMENT IN MAURITIUS
FINAL REPORT
OCT 2007
J. A. RADHAY
UNEP-GEF WIO-LaB PROJECT NATIONAL REPORT ON STATUS OF MUNICIPAL WASTEWATER MANAGEMENT IN MAURITIUS
TABLE OF CONTENTS Page List of Tables (iii)
List of Annexes (v)
List of Abbreviations (vi)
List of Photographs (viii)
Executive Summary 1
Introduction 3
Country Profile 5
Chapter 1 – National Level Review of the GPA Guidelines
1.0 – Introduction 8 1.1 - Enabling policy environment for sustainable wastewater management 8 1.2 – Institutional Arrangements and Social Participation 9 1.3 – Planning Sustainable and Cost-Effective Technologies 9 1.4 – Financial Mechanisms for Wastewater Management 10 1.5 – Specificities of Mauritius that can affect applicability of the GPA Guidelines 11 1.6 – Applicability of the ten keys for local and national actions on MWW 12 1.7 – Conclusion 15
Chapter 2 – Review of Enabling Policy, Regulatory and Institutional Environment for Municipal Was tewater Management
2.1 – Assessment of existing policy framework 16 2.2 – Assessment of existing legal regulatory framework 28 2.3 – Assessment of existing institutional mechanisms 39 2.4 – Assessment for mechanisms for stakeholder involvement in MWW Management 52 2.5 – Assessment of existing financial mechanisms 59 2.6 – Conclusions and recommendations 63
Chapter 3 – Inventory of Municipal Wastewater Infrastructures
3.1 – Background 66 3.2 – Public Sewer Systems 79 3.3 – Inventory of Major Municipal Wastewater Treatment Plants 84 3.4 – Overview of Most Important Wastewater Producing Enterprises 97 3.5 – Major Rivers draining Wastewater into the Ocean 100 3.6 – Standards for Assessment of Performance of Wastewater Treatment Plants 101 3.7 - Sludge Management in Mauritius 104 3.8 – Re-use of wastewater and sludge in Mauritius 105 3.9 – Status of Sanitation in Rodrigues 108 3.10 – Conclusions 109 Page (i) J. A. Radhay Oct 07
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Chapter 4 – Assessment of Existing MWW Management Practices and Methods
4.1 - Assessment of existing MWW management practices and methods 110 4.2 – Assessment of existing constraints in MWW management practices and methods 116 4.3 – Recommendations for improved MWW management practices and methods 122
Chapter 5 – Review Existing Technologies used for MWW Management
5.1 – Overview of existing technologies in Mauritius 127 5.2 – Description of existing technologies and constraints in MWW 132 5.3 – Recommendations for Appropriate Technology 142
Chapter 6 – Lessons learnt and ‘best practices’ from projects on MWW Management
6.0 – Introduction 147 6.1 – Selection Consultant 147 6.2 – Securing of Funds 148 6.3 – Involvement of Other Stakeholders 148 6.4 – Internal and External Processes for Approval 149 6.5 – In –house capacity to handle major projects 149 6.6 – O & M facilities and commissioning 149 6.7 – Use of equipment & material from abroad 150
Chapter 7 – Mechanisms for Domestication of Regional Guidelines
7.1 – Mechanisms for Domestication 151 7.2 – Opportunities for Domestication 152 7.3 – Impediments for Domestication 152 7.4 – National Mechanisms, Strategies and Policies that can be used to internalize the Regional Guidelines on MWW Management 152
References 156
Photographs
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LIST OF TABLES
Table 2.1 Summary of Key Institutions Involved in the Environmental Aspects of Water Resources 47
Table 2.2 Water Utilization in Mauritius per category 49
Table 2.3 Responsibilities of Main Institutions Involved in Wastewater Management 54
Table 2.4 Sector Policy Tariffs and Tariffs applied for the period 2000-2006 61
Table 3.1 Mid -year geographical distribution of population as at 2003 66
Table 3.2 Estimated Mid -Year Resident Population of Towns – 2003 67
Table 3.3 Estimated Mid Year Resident Population of Large Villages as at 2003 67
Table 3.4 Number of towns and villages within different bands of population density 68
Table 3.5 Pamplemousses Sub-areas: Population and Housing 69
Table 3.6 Riviere du Rempart Sub-areas: Population and Housing 70 ` Table 3.7 Flacq Sub-areas: Population and Housing 71
Table 3.8 Grand Port Sub-areas: Population and Housing 72
Table 3.9 Savanne Sub-areas: Population and Housing 73
Table 3.10 Moka Sub-areas: Population and Housing 73
Table 3.11 Black River Sub-areas: Population and Housing 74
Table 3. 12 Influent and Treated Effluent Characteristics for St. Martin WWTP 86
Table 3.13 Influent and Effluent Characteristics for Grand Baie WWTP 89
Table 3.14 Influent and Effluent Characteristics for Baie du Tombeau WWTP 93
Table 3.15 Influent and Effluent Characteristics for Montagne Jacquot WWTP 96
Table 3.16 Annual flow of Major Rivers 100
Table 3.17 Environment Protection (Standards for Effluent Discharge) Regulations 2003 101
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Table 3.18 Environment Protection (Standards of Effluent for Use in Irrigation) Regulations 2003 102
Table 3.19 Environment Protection (Standards for Effluent Discharge) Regulations 2003 103
Table 3.20 Sludge Management in Mauritius 104
Table 7.1 Applicability of the ten keys for local and national actions on municipal wastewater 151
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LIST OF ANNEXES
Annex 3.0 Geographical Position of Mauritius and its outer islands in the Indian Ocean
Annex 3.1 Geographical Districts of Mauritius
Annex 3.2 Districts Indicative Built-up Areas
Annex 3.3 Sewered Regions of Mauritius
Annex 3.4 Distribution of CHA Estates across Mauritius
Annex 3.5 Distribution of NHDC Estates across Mauritius
Annex 3.6 Location of Nine Public Wastewater Treatment Plants
Annex 3.7 Plaines Wilhems Sewerage System
Annex 3.8 Grand Baie Sewerage System
Annex 3.9 Baie du Tombeau Sewerage System
Annex 3.10 Port Louis North and Port Louis South – Lower Beau Bassin/Coromandel Sewerage System
Annex 3.11 Flow Process Diagram for St. Martin Wastewater Treatment Plant
Annex 3.12 Flow Process Diagram for Grand Baie Wastewater Treatment Plant
Annex 3.13 Flow Process Diagram for Montagne Jacquot Wastewater Treatment Plant
Annex 3.14.1 Details of Most Important Sewered Industries
Annex 3.14.2 Details of Coastal Hotels Having Wastewater Treatment Plant
Annex 3.15 Rivers of Mauritius and Their Catchment Areas
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LIST OF ABBREVIATIONS
AFRC Albion Fish Research Centre AREU Agricultural and Research Extension Unit AGR Average Growth Rate AHRIM Association des Hoteliers et Restaurateurs de Maurice BOD Bio Oxygen Demand BRL Bas Rhone - Languedoc CAATT Computer Aided Audit Tools and Techniques CHA Central Housing Authority COD Chemical Oxygen Demand CSO Central Statistical Office CWA Central Water Authority DI Ductile Iron DoE Department of Environment DWF Dry Water Flow EC European Community ECC Environment Co-ordination Committee E.coli Escherichia coli EDF European Development Fund EEZ Exclusive Economic Zone EIA Environmental Impact Assessment EIP Environmental Investment Programme ELO Environment Liaison Officer EPA Environment Protection Act EU European Union FA Financing Agreement FAO Food and Agriculture Organization FC Faecal Coliform GoM Government of Mauritius GPA Global Programme of Actions GRP Glass Reinforced Plastics HRAP High Rate Algal Pond IA Irrigation Authority IBRD International Bank Reconstruction Development IFC International Finance Corporation IRS Integrated Resort Scheme IT Information Technology JEC Joint Economic Council KPI Key Performance Indicator MCCI Mauritius Chamber of Commerce and Industry MDG Millennium Development Goal MEPZA Mauritius Export Processing Zone Authority MHQL Ministry of Health and Quality of Life MoE Ministry of Environment MOFED Ministry of Finance and Economic Development MPN Most Probable Number MPU Ministry of Public Utilities
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MTEF Medium Term Expenditure Framework MWW Municipal Waste Water NDS National Development Strategy NEC National Environment Commission NEL National Environment Laboratory NDU National Development Unit NEAP National Environmental Action Plan NGO Non Governmental Organization NHDC National Housing Development Company NNSD National Network for Sustainable Development NSP National Sewerage Programme O&M Operation and Maintenance PE Population Equivalent PE pipe Poly -Ethylene pipe PER Preliminary Environmental Report PR Public Relations PRB Pay Research Bureau PS Pumping Station PSO Private Sector Operator PSP Private Sector Participation PVC Poly Vinyl Chloride PWSP Plaines Wilhems Sewerage Project RBC Rotating Bio-Contactors SAR Sodium Absorption Ratio SBR Sequential Batch Reactor SPL Sector Policy Letter SSV Solid Sludge Volume TA Technical Assistance TDS Total Dissolved Solids TKN Total Kjeldahl Nitrogen TSS Total Suspended Solids UASB Upward Air-flow Sludge Blanket UNEP United Nations Environment Programme UPVC Unplasticised Poly Vinyl Chloride URA Utility Regulatory Authority UV Ultra-Violet WAC Water for Asian Cities WMA Wastewater Management Authority WRU Water Resources Unit WSPSP Wastewater Sector Policy Support Programme WUA Water Users Association WWA Waste Water Authority WWTP Waste Water Treatment Plant
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LIST OF PHOTOGRAPHS
Photo P1 Northern Works Pumping Station
Photo P2 Baie du Tombeau WWTP
Photo P3 St. Martin WWTP – Aerial View
Photo P4 Grand Baie WWTP – Aerial View
Photo P5 Montagne Jacquot Sea Outfall Details
Photo P6 Plaines Wilhems Trunk Sewer Construction
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FINAL REPORT UNEP-GEF WIO-LaB PROJECT NATIONAL REPORT ON STATUS OF MUNICIPAL WASTEWATER MANAGEMENT IN MAURITIUS
Executive Summary
This study analyses the status of municipal wastewater management in the Republic of Mauritius. The existing policy with regards to wastewater management, stemming from the National Environmental Policy, the Sewerage Masterplan and the Sector Policy Letter has been described. The present status of the Wastewater Management Authority is also outlined, in terms of capacity building and National Sewerage Programme. It has been found that most of the objectives set in the Sector Policy Letter of 1998 have been achieved.
A systematic assessment of the existing legal and regulatory framework governing the sector has been undertaken. This covers the Environmental Protection Act 2002 under which all Regulations governing discharge of wastewater and the corresponding Enforcement Agencies are described. The different Standards and Regulations are also outlined and the strength and weaknesses of the Regulations are assessed. In general, the Regulations have been found to be well drafted and provide efficient tools for environmental protection. However some drawbacks identified include the need for more institutional capacity for implementation and enforcement as well as for more stakeholder awareness and more flexibility.
An assessment of the existing institutional mechanisms describes the responsibilities and inter- relationships between different ministries and organizations involved in water resources management. The existing financial mechanisms have been analyzed as well as stakeholder involvement in municipal wastewater management. It has been found that the right environment prevails for practicing sound municipal wastewater management in the Mauritius. Items that need to be reinforced for the future include maintaining financial sustainability, improving public awareness and sensitization, increase in institutional capacity, legal aspects regarding on-site sanitation, synergy between public laboratories for regulatory and monitoring aspects and enforcement of environmental laws.
An inventory of existing municipal wastewater infrastructure has been undertaken. It has been shown that, while 25% of the population is sewered, the wastewater is drained to well designed and operated municipal treatment plants. Re-use of treated wastewater in irrigation is practiced. An inventory of industrial wastewater infrastructure and quality of industrial effluent is provided. Control of industrial effluent under the relevant Regulations has been a success. Treated effluents from coastal hotels are well managed.
An assessment of existing municipal wastewater management practices and methods shows that political commitment is high, a strong organization equipped with the necessary legal and institutional framework has been set up to be responsible for the wastewater sector. The national strategy to provide water borne sanitation to 50% and 80% of the population by the years 2015 and 2030 respectively is well under way. Stakeholder involvement needs to be enhanced while private sector participation is highly encouraged.
A review of existing technologies used for municipal wastewater management shows that water borne sewerage with end of pipe conventional treatment consisting of activated sludge systems is the prevailing technology. Low – cost sanitation technologies such as waste stabilization ponds and constructed systems are not appropriate for large communities due to the large land requirements and the relatively small size of Mauritius. An overview of existing technologies has been undertaken and it has been found that extended aeration systems would be best suited for Mauritius as these systems are simple, robust and not highly mechanized.
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It was also found that on-site sanitation practices consist mainly of individual cesspits. Proper on- site sanitation systems such as septic tanks followed by absorption systems need to be enforced.
Finally, it has been found that most of the GPA Guidelines and keys for local and national actions on municipal wastewater are already practiced in Mauritius. However, due to the specificity of Mauritius, it has been found that it is best to have a central organization responsible for wastewater management, while management of on-site disposal systems could best be delegated to the local authorities.
In general, since the elaboration of the first National Sewerage Masterplan of 1994, Mauritius has made a remarkable improvement in wastewater management and environmental protection. Sound laws and institutions have been set up, tools such as the EIA process, stakeholder involvement, private sector participation are in place. Public laboratories with sophisticated equipment have been set up for monitoring. Integrated water resources management is being promoted and Mauritius possesses one of the most sophisticated wastewater treatment plants in the Western Indian Ocean region, with tertiary treatment, re-use in irrigation and sludge digestion for biogas production and power generation.
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Introduction
Municipal wastewater discharges to the marine and coastal environment has been recognized worldwide as having disastrous consequences on the coastal environment, on the environmental health of oceans and consequently on biodiversity, livelihoods of economies and societies. Thus the Global Programme of Action for the protection of the marine environment from Land- based Activities (GPA) was established in November 1995 when representatives of governments and the European Union met in Washington DC. The UNEP/GPA Coordination Office was established to provide the required Secretariat and to facilitate the implementation of the GPA.
The GPA framework provides a series of recommendations for action including specific criteria for their development at various levels, aiming at assisting countries in fulfilling their duties to preserve and protect the marine environment from sewage and other sources of pollution. To assist implementation of the GPA, key principles and checklists have been developed, advocating innovative approaches on relevant components such as institutional set-up, financing mechanisms, alternative technologies and stakeholder involvement. A Strategic Action Plan on Municipal Wastewater has been prepared by the UNEP/GPA Coordination Office, in collaboration with other international and regional organizations, donor agencies, financial institutions and development assistance agencies, with the aim of initiating concrete actions at both local and national levels for endorsement of the relevant key principles. These principles aim at promoting the use of alternative solutions, including sound institutional set-up, low-cost sanitation technologies, innovative financial mechanisms, stakeholder involvement, and the creation of an enabling environment for sustainable development of the municipal wastewater sector.
Under the UNEP Regional Seas Programme, seven countries in the Western Indian Ocean region, namely Kenya, Tanzania, Mozambique, South Africa, Madagascar, Seychelles, Comoros and Mauritius are signatory to the Nairobi Convention. Under the Nairobi Convention, the Project entitled “ Addressing land-based activities in the Western Indian Ocean” thrives to address some of the major environmental problems and issues related to the degradation of the marine and coastal environmental problems in the Western Indian Ocean region. The efforts of the UNEP Coordination Office for the GPA, in collaboration with the Nairobi Convention and the WIOMSA have further been endorsed by the WIO-LaB Project which aims at enhancing effective and efficient management of MWW in the Western Indian Ocean region partly through the internalization and domestication of Guidelines on MWW Management as developed by the GPA. To this end, the Project has established a Regional MWW Taskforce to lead the implementation of activities in the WIO region. One of the goals of the MWW Taskforce is to facilitate the development of a Regional Annex to the Global MWW Guidelines, targeted specifically for application in the WIO region.
To this effect, a proper assessment of existing wastewater management practices, including policy, regulatory and institutional arrangements, legal set up, financing mechanisms and technologies is required for each signatory country. Relevant data on geographical, ecological, socio-economic, demographical set-up, governance structure and technical and institutional capacity have to be undertaken. The above study will identify existing gaps, weaknesses or strengths in existing national mechanisms, which can either enhance or compromise the domestication of the Regional Guidelines. The study will also indicate whether the Regional Guidelines are readily applicable to the country’s specificities.
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This study has been undertaken so as to fulfill the above task as per the Terms of Reference described in the Guidelines for national level review of the GPA Guidelines and inventory of the status of MWW Management in the WIO region prepared by the Regional MWW Expert.
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Country Profile
Geographical location and characteristics of the Republic of Mauritius
The Republic of Mauritius is situated in the South West Indian Ocean and consists of the main island, Mauritius, and a group of outer islands and islets. The total land area is 2, 040 km2 and the maritime EEZ covers an area of about 1.9 million km2 extending from latitude 10o S to 20o S and from longitude 55o E to 75o E.
The outer islands constitute of Rodrigues, the Cargados Carajos Archipelago (including St. Brandon and Tromelin) and Agalega.
● Mauritius Mauritius lies approximately 20.170 S and 57.330 E and is situated in the south west of the Indian Ocean. It is about 2,000 km off the eastern coast of Africa and about 855 kilometers east of Madagascar. The island of Mauritius is of volcanic origin, with an area of 1, 864 km2. The land rises from the coastal plains to a central plateau where it reaches a height of 670 meters. The island has a coastline of 322 km and 200 km of coral reef enclosing a lagoon area of 243 km2 Reefs are absent opposite river mouths, estuaries and also from two areas, one strip of about 10 km in the West coast and another stretch of 15.5 km in the South coast. Mauritius is geologically and hydrogeologically very heterogeneous, consisting of basaltic rocks of volcanic origin. The complex nature of its formation, through various volcanic eruptions, has given rise to basalt of various densities, from impermeable compact basalt to highly porous basalt.
There are five main aquifers in Mauritius which are mostly porous, with secondary fractured aquifers. The texture and type of geological formation from the different volcanic activities determine the natural infiltration rates, the contribution of rainfall recharge to aquifers and also the amount of runoff. The estimated runoff from the rainfall is about 60%, evapotranspiration is about 30% and ground water recharge is about 10%. There are 25 major rivers and 21 minor ones in Mauritius. Most of the rivers spring from the Central Plateau and flow radially to the sea. Catchment areas vary from 3 to 166 km2, with most of the rivers being perennial. Water flow in streams and rivers may vary from a few liters per second to more than 500 m3/s, during heavy rains and cyclones. Surface water and ground water interact, although ground water and surface water catchment boundaries do not necessarily coincide. Groundwater plays a major role in sustaining flow in the rivers particularly in the dry season.
The Island of Mauritius covers 1864 km2 of land of which 840 km2 was estimated to be under agriculture in 2004. Of this area, about 750 km2 was under sugar cane. The area covered by forests and scrubs was estimated at 570 km2 and the built development including roads and utilities was estimated at about 430 km2. Housing has grown in most settlements including those in rural areas, with a trend towards further increasing urbanization in and around the capital, Port Louis and the adjacent Plaines Wilhems urban conurbation. The coastal zone in Mauritius is defined in the Environment Protection Act 2002 as any area situated within 1 km from the high water mark, extending either side into the sea or inland. For the past 15 years, there has been a drastic decrease in the area under vegetation and an increase in
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FINAL REPORT UNEP-GEF WIO-LaB PROJECT NATIONAL REPORT ON STATUS OF MUNICIPAL WASTEWATER MANAGEMENT IN MAURITIUS the number of hotels, public beaches and, more recently, integrated resort schemes due to a boosting tourism industry.
Climate Mauritius enjoys a sub-tropical climate and experiences two seasons, summer and winter. Summer occurs between the months of November to April, and winter between the months of May to October. Maximum temperatures of 31 oC are experienced along the northern and western coasts in December and January. A minimum temperature of about 14 oC is recorded on the Central Plateau in July and August. The mean annual rainfall is about 2, 100 mm. The West has the least rainfall with a mean of 1, 050 mm while the Central Plateau has the highest rainfall with a mean of 3, 340 mm. The Central Plateau is usually well watered throughout the year with 2, 100 mm in summer and 1, 200 mm in winter.
Population As at 1st July 2007 the resident population of Mauritius was estimated at 1, 223, 091 and the population has grown at an annual rate of 1.1 % during the last ten years. 40% of the population is concentrated in 5 urban centers, a further 16.4 % is concentrated in 15 major villages and the rest is scattered in villages all over the island.
Political Profile The Republic of Mauritius accessed independence from being a British Colony since 12 March 1968 and became a Republic on 12 March 1992. It enjoys a democratic regime and has a Cabinet Government. General Elections are held every five years and the National Assembly comprises of 70 elected members. The Prime Minister is the head of the Government while the President of the Republic is the head of the State. Mauritius has a multiparty democracy based on the British parliamentary system. The legal system is a composite of English laws and the French Code Napoleon. The highest Court of Appeal is the British Privy Council. Mauritius enjoys a high level of political stability that makes it attractive for investors.
Economic Profile The Republic of Mauritius has one of the strongest economies in Africa, with a GDP of $6.8 billion in 2007 and per capita GDP close to $5, 400. Mauritius has developed from a low-income, agricultural economy based mainly on sugar production to a middle-income, diversified economy with growing industrial, financial and tourism sectors. According to a study undertaken by the newspaper “ Les Afriques”, Mauritius presently rates third among the most performing economies in Africa, behind South Africa and Tunisia. Mauritius has also recently been elected as the most well governed country in Africa. While Mauritius relies heavily on exports of sugar, the textile and tourism sectors, as well as services like Freeport, offshore business constitute other pillars of the economy. The offshore sector is playing an increasingly important role in the financial services and is emerging as a growth vehicle for the economy. The Mauritius Freeport, the customs duty-free zone in the port and airport, aims at transforming Mauritius into a major regional distribution, transshipment, and marketing centre. Government is giving high priority to the development of the Information and Communication Technologies (ICT) sector with the aim of transforming Mauritius into a cyber island. The Business Parks of Mauritius of Mauritius has been set up to lead the development, construction and management of major business and IT parks in Mauritius. The seafood industry is being exploited and will most probably become the sixth pillar of the economy.
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Over the last five years, the country has registered an average real growth rate of 5.1 % with single digit inflation on average. However, the average unemployment rate has been of the order of 9.6%.
● Rodrigues Rodrigues is an island district of the State of Mauritius and lies approximately at latitude 19o 42’S and longitude 63o 24’ E at about 720 km to the North East of Mauritius. The island is roughly elliptical in shape with dimensions of about 19 km long by 8.5 km wide. It covers an area of 104 km2 and is the smallest and oldest island of the Mascarene Archipelago. Rodrigues is a volcanic island formed by a series of volcanic eruptions. It has a mountainous topography, with a narrow central ridge reaching 398 m. More than 60% of the land has slopes exceeding 20% and this favors surface run-off rather than infiltration. The soil is generally very clayey, with low percolation rates. The population of Rodrigues is around 37, 000 and the Port Mathurin, the only port area, is the principal urban development where most of the public, commercial and administrative activities are located. It has a population of about 8, 000 people. Although Rodrigues is under the control of the Central Government of Mauritius, it has some degree of autonomy as it possess its own Regional Assembly which was established in 2002, the Rodrigues Regional Assembly, whereby local planning and management of the island’s economy can be decided. The economy of Rodrigues is mostly based on subsistence agriculture and fishing, livestock breeding and small scale local handcrafts. There are also a few hotel developments.
● Agalega Agalega consists of an atoll of two islands, North Island and South Island of a total land area 26 km2 situated at about 1000 km to the north of Mauritius around latitude 10o 4’ S and longitude 56o 7’ East. It is surrounded by a coral reef and the two islands are linked by 1.3 km shallow bank. The land is sandy and highly porous. The islands are relatively flat and are, on average, not more than 3m above sea level, while maximum height above sea level is of the order of 6m. The water table is encountered generally at a depth of about 1.2m below ground level. Precipitation is very high. The population of Agalega is about 300 persons living in 3 villages:
North Island: Village Vingt Cinq – About 40 houses Village La Fourche – 10 houses South Island : Village St. Rita – 25 houses
Cattle, pig, poultry and goat rearing are practiced in a small scale in order to feed the population. Main activities consist of oil manufacture from coconuts, fishing and agriculture for vegetable production.
●St. Brandon and Tromelin St. Brandon (also called The Cargados Carajos islands) is an archipelago consisting of a number of sand-banks, shoals and 28 islets situated at about 450 km to the north north east of Mauritius, at latitude 15o 23’ S and longitude 59o 27’ E. Tromelin is a small island of 1 km2. Both St. Brandon and Tromelin are fishing banks and the human population is small, consisting mainly of fishermen.
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Chapter 1 – National Level Review of the GPA Guidelines
1.0 – Introduction
In this Chapter, the application of the UNEP/GPA Guidelines, key principles and checklist on MWW management, and the extent to which they have already been established or can be established in Mauritius are discussed, with specific reference to the following four items:
-Enabling policy environment for sustainable wastewater management - Institutional Arrangements and Social Participation -Planning Sustainable and Cost-Effective Technologies -Financial Mechanisms for Wastewater Management
1.1 - Enabling policy environment for sustainable wastewater management
The Mauritian population may be considered to have access to sanitation. 98% of households in Mauritius make use of cistern – flush toilets, mostly located within the main dwelling unit. Only 2% of the populations make use of pit latrines and this small percentage normally concerns people squatting state land where there is no provision for piped potable water supply. 25% of all households are connected to a public sewerage systems discharging wastewater to centralized wastewater treatment plants where treated effluents meet prescribed standards for the relevant modes of disposal. 73% of the populations make use of on-site disposal systems consisting of either cesspits or septic tanks followed by absorption systems. The National Sewerage Programme gives an important contribution to access to adequate sanitation for the poor by implementing or rehabilitating sewerage infrastructure on low cost housing estates. Since recently, Government is granting sewerage connection free of charge to residential households. The aim of the National Sewerage Programme is to connect 50% and 80% of the population to the public sewerage network by the years 2015 and 2030 respectively.
The small size of Mauritius justifies the presence of a central organization with a clear mandate as responsible for the wastewater sector. Thus the Wastewater Management Authority has been established as a parastatal organization responsible for extending the sewerage network, for the operation and maintenance of sewerage infrastructure and for overall wastewater pollution control.
Other stakeholders such as public institutions, international funding agencies, the industrial sector and the media are actively involved in the wastewater sector.
Financing mechanisms consist mainly of project management fees payable by the parent ministry and by the raising of wastewater tax, which is normally fixed by Government. The sector is presently financially sustainable. Following the Sewerage Master Plan of 1994, Government came up with the National Sewerage Programme whereby priority capital sewerage projects, representing major investments of MUR 13 billion ( USD 520 million), were identified so as to halt and reverse the pollution trend inherent to the existing domestic and industrial wastewater disposal methods.
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1.2 – Institutional Arrangements and Social Participation
The first Sewerage Masterplan was commissioned in 1994 so as to elaborate an orderly guide over a period of 20 years for addressing the technical, institutional and financial issues of the wastewater sector. An Institutional Study was commissioned in 1997 for a comprehensive reform of the sewerage and sanitation sector policy. The WMA has been strengthened into an autonomous agency with the necessary institutional and legal framework. It interfaces with other public institutions and stakeholders in the water sector and wastewater sub-sector, though the level of collaboration may require some fine tuning due to overlapping responsibilities. The administrative management of the environment at national level lies with the Ministry of Environment which is responsible for formulating and implementing policies for the protection of the environment. It also acts as a “watchdog” to ensure that the Enforcing Agencies, within their sphere of responsibility, supervise the enforcement of national environmental standards and conduct regular monitoring to ensure compliance with environmental laws. The Ministry of Public Utilities, through the WMA, enforces the environmental standards for discharge of all wastewaters.
Due to constant dialogue and collaboration with the industrial sector, the passing of the Wastewater (Standards for discharge of Industrial Effluents into a sewer network) Regulations 2004 has been a success. Private Sector Participation has been encouraged by way of service contracts for operation and maintenance of sewer networks and recruitment of private consulting engineering and contracting firms for implementation of wastewater projects. Public relations campaigns on sewerage projects, creation of a Public Relations and Customer Care Unit, regular radio programmes with live interaction with customers, meeting with representatives of the civil society and setting up of a Hot-line to register and handle complaints are among the initiatives adopted to encourage social participation in the wastewater sector.
1.3 – Planning Sustainable and Cost-Effective Technologies
Mauritius is a small country where the majority (about 57 %) of the population is concentrated in 5 major urban centers (population density 3000 – 5000 cap/km2) and 15 large villages (population density 800 – 1500 cap/km2). The remaining 43 % of the population is found in villages scattered all over the island. Under the first National Sewerage Masterplan conventional waterborne sewerage facilities have been provided to the most densely urban parts of the island and main treatment systems adopted have been activated sludge systems with biological nutrient removal and re-use of treated effluent in irrigation. These systems have quite high capital and O & M costs. The same effluent quality could be achieved through low-cost treatment technologies such as pond systems or constructed wetland. However these are highly land intensive. Land has a high value in Mauritius and land development patterns indicate that zones around the periphery of urban centers are being developed at an increasing pace. Thus natural treatment systems could restrict the development of such zones because of potential odor, mosquito and unaesthetic problems.
The presently sewered urban areas in Mauritius also contain a number of polluting industries whose effluents might inhibit the action of microorganisms and ecosystems at work in natural treatment systems.
The priorities of the coming second Sewerage Masterplan would be to provide sewerage facilities to the fifteen major villages in Mauritius. These major villages are densely populated, with populations ranging from 10, 000 to 22, 000 inhabitants, and are located throughout the districts.
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Due to high population density, the need for a centralized sewerage system is justified. However major villages, by virtue of their geographical distributions, will require separate treatment systems. As discussed above, pond systems are not appropriate due to their large land requirements, need to provide impermeable lining to bottom surfaces at high costs, odor and mosquito nuisances and unaesthetic look. Constructed wetland systems cannot be applied to populations of such magnitude.
On the other hand, activated sludge WWTPs have high capital and O & M costs, require close monitoring and produce high amounts of biological sludge which need to be further treated, transported and disposed of.
Extended aeration systems could therefore be explored as suitable wastewater treatment technology for the major villages. The system is simple, robust and not highly mechanized. It does not require close supervision and monitoring, it produces effluent of very high quality, with biological nutrient removal. The resulting effluent easily meets the required norms for irrigation and the wastewater management scheme can incorporate re-use in irrigation. Well stabilized sludge is produced in smaller quantities, thus the cost of sludge treatment, dewatering, transportation and disposal is avoided. The stabilized sludge can readily be used in agriculture.
Other smaller villages scattered all over the island, with lower population densities, not located along the coast, with no high water table and with soils of reasonably good permeability do not pose significant risks for ground water or lagoonal water pollution. Proper individual on-site disposal systems such as conventional individual septic tanks followed by absorption pits would be appropriate for such villages. Rural regions with problems of high water table or impermeable soils can be provided with small bore diameter sewers and the primary effluent from septic tank be treated using sand filtration. In the case of smaller communities, additional nutrient removal can be applied by constructed wetlands, while for larger communities, polishing can be applied by the use of trickling filters or RBC, before final disposal into water bodies or water courses. Alternatively, the treated effluent may be disposed of by infiltration in the soil if a suitable site can be found nearby.
Finally, coastal villages are normally too small and set too widely apart to seriously consider providing a central sewerage system. Moreover these coastal regions tend to be flat and may not favor gravitational flow.
An appropriate individual on-site disposal system which can also provide some nutrient removal should therefore be considered so as to limit risks of eutrophication caused by nutrients leaching into the lagoon.
One possible system that can be recommended in such circumstances is an individual septic tank followed by sand filter and/or individual constructed wetland.
All the possible scenarios that can be encountered in the Mauritian context have been discussed in this section.
1.4 – Financial Mechanisms for Wastewater Management
The specificity of Mauritius, in terms of size, demography and socio-economic aspects, dictate the financial mechanisms applicable. Globally, the main sources of revenue for the wastewater
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Domestic tariff has been increased from Rs 6.00 per m3 to Rs 6.90 (USD 0.23) per m3, since 1st August 2003 and all commercial / industrial tariffs have been fixed at Rs 15.50 (USD 0.52) per m3 as from January 2004. The aim of implementing the tariff increases is to improve the financial sustainability of the WMA in terms of recovery of O& M costs and depreciation costs. A tariff study has been commissioned. The objective of the study is to provide the necessary recommendations for ensuring the financial sustainability of the WMA, taking into account the capital sewerage projects recently implemented or in the course of implementation.
Tariff collection ratio for both domestic and non-domestic customers is of the order of 85%.
The Wastewater (Standards for Discharge of Industrial Effluents into a Wastewater System) Regulations 2004 contains the necessary provisos for surcharge tax in case of effluent quality exceeding prescribed limits (Polluter Pays Principle).
A study was undertaken in 2003 for the reform of the water and sanitation sectors with a view to improving the overall performance of the utilities through the enlistment of Private Sector Participation.
1.5 – Specificities of Mauritius that can affect applicability of the GPA Guidelines
The relative applicability of the GPA Guidelines, and more specifically the keys for local and national action, for municipal wastewater depends on the specificity of different countries. The main relevant characteristics are:
Geographical and demographical situation
The situation in Island States like Mauritius differs considerably from continental countries in terms of relative geographical sizes, density and scatter of population and absence of slums. Towns, populations and distances are relatively smaller.
Socio-economic situation
Mauritius has one of the strongest economies in Africa. It is classified as a middle-income country and ranks, on the basis of the recent Human Development Index for 173 countries, 67th globally, 40th among developing countries, and third in Africa. The political stability and high rate of literacy makes it very attractive for investors and funding agencies. The relatively high standard of living, consciousness to protect the health of the population as well our fragile ecosystem rates high on the Government’s agenda.
Institutional Set-up
Mauritius has a multiparty democracy modeled on the British parliamentary system. There are a number of ministries and parastatal organizations involved in water resources management. Coordination exists between these but needs to be reinforced. Relatively good legislation exists to ensure proper water resources management but there is some overlapping of responsibilities.
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Socio-cultural situation
The water sector in Mauritius has been developed to such an extent that almost 99 % of the population has access to safe piped drinking water. Sewage borne diseases such as cholera, typhoid, poliomyethilis and yellow fever have been eradicated. Gender issues such as women having to walk long distances to fetch water, and security aspects while making use of public toilets do not exist. Provision of piped water in the home favors the use of cistern-flush toilets, which are used by almost 98 % of the population. There is thus little scope for dry sanitation technologies such as pit latrines, ventilated pit latrines or composting toilets.
Existing Framework for Environmental Protection
The Environmental Protection Act 2002 provides sound legal tools for effective protection of the environment. In particular, the Environmental Impact Assessment (EIA) process provides for a strict mechanism whereby the proposed wastewater management scheme for any infrastructural or industrial development can be scrutinized before formal approval is granted. The process also includes public consultation and interaction and thus encourages stakeholder involvement and transparence. Highly sophisticated public laboratories exist for monitoring of water pollution but enforcement stills needs to be improved. A synergy of laboratories is desirable to ensure proper allocation of resources and avoid duplication of work.
Existing Framework for Wastewater Management
The WMA has been strengthened into an autonomous agency with the necessary institutional and legal framework. It interfaces with other public institutions and stakeholders in the water sector and wastewater sub-sector, though the level of collaboration may require some fine tuning due to overlapping responsibilities. Construction of new sewerage infrastructure according to an established Masterplan, operation and maintenance of existing public sewerage infrastructure and pollution control of domestic and industrial discharges to existing infrastructure have been well developed. However, on-site sanitation needs to be reinforced, both legally and technically. Though Guidelines exist for conventional septic tank followed by absorption systems, a mechanism needs to be put in place for enforcement, control of construction practices and monitoring of proper maintenance.
1.6 – Applicability of the ten keys for local and national actions on municipal wastewater
1.6.1 – Secure political commitment and domestic financial resources In Mauritius, political commitment to develop the wastewater sector is very strong. This is clearly seen through the large share of the National Budget allocated each year (15% for Financial Year 2007-2008) to the wastewater sector as well as the commitment of the international funding agencies in Mauritius. An existing Sewerage Division which was just a small unit responsible for the O & M of existing sewerage infrastructure has been developed institutionally and strengthened legally into a powerful parastatal organization responsible for the whole wastewater sector. This organization, the WMA, operates under a close follow up of the Ministry of Public Utilities. Political commitment is a strong ally in Mauritius for domestication of the GPA Guidelines.
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1.6.2 – Creating an enabling environment at national AND local levels Mauritius is a small country with a small population, the majority of which is concentrated in five major towns and 15 large villages. Remote parts of the island can easily be accessed within less than one hour. It is therefore more sustainable for Mauritius to possess a central organization in charge of the wastewater sector. It is not appropriate to delegate O & M of wastewater infrastructure to municipalities since towns are relatively much smaller than in continental countries and are found close to one another. The relatively smaller population requires that all wastewater tax be allocated to the WMA so as to ensure its financial sustainability. However it would be more appropriate for the enforcement aspects of on-site disposal to be delegated to local authorities since the institutional set-up of the WMA does not allow it to assume such a role. Delegation of responsibility to local authorities can therefore only be envisaged for on-site disposal while the WMA remains the organization for wastewater management responsible for strategic planning, policy and regulatory aspects of the sector.
1.6.3 – Do not restrict water supply and sanitation to taps and toilets Water resources management, potable water supply, sanitation and water pollution control in Mauritius goes well beyond taps and toilets. Necessary mechanisms exist in terms of EIA Process, Building Permits, Guidelines for Application for Design of Wastewater Treatment Plants and Guidelines for on-site disposal systems so as to ensure that wastewater produced from proposed infrastructural and industrial development are collected, transported, treated and disposed of according to international standards. Enforcing Agencies, equipped with the required legal set-up and laboratories ensure that the quality of treated effluents from different activities and the quality of water bodies are within local standards which have been developed as per international norms. Co-ordination is ensured at the highest level via the National Environment Commission which is chaired by the Prime Minister and attended by Ministers and Permanent Secretaries. Other co- ordination committees between different relevant Ministries and organizations include the Environment Co-ordination Committee, which is chaired by the Permanent Secretary of the Ministry of Environment and high level officers from other Ministries and organizations, as well as the Environment Liaison Officer Committee. Other Steering Committees or Ad-hoc Committees are called whenever there are environmental hotspots.
1.6.4 – Develop integrated urban water supply and sanitation management systems also addressing environmental impacts As discussed in Section 1.6.3 above, water pollution control is well addressed along with water supply and sanitation. A study was undertaken in 2003 for the reform of the water and sanitation sectors with a view to improving the overall performance of the utilities through the enlistment of Private Sector Participation. In the same context, a Utility Regulatory Authority (URA) Bill has been passed and remains to be proclaimed.
Thus environmental impacts are being fully addressed while Mauritius is well on the way to develop integrated water supply and sanitation management systems, consistent with the world’s trend of integrating water and sanitation services.
1.6.5 – Adopt a long term perspective, taking action step-by-step, starting now The First Sewerage master Plan of 1994 provided an orderly guide for a step by step approach while identifying priority projects that need to be implemented over the next twenty years. Most
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FINAL REPORT UNEP-GEF WIO-LaB PROJECT NATIONAL REPORT ON STATUS OF MUNICIPAL WASTEWATER MANAGEMENT IN MAURITIUS of these projects have been successfully implemented over the years so as to sewer the most sensitive regions of the island. The Sector Policy Letter of 1998 provided a sound strategy to be developed for the wastewater sector. Thus, necessary studies have been undertaken and the WMA has been reinforced both institutionally and legally so as to be able to fulfill its role. Necessary capacity has been built so as to implement pollution control and monitoring with the setting up of a Pollution Control and Monitoring Department, comprising a Wastewater Laboratory. Necessary Regulations have been passed so as to licence industries on the Polluter Pays Principle. Necessary tariff studies have been undertaken and tariff is being implemented in a step-wise manner, aiming towards financial sustainability.
The objectives under the First Sewerage Masterplan have almost been achieved. Thus, the Terms of Reference to recruit a Consultant so as to undertake a Second Masterplan are being prepared. A Tariff study as well as an Institutional Study have recently been undertaken so as to define the needs of the WMA in the light of changing environment. Adopting a long term perspective, while taking action step-by-step, is an in-built approach in developing the wastewater sector in Mauritius.
1.6.6 – Use well-defined time-lines and time-bound targets and indicators Properly chosen and measurable performance indicators are indispensable to assess that the ultimate goals of any enterprise are being achieved. A number of key performance indicators have been identified to measure the performance of the WMA. These include:
• Annual Capital Expenditure under NSP expressed as a percentage of approved budget • Annual Increase in Domestic and Non-Domestic House Connections with respect to set target • WMA financial sustainability expressed as Tariff Revenue Collection Ratio • No. of Industrial Discharge Permits issued annually to industries • Improvement of access of poor to sanitation (No.of inhabitants concerned under relevant projects) • Implementation Capacity of WMA expressed by award of 2 major contracts annually and annual number of monitoring inspections among industries
1.6.7 – Select appropriate technology for efficient and cost-effective use of water resources and consider ecological sanitation alternatives The specificity of Mauritius in terms of size, demographical distribution, large water coverage and socio-economic aspects restricts sanitation to centralized water borne sewerage systems and on-site sanitation consisting of septic tank followed by absorption system. There is little scope for ecological sanitation from a socio-cultural and land use standpoint. However all feasibility studies undertaken for setting up of municipal wastewater treatment plants assess the possibilities of re-use of treated wastewater in agriculture. In the case of one major wastewater treatment plants, treated effluent is re-used in irrigation of sugar cane fields, negotiations are under way with a potential buyer for another wastewater treatment plant. For two other major wastewater treatment plants the studies showed that re-use in irrigation would not be cost-effective in the immediate future. However the plants have been designed and built in such a way that these can easily be upgrade to treat to tertiary level when conditions would be favorable for re-use in irrigation. In the case of one wastewater treatment plant, the secondary sludge is anaerobically digested and the biogas produced is used for power generation to cater up to 30% of the plant’s electricity requirements.
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1.6.8 – Apply demand – driven approaches The restriction of applicable technologies to water borne sewerage and on-site disposal systems, as well as the need for a central organization for wastewater management, makes demand-driven approaches not applicable in Mauritius.
1.6.9 – Involve all stakeholders from the beginning and ensure transparence in management and decision-making process Most stakeholders are involved on wastewater projects. These include the public, media, industrial sector, funding agencies and other governmental institutions. An aggressive public awareness campaign linked with values-based water education is necessary for a better appreciation and cooperation of all stakeholders.
1.6.10 – Ensure financial stability and sustainability Financial resources are made available to the WMA through a Project Management Fee for Project Management services and the raising of sewerage tax for recovering O & M costs and depreciation costs. A tariff structure has been established and raises in tariff have been implemented in a timely manner. A tariff study has recently been commissioned with the objective of providing the necessary recommendations for ensuring the financial sustainability of the wastewater sector, taking into account the projects that are being executed under the NSP. Till now, highly populated urban areas have been provided with water borne sewerage followed by end of pipe conventional wastewater treatment technologies. While this approach is fully justified for such drainage areas, with industrial zones, such technologies have high capital as well as O & M costs. The application of such technologies to other regions would significantly increase the financial needs of the WMA. High tariff may then result in a low collection ratio, thereby adversely affecting the overall financial stability and sustainability of the sector.
1.7 – Conclusion
Generally, the GPA Guidelines can be applied in Mauritius. Most of these are already in-built in the environmental policies, environmental laws, wastewater sector policy, National Sewerage Masterplan, water policy, and direction towards integrated water resources management.
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2.1 – Assessment of existing policy framework
Introduction - Wastewater Sector History
The first report relating to sanitation in Mauritius appears to be that of one Mr. Osbert Chadwick dated May 1892. In his report, Mr., Chadwick had proposed that the disposal of sullage, which was then discharged into street gutters, could be more safely and satisfactorily be collected through a system of underground conduits. Mr. Chadwick also advised that the system should be of adequate capacity to receive at a later stage the products of human defaecation, when the people would be prepared to change their buckets for water closets.
The system proposed by Mr. Chadwick was constructed and by the beginning of the 20th century the larger part of the town of Port Louis by the water front and to the south east of the harbor was sewered. The wastewater was collected at two points, in deep wells, the main one being 20 feet below sea level. Sewage passed from the subsidiary well to the main well through true siphons. The crude sewage was finally disposed of into the sea near Fort Victoria by pumping through a 12 inch cast iron pipeline.
The existing Port Louis Sewerage System is basically that proposed by Mr. Chadwick and this was recommended, in 1922, by James Mansergh and Sons, Consulting Engineers as being the natural method dictated by the site conditions.
Since then, and until the end of the mid 20th century, development was very slow and major improvements were made to the Port Louis system in the late 60’s and early 70’s.
The second major area of Mauritius in which public sewerage facilities have been developed is the urban area of Plaines Wilhems. A main purpose of this sewerage scheme was to eliminate the pail system of sewage collection in areas where hydro-geological ground conditions did not allow soakaways to operate satisfactorily, principally Curepipe. In 1959 works started on Stage 1 of this Scheme, which involved construction of a trunk sewer from Curepipe through Rose Hill to a treatment works consisting of oxidation ponds at St. Martin, leading to a sea outfall. The Scheme also involved construction of reticulation of areas in Curepipe and Rose-Hill/Beau Bassin.
The Sewerage Division, a unit under the Ministry of Works, was responsible for the O & M of these systems as regulated by the Port Louis Sewerage Act and the Plaines Wilhems Sewerage Ordinance of 1904 and 1954 respectively. The responsibility for sewerage lay with the Ministry of Works till 1991 until it was transferred to the Ministry of Energy.
The responsibility for the wastewater sector has come under the jurisdiction of several Ministries, as follows:
Up to 1995 Ministry of Energy, Water Resources and Postal Services
1995 – 1996 Ministry of Public Infrastructure
1996 – 1997 Ministry of Public Utilities
1997 – 1998 Ministry of Environment & NDU
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2.1.1 – National and local policy governing the sector
2.1.1.1 - The National Environmental Policy
Mauritius experienced rapid economic growth in the eightees, with the setting up of major textile industries and high class coastal tourist hotels, thus deviating from a purely monocrop economy, based on sugar cane. In response to concerns that environmental degradation was accelerating in the context of the rapidly expanding industrial sector, the Government of Mauritius (GoM) took steps to review existing institutional and legislative arrangements for the protection of the environment. Subsequently, in 1988, the GoM requested assistance from the World Bank for the preparation of a National Environmental Action Plan covering all key sectors and the country as a whole. The NEAP 1 was endorsed by the Government in 1990.
The output of this first National Environmental Action Plan (NEAP 1) and Environment Investment Program (EIP 1) included the identification of the major environmental problems in Mauritius and proposals for short, medium and long term measures to address this. The recommendations were packaged into 32 specific projects that constituted EIP 1 and covered six main areas, classified A to F, namely: A-Institutional Strengthening, B-Land Management and Tourism, C-Industry, Sewerage and Solid Waste, D-Agriculture, E-Marine Conservation and F- Terrestrial Conservation.
Effective water resources management was identified by the NEAP 1 as the most urgent action to be taken for the next 50 years for water conservation. At the same time attention focused on water quality. It was necessary to protect our ground water from discharge of polluting effluents. associated with textile factories, and from domestic wastewater pollution especially around the more densely populated urban areas. The NEAP 1 also identified other issues relevant to the wastewater sector such as:
● Existing wastewater infrastructure not handling effluent in an environmentally sound manner. ● Lack of maintenance due to financial constraints hampering infrastructure performance. ● An institutional framework inadapted to the needs of a growing organization ● Inadequate tariff structure.
Projects under Category C relevant to wastewater management are listed below and their Status as at preparation of the Second Environmental Action Plan of 1999 is shown below:
Projects Status / Remarks C1-Setting up of Environmental Laboratories and Completed. Labs require further strengthening Training Programmes for laboratory personnel
C2-Provision of Infrastructure for Proposed Industrial Project stopped at Phase 1 based on feqsibility study Park for Polluting Industries conclusion that project not economically sustainable
C3-Baie du Tombeau Urgent Sewerage Project Studies completed, implementation underway
C4-Preparation and Implementation of a National Sewerage Master Plan completed; urgent works 95% complete; Master Plan and implementation of Urgent Works tenders being launched for National Sewerage Plan projects
C9-Characterisation of Sugar Industry Wastes Completed standards for sugar industry prepared
*Source: National Environmental Strategies for the Republic of Mauritius, July 1999
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The major achievements attained in the wastewater sector are a result of the recommendations of the NEAP 1. These include the setting up of a Wastewater Laboratory and the undertaking of the National Sewerage Master Plan of 1994 which led to the implementation of a National Sewerage Programme, and the establishment of an organization, the WMA, equipped with the required institutional, legal and technical resources.
In fact, NEAP 1 is associated with substantial achievements and the projects were largely successful in establishing a policy, legislative and institutional framework to manage the environment.
2.1.1.2 - The Second National Environmental Action Plan (NEAP2) and Review of the NES2
As economic growth (around 5 to 6% per year in the 1990s) continued, Mauritius shifted from a low income country to a middle income country, aligning itself with Greece and Portugal, with per capita incomes equivalent to around $ 13, 000 per year in 1996. Agriculture was declining rapidly while textile was accounting for nearly all industrial exports. Tourism and financial services were becoming more important. Government policy was to encourage further economic restructuring, to maintain real growth at between 5% and 7% per year. Such changes were expected to be associated with a greater demand for resources of different kinds, greater consumption of products and increased volume of wastes. The GoM thus undertook the Second National Environment Action Plan (NEAP 2) which represented an environmental strategy and action plan for the period between 1999 and 2010. The NEAP 2 consists of three parts:
Part 1 is an Environmental Diagnosis that assessed the pressures on the environment in Mauritius and the impacts of these pressures upon critical environmental resources.
Part 2 developed the National Environmental Strategy for Mauritius summarizing the major causes of environmental degradation and suggesting policy changes and environmental improvement programmes.
Part 3 outlined a programme for the first 5 years of NEAP 2 implementation.
The National Environment Strategy for the period 1999 to 2010 can be summarized as follows:
“To follow the principles of sustainable development by providing environmental services, encouraging responsible environmental practices and enforcing appropriate environmental standards in order to safeguard the health and welfare, conserve the heritage, and enhance the quality of life of all the people of Mauritius.”
The environmental diagnosis expressed concern for the following in the wastewater sector:
●Violation of standards and discharge of dyestuff to surface water by textile industries
●Pollution of ground and coastal waters by improper wastewater disposal practices.
●No adequate disposal route for sludge to be generated from major wastewater treatment plants, including strict standards on industrial effluent to sewer in case of sanitary landfill disposal option.
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Measurement of wastewater and water quality was rated as insufficient and existing policy was rated as weak.
In a global manner, some important causes of policy and institutional failure needed to be addressed. This included:
●Insufficient awareness and understanding amongst decision makers causing low priority of the environment compared to economic growth sectors. ●The drafting of policies / laws themselves, in that they are fragmented and may not have taken due account of the technical and administrative implications of enforcement. ●insufficient staff numbers and shortage of qualified and experienced staff among the agencies with responsibility for policy formulation and enforcement. ●A lack of awareness among the general population leading to a reluctance to accept personal responsibility for their own environment, and ●lack of support to industry to encourage their compliance with regulations and their adoption of cleaner production technologies.
The National Environmental Strategy (NES2) for Mauritius focused on the following areas:
●Use of clean technologies ●Efficient use of resources ●Regeneration of renewable resources ●Miantenance of ambient environmental quality to international health standards ●Public awareness of environmental risks and how to manage them ●Control of any toxic substance release to the environment ●Identification and management of major environmental hazards
The Second Environmental Investment Programme (EIP 2) thus consists of 72 projects classified under 19 different programmes under the main headings of:
A - Overall Management and Coordination
A1- Strengthening the Department of Environment A2 – Environmental Quality A3 – Environmental Information and Awareness
B - Resource Management
B1 – Land Management B2 – Water Resources Management B3 – Air Quality Management B4 – Terrestrial Biodiversity B5 – Integrated Coastal Zone Management
C - Sector Management
C1 – Solid Waste Management C2 – Industrial Management C3 – Tourism Management C4 – Agricultural Management
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C5 – Transport Management
D - Programmes for Rodrigues
D1 – Rodrigues Environmental Management Programme D2 - Rodrigues Land Management Programme D3 - Rodrigues Water Resources Management Programme D4 - Rodrigues Integrated Coastal Zone Management Programme D5 - Rodrigues Tourism Management Programme D6 - Rodrigues Solid Waste Management Programme
Presently, only 9 projects have been completed, works are on-going for 37 projects while actions have been initiated in the case of 11 projects and 13 projects are yet to start.
An international Consultant has recently been recruited by the Ministry of Environment for updating of the NES and review of the implementation of the NEAP 2. The purpose of this project is: (a) to update the NES2 in the light of new economic and environmental issues and taking into consideration recent commitments taken at regional and international levels in the field of environment (such as the Johannesburg Plan of Implementation and the Multilateral Environmental Agreement on chemicals, climate change, biodiversity and hazardous wastes. (b) to review the action plan and implementation phase of NEAP2 and propose a new implementation framework taking into consideration recent environmental developments. The wastewater sector has been involved in the EIP 2 projects in the light of setting up of an environmental information system and the Wastewater Laboratory Capacity Building and Accreditation under sub-heading A3.
2.1.1.3 - The National Sewerage Master Plan
In line with the recommendations of the NEAP 1 and with a view to address the technical, institutional and financial issues of the wastewater sector, the GoM undertook the National Sewerage Masterplan Study so as to elaborate an orderly guide for implementation over a period of 20 years. The Sewerage Masterplan which was completed in 1994 provided a global framework for long term commitment for sound financial and operational management policy to maintain water quality goals.
The Masterplan was prepared to address simultaneously the legal, institutional and financial aspects of the wastewater sector.
In the framework of the Sewerage Masterplan, a National Sewerage Programme (NSP) comprising priority projects to be implemented over a decade was prepared. The key objectives of the NSP were to:
● increase sewerage coverage from the then 18 % to 50% of the population by the year 2010 by the connection of 106, 800 households.
● provide adequate wastewater treatment with the construction of new wastewater treatment plants (WWTP) and upgrading existing ones.
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The existing institutional structure had to be reinforced for smooth implementation of the NSP, therefore an Institutional Study was commissioned in 1997.
2.1.1.4 - Sector Policy Issues
The Institutional Study looked into details at all the aspects of wastewater management as a basis for a comprehensive reform of the sewerage and sanitation sector policy. The study, completed in October 1997, identified several issues – technical, institutional, organizational, legislative and financial – that required urgent attention from Government. These included:
● Inadequacy of sewerage infrastructure
(a) Sewerage coverage was only 18 % of the population, while piped water supply was more than 95%. Thus a great majority of the population relied on on-site wastewater disposal facilities. This constituted potential pollution threats to ground water resources. No proper industrial effluent monitoring and control were exercised in major industries which entertained little or no pre- treatment of their process wastewaters. Wastewater disposal facilities were in a deplorable state and constituted serious health hazards on many low cost housing estates. (b) The existing sewer networks which had been designed as separate systems were frequently operating as combined systems, due to illicit surface water connections and heavy infiltration. These also suffered from frequent blockages. The treatment works in Port Louis, the capital city, provided only preliminary treatment before discharging sewage through short marine outfalls.
● Environmental and health concerns
(a) The resulting effects raised awareness on the environmental and health concerns of ground water resources and lagoons by domestic wastewater, industrial effluents and agricultural chemical run-off. (b) The effluent quality limitations published under the Environmental Protection Act (EPA) of 1991 had certain deficiencies and there was a need to prepare a comprehensive set of regulations to protect the environment from wastewater pollution.
● Institutional and legislative weakness
(a) The Wastewater Authority (WWA), by virtue of the WWA Act-1991came into force in 1996, functioning as a Division of the Ministry of Public Utilities (MPU). Though this gave some autonomy to the WWA, the WWA Act did not confer any clear legal status or identity to the WWA as an autonomous entity. In addition, no adequate set of Regulations had been formulated to operationalize the Act. The limitations and deficiencies of the Act had already been underlined in the Sewerage Masterplan which proposed specific amendments and additions to 21 out of 23 Sections of the Act.
(b) The WWA had an inadequate number of senior staff at managerial level and had not been exposed to the problems likely to face in the planning, engineering, implementation and O&M of the facilities to be created. It also lacked the appropriate blend of skills required to adequately manage and operate the sector. The then prevailing salary structure and lack of attraction of wastewater services inhibited recruitment of potential candidates.
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● Need for financial sustainability
(a) Since July 1996 new wastewater charges had been promulgated. The billing system constituted of fixed monthly rate for domestic connections, which increased substantially the tariff, with commercial users being charged on net annual rental value and the industries paying according to the volume of water used. The new charge system represented significant progress towards the cost-recovery objective. Nevertheless, domestic and industrial tariffs still corresponded to less than 30 % and 50 % respectively of the wastewater treatment facilities. In addition, the system of billing was highly cumbersome and inefficient.
Although not specifically identified in the Institutional Study, Government became aware of the need to increase the rate of sewer connections so as to enhance the quality of sewerage services provided, to optimize the use of sewerage infrastructure and to have a base for cost recovery.
2.1.1.5 - Objectives of Sewerage and Sanitation Sector Policy and Strategy
GoM strategy to address the above constraints and develop the wastewater sector is embodied in its Sector Policy Letter in 1998 which is guided by the need to achieve the following objectives:
● halt and reverse the trend of wastewater pollution on the island and its coastal zone ● improve health and sanitary conditions of the population; and
● provide the technical, legal, institutional and financial framework necessary for sustainable development of the sector.
The Sector Policy Letter stated that Government’s policy for the sector will be implemented through:
• expansion of the sewerage infrastructure for environmental and public health protection • strengthening of the WWA with adequate legal status, human resources and tariff structure • integrated vision of the water supply and wastewater sectors • cost-recovery subject to affordability of service • development, monitoring and enforcement of environmental standards • stakeholder participation and consultation • opening of the sector to private sector involvement • Over the long run, the Government’s objective is to invest in developing the Mauritius Wastewater Sector into a centre of excellence in sanitation services to provide expertise to the Indian Ocean Region as a whole.
2.1.1.6 - Key Components of the Sector Policy Implementation
The sewerage and sanitation sector policy as laid out in the Sector Policy Letter of 1998 included:
(i) Rehabilitation and extension of wastewater facilities Preparation and implementation of the National Sewerage Programme in the framework of the Master Plan. The Government has mobilized extensive international cooperation for co- financing the various components of the programme.
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(ii) Institutional Strengthening Transformation of the WMA into an institution with the functions of: “Maitrise d’Ouvrage Deleguee” of the public sewerage and sanitation infrastructure and providing wastewater facilities.
(iii) Legislative Requirement Transformation of the WMA into an autonomous agency with defined legal status, to allow it to perform its role, through a new Act and subsequent Regulations under the Act.
(iv) Financial Sustainability Setting up of a cost recovery system to generate resources to finance the O&M and depreciation costs of the sewerage installations and some contribution to the debt recovery service, taking into consideration equitability and affordability for domestic customers.
(v) Linkages with other organizations Interfacing with other corporate bodies, Governmental Departments, NGO’s and industries. Dealing with industries regarding effluent standards and Regulations. Definition of a general framework for industrial pre-treatment with industries for phased introduction and compliance with pre-treatment standards and the establishment of an industrial mutual fund for water ecosystem protection. (vi) Public Awareness Launching of multi-media awareness campaign to make people aware of the goals and objectives of the WMA on implementation of the NSP to ensure extensive public co-operation. This would also help in attracting personnel to the career opportunities of the WMA.
(vii) Private Sector Participation Encouraging local entrepreneurs or Private Operators in taking service contracts for O&M of the sewer systems while keeping fully open for the medium and long term all privatization opportunities for the sector.
2.1.2 - Main achievements following Sector Policy Letter of 1998
2.1.2.1 – Legal and Institutional Framework
(i) Legal Framework The Wastewater Management Authority Act of 2000 (WMA Act) was proclaimed on the 30th August 2001, thereby giving a clear institutional set up to the WMA. The WMA has been transformed into a corporate autonomous body with defined legal status. The WMA Act details the objects, duties and powers of the WMA as the sole agency responsible for the wastewater sector in Mauritius. The WMA is administered by a Board, called the Wastewater Management Authority Board (WMA Board) consisting of:
(a) A Chairperson appointed by the Minister (b) A representative of the Ministry responsible for the subject of finance (c) A representative of the Ministry responsible for the subject of economic development (d) A representative of the Ministry responsible for the subject of wastewater (e) A representative of the Ministry responsible for the subject of water resources (f) A representative of the Ministry responsible for the subject of health
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(g) A representative of the University of Technology, Mauritius (h) One member with wide experience in environmental matters, appointed by the Minister (i) 2 members having wide experience in consumer interests, appointed by the Minister.
The WMA is headed by a General Manager who is responsible for the execution of the policy of the Board and for the control and management of the day to day business of the Authority.
(ii) Institutional Framework The WMA operates under two legal instruments/contracts between the WMA and the Ministry of Public Utilities:
(a) Convention de Maîtrise d’Ouvrage Déléguée (for the construction of new works) (b) Contrat de Délégation (for the operation and maintenance of the public wastewater system)
Under the first contract, Government has entrusted the WMA the overall responsibility of all projects under the NSP which seek to connect 50% of households to the public sewer system by the year 2015.
Under the second contract, the WMA is responsible to Government for the O&M of all assets used in the public sewerage system. All these assets remain vested with the Government.
2.1.2.2 – Implementation of the National Sewerage Programme
GoM was successful in securing funds from donor countries and funding agencies and most projects identified under the NSP have been completed. The wastewater sector is funded by international funding agencies such as The European Union, The World Bank, the African Development Bank, the Exim bank of India and China and the European Investment Bank. Due to low rate of connection in the past, Government has decided to grant connection free of charge to domestic premises so as to ensure prompt generation of revenue in the form of sewerage tax.
2.1.3 – Post Sector Policy Letter 1998 direction
The implementation of the NSP required considerable investment and the presence of a number of donors and funding agencies in the sector has meant both that there is a high level of donor co- ordination on projects and that conditionality are respected. There has also been a growing recognition that the success of individual projects is constrained by the policy, institutional and economic environment in which they are implemented. This has led to an increased interest by donors over the past few years in budgetary support and sector-wide approaches rather than funding specific projects.
The following six KPI have been set up by the EU and agreed with other Donors so as to assess and monitor the performance of the wastewater sector:
● Annual capital expenditure as a percentage of approved budget. ● Annual number of sewer house connections effected as per EU target ● Financial sustainability in terms of tariff collection ratio ● Annual number of industrial discharge permits issued (target 50 industries per year)
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● Improvement of access of the poor to sanitation in terms of rehabilitation of existing sewerage infrastructure and provision of new sewerage facilities in low-cost housing estates. ● Implementation capacity in terms of annual number of major contracts awarded and annual number of monitoring inspections among industries.
2.1.4 – Present Status of the WMA
2.1.4.1 – Capacity Building
(a) Human Resources Since it setting up, the WMA has been facing human resources problems due to a number of staff opting to stay in the Civil Service. There has also been a high turnover due to lack of attractiveness to work in this sector. The following measures have been taken to retain staff:
● Recruitment on contract
Contractual employment offers greater flexibility to Management as better packages can be offered to attract high caliber professionals, especially to manage capital projects.
● Recruitment of Trainee Engineers The WMA has constantly recruited trainee engineers – Civil, Mechanical and Electrical. Many of these engineers have joined the WMA as full-fledged engineers following their internship.
● Internal promotion Internal promotion provides added incentive to existing personnel to climb up the ladder.
● Opting out of PRB The WMA conditions of employment are governed by the Pay Research Bureau (PRB) which sets salary for Government employees and parastatal organizations However, working in the wastewater sector is comparatively more arduous and not image enhancing. The WMA Management has held consultations with all its employees and the Employee’s Union to gauge the willingness to opt out of PRB whereby terms and conditions would suit the requirements of the wastewater sector.
● Training and Development To face the challenges of the Wastewater Sector, the WMA lays much emphasis on continuous training and development of its employees.
The WMA takes full opportunity of courses provided by both international and local organizations so as to improve the skills and performance of employees. An organized training and development program is also planned under the European Union Technical Assistance Program.
● Computerization The IT Unit of the WMA became operational in June 2006, following recruitment of an IT Manager. An IT Plan has been prepared so as provide the WMA with the appropriate technical infrastructure and business applications/services that will enable it to operate more effectively and efficiently through the streamlining of business processes, better control of operations, performance monitoring and decision making.
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2.1.4.2 - National Sewerage Programme
As stated in Section 2.1.2.2 above, negotiations were successfully held with international funding agencies and funding were secured for the implementation of the priority NSP projects namely, Montagne Jacquot, Grand Baie, Baie du Tombeau, St. Martin, Plaines Wilhems Sewerage Projects and the upgrading of Infrastructure on Low Cost Housing Estates. Most of these projects have been successfully implemented.
The implementation of identified priority sewerage projects is in progress, with some revisions in the scope of works, as envisaged in the original Master Plan.
At present 40 contracts pertaining to consultancy services and works contracts are at various stage of implementation, representing an investment budget of about MUR 13.57 billion.
2.1.5 – The way forward in sector policy
2.1.5.1 - New Wastewater Sector Policy The Wastewater Sector Policy Statement 2007 – 2010 is under preparation
2.1.5.2 – Technical assistance (TA) Back Up Facility – 9th EDF
Under the 9th EDF, the following 6 main areas have been identified for the Technical Assistance Back-up Facility. Task 1: Preparation of the Terms of Reference and Request for Proposals for the updating of the National Sewerage Master Plan; Task 2: Assistance in Operation and Maintenance of Wastewater Systems; (i) Preparation of Operation and Maintenance Manual including Standard Operation Procedures, Emergency Response Protocols and Performance Evaluation Criteria; (ii) Training of WMA staff in all aspects of Operation and Maintenance Task 3: Assistance to the Pollution Control Unit (i) Development of Environmental Management System for the WMA (ii) Important Technical, Legal and Administrative Aspects (iii) Technical Assistance to the Wastewater Laboratory Task 4: Strengthening Capacity to carry out Internal Audit Task 5: Capacity building in Monitoring and Evaluation for the Wastewater Sector Policy Support Programme (WSPSP) to officers from the MOFED, MPU and WMA. Task 6: Setting up of a programme / performance – oriented budgeting and monitoring and evaluation system for the wastewater and other environment related sector in the context of the MTEF
• An Institutional Framework Review and a Tariff Study were also assigned to the Consultant who has been recruited for Technical Assistance.
2.1.5.3 - Implementation of Medium Term Expenditure Framework (MTEF)
In June 2001, Government announced its economic strategy and policy orientation for the next five years in its Economic Agenda for the Millennium. A comprehensive budget reform with the centerpiece being the introduction of the Medium Term Expenditure Framework (MTEF).
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MTEF is the casting of the budget on a three-year rolling basis within a sustainable macroeconomic framework. It is an integrated version, which includes a Programme-based budgeting component also called Results-based budgeting. The MTEF is intended to focus on outputs as a means of improving the efficiency and effectiveness of expenditures. Consultations with the Ministry of Finance and Economic Development (MOFED) have been held with a view to implementing the MTEF.
2.1.5.4 - Private Sector Participation (PSP) in the Water & Wastewater Sector
Government has taken steps to reform the water and sanitation sectors with a view to improving the overall performance of the utilities through the enlistment of Private Sector Participation. The International Finance Corporation (IFC) was appointed as Lead Advisor to the transaction(s) in 2003.
2.1.5.5 - Utility Regulatory Authority Act (URA Act) In the context the on-going International Finance Corporation (IFC) Study on private sector participation in the water and wastewater sectors, a Utility Regulatory Authority Act (URA) has been passed and stands yet to be proclaimed.
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2.2 Assessment of existing legal and regulatory framework
2.2.1 – National Environmental Legislation The Environment Protection Act (EPA) 2002 is the main legislative framework for the protection and management of environment for the Republic of Mauritius. Its main objective is highlighted in the preamble of the Act, which reads as follows:
“To provide for the protection and management of the environmental assets of Mauritius so that their capacity to sustain the society and its development remains unimpaired and to foster harmony between quality of life, environmental protection and sustainable development for the present and future generations; more specifically to provide for the legal framework and the mechanism to protect the natural environment, to plan for environmental management and to co-ordinate the inter-relations of environmental issues, and to ensure the proper implementation of governmental policies and enforcement provisions necessary for the protection of human health and the environment of Mauritius.”
The technical arm of the Ministry is the Department of Environment. The DoE comprises the following divisions that are devoted to: Policy and Planning, Environmental Law, Co-ordination and Project Implementation, Environmental Assessment, Pollution Prevention and Control, Information and Education, Integrated Coastal Zone Management and Monitoring (by the National Environmental Laboratory). The Police de L’Environnement, a unit of the Mauritius Police Force, has also been established under the EPA to provide assistance to the Director and to the Island Chief Executive of the Island of Rodrigues, in relation to enforcement of environmental law.
The EPA gives a pivotal coordinating role to MoE to ensure enforcement of its provisions necessary for the protection of human health and the environment of Mauritius. While MoE now assumes the responsibility to enforce air, other Ministries/Authorities are designated under the Fourth Schedule to the EPA as Enforcing Agencies in respect of other environmental media or pollutants. The Enforcing Agencies must, within their sphere of responsibility, supervise the enforcement of national environmental standards, orders and directives, conduct regular monitoring to ensure compliance with environmental laws and provide assistance in reviewing Environmental Impact Assessment Reports.
Through the EPA 2002, the Permanent Secretary of the Ministry of Public Utilities is responsible for enforcing environmental legislation related to inland water and effluents. This Ministry is responsible for planning and co-ordination activities in the energy, water and wastewater sub-sectors.
2.2.1.2 - Environmental Protection Act 2002
The EPA 2002 is of particular relevance to the wastewater sector. Thus under the EPA 2002, Regulations have been prepared and promulgated by the Ministry of Environment, after consultation with other stakeholders such as the WMA and WRU to control the quality of effluents that are discharged to the natural environment. All environmental regulations, including those relevant to discharge of effluents to the environment, are now available on the web-site of the Ministry of Environment (http://environment.gov.mu) and also on the recently launched website on environmental legal database (http://muelex.gov.mu). The legislations relevant to the discharge of effluents are discussed in the following section.
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2.2.1.3 - List of Regulations under the EPA 2002 relevant to the discharge of effluents
2.2.1.3.1 - The Environment Protection (Effluent Limitations for the Sugar Industry) Regulations 1997 The Environment Protection (Effluent Limitations for the Sugar Industry) Regulations 1997 were gazetted under Government Notice No. 34 of 1997 and came into operation on 1st October 1999.
Section 3(1) of the Regulations specify the national environmental standard in relation to effluent limitations for the sugar industry, regarding effluents discharged underground or into a river, stream, spring, canal, reservoir or lake by a factory. A Schedule attached to Section 3(1) of the Regulations specifies standards as maximum limits for the corresponding parameters except where an upper and a lower limit are specified.
Parameter Standards
Condensor wastewater Other factory wastewater pH 6.0 – 9.0 6.0 – 9.0 Temperature ( OC) 40 40 COD (mg/l) * + 50 60 TSS (mg/l) * + 30 60 Oil (mg/l) * + 5 * + 5
Note: * refers to influent raw water
Section 3(3) of the Regulations specifies that any effluent which has one or more of the above parameters not complying with the corresponding limit, shall be deemed to be a pollutant.
The Regulations are therefore defined on the basis of upper limits of concentration for three main parameters, namely COD, TSS and Oil.
2.2.1.3.2 - Environment Protection (Standards of Effluent for Use in Irrigation) Regulations 2003 The Environment Protection (Standards of Effluent for Use in Irrigation) Regulations 2003 were gazetted in Government Notice No. 46 of 2003. These Regulations came into operation on 1st September 2003.
Section 2 of the Regulations defines “effluent” as water sullied or contaminated, in solution or suspension and derived from the use of the water in connection with domestic, industrial or other activities.
Section 3 of the Regulations sets, in the relevant Schedule, the national environmental standards in relation to effluent limitation for use in irrigation
Section 4 of the Regulations specifies that any person treating effluent for irrigation shall ensure that the quality of the treated effluent complies with the standards set out in the Schedule.
The standards are maximum limits of concentration for the corresponding parameters except where upper and lower limits are specified.
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The parameters are classified in four sub-lists as follows:
Sub-list A: pH and colour
Sub-list B:Biochemical Oxygen Demand, Chemical Oxygen Demand, Suspended Solids, Chloride, Sulphate, Nitrate N, Total Dissolved Solids, Sodium Adsorption Ratio. Sub-list C: Aluminum, Arsenic, Boron, Cadmium, Chromate chromium, Cobalt, Copper, Fluorine, Iron, Lead, Lithium, Manganese, Molybdenum, Nickel, Mercury, Selenium, Vanadium and Zinc.
Sub-list D: Total Pesticides, Oil and Grease and Detergents
Sub-list E: Faecal Coliforms and Intestinal nematodes
For sub-lists D and E, a 95% compliance limit is required on the series of samples taken in a year.
Faecal coliforms and intestinal nematodes are prohibited for irrigation of crops to be eaten raw.
The standards specify 1000 MPN/100 ml for faecal coliforms but restrict to 200 faecal coliforms MPN/100 ml for public lawns such as hotel lawns, with which the public may have direct contact.
2.2.1.3.3 - Environment Protection (Standards for Effluent Discharge) Regulations 2003 The Environment Protection (Standards for Effluent Discharge) Regulations 2003 were gazetted in Government Notice No. 44 of 2003.
This piece of legislation regulates the discharge of effluent from domestic, industrial or other activities onto land, into water courses and water bodies. Such activities will normally be located in unsewered regions.
Under the Regulations, no person is allowed to discharge effluent onto land, into a watercourse or into a water body unless he ensures that the parameters of the effluent do not exceed the permissible limits set out in the Second Schedule of the Regulations The first Schedule of the Regulations sets out a list of different industrial activities together with specific relevant parameters which need to be complied. The First Schedule was subsequently amended under the Environment Protection (Standards for Effluent Discharge) (Amendment) Regulations 2004, with the main Regulations remaining unchanged. The list of industrial activities under the First Schedule is as follows:
Beverage industries, breweries and distilleries, canning and food processing, dairy processing, dye houses and washing units in the textile sector, edible oil refining, industrial slaughtering, laundry processes, livestock breeding, manufacture of chemical fertilizers, manufacture of soaps/detergents and bulk storage of raw materials, mechanical workshop, metal plating and galvanizing, paint manufacturing, tanning and thermal power plant.
The Regulations also provides a Third Schedule which sets a list of permissible limits that should not be exceeded for industries that existed prior to the promulgation of these Regulations. Under the Regulations, no person is allowed or cause to be discharged any effluent into a water body or watercourse used or earmarked to be used for potable water supply.
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The MoE is reviewing the above regulations in the light of certain constraints experienced by the enforcing agency during their implementation.
2.2.1.3.4 - Environment Protection (Standards for Effluent Discharge into the Ocean) Regulations 2003 The Environment Protection (Standards for effluent discharge into the ocean) Regulations 2003 were gazetted in the Government Notice No. 45 of 2003 and came into operation on 1st September 2003. The Regulations specifies that no person shall discharge or cause to be discharged effluent into the ocean-
(a) unless it complies with the standards prescribed in the Schedule attached to the Regulations. The Schedule gives permissible limits or range for the following parameters:
Temperature, pH, flotables, biochemical oxygen demand, chemical oxygen demand, suspended solids, cadmium, chromium (VI), total chromium, cyanides (as CN), lead, zinc, nickel, total mercury, arsenic, total pesticides, oil & grease.
(b) at a distance less than 300m off the reef barrier and at a depth of less than 30m where there is a lagoon ; or (c) at a depth less than 500m from the High Water Mark and at a depth of less than 25m where there is no lagoon.
Also, no person shall discharge any effluent into the ocean at a point where sea currents will cause the effluent to be taken back into the lagoon.
2.2.1.3.5 - Environment Protection (Effluent Discharge Permit) Regulations 2003 The Environment Protection (Effluent Discharge Permit) Regulations 2003 were gazetted in Government Notice No. 43 of 2003 and came in force on 1st September 2003.
Under these Regulations, no person can discharge or cause to be discharge any effluent from any of the activities mentioned below into a watercourse, water body or onto any land unless he has an Effluent Discharge Permit from the appropriate enforcing agency. Again, this concerns activities located in unsewered regions and the enforcing agency is the Ministry of Public Utilities.
The relevant activities as listed in the First Schedule of the Regulations are as follows:
Sugar Manufacturing Industries and Refineries, Textile manufacturing, dyeing, washing and finishing units, metal plating and galvanizing, slaughtering, canning & food processing, soft drink bottling, breweries and distilleries, laundry processes, edible oil refining, paint manufacturing, operating mechanical workshop, thermal power plant operation, soap & detergents manufacturing, manufacture of pharmaceutical products, tanning, manufacturer of chemical fertilizers, livestock breeding, wastewater treatment plant. Also, no person is allowed to discharge or cause to be discharged any effluent into any watercourse or water body from which water is, or is likely to be, abstracted for domestic purposes.
The Regulations provide a format for application for a permit which essentially contains:
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The particulars of the applicant, the name and location of the water body/watercourse, the nature and composition of the effluents to be discharged (analysis certificate to be attached), the frequency of discharge of effluent, the maximum daily volume of effluent to be discharged, the maximum rate of discharge, the equipment/device for measurement of volume/rate of discharge of effluent, the sampling method, frequency and location and the method of analysis to be adopted per parameter
Under Section 5 of the Regulations, where it is satisfied that the applicant has complied with the requirements of the EPA 2002 and the Regulations, the enforcing agency may issue a permit to the applicant.
Finally, the person responsible for the activity shall cause the result of analysis of effluent to be sent to the Department of Environment and to the enforcing agency on a monthly basis, specifying the method, time and location of the sampling for each and every sampling.
2.2.1.4 - Mechanisms for compliance and enforcement of Regulations under EPA 2002 The Environment Protection (Effluent Discharge Permit) Regulations 2003. The mechanism for compliance and enforcement for the four Regulations regulating discharge of effluent in the environment, other that in a sewer network:
● the Environment Protection (Effluent Limitations for the Sugar Industry) Regulations 1997 ● the Environment Protection (Standards of Effluent for Use in Irrigation) Regulations 2003 ● the Environment Protection (Standards for Effluent Discharge) Regulations 2003 ● the Environment Protection (Standards for Effluent Discharge into the Ocean) Regulations 2003 is provided in the last piece of legislation described above, namely the Environment Protection (Effluent Discharge Permit) Regulations 2003.
Under the EPA 2002, the Ministry of Public Utilities is responsible for enforcing environmental legislation related to inland waters and effluents.
The methodology for issuing the Effluent Discharge Permit, the frequency of carrying the tests of parameters and the quality of results from laboratories which are not yet accredited are being further discussed so that the Permit and any legal sanction under the EPA can be properly monitored.
However the major industries that would normally require a license from the WRU are being monitored by the Wastewater Management Authority or by the Ministry of Environment as explained below.
2.2.1.4.1 - Mechanism for monitoring and compliance for activities that would fall under the Environment Protection (Effluent Limitations for the Sugar Industry) Regulations 1997 There are ten sugar factories in Mauritius which possess pre-treatment facilities to pre-treat their industrial effluent before discharge into watercourses as all sugar industries are located in unsewered regions. The number of sugar industries is expected to fall drastically by next year.
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2.2.1.4.2 - Mechanism for monitoring and compliance for activities that would fall under the Environment Protection (Standards of Effluent for Use in Irrigation) Regulations 2003 Such activities would comprise mainly coastal hotels and two public wastewater treatment plants, namely the St. Martin WWTP and the Grand Baie WWTP.
In the first case, there are presently about 45 coastal hotels which pre-treat their effluents and use it for irrigation of lawns and golf courses. Mauritius has a flourishing tourism industry and it is in the prime interest of the tourist hotels to ensure that the water is treated to the required norms so as to protect the industry, as an outbreak of waterborne disease or odor nuisance would be the most inappropriate marketing tool. In most cases, the local hotels are either ISO certified or must demonstrate to their international counterparts that their treatment plant is functioning to the desired level of performance.
A number of hotels are required to submit monthly results of analysis to the WMA which has also undertaken a survey of all hotels with WWTP so as to monitor closely the performance of hotel WWTPs. All these hotels use either activated sludge systems or septic tank followed by rotating bio-contactor systems. Recently one hotel has proposed to use a constructed wetland and this is under commissioning.
Regarding the St. Martin WWTP, the WMA has an operation and maintenance contract with the contractor who built the WWTP and, under the contract, the contractor has a duty to make daily sampling and analysis of effluent at both inlet and outlet. The St. Martin WWTP is an activated sludge system treating up to tertiary level for selling to the IA for the irrigation of sugar-cane fields. It is presently treating about 40, 000 m3 of effluent daily, which represents about 58 % of its design capacity.
The WMA has a Sale Agreement with the Irrigation Authority and there are of course stringent requirements in the Agreement regarding the quality of the treated effluent.
The daily sampling and analysis made by the contractor shows full compliance.
2.2.1.4.3 - Mechanism for monitoring and compliance for activities that would fall under the Environment Protection (Standards for Effluent Discharge) Regulations 2003 These Regulations concerns a scheduled list of industries. However, the great majority of industries, where wet processes are involved, are located in the sewered regions and are covered by the Wastewater (Standards for Discharge of Industrial Effluents into Sewers) Regulations 2004. Other industries which discharge their effluents into water courses are also monitored by the Wastewater Laboratory of the WMA and by the National Environmental Laboratory of the Ministry of Environment in their routine monitoring exercises.
The Pollution Prevention and Control Unit of the Department of Environment, assisted by the Police de L’Environment are also involved in ensuring that industries abide by the Regulations.
2.2.1.4.4 - Mechanism for monitoring and compliance for activities that would fall under the Environment Protection (Standards for Effluent Discharge into the Ocean) Such activities would comprise ocean outfalls pertaining to public wastewater treatment plants operated and maintained by the WMA. There are presently two such sea outfalls located at Baie
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Under this Independent Audit, the AFRC has the responsibility to monitor the seawater quality at outfalls of WWTP’s as well as lagoonal water quality. The results of the monitoring so far have indicated good compliance of seawater quality except for isolated instances that were found to be associated with heavy rainfall conditions.
2.2.2 – Legislation under WMA Act 2000
The Wastewater Management Authority Act 2000 establishes the WMA as a corporate autonomous body with a clear mandate for the overall administrative and technical management of the wastewater sector. The WMA is also the main undertaker for the collection, treatment and disposal of wastewater throughout the country.
One main object of the WMA is to control and monitor pollution, private systems and the use of equipment in relation to wastewater systems. The WMA should also control and monitor pollution discharged to wastewater systems by any person. The Authority also has all the powers necessary for the administration of the WMA Act 2000 and can do all such things as may be required for the efficient collection, treatment and disposal of wastewater and related functions, including the necessary functions for the prevention of discharge of industrial and other wastes into the wastewater system.
Also, under the Act, no person can construct or allow the construction of any house sewer, treatment plant or disposal system otherwise than in accordance with the designs prescribed or approved by the WMA. Approval needs to be granted by the WMA either at EIA stage if the undertaking is a scheduled activity requiring an EIA license, or at building permit whereby local authorities request for formal approval of the wastewater system before granting the building permit.
2.2.2.1 - Wastewater (Standards for On-Site Disposal Systems) Regulations 2002 (Draft) These draft regulations have not been passed but the same principles have been taken up in the Planning Policy Guidelines for Urban Authorities.
The Guidelines are essentially structured as follows
Different water consumption rates are proposed for different activities, such as for households, offices, schools etc.
Different infiltration application rates are recommended depending on different rates of soil permeability as evidenced by soil percolation tests.
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Recommendations are given for the design of septic tanks based on 2 day retention, and for design of absorption pits or leaching fields, depending on soil characteristics and depth of water table. For straight forward cases such as for individual dwelling units, customers need to submit their building plans to the survey section of the WMA which will verify that the development cannot be sewered before recommending an on-site disposal system.
For more important projects such as schools, public buildings or blocks of apartments, a design report is required, describing the proposed activities, substantiating the daily water consumption. A soil test report giving results of percolation tests, depth of water table and visual description of soil strata, signed by a registered civil engineer is also required, for substantiating the proposed design and dimensioning of on-site wastewater disposal system.
However there is no mechanism in place to ensure that the on-site disposal systems are built as per approved plan and, for individual houses, it is common practice to make use of cesspits, although septic tank followed by absorption system has been recommended at building permit stage.
2.2.2.2 - The Wastewater (Standards for Discharge of Industrial Effluents into Sewers) Regulations 2004. Numerous meetings were held with representatives of the industrial sector since 2000 before the Wastewater (Standards for Discharge of Industrial Effluents into Sewers) Regulations 2004, being gazetted in November 2004, came into operation on 1st January 2005.
Under the Regulations, no person can discharge or cause to be discharged industrial effluent into the public wastewater system unless he holds a license from the WMA. All licensed industries should install necessary pre-treatment systems, as approved by the WMA to ensure that any discharge of industrial effluent is in compliance with the permissible limit as specified under the Fourth Schedule of the Regulations.
Licensed industries are also required to submit monthly reports of daily water consumption, daily volumes of wastewater discharged to sewers and results of analysis of effluent for parameters relevant to the industrial activity. The relevant parameters are specified in the Third Schedule.
Provision is made under the 5th Schedule for application of a monthly penalty by the licensees for the discharge of any pollutant with concentrations in excess of the permissible limits specified under the 4th Schedule. The relevant parameters to which the penalty is applicable are: arsenic, boron, cadmium, COD, total chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, oil & grease, settleable solids, TKN, total organic halides, total phosphorous, total suspended solids, zinc. The penalty is calculated as the amount (in kg) of the pollutant discharged per month times the penalty in Rs/kg
The list of scheduled activities that require a license under the Wastewater (Standards for Discharge of Industrial Effluents into Sewers) Regulations 2004 is as follows: Textile, (dye- house and others), metal plating and galvanizing plant, slaughterhouse, fish canning plant, meat canning plant, vegetable and fruit canning plant, soft drink bottling plant, brewery and distillery, soap and detergent manufacturer, chemical conditioning plant, mechanical workshop, paint manufacturer, dairy processing plant, edible oil refinery and manufacturer of edible oil product, tannery, pharmaceutical industry.
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2.2.2.3 - Mechanism in place for implementation and enforcement The Regulations are being implemented by the Pollution Control and Monitoring Department of the WMA. Some 153 licenses have already been implemented to date, with the most important industries targeted at the beginning.
The industries are requested to fill in the application form. An officer of the WMA then makes a site visit to ensure that all information provided is correct. The industry is also requested to submit water bills to ascertain the water consumption as well as results of analysis of effluent from an independent laboratory. If the results of analysis comply with the standards, the industry is requested to make payment of five hundred rupees and a license is issued for a period of three years.
Each month, the industry submits a report containing records of water consumption and results of analysis of effluent. One post monitoring site visit is undertaken each year to ensure that the conditions of the license are still being followed and that no major change has occurred. The Wastewater Laboratory also takes one sample for analysis each year for cross-checking.
Due to a long standing collaboration between industries and the WMA, well prior to the enactment of the Regulations, the great majority of industries connected to the sewer network have already installed pre-treatment facilities to that ensure that their industrial effluents are within norms. At the very inception stage, the WMA has held numerous consultations with representatives of the industrial sector so as to ensure their active participation and collaboration in the process of implementation of these Regulations. Thus, a Draft Memorandum of Understanding was signed in 2000 with the Joint Economic Council. Discussions were held with different representatives of the industrial sector.
Thus the implementation of the Regulations proceeded smoothly and the WMA has already issued some 153 discharge permits to date.
2.2.3 – Strength and Weaknesses of the legislations
2.2.3.1 – Environmental Regulations under EPA 2002 The Regulations for discharge of effluent into the environment have been very well drafted and provide a good tool for the protection of the environment, water table, water bodies and water courses from individual industries. It is based on internationally practicing standards with very stringent requirements. The Standards and Regulations provide the basis for promoters to propose relevant pre-treatment mechanisms at the EIA stage before being delivered with an EIA License. It also provides the necessary framework for post-monitoring by relevant institutions so as to ensure that pre-treatment systems are operating to the required levels and that treated effluent quality are being met before being discharged into the environment. However a number of inherent weaknesses are observed.
2.2.3.1.1 – Lack of institutional capacity to implement and enforce the Regulations The Regulations for discharge of effluent have been prepared with the view that same would be implemented and enforced by the Water Resources Unit. However this organization does not yet possesses the required resources for implementation and enforcement.
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2.2.3.1.2 – Lack of stakeholder awareness It appears that no prior consultations and co-ordination meetings were held with representatives of the industrial sector so as to prepare them beforehand for promulgating the Regulations. This resulted in a low response from industries to apply for the license. There are also no incentives to enhance environment stewardship and encourage auto-regulation.
2.2.3.1.3 - Stringent standards Some parameters are very stringent for industries to abide by in a restrained timeframe. Some industries would have to invest significantly in pre-treatment facilities so as to be able to bring BOD level to less than 40 mg/l. Incentives such as soft loans to enable industries to invest into pre-treatment and a moratory period for the industries to plan the implementation of pre-treatment facilities must be put in place.
2.2.3.1.4 - Insufficient capacity for analysis Some parameters such as total organic halides cannot be tested by laboratories in Mauritius. Public laboratories are in the process of obtaining accreditation.
2.2.3.1.5 - Lack of flexibility The Regulations have been formulated in a somewhat rigid matter and does not allow any flexibility. In particular, no survey has been done so as to ascertain what are the types of raw materials being used in particular fields of industry. It may have been more relevant to specify parameters to be tested in line with raw materials and chemicals being used.
2.2.3.2 – Legislation under WMA Act 2000
2.2.3.2.1- Wastewater (Standards for On-Site Disposal Systems) Regulations 2002 (Draft) As stated at Section 2.2.2.1 above, the draft regulation have been incorporated in the Planning Guidelines for Urban Authorities. As such major developers now require a clearance from the WMA to be issued a land use and building permit by the local authorities.
Formerly, it was only developments found within the sewered municipal jurisdictions that required a clearance from the WMA. The great majority of residential buildings in the rest of the country did not require any clearance from the WMA with the result that building permits were issued without proper assessment of proposed on-site wastewater disposal systems. Thus most people have been making use of cesspits.
In cases of malfunctioning and overflow of cesspits, complaints are invariably made to the Ministry of Environment and the Police de L’Environment. These institutions redirect the complaints to the WMA for taking action.
Though the WMA Act 2000 describes the WMA as main undertaker for pollution dealing with wastewater, neither is the WMA is specifically structured to tackle such issues, nor is it remunerated for same.
The WMA has a contractual relationship with the Ministry of Public Utilities through the Contrat de Délégation and Convention de Maîtrise d’Ouvrage Déléguée. It advocates a lean and thin organization structure with roles of a supervisory nature, most of its activities being contracted out. It will not therefore be possible for the WMA to take overall responsibility for on-site disposal systems.
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2.2.3.2.2 - The Wastewater (Standards for Discharge of Industrial Effluents into Sewers) Regulations 2004. The Regulations provide an invaluable piece of legislation that enables the WMA to fulfill one of its principal control functions. It provides the required framework to monitor the quality and quantity of effluent that an industry can discharge to the public sewerage system. If the effluent from an industry exceeds the quality standards laid down in the Regulation, a wastewater surcharge over and above the monthly wastewater tariff can be levied on the industry. This will act as an incentive for the industry to invest in pre-treatment. The implementation of this Regulation has been more successful than the Environmental Regulations for Discharge of Effluents under the EPA 2002 for a number of reasons, namely:
● there has been extensive collaboration between the WMA and the industrial sector in the process of drafting and implementing the Regulation. ● the Standards for discharge into sewers are much less stringent and effluent quality can easily be achieved with less pre-treatment than for discharge into the environment. ● the fees for applying for the license is nominal, (five hundred rupees for three years) and does not act as a deterrent for industries to apply.
Enforcement is easier as good working relations have been established between the Pollution Control and Monitoring Division of the WMA and the industries. Most industries do submit monthly reports of results of analysis and water consumption. The WMA has the minimal staff required to ensure at least one post-monitoring site visit per year. The Wastewater Laboratory also makes one sample and analysis of each licensed industry every year. However such post- monitoring exercises should be done a greater frequency, ideally on a quarterly basis.
The main weakness of the Regulations is lack of flexibility as described in Section 2.2.3.1.5 above.
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2.3 – Assessment of Existing Institutional Mechanisms
The main institutions involved in wastewater management are the Wastewater Management Authority, the Ministry of Environment & National Development Unit, the Ministry of Public Utilities, the Ministry of Agro-Industry and Fisheries, the Irrigation Authority and the Ministry of Health & Quality of Life
2.3.1 – The Wastewater Management Authority
Since 1st September 2001, under the Wastewater Management Authority Act 2000, the WMA has been the sole organization responsible for the provision and O&M of all public wastewater systems in Mauritius. It is also responsible for monitoring the quality of wastewater discharges, particularly, industrial discharges, to the sewers and for the setting and enforcing of discharge standards by way of Regulations under the main WMA Act 2000. The WMA is a parastatal organization operating under two legal instruments/contracts between the WMA and the Ministry of Public Utilities:
The Convention de Maîtrise d’Ouvrage Déléguée under which the Government has entrusted the WMA the overall responsibility of all projects under the National Sewerage Programme which seeks to connect 50% of the households to the public sewer system by 2015.
The Contrat de Délégation under which the WMA is responsible to the Government for the operation and maintenance of all assets used in the public sewerage system while all assets remain vested with the Government.
Thus Government has empowered the WMA to manage, service, operate and maintain the country’s public wastewater systems and to manage the design, procurement and construction of new infrastructures that are required to implement the NSP. The WMA also has a pollution control function whereby it is required to control the discharge of wastewaters into the public sewers and also to monitor the quality of effluents from wastewater treatment plants to ensure that these comply with the discharge standards set by the Department of Environment.
2.3.1.1 – WMA Organization Structure
The Technical Department of the WMA consists of a New Works, House Connection and Mapping Division, the Operation & Maintenance Division and the Pollution Control and Monitoring Division. The Administrative Department gives the necessary back-up facilities for the proper functioning of the WMA and consists of the Finance Division, the Administrative and Human Resources Division, the Documentation Centre and Library Unit, the Information Technology Unit, the Internal Audit Unit, the Publics Relation and Customer Care Unit and the Occupational Safety, Health and Welfare Unit.
2.3.1.1.1 – The New Works, House Connection and Mapping Division
● The New Works Unit
The New Works Unit is responsible for implementing sewerage projects under the NSP. It holds a project management function, making all necessary procurement exercises for the recruitment of
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● The House Connection Unit
All sewerage projects in the past consisted of providing street sewers under construction contracts supervised by private consultants. It would then be up to members of the public to make an application with the WMA to have their premises connected at their own costs. This resulted in a low connection rate and low willingness for connection, sometimes causing newly built sewerage infrastructure to stay idle for long period of time and constituting a lack of revenue to the WMA through sewerage tax.
With a view to ensuring maximum beneficial utilization of infrastructure constructed under the NSP, the Government has undertaken to provide free household connections to the sewerage system, under the Government Free Household Connections Program to residential properties. A feasibility study was carried out at the end of 2001 to prepare a strategy for developing the number of house connections to the public sewers. A major conclusion of the study was that within the area covered by the NSP, some 65, 000 properties have to be connected to sewerage systems, either existing or to be constructed. The House Connection Unit has been newly created and it is responsible for the project management of house connection contracts in unsewered pockets within existing sewered areas and newly sewered areas.
2.3.1.1.2 – The Operation & Maintenance Division The WMA is responsible towards the GoM, under the Contract de Délégation, for the operation and maintenance of some 500 km of sewer network, 950 manholes, 50 pumping stations and 9 treatment plants. All operation and maintenance activities for WMA electrical-mechanical assets (pumping stations and WWTP) are outsourced, be it in O & M contracts after recent years of construction or via separate O & M contracts
Currently the O & M of the two main WWTP, namely the St. Martin WWTP and the Grand Baie WWTP is fully outsourced as part of the construction contracts to the two contractors who built the plants. O & M of the smaller WWTPs and pumping stations are outsourced under several contracts to local contractors.
2.3.1.1.3 – Pollution Control and Monitoring Division The Pollution Control and Monitoring Division consists of the Pollution Control Unit and the Wastewater Laboratory which work in close collaboration.
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● The Pollution Control Unit The Pollution Control Unit manages and monitors all industrial effluent discharged to the public sewer network. It also investigates and reviews the wastewater aspect of all infrastructural and industrial development which require a clearance from the WMA. The main tasks undertaken by the Pollution Control Unit are as follows:
• Monitoring of public wastewater treatment plants
This function relates to the monitoring of the performance of all public wastewater treatment plants to ensure that these are in compliance with relevant EPA effluent standard regulations, depending on the mode of disposal of the final effluent. The Pollution Control Unit undertakes this task as a means and mechanism to protect the receiving environment from the discharge of sub-standard WWTP effluent. A monitoring frequency has been agreed with the Wastewater Laboratory which samples and analyses influents and effluents from the public wastewater treatment plants. The results of analysis are sent to the Pollution Control Unit for scrutiny. Quality of influent can give valuable information on types of industries on which more strict control is required by virtue of parameters exceeding standards. The Pollution Control Unit also scrutinizes results of analysis performed by contractors to whom the operation and maintenance of some WWTPs have been outsourced.
• Manage industrial effluent discharge to public sewer network This task concerns the delivery of Industrial Discharge Permits to industries discharging industrial effluents to the public sewer, after ascertaining that required pre-treatment are applied by the industries to ensure compliance with relevant standards, under the Wastewater (Standards for Discharge of Industrial Effluents into a Public Sewer) Regulations 2004. This includes the most polluting wet industries.
Monthly reports of analysis of effluent and water consumed are sent by the industries to ensure compliance. Post–monitoring site visits and independent sampling and analyses are also performed by the WMA.
Should the effluent discharge by an industry not meet the prescribed norms, a number of actions can be initiated by the WMA ranging from a formal letter requesting the defaulting industry to take remedial action, the levying of a penalty under Schedule Six of the Regulations, and ultimate legal action including issue of an Enforcement Notice or a Stop Order.
• Review Wastewater Related Infrastructural and Industrial Development.
This task concerns the review, assessment and approval for EIA/PER applications, land subdivision, infrastructural development for public institutions, building permit applications, land conversion permits, housing projects, coastal hotels and Integrated Resorts Schemes. This includes site visits, interaction with Promoters and their Consultants, attending relevant committees such as the EIA Committee, the Building Plan Committee, and Morcellement (land sub-division) Committee, Town and Country Planning Board etc. and issuing of views/recommendations/clearances. This is to ensure that all new infrastructural and industrial developments comply with the EPA Regulations, Standards and Guidelines in regard to wastewater related issues.
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• Advice and Assistance on wastewater related issues
The Pollution Control Unit, upon request, makes necessary investigations and provides advice and assistance on wastewater related issues to governmental and national public organizations, as well as to members of the public and local consultants.
• Undertake ad-hoc investigations related to wastewater pollution
The Pollution Control Unit is requested, from time to time to undertake or participate in ad hoc investigations, e.g. investigate pollution (microbiological) and nuisance (odors) related complaints related to the overflow of cesspits and absorption pits and recommend appropriate action by the relevant WMA Departments, enforcing agency, and affected party; investigate the appropriate management of piggery wastes, poultry wastes, contribute to the guidelines for pollution control with respect to various fields of activity, and prepare guidelines for the approval of wastewater treatment facilities.
● Wastewater Laboratory
The primary function of the Wastewater Laboratory is to regularly sample and analyze influents and effluents from wastewater treatment plants and effluents from industries, as well as from other potentially polluting activities which generate effluents such as hotels, housing estates, large commercial buildings and shopping complexes. Such analyses provide an analytical service to other departments within the WMA, so as to support them in their tasks of protecting the existing sewers and WWTPs, as well as the receiving environment.
The second function of the Wastewater Laboratory is to provide a professional service to the laboratory’s clients by managing the laboratory in an efficient and effective manner, including: maintenance of a standard range of analytical procedures, refining existing and development of new analytical procedures, data storage and retrieval, the maintenance of quality assurance manuals, timely reporting of analytical results to Clients, accreditation to international laboratory standards.
The third function of the Wastewater laboratory is to provide on request advice and assistance on wastewater pollution control analytical issues to Government, industry and the public. This is achieved by: attending meetings, undertaking site visits, reviewing reports and other documentation, undertaking ah-hoc investigations, analyzing suspected wastewater contaminated waters, and interacting with the professional organizations.
2.3.2 - The Ministry of Environment & NDU
The Ministry of Environment has a fundamental role in the formulation of national environmental policies at different time frames in line with new priorities due to dynamic process in the socio- economic environment. The formulation of policies profoundly determines the policies, strategies and action plans in the wastewater sector.
Environmental degradation due to increased economic activity in the eighties led to the creation of the Ministry of Environment. One of the first tasks of the Ministry of Environment was the formulation of the first National Environmental Action Plan which identified shortcomings in the wastewater sector as a potential threat to ground water resources. This led to the National
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Sewerage Master Plan, the National Sewerage Programme and was thus the booster that triggered huge changes and massive investments in the wastewater sector. Generally speaking, the NEAP 1 objectives were to establish a policy and the legislative and institutional framework to manage the environment in Mauritius. The main projects undertaken in the wastewater sector under NEAP 1 of 1990 are:
● Setting up of environmental laboratories and training programmes for laboratory personnel ● Baie du Tombeau Urgent Sewerage Project ● Preparation and Implementation of a National Sewerage Masterplan ● Study of economic incentives for industrial pollution control
Further on, the NEAP 2 undertaken in 1999 identified the following problems with regard to the institutional and legislative aspects of the water sector:
● Unclear institutional responsibilities ● Unclear legal standards for both emission of pollutants and for the quality of natural waters ●inadequate availability of water monitoring data ● Ineffective control of industrial effluents ● Low awareness of critical groups such as industrialists and agrochemical users ● Inefficient pricing, particularly with regard to the subsidy of irrigation water ●Insufficient water management
These points were all considered during the identification of the projects in the NEAP 2 and its associated Environmental Investment Programme (EIP2). The development of NEAP2 included the participation of all stakeholders at national level and enabled the identification of priority problems and actions and the development of plans for the implementation, monitoring and evaluation of the proposed action plan. Thus, with regard to the field of wastewater management, the following actions were recommended by the NEAP2:
● cost recovery charging for wastewater disposal ● undertaking training by both the CWA and the WMA with overseas companies in the context of management contracts. ● helping the WRU in the process of reduction of pollution at source, regulating the aspects of water resource use, issue of standards and enforcement and monitoring for discharge of industrial effluents.
2.3.2.1 - National Environmental Advisory and Co-ordination Bodies
The administrative management of the environment at national level rests with the Ministry of Environment (MoE), which is responsible for formulating and implementing policies for the protection of the environment. This Ministry is also responsible for the publication and dissemination of information concerning protection of the environment. The Ministry also acts as a ‘watchdog’ to ensure that the different Enforcing Agencies are discharging their functions.
The MoE does not currently have the capacity to enforce the entire environmental legislation in all fields of environment. As a result, the MoE has designated Enforcing Agencies through the Environmental Protection Act 2002 (EPA 2002). The Enforcing Agencies must, within their sphere of responsibility, supervise the enforcement of national environmental standards, orders
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The EPA 2002 gives the Ministry a central role in terms of coordination with other Ministries and organizations through the setting up of various coordination committees.
2.3.2.1.1-The National Environment Commission The National Environment Commission (NEC), chaired by the Prime Minister and comprising most of the Ministers of the Government who are responsible for subjects linked to the environment, is the highest instance where environment policy decisions are taken. The major functions of the NEC are to set national objectives and determine priorities and policies for the protection of the environment and to ensure co-ordination and co-operation between public institutions, governmental bodies and local authorities that are engaged in environmental programmes.
2.3.2.1.2- The National Network for Sustainable Development The National Network for Sustainable Development (NNSD) comprises the Minister, Permanent Secretary, representatives of different departments of the Ministry of Environment, representatives of Ministries involved in the NEC and representatives of all NGO’s registered with the Ministry of Environment. This committee meets at least once every three months and acts as a forum of discussion on issues related to integration of the various economic, social and environmental policies operating in Mauritius, the quality and state of the environment, the development of an integrated approach to pollution prevention and control and the protection of environmental assets.
2.3.2.1.3-The Environment Co-ordination Committee The Environment Co-ordination Committee (ECC) chaired by the Permanent Secretary of the Ministry of Environment and comprising high officials of other Ministries/Authorities, implements policies emanating from the NEC. This committee meets at least once a month and its major task is to ensure the maximum co-operation and co-ordination among enforcing agencies and other public departments dealing with environmental protection. The ECC may also advise the Ministry of Environment and the NEC on matters related to environmental standards, guidelines and codes of practice.
2.3.2.1.4-The Environment Liaison Officers (ELO) Committee The Environment Liaison Officers (ELO) Committee is a sub-committee of the ECC and comprises enforcement officers from all enforcing agencies. Liaison Officers from the local authorities have recently been included in the ELO Committee. The main purpose of the Committee is to ensure that a synergistic and effective approach is taken in dealing with local environmental cases as well as pollution from the industrial sector. Complex cases requiring policy decision are brought up to the ECC
2.3.2.2-The Department of Environment
The main technical arm of the Ministry is the Department of Environment (DoE). It is responsible for: ● the administration of the Environmental Protection Act 2002;
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● the development of environmental guidelines and standards; ● acting as a national focal point for information and research on all environmental matters; and assisting other Ministries and government agencies in their task of protecting and enhancing the quality of life.
The DoE is comprised of the following divisions: Information & Education, Pollution Prevention and Control, Integrated Coastal Zone Management, Planning and Policy, Environment Law, Environmental Assessment, Coordination and Project Implementation and the National Environmental Laboratory. The “Police de L’Environnement” set up under the EPA provides assistance round-the-clock to the Director of Environment in the enforcement of environmental laws. Their different roles in wastewater management within their specific mandates can be summarized as follows:
2.3.2.2.1-Information & Education This Division is responsible for the development of Environmental Information System/GIS, the development and environmental indicators and for promoting public awareness and environmental education. It also co-ordinates the celebration of important events such as the World Environment Day, Clean up the World whereby different institutions such as the WMA can disseminate information on various topics through seminars, presentations and papers.
2.3.2.2.2- Pollution Prevention and Control The Pollution Prevention and Control Division is mainly responsible for the enforcement and compliance of Standards and Regulations. It also advises industrialists and members of the public in appropriate abatement measures and cleaner production. The Division acts as Secretariat for the ELO Meetings, implements Integrated Pollution Prevention Control Licenses, co-ordinates post EIA monitoring with other institutions to ensure that the recommendations imposed in the EIA License have been adhered to. The Division also attends to complaints of various nature, including wastewater overflows, malfunctioning on-site wastewater disposal systems, odor nuisances and non-performing wastewater treatment plants.
2.3.2.2.3 - Integrated Coastal Zone Management The Integrated Coastal Zone Management is mainly responsible for the development and implementation of an integrated coastal management plan, assessing and monitoring coastal resources including wetlands, issuing guidelines for coastal construction and for the identification and mapping of environmental sensitive areas. This Division ensures that the wastewater management aspect of developments within the coastal zone is in line with existing regulations and do not impact negatively on the coastal zone.
●2.3.2.2.4 - Planning and Policy • The Planning and Policy Division has the following roles: • Review and update environmental policy documents • Formulate policies on key environmental issues • Liaison/Coordination in connection with national and international environmental issues • Act as Secretariat for the Conventions • Prepare state of environment report and other associated reports • Act as Secretariat for the NEC • Environmental Planning
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2.3.2.2.5 - Environment Law The Environment Law Division is responsible for developing / reviewing standards, guidelines and new regulations as required under the Environmental Protection Act and for amending the EPA and other Environmental laws. It also develops licensing systems such as Integrated Prevention and Control License, drafts legislation to make specific provisions for conventions on environment and develops quality objectives. The Environmental Law Division also serves as a link between the various divisions and the State Law Office on legal matters, and also acts as secretariat for the inter-Ministerial MEAs Coordinating Committee recently set up to coordinate with other organizations the implementation of multilateral environmental agreements (MEAs) ratified by Mauritius
2.3.2.2.6 - Environmental Assessment The Environmental Assessment Division has a very crucial role in coordinating with other institutions for the environmental impact assessment of most industrial and infrastructural development. The environmental impacts of proposed development projects are identified, predicted and evaluated. Hence environmental problems are foreseen and addressed at the very project inception and design stage. The list of scheduled undertakings requiring application for an EIA Licence or approval of a PER is now defined under the Environment Protection (First Schedule) Regulations, 2006. The Promoter submits his EIA or PER Report to this Division which disseminates copies to the various relevant institutions to study and submit their views/clearance. This Division also arranges for a joint site visit with all stakeholders and holds EIA / PER meetings where the application can be discussed with all public institutions before delivering the EIA or PER License. The WMA has thus the possibility to evaluate the quantity and quality of wastewater to be generated from a particular undertaking, gauge the method of collection, treatment and disposal proposed and give its approval with all necessary conditions.
This Division also co-ordinates with relevant public institutions for: • Processing of environmental clearance • Processing of land-subdivision application • Processing of land conversion application • Review of strategic EIA • Prepare guide on EIA and PER • Prepare sectoral guidelines • Assist Post EIA monitoring • Prepare brief and status reports on applications
The WMA is consulted for all the above tasks so as to give its views and recommendations on wastewater collection, treatment and disposal aspects.
2.3.2.2.7 - Coordination and Project Implementation The Coordination and Project Implementation Division co-ordinates / implements the National Environment Strategies and co-ordinates projects implemented by Enforcing Agencies and by regional and international organizations. The Division also assists other Ministries in environmental projects.
2.3.2.2.8 - National Environmental Laboratory. The National Environmental Laboratory ensures a monitoring function by effecting sampling and analysis of effluents on industrial premises, WWTPs, hotels and environmental hotspots.
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2.3.2.2.9 - The Police De L’Environment The Police de L’Environment ensures that the environmental laws are enforced. It works in consultation with all other Enforcing Agencies to sensitize the population for the protection of the environment. Complaints, including wastewater problems such as overflow, illegal discharges, and malfunctioning WWTPs are recorded at the Pollution Prevention & Control Division and at the Police De L’Environment. Subsequently, officers undertake site visits, individually or in the company of the relevant Enforcing Agencies. Contravenants of an environmental law are, in the first place, directed to take appropriate mitigative measures to abate the pollution problem. In the event of persisting problems, Notices are served in accordance with the provisions of the EPA 2002.
2.3.3 - The Ministry of Public Utilities
The prime institutional responsibility for water resource management and energy sector lies with the Ministry of Public Utilities. This Ministry is responsible for co-coordinating activities in the water, wastewater and energy sub-sectors through its different agencies (Wastewater Management Authority, Central Water Authority, Water Resources Unit and Central Electricity Board). The role of the Wastewater Management Authority has been described in Section 2.3.1 above.
Table 2.1 below summarizes the various institutions with responsibilities in the water resources sector in Mauritius and the particular fields for which they are responsible.
Table 2.1 – Summary of Key Institutions Involved in the Environmental Aspects of Water Resources (Source: Sectoral Study for the 9th EDF Budgetary Support to the Environment Sector)
Abstraction Treatment Distribution Quality Legislation / Monitoring Enforcement Collection Natural surface and CWA - - WRU WRU ground waters Drinking water - CWA CWA MHQL MHQL
Water for irrigation CWA - CWA CWA WRU purposes IA IA Farmers(*) Farmers
Water for industrial CWA - CWA CWA - purposes Wastewater in sewers - WMA WMA WMA WMA
Wastewater in natural - - - WRU WRU drains Stormwater - - WRU/LA - WRU
Legend: (*): with abstraction license LA: Local Authorities
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2.3.3.1 - The Central Water Authority (CWA)
The Central Water Authority (CWA) was established in July 1971 under the Central Water Authority Act as the only national organization responsible for the supply of drinking water throughout Mauritius. It is a parastatal organization operating under the aegis of the Ministry of Public Utilities. Its mission is to secure and provide an excellent sustainable water supply service of appropriate quality, at a reasonable price, to meet the growing needs of domestic and industrial consumers.
Nearly 99% of the population has access to pipes drinking water, 95% of whom are provided through individual household connection. The total number of subscribers is around 280, 000. There has been an average rate of increase in the water demand in the last decade of 3% per annum and this is expected to continue. The current per capita consumption for domestic usage is estimated to be 160 l/cap/day.
Unaccounted for water is estimated to be in the region of 50% mainly due to leakage and illegal connections and the CWA has launched a project partially funded by the European Investment Bank for reducing the level of unaccounted for water to an acceptable level of 30% by cutting down system leakages.
The primary principle dictating the water tariff endeavors full recovery of “generalized cost” which should include production and distribution operating costs. It also makes provision for capital expenditures (rehabilitation and expansion works), and taxes to finance measures for environmental protection.
The second principle of water tariff is to take into account the affordability for payment of the users and also encourage the consumers to reduce water wastage and leakages. Sound water consumption behaviour will have a direct effect on wastewater management.
● Joint Billing The wastewater charges applied to WMA customers is based on the volume of potable water consumed. The preparation of bills and the collection thereof are managed by the Central Water Authority, under a Joint Billing Agreement between the WMA and CWA which entails payment of a fee to the CWA
The joint billing system provides many administrative advantages:
• There is no duplication in the preparation and delivery of bills and customers paying the CWA bills cannot deny the receipt of WMA bills.
• The customer database of the CWA is used to monitor the management of customer accounts, as a CWA connection is a pre-requisite for providing the sewerage connection.
• Since the WMA does not provide an essential commodity, such as potable water, being more a service provider, there was no leverage, apart from prosecution, to compel customers to pay the sewerage tax. The Joint Billing Agreement now provides an option to disconnect the water supply for defaulting customers.
The enforcement for environmental legislation concerning the quality of drinking water rests with the Ministry of Health, but the CWA is obliged to provide drinking water that complies with
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The CWA is administered by a Central Water Board consisting of a Chairman appointed by the Minister of Public Utilities and representatives of Ministries in charge of finance, economy, local development, labour and industry and two members with experience in agricultural, industrial, commercial, financial, scientific or administrative matters, appointed by the Minister.
2.3.3.2 - The Water Resources Unit (WRU)
The Water Resources Unit (WRU) was created in 1992 within the Ministry of Public Utilities as the central organization for the coordination of activities regarding water resources management together with major water users such as the Central Water Authority, the Irrigation Authority, the Central Electricity Board and the Wastewater Management Authority. This resulted from a Government decision to separate the responsibilities for water service provision from water resources management. As soon as it was created, the WRU took over all water resources management and bulk water supply activities from the CWA.
The WRU is a division under the Ministry of Public Utilities and is the Ministry’s operating arm for water resource management. It is responsible for the formulation of policy regarding:
● The control and use of water resources for the provision of water for domestic, industrial, agricultural and commercial purposes and for hydropower irrigation,
● Land drainage and reclamation,
● Flood control and the control of soil erosion.
The WRU is also the enforcement agency with regards to inland water and the discharge of effluents to them. According to the EPA 2002, the WRU is responsible for enforcing environmental standards regarding the quality of inland waters. It therefore holds a crucial role in pollution prevention and control for industries and other activities discharging wastewater into the environment.
The present water utilization in Mauritius can be summarized as follows in Table 2.2 below:
Table 2.2 – Water Utilization in Mauritius per category
Category Water Utilization (Mm3/year) Domestic, industrial and tourism 224 Industrial (private boreholes) 11 Agricultural 490 Hydropower 289 Overall utilization 1014
Mauritius relies both on surface and ground water resources to meet its water demands. Ground water resources contribute up to 51% of the domestic water supply and 15% of the total water demand.
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However, it has been found that groundwater abstraction has almost reached saturation in certain regions. Furthermore, the following factors are increasing the pressure of the water supply capacity on the island:
• High variation in rainfall throughout the year and across the island. • Water shortages in the dry period from September to December • Rapid run-off due to topography • Decrease in average rainfall over the last 50 years • Submarine groundwater intrusion • High conveyance and distribution losses in water supply systems.
According to UNDP’s definition Mauritius is already water stressed as the present usable fresh water potential is equivalent to 1,083 m3/person/year compared to the threshold value of 1700 m3/person/year. Furthermore, the WRU has predicted that the country will suffer from water scarcity by the year 2030. Municipal water supply is expected to increase by 28Mm3/year and irrigation water needs will triple from 51Mm3/year to 152Mm3/year up to year 2040. The existing water resources will not be able to satisfy the water requirement by 2010
To address the growing water needs, the WRU has established a programme for future projects which includes construction of new dams, rehabilitation of existing reservoirs and feeder canals to reduce conveyance losses, additional hydrological investigations and borehole drilling to harness groundwater, construction of additional flow measuring stations and implementation of Water Demand Management measures.
The St.Martin WWTP is currently treating wastewater which is being sold to the Irrigation Authority for irrigation of sugar-cane fields. Some 45,000m3 of wastewater are being treated presently, representing only 52% of the final design capacity of 87,000m3/day. This represents a potential of 32Mm3/year for irrigation purposes and with future projects, re-use of treated wastewater will become an important component of water resources management.
2.3.4 - The Ministry of Agro-Industry and Fisheries
This Ministry is responsible for crops, forestry and livestock development, food technology and national parks and conservation services. According to the EPA 2002, the Department of Agriculture is responsible for enforcing legislation regarding the use of agrochemicals in order to prevent accumulation of pesticide residues in soils and waters.
The Ministry of Agro-Industry is responsible for monitoring the quality of coastal water quality through its Albion Fisheries Research Centre.
Agriculture is the biggest consumer of water, consuming about 48% of the total water resources of the country. In Mauritius, food security is highly dependant on irrigation development and planter’s security. Presently, the average annual demand is of the order of 425 Mm3/year.
The Irrigation Authority is the principal operating arm of the Department of Agriculture with respect to water use. It submits proposals to the CWA for the preparation of new irrigation schemes, it implements and manages irrigation projects, and it undertakes studies to optimize the use of water for irrigation purposes. Water for irrigation purposes is currently allocated by the WRU through the CWA. The IA has the duty to provide water to subsidized cost to farmers and
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The main development strategies of the IR are:
● Modernization and consolidation of existing irrigation schemes
● Development of new irrigation schemes, either of large or small scale, based on new water resources rationally used, among which is treated wastewater.
In Mauritius, the following methods of irrigation are used:
• Overhead irrigation • Drip irrigation • Surface irrigation
Overhead irrigation is the most extensively used, followed by surface irrigation. As a step towards more economical use of water resources, surface irrigation is being replaced by other forms of irrigation.
One recent major event in water resources management has been the Agreement between the Wastewater Management Authority and the Irrigation Authority for the sale of treated effluent from the St. Martin WWTP. The treated effluent is purchased by the IA to be injected into irrigation canals to supplement water for the West Coast Irrigation Project. The WMA is responsible for the supply of 46, 000 m3/day for the first year of the coming into force of the Agreement which came effective on the 11th February 2006. This volume will be increased gradually to approximately 68, 700 m3/day within 5 to 10 years; the effective annual available flow for each year will be communicated by the WMA to the IA, in writing, before the end of July of each year. The guaranteed minimum flow will be agreed mutually on a yearly basis.
The maximum flow of approximately 87, 000 m3/day will be conditional upon future connection levels and population growth. This amount of water will represent 85 % of the irrigation requirements of the 1, 500 ha of sugarcane being presently irrigated in the Western Coastal Plain.
2.3.4 - Ministry of Health and Quality of Life (MHQL)
This Ministry is responsible for public health infrastructure, and is also devoted to the health and well-being of the public. Through the EPA 2002, the Ministry is responsible for enforcing environmental legislation regarding level of noise, the quality of air and the quality of drinking water. The Ministry of Health and Quality of Life monitors the quality of drinking water delivered to the public with regard to the physical, chemical and microbiological parameters.
Under the Sanitary Act, the Ministry of Health can issue Sanitary Notices for cases of nuisance from on-site wastewater disposal systems.
2.3.5 – Existing Institutional Arrangement
The existing institutional arrangement between the main institutions involved in wastewater management is depicted at ANNEX 2.2
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2.4 – Assessment for Mechanisms for Stakeholder Involvement in Municipal Wastewater Management
2.4.1 – Stakeholders involved in Municipal Wastewater Management
The stakeholders involved in municipal wastewater management are:
● Central Government ● International Funding Agencies ● Main Institutions involved in wastewater management: • Ministry of Finance and Economic Development • Ministry of Public Utilities ▫Wastewater Management Authority ▫ Water Resources Unit ▫ Central Water Authority • Ministry of Environment & NDU • Ministry of Agro-Industry and Fisheries ▫ Irrigation Authority • Ministry of Health and Quality of Life ● Other Institutions in wastewater management • Ministry of Public Infrastructure • Ministry of Housing and Lands ● The Industrial Sector ●The Public and Media
2.4.1.1 – Central Government
The Government of Mauritius has shown its full commitment for the development of the municipal wastewater infrastructure, for the collection, conveyance, treatment and safe disposal of wastewaters.
Since the development of the first National Environment Action Plan and recommendation for a Sewerage master Plan and National Sewerage Programme, its efforts and constant strive have been successful in securing the necessary funding from international funding agencies for necessary financial resources. Government has always kept a close follow-up on the development of the wastewater infrastructure.
Major wastewater projects, including the construction of four major wastewater treatment plants, have been completed.
Additional funds required to top up loans and grants for the capital sewerage projects are made available through the National Budget.
The percentage coverage will increase from a mere 18% before the NSP to 50% by the year 2015 with the implementation of the Plaines Wilhems Sewerage Project which has already started.
Government policy in environmental matters has ensured that existing environmental laws and regulations specify that the wastewater aspects of all infrastructural and industrial development are properly assessed and handled.
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The protection of water resources has also been given prime importance with the setting up of national laboratories, monitoring and enforcement programmes. Coordination is ensured through a system of committees starting as from the highest level, i.e. the National Environment Commission chaired by the Prime Minister.
The Wastewater Management Authority has been established as the sole organization responsible for wastewater management in the country. The development and performance of this organization is closely monitored by the Government.
It is obvious that wastewater management lies very high on the Government’s agenda as the overall development of the country, including well-being of its citizens, and future of new pillars of the economy, such as the tourism industry, are directly concerned.
2.4.1.2 – International Funding Agencies
From the First to the Fourth Lome Convention, funds have been made available under co- operation administered by the European Commission, under the National Indicative Programmes to finance projects in areas such as agriculture, industry, infrastructure, tourism, health, education and human resources development, the environment, the private sector and poverty alleviation.
Under the 8th European Development Fund, more emphasis was laid on the environment sector whereby there will be a measurable impact in terms of strengthening of institutional capacity and the sustainability of the sectoral investments.
A number of EU Member States and other Donors are involved in the environment sector in Mauritius. Government arranges regular donor co-ordination meetings in sectors in which a number of donors are involved.
However, over the last decade, Mauritius has experienced a decline in Official Development Assistance from all sources due to increase in per capita income levels. There has correspondingly been a significant increase in loans.
After due consideration of the strategic options, it was concluded that the environment sector, and specially the wastewater sub-sector, was the area to which the bulk of the European Commission’s support could most usefully be directed.
The presence of a number of donors and lenders in the wastewater sector indicates that there is high level of donor co-ordination on projects and that conditionalities are respected.
Indeed more than ten major international funding agencies and Donor Countries have been funding wastewater projects in Mauritius.
2.4.1.3 - Main Institutions involved in wastewater management:
The roles and mandates of the main institutions involved in wastewater management have been discussed in depth in Section 2.3. Their responsibilities are summarized in the Table 2.3 below.
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Table 2.3 – Responsibilities of Main Institutions Involved in Wastewater Management
Institution Responsibilities
Ministry of Public Utilities Water Resources Management
Wastewater Management Construction of Sewerage Infrastructure, Operation & Authority Maintenance of Existing Infrastructure, pollution control & monitoring of effluents Central Water Authority Sole undertaker for the supply of water for domestic, commercial and industrial purposes Water Resources Unit Assessment, development, management and protection of water resources in Mauritius Ministry of Environment & Policy making and quality conservation of water bodies and NDU overall planning and regulation of inland and coastal waters
Ministry of Agro-Industry & Monitoring of Coastal Water Quality Fisheries – Fisheries Division
Irrigation Authority Provide agricultural water to farmers to an affordable price
Albion Fisheries Research Coastal water quality monitoring Centre
Ministry of Health & QL Sampling and analytical testing of water quality at consumer’s end
2.4.1.4 - Other Institutions in wastewater management
2.4.1.4.1 - Ministry of Public Infrastructure The Ministry of Public Infrastructure is responsible for the design, construction, supervision, maintenance and furnishing of Government buildings. These responsibilities are shouldered by the Engineering Division whose tasks are:
• The supervision and monitoring of all government building works;
• The structural design of all Government Building projects;
• The provision of an advisory service to other Governmental / parastatal bodies on building construction matters, accidents or complaints;
• The reviewing of proposals from Engineering Consultants who are appointed to perform such works that the Engineering Division entrusts them;
• The advising of architects of the Ministry in correctly formulating architectural drawings;
• The development of a structural proposal for a buildable architectural project;
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• The carrying out of all necessary soil tests and explorations for safely designing foundations to building structures;
• The provision of an asset management service through its maintenance section;
• The drafting of policies / instructions for new regulations
The Engineering Division is responsible for the implementation of public buildings and infrastructure such as hospitals, schools and liaises with the WMA for the necessary information regarding population, water consumption, soil investigations such as percolation tests, and depth of water table and description of soil strata. This is to ensure that on-site wastewater disposal systems are properly designed and constructed. The Engineering Division and the WMA liaise through different meetings and Building Plans Committees and the WMA approval is sought before giving final Building Clearance to any infrastructural development.
2.4.1.4.2 – The Ministry of Housing and Lands The role of the Ministry of Lands and Housing is to provide a basis for the long term development of the country which supports the national development strategy and direct development while taking into consideration economic competitiveness with environmental sustainability and social equity. The responsibilities of the Ministry of Housing can be summarized as follows:
• To provide the special context for a co-coordinated approach to a physical infrastructure planning and programming which supports national development objectives;
• To integrate and modernize the legal and institutional structure for physical development planning, control and enforcement so that meaningful lasting results can be achieved;
• To satisfy the housing and land needs of the people of Mauritius;
• To achieve more effective management and use of State Lands;
• To devise plans, policies and programmes which are robust, flexible and balanced.
• To integrate land use planning with the forthcoming new transport choice;
The Ministry of Housing and Lands normally liaises with the WMA for, guidance in the wastewater aspects, through correspondences, meetings committees and seminars:
• in the preparation of National Development Strategies for the long term growth and physical development of the country
• To prepare framework for the local authorities to guide and control development in their area
• To devise and implement housing and land policies and programmes
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2.4.1.5 – The Industrial Sector
The industrial sector has an important role in wastewater management in helping to ensure that industrial processes do not impact negatively on the environment .There has been a long standing co-operation between the WMA and sewered industries well before the implementation of the Wastewater (Standards for the Discharge of Industrial Effluents into a Waste Water System) Regulations 2004. The necessary framework to ensure that industries install the necessary pre- treatment facilities and monitor results of effluent through sampling and analysis has been in force for more than ten years and has been formalized by the implementation of the above- mentioned regulations.
As discussed in Sections 2.2.2.2 and 2.2.2.3, numerous meetings were held with representatives of the industrial sector during the preparation and implementation of the Regulations.
The requirement for either an EIA, PER License and a Land Use and Building Permit from the WMA for most industrial activities also ensures strong commitment from the industrial sector to see to it that necessary pre-treatment facilities are designed and constructed before final clearance for operation is granted.
Industries which are operating with an Industrial Discharge Permit submit monthly reports with results of analysis of their effluents and compliance with the requirements of the Permit is verified.
2.4.1.6 - The Public and Media
The Sector Policy Letter states that one of the key features through which the objectives of the Policy are to be achieved is stakeholder participation and consultation. In that spirit, the WMA undertook public media campaigns under the IBRD Loan for the Montagne Jacquot Project. These have been carried out over a number of years and comprised television clips, radio announcements, posters, brochures and pamphlets, to encourage safe hygienic habits, and to encourage and promote the connection of premises to the sewerage system, where available. It is now the policy of the WMA to include a Public Relations component in every major sewerage implementation project to reinforce public awareness and also to mitigate problems that might be encountered during project implementation.
2.4.1.6.1 – Public Awareness on Sewerage Projects - Press Conference for the Plaines Wilhems Sewerage Project (PWSP) The Plaines Wilhems Sewerage Project consists of the laying of about 25 km of trunk sewer of diameter ranging from 300 mm to 1100 mm, 270 km of secondary and tertiary sewers and the connection of some 32, 500 existing households. The first component which is the laying of the trunk sewers has reached about 92 % completion. The project area consists of densely urbanized and commercial regions with heavy traffic.
A Press Conference and a Press Information Tour were organized to explain to the general public the importance of the new trunk sewer project and to inform about the progress of the works. The news
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2.4.1.6.2 – Public Relations and Customer Care A road map of the Public Relations and Customer Care Unit has been developed so as to boost up the image of the Organization and to respond in a proactive manner towards the different stakeholders.
The Public Relations Strategy of the organization focuses on:
• Respond to the needs and requests of Customers
• Organize awareness campaigns where emphasis is laid on the protection of the environment
• Register complaints and ensure follow up
2.4.1.6.3 - Radio Programmes Regular radio programmes are broadcast on the various Radio Channels so as to explain the different activities related to the implementation of WMA major projects. Communiqués are issued as and when required. Live radio interaction with customers is carried out.
2.4.1.6.4 - Meeting with the Representatives of Inhabitants in different localities Several meetings are held to explain the importance of the PWSP to the inhabitants and its benefits to the environment. This interaction enables the contractors to proceed with the works smoothly and close monitoring is exercised by the PR Department.
2.41.6.5 - Complaints A Hotline is operational so as to enable the WMA to handle and response to customers’ grievances and complaints. Also, the PR Department has two PR Coordinators whose role is to communicate constantly with all stakeholders to keep them informed about the progress of work.
2.4.2 – Private Sector Participation
It is Government policy to encourage private sector participation in the wastewater sector. Thus, to this end, the operation and maintenance of several small wastewater treatment plants and pumping stations has been outsourced to private contractors through service contracts. The construction contracts for the major wastewater treatment plants require the contractor to provide a reasonable period of O&M of the works after the date of commissioning. This ensures the achievement of good technical practices as well as providing technology and knowledge transfer to WMA staff.
Outsourcing of engineering services including feasibility studies, detailed design, works supervision, and in some cases public relations campaigns, for major sewerage projects to international consultants, in association with local sub-consultants, through competitive bidding, is a prerequisite of most of most loan conditionalities. This ensures that proper design methods are adopted and that works are implemented to the required standard and at reasonable costs. In the same spirit, major works contracts are outsourced to international and local private contractors through competitive bidding. It has been observed that local contractors do not have the required experience for operating and maintaining WWTPs and PS and the WMA has decided that a hybrid system of in-house O&M and outsourcing be put in place.
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In the past, sewerage projects were implemented by constructing only street sewers and providing a side connection that stopped at boundary limit for each property. It was then up to the residents to make an application for connection. The resident had to hire a contractor to construct the sewer network inside his premises at his own costs, as well as the connection to the main sewer. As the cost of such works were prohibitive, this led to slow rates of house connections, meaning a loss of income for the WMA To overcome this problem, the Government decided that domestic house connections be free of charge. The WMA now outsources the construction of the individual house sewers to private contractors through competitive bidding. In this way the rate of house connections has increased as well as rate of income generation for the WMA. This also ensures employment generation in the construction industry.
For a number of years, the WMA was the only service provider for cesspool emptying. However, the organization did not have the necessary resources to cope with the demand from the public. The cesspool emptying services has therefore been outsourced to a list of about 24 cesspool emptying operators who are duly registered with the WMA.
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2.5 – Assessment of Existing Financing Mechanisms
2.5.1 – Financial Obligations pertaining to legal and institutional mechanisms
As discussed in Section 2.1, the legal framework in which the WMA should operate is specified by the WMA Act 2000. Institutionally, the WMA also operates under two contracts which it has with the Ministry of Public Utilities, namely, the Contrat de Délégation and the Convention de Maîtrise d’Ouvrage Déléguée. The need for financial sustainability of the wastewater sector is also one of the objectives of the Sector Policy Letter -1998.
The existing financial mechanisms in the wastewater sector are therefore dictated by the various provisos specified in the above-mentioned documents.
2.5.1.1 – Wastewater Management Authority Act 2000
Part II, Section 4, Objects of the Authority, part (d): Ensure the generation of sufficient resources from tariffs to finance the operation, maintenance and depreciation costs of wastewater systems, sewerage and sewage treatment installations.
Part II, Section 5, Duties of the Authority, part © Recover through tariff user fees that may be claimed in respect of the lease of assets under a ‘Contrat de Délégation’
Part VI, Section 43 (1) and (4)
(1) The Authority may claim from the owner or occupier of premises any expenses properly incurred for any services provided or performed by the Authority under this Act for the collection, treatment or disposal of effluent from such premises. (4) The expenses recoverable by the Authority under this section and the fees, rates and charges due to it pursuant to sections 25 and 26, may be secured by the Authority by the inscription of a charge on any of the properties of the owner or occupier of premises who has not paid any sum due by him within the delay fixed for payment.’
2.5.1.2 – Contrat de Délégation
Article 20. Provides for the payment by the delegataire (WMA), of user fee to the delegating authority (the Ministry of Public Utilities) which shall ‘increase until the revenues provided by the tariff covers the full cost of services…..plus the annuities in respect of project cost on all sanitation services assets belonging to the delegating authority and in respect of investment made by the delegating authority’
Article 21. Provides that all revenue collected belongs to the delegataire, and that prices shall be entitled to be increased annually, by applying the Consumer Price Index to them.
2.5.1.3 - Convention de Maîtrise d’Ouvrage Déléguée.
Article 12; Authority’s Remuneration
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12-1 In consideration for its mission, the Authority shall receive from the Government a bulk remuneration amounting to 2% of the cost of the works.
2.5.1.4 – Sector Policy Letter - 1998
One of the objectives of the Sector Policy Letter is that the wastewater sector shall be financially sustainable and that a cost recovery system should generate enough resources to cover
• Depreciation – for replacement of assets • Recovery of all operating costs – Operation and Maintenance, Administrative, Commercial Costs – associated with the WMA. • Interests – recovery of cost of capital.
Appropriate tariffs for all customer categories are to be selected to generate revenues during the useful life of the assets. These tariffs should take into account equitability.
2.5.2 – Capital Expenditure
Funding for implementation of capital projects earmarked under the National Sewerage Programme comes mostly from loans and grants from international funding agencies.
The Ministry of Finance and Economic Development is the interface between the Government of Mauritius and the international funding agencies. The needs and priorities of the country in the field of wastewater are discussed with the funding agencies and loans or grants are negotiated.
The Government of Mauritius has successfully secured the necessary funds through loans and grants with international funding agencies to finance the National Sewerage Programme. The implementation of identified priority projects is in progress, with some revisions in the scope of works, as envisaged in the original Master Plan.
At present 40 contracts pertaining to consultancy services and works contracts are at various stages of implementation, representing an investment budget of about MUR 13.57 billion.
The WMA has achieved the relevant performance indicators established by the international donors for the Financial Year 2005/2006, namely, ‘Annual Capital Expenditure under NSP as a percentage of approved budget’.
2.5.3 - Recurrent Budget
Revenue to cover user fee payable to the Ministry of Public Utilities, Operation & Maintenance costs, Project Management costs and all associated overhead costs is generated mainly from the following sources:
• Domestic and Non-Domestic Tariff • Project Management Fee (from the Government of Mauritius for managing the capital projects) • Sale of treated effluents
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2.5.3.1 – Tariff
The structure of tariffs, effective since January 2000, is in accordance with the commitments spelt out in the Sector Policy Letter – 1998.
The following table illustrates wastewater tariffs agreed by GoM for the domestic and non- domestic customers under the 1998 Sector Policy Letter and Tariffs for the period 2000 to date
Table 2.4: Sector Policy Tariffs and Tariffs applied for the period 2000-2006 (USD = MUR 32.00) WASTEWATER TARIFFS MUR PER M3 FINANCIAL YEAR 98/99 99/00 00/01 01/02 02/03 03/04 04/05 05/06
DOMESTIC TARIFF 7.50 9.10 - -
Domestic Tariff as per SPL 2.80 2.80 4.40 6.40 - - - -
Domestic Tariff Implemented 2.30 4.40 6.00 6.90 6.90 6.90 6.90
Date Implemented Jan 00 Jan 01 Jan 02 Aug 03
NON DOMESTIC TARIFF
Non-Domestic Tariff as per 13.00 13.60 14.20 14.90 15.50 16.20 - - SPL
Non-Domestic Tariff 6.00 8.60 12.00 15.50 15.50 15.50 15.50 Implemented 12.00*
Date Implemented Jan 00 Jan 01 Jan 02 Aug 03 Jan 04 * Textile and clothing companies that had been granted a certificate under Section 15 of the Investment Promotion Act paid Rs. 12.00/m3 during period 1 Aug to 31 Dec 2003
The wastewater charges applied to WMA’s customers is based on the volume of water consumed and was fixed as a percentage of water charges at the start of 1998/1999.The preparation of the bills and the preparation thereof are being managed by the Central Water Authority, under a Joint Billing Agreement between the WMA and CWA which entails payment of a fee of 5% to the CWA, based on the value of income collected and remitted to the WMA each month.
During the financial year 2005/2006, a recovery ratio of 87.52 was achieved.
● Tariff Study
The Ministry of Finance and Economic Development (MOFED) has, as contracting agency, engaged an international firm of consultants to carry out Technical Assistance for the Mauritius Wastewater Sector policy Support Programme. A Tariff Study, as additional task, was also requested under the same Technical Assistance. The objective of the study is to provide the necessary recommendations for ensuring the financial sustainability of the wastewater sector, taking into account the projects that are being executed under the National Sewerage Programme.
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A new Sector Policy Statement for the period 2007-2012 is in the process of being prepared.
2.5.3.2 – Project Management Fee
The WMA receives a fee payable by the Ministry of Public Utilities for managing projects under the NSP. This is set at 2% of the value of projects (including design and supervision) carried out each year. This project management fee will normally last until the NSP is completed.
2.5.3.4 - Sale of treated effluents
Under an Agreement between the WMA and the Irrigation Authority, the WMA is selling about 45, 000 m3 per day to the Irrigation Authority at the rate of MUR 0.80 per cubic meter. This volume will be increased depending on the implementation of the Plaines Wilhems Sewerage Project, whereby the flow channeled to the St Martin WWTP is expected to be of the order of 87,000 cubic meters per month.
Some 3,000 cubic meters of treated effluent are expected to be sold under an on-going negotiation with an international firm which is implanting a waste-to energy facility by incineration of municipal waste.
2.5.4 – Discussion
The Government of Mauritius has successfully secured loans and grants from international donors so as to fund the priority wastewater projects earmarked under the NSP. It is fully committed to provide the necessary additional funds under the National Budget so as to ensure that the NSP is fully implemented.
Revenue collection through tariff and project management fee have provided the necessary financial resources to sustain the recurrent budget and to finance the operation and maintenance of the assets vested into the WMA, to undertake the project management of capital projects and to cater for all other overheads associated with these two main activities.
The WMA has been able to be financially sustainable till now. However, the St. Martin WWTP, which has recently been constructed, is being operated and maintained by the contractor who constructed the plant. The financial resources are still being provided under Capital Budget. Likewise, for the Grand Baie sewerage system, the pumping stations are being operated and maintained by the contractor; only the WWTP is being operated and maintained by the WMA personnel. Upon completion of these contracts, the WMA would be required to take over fully and would need to provide the financial resources to operate and maintain these WWTP and PS in house or through service contracts.
Also all new wastewater infrastructures, upon completion will be vested into the WMA to operate and maintain.
Consequently, the recurrent expenditure of the WMA is expected to increase significantly over the next few years and the revenue would be increased through the increasing number of house connections and review of tariff so as to ensure the financial sustainability.
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2.6 – Conclusions and Recommendations
The existing policy, regulatory and institutional setup in Mauritius has been conducive to important progress in the wastewater sector. Indeed, a clear and comprehensive statement of the policy of the Government of Mauritius has been declared in the Sector Policy Letter of 1998.
The National Sewerage Plan which comprises a list of priority sewerage projects that are focused on the most urbanized areas of the island and the most environmentally vulnerable areas will be completed by 2012/13. Most of the projects under the National Sewerage Programme have been successfully completed and the NSP itself will be implemented with a delay of about 3 years. Thus Government’s objective to connect 50 % of the population by the year 2015 will be attained. The Terms of Reference for a second master plan is under preparation and thus the priority projects and overall plan to connect 80 % of the population by the year 2030 is well under way.
As a direct result of the Sector Policy Letter of 1998, institutional reforms have established the WMA in 2001 as the provider and operator of public wastewater services. It has been equipped with the necessary technical, legal, institutional and financial frameworks to enable the WMA to pursue its objectives.
Inter-sectoral co-operation between the industrial sector and the WMA for the implementation of the Wastewater Regulation for the acceptance of industrial wastewaters in the sewers has been a success as most of the most important industries located in the sewered areas have been licensed and are being regularly monitored. For almost all cases, quality of effluents discharged to sewers is within required standards as a result of implementation of required pre-treatment facilities by the industries.
The WMA is encouraging private sector participation in the wastewater sector.
The large share of the National Capital Budget that is targeted at the wastewater sector shows the strong political commitment of the Government of Mauritius to ensure that the Sector Policy in wastewater is achieved. For the financial year 2007/08, MUR 1.5 billion, representing 15% of the National Budget, has been allocated to the wastewater sector
However certain considerations will be critical in determining the future success in the wastewater sector.
2.6.1 – Maintaining financial sustainability
One of the main challenges facing the WMA in the near future is maintaining financial sustainability. As the number of WWTPs/PS and the sewerage network increases every effort should be put in place to increase the number of house connections so that enough revenue is collected for the O&M of the system. Also, presently only 25% of the population has been provided with sewerage facilities. This will increase to 50% and 80% by the year 2015 and 2030 respectively. The sewerage infrastructure that will need to be operated and maintained by the WMA will therefore increase considerably and necessary funds will have to be raised accordingly. The tariff needs to be constantly reviewed to ensure financial sustainability of the WMA.
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Piped sewerage technology adopted require extensive disbursement of funds. However such technology is justified by the high level of individual water connections in urbanized areas, together with a large number of industrial users. Similarly, the sophisticated wastewater treatment methods adopted are justified by the quality standards required for the disposal and re-use methods. Also, in the financial feasibility of re-use of wastewater for agriculture, due consideration should be given to savings made in existing water resources as well as savings in dam infrastructure and associated environmental/social impacts.
In the future, feasibility studies should also consider implementation of new low-cost treatment technologies and alternative treatment technologies in regions with relatively low population and no industries. Low-cost treatment technologies such as constructed wetlands can also be linked with effluent re-use and valorization of protein and nutrients in wastewater through crop production, fodder production for animal rearing, other plants like papyrus for craft products and aquaculture. This could alleviate the high capital and O&M costs associated with conventional municipal wastewater collection, treatment and disposal
According to the Sector Policy Letter -1998, the Government’s objective, over the long run, is to invest in developing the Mauritius Sewerage Sector into a centre of excellence in sanitation services to provide expertise to the Indian Ocean Region as a whole.
2.6.2 – Public Awareness and Sensitization
There is a general attitude in developing countries that potable water and sanitation should be obvious services to be provided at a minimum cost by a government. Introduction of tariff in the wastewater sector initially faced serious opposition due to a lack of understanding from the general public regarding the need for proper collection, treatment and disposal of wastewater and its effect on the environment and public health. A low connection ratio can seriously jeopardize the financial sustainability of the wastewater sector. Hence an appropriate Information Campaign can sensitize the public as to why their premises should be connected to the public sewer even though on-site sanitation had been practiced for years without any apparent problem.
The lack of proper understanding and appreciation of the whole sanitation sector stems mainly from a lack of information. It is therefore recommended that basic sanitation principles be introduced at primary school level to change the whole cultural attitude of the coming generation. The attitude and perception of the public can be upgraded by media campaigns and television programs where dedicated WMA staff can provide useful information on sanitation to the general public. This, coupled with the need for better water resources management, can sensitize the public on water conservation and better use of sanitation facilities, increased willingness to pay for sanitation services as an informed and educated population will feel more concerned by knowing that their behaviour will affect the future generation is terms of water availability and environmental degradation. Annual presentations to inform the public about the achievements of the WMA in terms of expansion of the sewerage infrastructure, environmental protection through monitoring and control of effluent discharges, re-use of treated wastewater will also increase the public’s interest and participation in the wastewater sector. An educated and informed population will ensure full participation and co-operation of stakeholders at all levels, be it the general public or the industrial sector.
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2.6.3 –Capacity Building
As more complex projects are implemented and sewerage coverage is increased, the skills and competencies of the WMA need to be refined.
2.6.4 – Legal aspects regarding on-site sanitation
The responsibility of the WMA regarding on-site sanitation is not specifically spelt out in the WMA Act 2000. However interpretation of various sections of the Act indicate that the WMA does have a responsibility in ensuring that all disposal systems are built according to designs prescribed or approved by the WMA. Necessary guidelines for on-site disposal systems have been incorporated in the Planning Guidelines for Urban Authorities. As discussed in Section 2.2.3.2, only developments found within the sewered municipal jurisdictions required a clearance from the WMA. The majority of buildings in the rest of the country did not require a clearance from the WMA. As such, building permits were issued without proper assessment of proposed on-site wastewater disposal systems and due to absence of any enforcement, most people have been using cesspits or completely undersized/ unsuitable on- site disposal systems. In some cases, conventional septic tanks followed by absorption systems have been built in regions of low permeability or high water table, leading to rapid failure and overflow.
A proper institutional structure needs to be set up to implement sound on-site wastewater disposal practice.
It has been discussed that, by virtue of its existing institutional structure, it is not possible for the WMA to take responsibility for on-site disposal systems islandwide.
The role of the WMA should therefore be limited to an advisory capacity and the responsibility for approval of designs and enforcement of proper construction of on-site wastewater facilities should rest with the local authorities. Guidelines can be prepared for the District Councils and Municipalities for simple systems. For this purpose, building inspectors and technical staff in local authorities should be given the necessary training to shoulder this responsibility. This would not entail much additional responsibility since building inspectors are already responsible for making frequent site visits to construction sites to ensure that construction is proceeding as per approved plans.
2.6.5 – Regulatory aspects
Each public laboratory monitoring water quality work has its own work schedule. A synergy of laboratories should therefore be sought whereby public laboratories should not work as different entities belonging to individual organizations. An optimum management of the public laboratories by sharing of resources and staff will be in the definite advantage of all organizations.
2.6.6 – Enforcement of environmental laws
Enforcement of Regulations under the EPA 2000 has not been fully implemented due to lack institutional capacity. In some cases, institutions are too much taken up with their core activities and do not have the required resources for enforcement. Better co-ordination and co-operation is required between enforcing agencies.
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Chapter 3 – Inventory of Municipal Wastewater Infrastructures
3.1 – Background
3.1.1 – Mauritius : A Coastal Island
Though, under the Terms of Reference for this study, the coastal zone has been defined as any area situated within 100 km from the ocean, this definition obviously applies only to continental countries, and not to Island States with sizes less than 100 km. In Mauritius, due to the interconnectivity of surface water, ground water and the sea, all activities, inland and coastal, have an impact on the lagoonal and sea water quality, either by point discharge or diffuse discharge. The coastal zone in Mauritius is defined in the Environment Protection Act 2002 as any area situated within 1 km from the high water mark, extending either side into the sea or inland. In view of the small size of Mauritius, demographic data within the coastal zone and the level of migration is negligible. It is therefore relevant, for the purpose of this assignment, to extend this study to the whole of Mauritius, as being a coastal zone.
3.1.2 – Mauritius: Demographics
3.1.2.1 – Introduction
The island of Mauritius is divided into nine geographical districts as shown at ANNEX 3.1 which also shows the major towns and villages. The estimated mid-year population for 2003 based on the year 2000 Census extrapolated on a basis of 1% increase per year is shown in Table 3.1 below.
Table 3.1 – Mid-year geographical distribution of population as at mid 2003 District Estimated Mid-year Area Population Population (Square Density / km2 kilometers) Port Louis 130, 188 42.7 3, 049
Pamplemousses 128, 123 178.7 717
Riv. du Rempart 103, 085 147.6 698
Flacq 132, 401 297.9 444
Grand Port 110, 610 260.3 425
Savanne 68, 292 244.8 279
Plaines Wilhems 370, 089 203.3 1, 820
Moka 77, 934 230.5 338
Black River 65, 641 259.0 253
WHOLE ISLAND 1, 186, 363 1, 864.8 636
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The urban population (Port Louis and Plaines Wilhems Districts) total to 518, 368, representing 43.7 % of the population. The remaining 7 Districts, called the Rural Districts have a population of 667, 995, representing 56.3% of the total population. Furthermore, the estimated mid-year population for the 5 towns, located in the urban districts, and 15 major villages, located in the rural districts, are shown below in Table 3.2 and Table 3.3 respectively
Table 3.2 – Estimated Mid-Year Resident Population of Towns – 2003
District Municipal Council Area Population Population Density Per km2 Port Louis Port Louis 147, 688 3, 164.5 Beau-Bassin-Rose Hill 106, 978 5, 137.1 Plaines Wilhems Vacoas-Phoenix 103, 564 1, 856.9 Curepipe 81, 600 3, 339.8 Quatre Bornes 78, 538 3, 606.7 Total 518, 368
Table 3.3 – Estimated Mid Year Resident Population of Large Villages – 2003
Rural District Village Council Area Population Population Density /km2 Pamplemousses Triolet 22, 271 1, 572.5 Le Hochet 14, 545 2, 586.4 Baie du Tombeau 12, 588 1, 639.5 Riviere du Rempart Goodlands 20, 096 1, 060.3 Riviere du Rempart 11, 222 737.9 Flacq Central Flacq 16, 937 808.1 Bel Air-Riviere Seche 16, 898 901.0 Grand Port Rose Belle 12, 097 1, 518.4 Mahebourg 16, 333 7, 332.8 Plaine Magnien 10, 331 727.7 Savanne Chemin Grenier 12, 130 1, 357.0 Surinam 10, 340 1, 164.9 Moka St Pierre 15, 880 1, 185.2 Pailles 10, 276 738.8 Black River Bambous 12, 348 546.7 Total 196, 686
Table 3.3 above shows that about 16.3% of the total population lives in fifteen large villages in the rural district. Tables 3.2 and 3.3 show that 60% of the total populations live in the five towns and 15 major villages. The rest 40% of the population is scattered over the island, which has nearly half of its area under cultivation. The distribution of the population in the various districts can be seen from the indicative built-up areas for the different districts on Maps at ANNEX 3.2 Table 3.4 below shows the number of towns and villages within different bands of population density. There are five towns (Municipal Council Areas) and 124 Village Council Areas in Mauritius
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Table 3.4: Number of towns and villages within different bands of population density
No. of Towns / Villages Range of Population Density per km2 1 7000 – 7500 1 5000 – 5500 4 3000 - 4000 1 2500 – 3000 4 1600 – 2000 4 1400 -1600 5 1200 – 1400 6 1000 - 1200 9 800 – 1000 21 600 – 800 22 400 – 600 20 200 - 400 19 100 – 200 8 50 – 100 4 20 -50
3.1.2.2 – Demographics – Districtwise – Rural Districts
The population, housing trends, nature of activities and scatter of population over the rural districts are very different from the urban areas. These criteria, among others, will influence the type of sanitation to be adopted in these districts. In this sub-section, these issues are discussed.
The population and housing trends, per district, as per the 1990 – 2000 Censuses, Central Statistical Office, are given hereunder, for the rural districts. The maps of the different districts showing the settlement boundaries, the growth zones and indicative built-up areas are shown at ANNEX 3.2. Generally, for all the rural districts, households and housing units increased faster than population due to decreasing household size, reduced household/housing unit ratios and increases in the number of unoccupied dwellings.
3.1.2.2.1 – Pamplemousses
The population of the Pamplemousses district increased by nearly 20% from around 100, 000 in 1990 to 120, 000 in 2000, an increase of 20, 000 people. This rate of growth was higher than any other District except Black River and is well above the national and rural growth achieved during the same period. Households and housing units increased by 38% and 46% respectively over the same period. The increase in population and housing units over the period 1990 -2000 for the different district sub-areas are shown in Table 3.5.
There are substantial variations in growth rates between different parts of the District with slow or little growth in the inland areas but rapid growth in the coastal areas; the growth rates for the population and housing in Baie du Tombeau/Terre Rouge area were among the highest in the country due to their proximity and easy access to the capital and harbour, Port Louis. In this area, the number of housing increased by about two thirds between 1990 and 2000.
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Table 3.5 – Pamplemousses Sub-areas: Population and Housing
DISTRICT SUB-AREAS Population Housing Units-Year 2000 1990 2000 AGR 1990 2000 AGR Terre Rouge, Baie du 24, 259 33, 622 3.3% 5, 413 8, 914 5.1% Tombeau, Le Hochet Creve Coeur, Long 11, 994 13, 299 1.0% 2, 354 3, 176 3.0% Mountain, Notre Dame Congomah, Ville Bague, 10, 449 10, 711 0.2% 1, 981 2, 447 2.1% D’Epinay, Notre Dame Calebasses, 16, 811 18, 944 1.2% 3, 397 4, 448 2.7% Pamplemousses, Mapou, Plaines des Papayes Grand Baie, Fond du Sac, 11, 604 13, 524 1.5% 2, 542 3, 793 4.1% Morcellement St. Andre Arsenal, Triolet, Pointe 25, 263 30, 266 1.8% 5, 069 7, 550 4.1% aux Piments Pamplemousses District 100, 380 120, 366 1.8% 20, 756 30, 328 3.9%
The Terre Rouge area contains over a quarter of the District’s population. Triolet however, is the largest settlement, with a population in excess of 20, 000. Both are designated as growth zones in the National Development Strategy (NDS) as is the area of Pamplemousses and the main tourist area, Grand Baie.
Hotel development has clustered around the northern coastline from Grand Baie to Pointe aux Cannoniers and along the north-western coast at Trou aux Biches, Baie aux Tortues and Baie du Tombeau, primarily those sections of the coastline with sandy beaches.
3.1.2.2.2 – Riviere du Rempart
The population of Riviere du Rempart increased by nearly 20% from around 86, 000 in 1990 to 98, 000 in 2000, an increase of 12, 000 people. This rate of growth was slightly above the national growth rate achieved during the same period but was similar to that achieved by all rural districts.
Households and housing units increased by 31% and 37% respectively over the same period. The increase in population and housing units over the period 1990 -2000 for the different district sub- areas are shown in Table 3.6
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Table 3.6 – Riviere du Rempart Sub-areas: Population and Housing
DISTRICT SUB-AREAS Population Housing Units 1990 2000 AGR 1990 2000 AGR Grand Baie, Petit Raffray, Cap 20, 264 24, 397 1.9% 4, 960 7, 116 3.7% Malheureux, The Vale Roche Terre, Goodlands, Grand 24, 819 28, 580 1.4% 5, 012 6, 898 3.2% Gaube Poudre d’Or, Poudre d’Or Hamlet, 14, 853 16, 259 0.9% 2, 857 3, 769 2.8% Cottege, Esperance Trebuchet, Piton, Mapou Riv du Rempart, Roches Noires, 26, 089 28, 726 1.0% 5, 269 6, 968 2.8% Plaine des Roches, Amitie, Belle Vue Maurel, Amaury, Villebague Riviere du Rempart District 86, 025 97, 962 1.3% 18, 098 24, 751 3.2%
There is relatively little variation in growth rates between the different parts of the District although the area nearest the conurbation and that with the biggest concentration of tourist activity (Grand Baie) has grown at a significantly faster rate than other parts of the District. In this area, the number of housing units has increased by over 40% between 1990 and 2000.
Riviere du Rempart District contains three main urban centres: Grand Baie - Pereybere, Goodlands and Riviere du Rempart, plus a smaller number of village centres.
The Grand Baie/Pereybere cluster is a major tourist centre at the heart of the Northern Tourist Zone with significant development. Goodlands is a thriving commercial centre whereas Riviere du Rempart is essentially a residential zone.
3.1.2.2.3 – Flacq
The population of Flacq increased by around 12% from about 109, 000 in 1990 to 123, 000 in 2000. This growth rate was similar to the national and rural growth rates achieved the same period. Households and housing units increased by 29% and 33% respectively over the same period, similar to the national rates but lower than the all-District average. The increase in population and housing units over the period 1990 -2000 for the different district sub-areas are shown in Table 3.7.
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Table 3.7 – Flacq Sub-areas: Population and Housing
DISTRICT SUB-AREAS Population Housing Units 1990 2000 AGR 1990 2000 AGR Lallmatie/Bon Acceuil 24, 249 28, 042 1.5% 4, 436 6, 252 3.5% St. Julien/Camp de Masque 15, 202 17, 832 1.6% 2, 297 4, 042 3.3% Centre de Flacq 18, 470 18, 601 0.1% 3, 775 4, 411 1.6% Poste de Flacq/Quatre Cocos 10, 107 11, 950 1.7% 2, 082 3, 293 4.7% Camp Ithier/Ecroignard 9, 734 11, 257 1.5% 1, 777 2, 469 3.3% Bel Air 19, 356 21, 236 0.9% 3, 841 4, 720 2.1% Trou d’Eau Douce/GRSE 6, 392 7, 529 1.7% 1, 393 1, 882 3.1% Sebastopol 5, 671 6, 276 1.0% 1, 004 1, 260 2.3% Flacq District 109, 181 122, 723 1.2% 21, 235 28, 329 2.9%
There are some variations in growth rates between parts of the District but with no discernible trends. The fastest growth, especially in terms of housing, has been in the Quatre Cocos/Poste de Flacq area. The lowest level of growth was in Centre de Flacq.
The major population settlement is in Centre de Flacq although there are other concentrations of population around Bel Air/Riviere Seche and Bon Acceuil. Centre de Flacq however is, by some way, the major commercial centre, business and administrative centre in the District. Centre de Flacq, Bel Air/Riviere Seche and Bon Acceuil have been designated as growth zones, specifically Rural Regeneration Zones in the NDS, whilst Trou d’Eau Douce has been identified as a tourism development focus within the Eastern Tourism Zone.
Hotel development has clustered around Poste de Flacq, Belle Mare, and Trou d’Eau Douce, primarily those sections of the coastline with sandy beaches. A series of islets is found within the lagoon with two of the largest being Ile de l’Est and Ile aux Cerfs, the latter catering for tourist day trips and containing a recently built golf course.
3.1.2.2.4 – Grand Port
The population of Grand Port District increased by nearly 10% from around 99, 000 in 1990 to 109, 000 in 2000, the actual increase in population was just under 10, 000. This rate of growth was below the national and “all District” growth rates for the same period. The number of households and housing units increased by 26% and 31% respectively over the same period, again lower than the national rates. The increase in population and housing units over the period 1990 -2000 for the different district sub-areas are shown in Table 3.8
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Table 3.8 – Grand Port Sub-areas: Population and Housing
DISTRICT SUB-AREAS Population Housing Units 1990 2000 AGR 1990 2000 AGR L’Escalier/Riv.du Poste/Mare 16, 410 18, 861 1.4% 3, 306 4, 324 2.7% Tabac/Trois Boutiques Mare D’Albert/Plaine 13, 433 14, 102 0.5% 2, 581 3, 244 2.3% Magnien Rose Belle/New 33, 663 37, 494 1.1% 6, 510 8, 921 3.2% Grove/Union Park/Nouvelle France Petit Bel Air/Grand Bel 22, 849 24, 509 0.7% 4, 973 6, 401 2.6% Air/Mahebourg/Beau Vallon Quatre Soeurs/Grand 12, 749 14, 120 1.0% 2, 621 3, 224 2.1% Sable/Bambous Virieux/Bois des Amourettes/Old Grand Port/Riviere des Creoles Grand Port District 99, 104 109, 086 1.0% 19, 991 26, 114 2.7%
There is little variation in growth rates of population and housing units throughout the District. No areas are growing significantly faster or slower than others, indicating the absence of any major new employment generators in the recent years. There are two major population centers in the District, Mahebourg and Rose Belle; both are designated as growth zones in the NDS
Hotel development has clustered around Blue Bay on the southern coast and near Mahebourg, primarily those sections of the coastline with sandy beaches. The open rocky coast and lack of extensive sandy beaches has limited tourism development in the District. Two new Tourism Zones were identified in the Tourism Development Plan, the Mahebourg Tourism Zone and the South Coast Heritage Zone. Both zones promote specialized tourism growth building on conservation opportunities.
The Sir Seewoosagur Ramgoolam (SSR) International Airport is the only airport in Mauritius and the main entry and exit point for business visitors, tourists and residents. The airport is a major employment centre and significant industrial and air-port related activities have developed in the surrounding area.
3.1.2.2.5 – Savanne
The population of Savanne district increased by around 10% from around 59, 000 in 1990 to 65,000 in 2000, slightly lower than the national and rural area growth rates for the same period. Households and the number of housing units increased by 26% and 34% respectively over the same period, virtually the same as the national rates.
The increase in population and housing units over the period 1990 - 2000 for the different district sub-areas are shown in Table 3.9.
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Table 3.9 – Savanne Sub-areas: Population and Housing
DISTRICT SUB-AREAS Population Housing Units 1990 2000 AGR 1990 2000 AGR Chamouny/Chemin Grenier 14, 838 16, 425 1.0% 2, 947 3, 952 3.0% Surinam 8, 057 9, 688 1.9% 1, 696 2, 594 4.3% Souillac/St. Aubin/Riv. des 14, 591 14, 817 0.2% 3, 155 3, 791 1.9% Anguilles Benares/Camp Diable/ 6, 781 6, 883 0.1% 1, 290 1, 611 2.2% L’Escalier Britannia/Grand Bois/Bois 11, 914 13, 002 0.9% 2, 212 2, 952 2.9% Cheri Savanne District 56, 181 60, 815 0.9% 11, 300 14,900 3.0%
The main settlements within the District of Savanne are Souillac, Surinam, Chemin Grenier and Riviere des Anguilles.
Surinam was the only other area to exhibit above average growth. The major population centre is Chemin Grenier (around 12, 000 people). The linked settlements of Surinam and Souillac (combined population around 14, 000) are a focus within the South Coast Heritage Tourism Zone.
3.1.2.2.6 – Moka
Moka’s population increased by less than 10% from around 59, 000 in 1990 to 63, 000 in 2000. This rate of growth was the lowest of any District in the country and was significantly lower than the national and rural area growth rates for the same period. Households and housing units increased by 23% and 29% respectively over the same period, again lower than the national rates.
The increase in population and housing units over the period 1990 - 2000 for the different district sub-areas are shown in Table 3.10.
Table 3.10 – Moka Sub-areas: Population and Housing
DISTRICT SUB- Population Housing Units AREAS 1990 2000 AGR 1990 2000 AGR Moka, St. Pierre, 25, 527 27, 026 0.6% 5, 479 6, 774 2.1% L’Avenir, La Laura, Malenga Dagotiere, Verdun, 16, 256 18, 816 1.5% 3, 070 4, 290 3.4% Esperance, Quartier Militaire, Providence Ripailles, Camp Thorel, 4, 663 5,116 0.9% 831 1, 127 3.1% Lallmatie, St. Julien Camp de Masque, 12, 184 12, 367 0.1% 2, 361 2, 910 2.1% Melrose, Mt. Blanche, Dubreuil Moka District 58, 630 63, 325 0.8% 11, 741 15, 101 2.5%
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Most settlements experienced below average growth in population and the number of housing units. Only the settlements of Quartier Militaire and Lallmatie experienced growth above the national average. The major population centre is Moka/St. Pierre.
3.1.2.2.8 – Black River
The population of Black River District increased by just over 25% from around 36, 000 in 1990 to over 45, 000 in 2000, much higher than the national and rural area growth rates for the same period. The number of households and housing units increased by 41% and 66% respectively over the same period, again much higher than the national rates due to decreasing household size, reduced household/housing unit ratios and increases in the number of unoccupied dwellings.
The extremely high growth rate for housing partly reflects the large number of vacant units in Albion (28%) and especially Flic en Flac (73%) mainly because of their relatively advantageous locations which have given rise to the construction of holiday apartments to let for local and international tourists, as well as second homes.
The increase in population and housing units over the period 1990 - 2000 for the different district sub-areas are shown in Table 3.11
Table 3.11 – Black River Sub-areas: Population and Housing
DISTRICT SUB- Population Housing Units AREAS 1990 2000 AGR 1990 2000 AGR Petite Riviere/Richelieu 8, 000 9, 148 1.3% 1, 613 2, 127 2.8% Gros Cailloux/Albion 3, 793 5, 821 4.4% 835 1, 709 7.4% Bambous 9, 455 11, 072 1.6% 1, 932 2, 924 4.2% Flic en Flac/Cascavelle 2, 151 3, 972 6.3% 635 2, 359 14.0% Tamarin/Grand River 4, 095 5, 376 2.8% 1, 191 1, 819 Case Noyale/Le 3, 967 5, 087 2.5% 957 1, 362 4.3% Morne/La Gaulette Baie du Cap/Bel Ombre 4, 452 4, 671 0.5% 942 1, 144 3.6% Black River District 35, 913 45, 147 2.3% 8, 105 13, 444 5.2%
Population and housing units in all sub areas of the District have increased faster than the national average. However growth has been much faster in Albion and Flic en Flac due to the rapid development of these centers for both tourism-related accommodations. In these areas the number of housing units has more than doubled. Growth has also been substantial in the more southerly coastal settlements of Tamarin and Le Morne/La Gaulette, but less so in Bambous and Petite Riviere.
The major population centre is Bambous which has a number of administrative functions, including the District Offices, the District Court, as well as a new supermarket. The majority of other settlements are located along the coast.
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3.1.3 – Domestic wastewater management
In Mauritius, general methods of wastewater collection consist of centralized public sewer networks in the more urbanized parts of the country and on-site disposal systems consisting of either individual cesspit, individual septic tanks followed by absorption systems and communal on-site disposal systems consisting of sewer network draining to communal septic tanks followed by absorption systems. Most houses are equipped with flush-cistern toilets
All sewer systems in Mauritius operate as separate systems, i.e they are designed to carry only wastewater and not storm water.
3.1.3.1 – Public Sewer Systems
It is estimated that about 60,000 domestic premises, representing about 25 % of the population is connected to the public sewer system. These premises are mainly found in the most urbanized regions of Port Louis, Baie du Tombeau, Terre Rouge, Plaines Wilhems and Grand Baie. The high cost which had to be borne by the residents to get a sewer connection resulted in a low connections rate and, in 2002, the Government decided to grant domestic connections free of charge. The sewered parts of Mauritius are shown on Map at ANNEX 3.3
3.1.3.2 – On-site Sanitation (individual systems)
The remaining 75% of the population located mainly in the rural districts make use of individual on-site disposal systems and there are minor uses of pit latrines
70 % of the individual on-site disposal systems consist mainly of cesspits which are relatively easy to construct as it involves only of digging an excavation generally 3m x 3m x 3m deep and casting a concrete slab above. In these cases, it is customary to direct only black water from toilets into the cesspits and grey water, i.e water from kitchen sinks, wash hand basins, bath tubs and washing machines are normally discharged to separate soakaways. On-site wastewater disposal facilities such as cesspits may be degrading water quality especially during flooding with raw wastewater getting into the lagoon.
About 23% of the on-site disposal systems consist of proper individual septic tanks followed by absorption pits. Concrete septic tanks of 3m3 capacity are normally built but resiglas septic tanks are not uncommon. The absorption pits are usually 3m x 3m x 3m deep but, recently, the use of individual leaching fields of 20m2 plan surface area, for soils of good percolation rates, are recommended in regions of high water table. The construction of a proper individual septic tank can cost about 4 months of the average salary in Mauritius.
The actual number of residential premises making use of pit latrines is not known but is estimated to be less than 2% of the population. This is most probably due to the fact that more than 99% of residential premises in Mauritius are provided with pipes water supply. Pit latrines would normally be used in remote localities where it has not been possible to provide piped water due to technical reasons or in cases where people are squatting State Land.
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3.1.3.3 – On-Site Sanitation – High Density Low-Cost CHA Estates
Following cyclone Carole in 1960, 45% of the housing infrastructure was destroyed due to use of timber and corrugated iron sheets houses in those days. Government’s priority was to quickly provide housing infrastructure with basic facilities. A number of such housing estates (commonly referred as CHA Estates, as a Central Housing Authority was created to manage the construction programme), were constructed and the sanitation facilities provided consisted of either individual or dual cesspits consisting of a 2m x 2m x 2m excavation. No proper soil investigations were carried out as the limited financial resources had to be directed to providing basic requirements. Most of these on-site disposal systems were either improperly sized or were constructed in regions of high water table. In other cases, the household to housing unit ratio increased significantly as the children who got married extended the houses vertically and horizontally.
As a consequence, most of the sanitation facilities failed rapidly, leading to very unsanitary situations such as frequent overflows, on the low-cost CHA Estates, which could consist of up to 500 housing units in a heavily built environment.
However, with the help of international financial assistance, a Program for Rehabilitation of Sewerage Infrastructure in Low Cost Housing Estates has been put in place. In fact, provision of proper sanitation facilities to the poor is one of the various performance indicators imposed by the Joint Donors who finance the wastewater infrastructure in Mauritius.
The Phase I and II of the project was executed from 1990 to 1998 and improved the sanitary conditions on 27 CHA Estates. Extension to Phase II and Phase III of the project is on-going and concerns 7 and 9 estates respectively.
Where technically feasible, some of these estates have been provided with a sewer reticulation and have been connected to the public sewerage system. In other cases these have been provided with a sewer system connected to communal septic tank followed by absorption systems.
Phase IV has just started with the launching of requests fro proposals for consultancy services fro a feasibility study for 27 CHA estates.
The provision/rehabilitation of sewerage facilities has greatly contributed to the improvements of living conditions in such low cost housing estates.
There are about 78 CHA Estates in Mauritius.
The distribution of the housing estates across the island is shown on Map at ANNEX 3.4
3.1.3.4 – Communal On-Site Disposal Systems – NHDC Housing Estates
The Government’s aims and objectives in the formulation of housing policy has been guided by the need to provide a decent housing unit for each household. In particular, the main concern has been to facilitate access to housing provision for the lower socio-income strata of the population who cannot afford a plot of land and construct their own house. The implementation of Government sponsored housing projects fall under the responsibility of the National Housing Development Company Limited which is the executive arm of the Government.
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Since 1992 to date some 87 such NHDC Housing Estates have been constructed representing a total of 11, 155 housing units. 27 of these estates are found in the sewered regions and are thus connected to the public sewerage system. The 60 remaining estates, with sizes varying between 20 and 290 housing units, are located in the unsewered regions and are mostly provided with sewer network connected to communal septic tanks followed by absorption systems. The distribution of the NHDC Housing Estates across the island is shown on Map at ANNEX 3.5
3.1.3.5– Hotels located in the coastal zone
There are about 45 large hotels located along the coastal zone that possess their own wastewater treatment plant and treat wastewater for irrigation of golf courses and lawns. This number will increase in the near future with the number of new hotels and tourism related infrastructure in construction at the moment. There is a general guideline, originating from the Sewerage Master Plan of 1994, that all hotels having more than 75 rooms should treat their wastewater before disposal. Some hotels with less than 75 rooms do opt to install their own WWTP.
However, there are also several beach hotels and hundreds of bungalows along the coastline that make use of on-site disposal systems consisting of septic tanks followed by absorption systems.
3.1.4 – General Method of Storm Water Collection
Most town centers and their immediate suburbs as well as some localities have been provided with road drains which discharge surface water into the numerous tributaries and rivers which criss-cross Mauritius. As stated in Section 3.1.1 above, there are 25 major rivers and 21 minor ones in Mauritius. Most of the rivers spring from the Central Plateau and flow radially to the sea. Due to the steep topography of the island and its relatively small size, river water reaches the sea within a few hours.
In the past, most houses were provided with individual absorption pits specifically for disposing of roof surface water. Now, with the rising cost of land and relatively smaller plots of land on which people are constructing or extending their houses, this is no longer being practiced, especially in sewered regions where people have a tendency of illegally connecting their surface water to the public sewer system.
Port Louis, the capital and only harbor was built in the eighteenth century under French Colonization. The city has been provided with a system of road drains that dates from its construction. Most of the drains discharge surface water into major stone lined canals which in turn discharge surface water directly into the harbor.
With recent changes in climatic conditions, due to global warming and El-Nino effects, Mauritius has started to experience unprecedented drastic rainfall conditions in the month of January for the past 3 to 4 years. This has caused severe flooding even in regions where this has never been experienced in the past. Flooding has been more critical in Port Louis due to a number of recent constructions interfering with the flow pattern of existing drains.
Flooding has also been critical in the coastal areas of Grand Baie and Flic en Flac due to wetland being infilled for construction. The infilling of wetlands has hampered or blocked mainland runoff through such natural filter to the sea.
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In other town centers, flooding has occurred due to lack of maintenance of drains by the local authorities. The Government of Mauritius has commissioned a Land Drainage Master Plan which has been completed. The detailed design and construction phase is on-going.
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3.2 – Public Sewer Systems
It is estimated that about 100, 000 m3 of wastewater are collected and treated per day in all public sewer networks draining to the public WWTPs. The volume of septage from desludging of individual cesspits/septic tanks and from industrial wastewater carted away to the public wastewater system by tankers is estimated at about 1, 400 m3 per day.
The existing sewer networks are as follows:
• The Plaines Wilhems Sewerage System draining to the St. Martin WWTP • The Grand Baie Sewerage System in the northern coastal zone from Pointe aux Cannonniers to Grand Baie draining to the Grand Baie WWTP • The Port Louis Sewerage System consisting of the Port Louis Northern Sewerage System draining to the Baie du Tombeau WWTP • The Port Louis Southern Sewerage System and the Lower Beau Bassin-Coromandel Sewerage Systems draining to the Montagne Jacquot WWTP. • The Baie du Tombeau Sewerage System draining to the Baie du Tombeau WWTP.
There are five minor public wastewater treatment plants, the Dubreuil, Vuillemin, Riviere du Rempart, Centre de Flacq and Pailles WWTPs with population equivalents less than 500.
The locations of these nine public wastewater treatment plants are shown on the Map at ANNEX 3.6. The different urban settlements for these public wastewater treatment plants are described in the next Sections.
3.2.1 – The Plaines Wilhems Sewerage System
3.2.1.1 – Description St. Martin WWTP Drainage Area
The drainage area of the St. Martin WWTP consists of the sewered regions of the Plaines Wilhems District where the most highly populated urban areas (except for the capital, Port Louis) are located. The present drainage network covers an area of 1, 400 hectares out of the 3, 500 hectares of the district. The existing sewer system serves an estimated 135, 000 people (27, 000 households), representing 35% of the district population. The St. Martin WWTP receives between 35, 000 to 40, 000 m3 of wastewater daily.
The actual reticulation serves parts of the towns of Beau Bassin, Rose Hill, Curepipe and a small part of Phoenix.
The whole of Quatre Bornes and the remaining unsewered parts of Beau Bassin, Rose Hill and Curepipe will be sewered over the next five years with the implementation of the Plaines Wilhems Sewerage Project – Stage I for which construction works are expected to start by beginning of 2008. The town of Vacoas and some parts of Phoenix will be sewered under Stage II which should be implemented in ten years time under an optimistic schedule.
Commercial activities constitute mainly of shops, small shopping centers, hotels and restaurants. As such, wastewater draining from the residential premises and commercial activities is essentially domestic wastewater except for wastewater from hotels and restaurants which may contain a higher level of oil and grease. Such undertakings are however required to provide a grease trap prior to discharging their wastewater to the public sewer network.
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The existing industrial development in the Plaines Wilhems District can be subdivided into two categories: • Water intensive or wet industries located in or outside the Vacoas-Phoenix Industrial Estate and the Mangalkhan Industrial Estate. • Low water or dry industries, small industries, termed as light industries spread throughout the catchment area.
The industrial estates of Vacoas-Phoenix and Mangalkhan as well as the water intensive industries are sewered. Several major industries are located outside these industrial estates, in Curepipe, Forest Side, Vacoas, Rose Hill, Belle Rose and Beau Bassin. Most of these are connected to the public sewer system. The main industrial activities are textile industries including dye houses, brewery, chicken slaughter house, soft drinks bottling plants, and food processing plants.
16 of the 19 major industries in the catchment possess the necessary on-site pre-treatment facilities to treat their effluents to the required standard before discharge to the public sewer. Such pre-treatment facilities range from preliminary screening – sedimentation tanks to secondary treatment systems consisting of activated sludge systems, physico-chemical systems or anaerobic treatment systems. These industries are duly licensed under the Wastewater (Standards for Discharge of Industrial Effluent in a Sewer System) Regulations 2004. The three remaining industries have not installed any pre-treatment yet and negotiations are being held with these for installation of required pre-treatment facilities and subsequent licensing.
3.2.1.2 – Description of the Plaines Wilhems Sewerage Network
The existing Plaines Wilhems sewer system was constructed in the 1960’s and was designed as separate sewers, i.e. to carry wastewater only and not surface water. It is generally divided into the Upper Plaines System, serving part of the towns of Curepipe and Phoenix, and the Lower Plaines Wilhems System which serves part of the towns of Rose Hill and Beau Bassin. The upper and lower systems share a common trunk sewer which gradually increases in size from 450 mm in Curepipe to 750 mm at its downstream end where it discharges to the existing St.Martin WWTP.
The sewerage system consists of about 194 km of sewer pipes of diameter ranging from 150mm to 600mm. These are mainly vitrified clay pipes which are generally in quite a good state. There are some pitch fiber pipes, mainly on low-cost housing estates, which have outlived their useful life and have collapsed. These are being replaced on on-going projects. There are also concrete pipes which have experienced quite some cracks and are prone to infiltration from ground water. The existing trunk sewer is made of concrete and is in quite a deteriorated state in some parts due to chemical attack from industrial effluents.
The existing Plaines Wilhems Sewerage System is essentially a gravity sewer network.
Investigations carried out during the 1994 Sewerage Master Plan Study revealed that there is heavy infiltration due to ingress of ground water and storm run-offs, especially in the Curepipe area. A new trunk sewer is presently being laid to cater from the heavy infiltration in the existing one and to take flows from some 32, 500 new connections of existing households in the remaining unsewered 2,100 hectares of Plaines Wilhems District. These connections will be done over the
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3.2.2 – The Grand Baie Sewerage System
The Grand Baie Sewerage System extends from Pointe aux Cannoniers to Grand Baie in the District of Pamplemousses, in the coastal zone. The region is found in the Northern Tourism Zone with a great number of hotels, tourist oriented activities and restaurants. There are about 1,500 residential households already connected within the drainage area which comprises a total of 1,700 households, representing a total population of 10,000 inhabitants. There no major industrial activities.
The sewer network is relatively new and was commissioned in 2004. It consists of 27.6 km of UPVC gravity sewer network of diameter ranging from 160 to 400mm, 4.2 km of PE rising mains of diameter ranging from 63 to 250 mm, 4 km of DI rising mains of diameter ranging from 300 to 450mm and 0.5 km of 600mm gravity DI pipe. As the catchment is relatively flat, the network includes 12 pumping stations. The sewer network covers an area of 211 ha.
The Grand Baie Sewerage System is shown at ANNEX 3.8
3.2.3 – The Port Louis Sewerage System
The first sewerage works in Port Louis date back to the 1880’s with progressive improvements made to the system. The Port Louis Sewerage Network consists of about 182 km of sewer pipes of earthen ware, vitrified clay, ductile iron and PVC. It covers an area of 840 ha. The system was designed as a separate system but is now subject to heavy infiltration. It consists of two main drainage zones called the Port Louis North and Port Louis South Systems.
The Northern System includes residential, commercial and industrial areas. It consists of the town centre area, the Eastern Suburb, Ste. Croix, La Cure, Roche Bois and Abercrombie, Vallee Pitot, Plaines Verte, Fanfaron area and Latanier.
The Northern Interceptor sewer receives flows from: Vallee Pitot and Plaines Verte areas via the Plaine Verte Sewer Port Louis North and the commercial area (central Port Louis) The Fanfaron area via the Fanfaron Pumping Station Latanier area via the Latanier Trunk Sewer.
The Northern Interceptor Sewer drains to the Northern Treatment Works which also receives flows from Vallee des Pretres, La Cure and part of Cite Roche Bois through the La Cure Trunk Sewer. Other flows from the Cite Roche Bois are pumped to the Northern Works through the Roche Bois Pumping Station.
Previously the effluent from the Northern Treatment Works, which consisted basically of preliminary treatment, was pumped out to sea through a 900mm outfall at Mer Rouge. The Northern Works now pump the effluent to the Baie du Tombeau WWTP which discharges through a long sea outfall.
The Southern System includes residential and commercial zones as well as the Plaine Lauzun Industrial Zone. It consists of the regions of Tranquebar, Port Louis South, Cassis, Bell Village
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All the areas within the Port Louis Sewerage System are essentially residential areas with heavy commercial activity, Port Louis being the capital city and only harbor of the island. There are many light industries.
The Plaine Lauzun Industrial Zone draining to the Southern Sewerage System contains essentially light industries.
The Northern Works is the only site where tankers are allowed to cart away effluent from all over the island. This consists mainly of septage from cesspits/septic tanks from residential premises and industrial effluents.
3.2.4– Lower Beau Bassin and Coromandel Sewerage System
The Coromandel Trunk Sewer was constructed in 1978 to take flows from the Coromandel Industrial Estate which contains a number of wet industries. Later, a trunk sewer was laid to connect domestic flows into the Coromandel Trunk Sewer, from the region of lower Beau Bassin which is essentially residential.
The Coromandel Sewer also collects domestic flows from La Tour Koenig and Cite Illois via the La Tour Pumping Station. The Coromandel Trunk Sewer discharges to the Pointe Aux Sable Works where preliminary treatment is carried out. Previously, the Pointe aux Sable Treatment Works discharged the effluent to sea by gravity via a 650mm asbestos cement outfall. Since January 2007 the effluent is pumped to the Montagne Jacquot WWTP which discharges through a long sea outfall.
3.2.5 -Baie du Tombeau Sewerage System
The Baie du Tombeau Drainage Area shown at ANNEX 3.9 consists of the following:
• The Southern Drainage Area The Southern Drainage Area is essentially a high density residential zone with appreciable industrial areas to the south west. The total area is approximately 198 ha.
• The Central Drainage Area The Central Drainage Area covers almost exclusively a low-density residential area of approximately 116 ha
• The Northern Drainage Area The Northern Drainage Area drains the northern areas of Sinatambou and Baie du Tombeau which are low –density residential zones. It covers an area of about 90 ha of land primarily designated for residential development.
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• The Eastern Drainage Area and associated Riche Terre Industrial Zone The Eastern Drainage Area is a predominantly low-density residential area with a few light industries. The Riche Terre Industrial Zone covers an area of 58 ha and is considered as Dry Industry.The total area covered for the Eastern Drainage Area is about 149 ha. • Riche-Terre- Le Hochet-Terre Rouge Drainage Area The Riche Terre-Le Hochet –Terre Rouge Drainage Area is a highly residential zone with an area of 200 ha.
The Baie du Tombeau Sewerage System is relatively new and was commissioned in 2003. It consists of 20 km of UPVC pipes of diameter ranging from 150 to 500mm.
The Port Louis North - Baie du Tombeau Sewerage System and the Port Louis South - Lower Beau Bassion-Coromandel Sewerage System are shown at ANNEX 3.10.
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3.3 – Inventory of Major Municipal Wastewater Treatment Plants
3.3.1 – The St. Martin WWTP
3.3.1.1 - Location of the treatment facility Town: St. Martin District: Black River Distance from the sea shore: 5 (km) 3.3.1.2 - Specification of sewerage system Length of sewer: 194 (km) Minimum diameter: 150(mm) Maximum diameter: 750 (mm) Population served by the sewerage system: 27, 000 households
3.3.1.3 - General description of the state of the sewerage system:
The sewerage system was built in the 1960’s and consists mainly of vitrified clay pipes which are generally in quite good state. There are some pitch fiber pipes, mainly on low-cost housing estates, which have outlived their useful life and have collapsed. These are being replaced on on- going projects. There are also concrete pipes which have experienced quite some cracks and are quite prone to infiltration from ground water. The existing trunk sewer is made of concrete and is in quite a deteriorated state in some parts due to chemical attack from industrial effluents. A new trunk sewer is presently being laid to cater from the heavy infiltration in the existing one and to take flows from some 32, 500 new connections of existing households in unsewered parts of Plaines Wilhems District. These connections will be done over the next seven years. The new trunk sewer will consist of 25 km of GRP pipe of diameter ranging from 300 mm to 1, 100 mm. The existing manholes, reinforced concrete manholes on roads, are in quite a good state and are regularly inspected and maintained.
3.3.1.4 - Types of wastewater treated (Tick below boxes as appropriate) Domestic Sewage and Industrial wastewater
Quantity of wastewater treated: 35, 000 – 40, 000 m3/day (present situation)) Design Capacity: 69, 000 m3/day(1st Stage) 87, 000 m3/day (2nd Stage) Quantity untreated: NIL (m3/day)
3.3.1.5 - Description of the treatment plant 3.3.1.5.1 - Types of preliminary treatment (if any): Screening: 3x 25mm coarse screens followed by 3x 6mm fine screens, all mechanically raked. Grit Removal: 2 nos. flat bottom detritus tanks
3.3.1.5.2 - Description of operational units and processes of the main treatment facility:
• Secondary Treatment The secondary treatment consists of activated sludge plant with biological nutrient removal.
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•Sludge Treatment Picket fence thickeners are provided for primary sludge. Secondary sludge is thickened using belt thickeners fed with polyelctrolyte.
•Anaerobic Sludge Digestion Cylindrical reinforced concrete digestion tanks with roof and hopper bottom are provided for anaerobic sludge digestion
A hemispherical inflatable membrane type gas holder is provided for holding gas produced from the anaerobic sludge digestion.
Glass coated steel liquid sludge storage tanks are provided to buffer the continuous flow from the digestors against the intermittent operation of the dewatering tank. These also allow the sludge to finish degassing.
• Sludge dewatering The sludge from the sludge digestion plant is dewatered by means of platform mounted centrifuges together with polyelectrolyte dosage. A conveyor collects the sludge cake and transfers it to the cake storage area.
•Cake Storage Cake produced from the sludge dewatering is temporarily stored on a rectangular concrete slab with retaining walls on three sides.A drainage system collects the leachate and discharges it to the returned liquors pumping station.
A mechanical shovel places the cake within the storage area and loads the lorries which transfer the cake to the Mare Chicose Landfill Site.
•Sludge Liquor Treatment Radial flow settlement tank with ferric sulphate dosing is provided to settle out phosphrous from the liquors produced by the thickening and dewatering plants together with leachate from the cake storage area. The effluent from this tank is pumped back to the aeration tank.
• Tertiary Treatment and Disinfection The secondary effluent is passed through rapid sand filters and UV disinfection channels .
3.3.1.5.3 - General description of the state of the treatment plant: The St. Martin WWTP is quite new as it was put into operation in March 2005.
3.3.1.6 - Point of discharge (sea outlet, river, wetland, etc.): Treated effluent discharged to nearby irrigation canals, sold to Irrigation Authority for irrigation of sugar cane Existing sea outfall kept for emergency purposes such as quality of effluent not fit for irrigation or in case of cyclones and heavy rainfall where plant will be overloaded.
The flow process diagram for St. Martin WWTP is at ANNEX 3.11.
3.3.1.7 – Influent and Treated Effluent Characteristics Table 3.12 below shows the influent and treated effluent characteristics at the various stages of treatment for the St. Martin WWTP
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Table 3. 12 - Influent and Treated Effluent Characteristics for St. Martin WWTP
Parameter Unit Influent Settled 2dary Tertiary Design Standards for List Effluent Treated Treated Value Irrigation Effluent Effluent pH 7.42 7.19 7.4 7.8 5-9 A Colour 10.2 10 Not objectionable BOD mg / l 228 157 6.1 2.5 40 COD mg / l 503 316 52.7 29.7 120 TSS mg / l 199 69 11.4 4.5 45 Chloride mg / l 78 74 86.6 84 250 Sulphate mg / l 194 166 156.1 152 500 Nitrate-N mg / l 26 22 6.0 3.7 20 B TDS* mg / l 381 N.A N.A 377 2000 SAR < 6 Aluminium mg / l 0.045 N.A N.A 0.066 5 Arsenic µg / l 13.8 N.A N.A 1.4 100 Beryllium mg / l N.A N.A 0.10 Boron mg / l N.A N.A 0.75 Cadmium mg / l 0.002 N.A N.A 0.002 0.01 Chromate mg / l Chromium N.A N.A Chromium 0.10 Chromium 0.04 0.04 Cobalt mg / l 0.015 N.A N.A 0.017 0.0 5 Copper mg / l 0.024 N.A N.A 0.005 0.2 C Fluorine mg / l N.A N.A 1 Iron mg / l 2.21 N.A N.A 0.984 5 Lead mg / l 0.008 N.A N.A 0.009 2 Lithium mg / l 0.017 N.A N.A 0.017 2.5 Manganese mg / l 0.823 N.A N.A 0.12 0.2 Molybdenum µg / l 22.9 N.A N.A 3.32 10 Nickel mg / l 0.08 N.A N.A 0.09 0.02 Mercury mg / l N.A N.A 0.02 Selenium µg / l 9.21 N.A N.A 7.79 20 Vanadium µg / l 15.1 N.A N.A 2.54 100 Zinc mg / l 0.188 N.A N.A 0.08 2 Total Pesticides mg / l N.A N.A 0.025 Oil&Grease mg / l 204 N.A N.A 100 10 D Detergents* mg / l N.A N.A 1.95 5 FC MPN/ N.A N.A 362 10003 100ML E Intestinal N.A N.A N.A <= 1 Nematodes Phosphorous mg/l 6.0 5.0 2.5 2.5 - Helminth Ova N.A N.A N.A N.A < 1 -
The values quoted in Table 3.12 are derived as follows:
Values for parameters listed A represent monthly average of daily values for 30 sets of samples taken for the month of November 2006, except for Total Dissolved Solids where the quoted value is the average of the values obtained from two samples taken on 4.12.06 and 18.12.06.
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Values for Parameters listed C represent maximum values obtained from 67 samples taken during period January 2005 to September 2006.
Values for parameters listed D, Oil & Grease and Detergents are the average of the values obtained from two samples taken on 4.12.06 and 18.12.06.
Values for Phosphorous and Helminth Ova , at the bottom of Table 3.13, represent monthly average of daily values for 30 sets of samples taken for the month of November 2006.
3.3.1.7 - Discussion of Performance of St.Martin WWTP
It can be noted, from the influent and final treated characteristics, that the plant is performing to a very high standard as the required irrigation standards are being met. However high levels of Oil Grease are noted both in the influent and final effluent. The design value adopted for Oil & Grease content for the influent was 20 mg/l, much below the values being encountered. High grease content in the influent has been clogging the sand filters which have to be regularly overhauled and cleaned chemically using caustic soda.
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3.3.2 -Grand Baie Wastewater Treatment Plant
3.3.2.1 -Location of the treatment facility Town: Grand Baie District: Pamplemousses Distance from the sea shore: 1 (km) 3.3.2.2 - Specification of sewerage system Length of sewers: 40 (km) Minimum diameter: 160(mm) Maximum diameter: 600(mm) Population served by the sewerage system: 1, 500 households
3.3.2.3 - General description of the state of the sewerage system: The sewerage system is quite new, construction having been completed in 2004. It consists of UPVC and DI gravity sewers and 12 pumping stations, the sewered area being relatively flat.
3.3.2.4 - Types of wastewater treated: Domestic sewage
Quantity of wastewater treated: 1,200 (m3/day), (present situation) Design Capacity: 3, 500 (m3/day) Quantity untreated: NIL(m3/day) 3.3.2.5 - Description of the treatment plant
3.3.2.5.1 - Types of preliminary treatment (if any): Screening: 12mm mechanically raked fine screen Grit Removal: Aerated grit chamber with skimming and grease removal
3.3.2.5.2 - Description of operational units and processes of the main treatment facility: The treatment process consists of activated sludge with biological nutrient removal. The Grand Baie WWTP flow process diagram is shown at ANNEX 3.12
3.3.2.5.3 - General description of the state of the treatment plant: Newly constructed plant, operational since 2003
3.3.2.6 - Point of discharge Borehole injection Possibility of selling treated effluent to potential buyers for irrigation purposes
3.3.2.7 – Influent and Effluent Characteristics
The treatment plant was commissioned in February 2006. During the period August 2005 to September 2006, 211 samples (at inlet and outlet) were collected and analysed. The range of values for inlet and outlet for the different parameters are shown in Table 3.13 below.
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Table 3.13 – Influent and Effluent Characteristics for Grand Baie WWTP
Parameters Units Range Range Std. for Effluent Discharge Inlet Outlet onto Land/Underground Temperature oC 16.4 - 32.5 25 - 34.1 40 pH 6. 9 - 9.4 7.0 - 8.6 5-9 Conductivity µg / l 625 - 1732 936 - 9160 - Turbidity NTU 2. 1- 400 0.6 - 44 - SSV ml / l 0.8 - 71 0.0 TSS mg / l 14 - 1155 0.5 - 91 45 TDS mg / l 65 - 853 853 - 4490 - COD mg / l 50 - 666 15 - 279 120 BOD mg / l 6 - 288 1.2 - 108 40 Chloride mg / l 32 - 355 83 - 1050 750 Ammonia – N mg / l 2.5 - 58 0.05 - 57 1 Nitrate – N mg / l 0.1 - 35 1.0 – 22.6 10 Reactive phosphorous mg / l 1.1 – 6.8 0.3 – 4.6 10 Oil & Grease mg / l 6.0 - 910 0.04 - 937 10 Total Coliforms MPN/ 100 ml FC MPN/ 100 ml Heavy Metals Aluminium mg / l 0 – 4.81 0 – 1.91 5 Arsenic µg / l 0.016 - 5.44 0.282 – 9.14 100 Cadmium mg / l 0 – 0.005 0 – 0.0002 0.01 Chromium mg / l 0 – 0.04 0 – 0.046 0.05 Cobalt mg / l 0 – 0.022 0 – 0.10 0.05 Copper mg / l 0 – 0.153 0 – 0.026 0.5 Iron mg / l 0.08 – 89.1 0.07 – 82.3 2 Lead mg / l 0 – 0.12 0 – 0.011 0.05 Lithium mg / l 0 – 0.008 0 – 0.007 2.5 Manganese mg / l 0.018 – 0.342 0 – 1.58 0.2 Molybdenum µg / l 0 – 9.98 0 – 12.4 10 Nickel mg / l 0 – 0.122 0 – 0.166 0.1 Selenium µg / l 0 – 6.55 0 – 21.06 20 Vanadium µg / l 0 – 54.9 0 – 25.3 100 Zinc mg / l 0.005 – 0.664 0.005 - 1.58 2
3.3.2.8 – Discussion of Performance of Grand Baie WWP
The results of the monitoring period August 2005 to September 2006 showed that most of the parameters tested complied with the standards for most of the effluent samples. They exceeded limits only in a few cases, during temporary and short-lived circumstances, TSS was not complying because samples being taken while filters were being cleaned.
Also, since the WWTP is near the sea, hydrostatic pressure heads favor an intrusion of sea water into the WWTP. This can account for the periodic increases in chloride content, conductivity and TDS. Since chloride can be oxidized under the conditions of the COD test, this can account for high COD values in the treated effluent.
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However Oil & Grease level in the treated effluent exceeded the permissible limits on various occasions, when Oil & Grease levels were high in the influent itself.
The Grand Baie WWTP is therefore performing quite satisfactorily.
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3.3.3 –Baie du Tombeau WWTP
3.3.3.1 -Location of the treatment facility Town: Baie du Tombeau District: Pamplemousses Distance from the sea shore: 1km 3.3.3.2 - Specification of sewerage system Northern Port Louis Baie du Tombeau Length of sewers: 91 km 20 km Minimum diameter: 160 mm 160 mm Maximum diameter: 600 mm 500 mm Population served by the sewerage system: N.A 1,500 households
3.3.3.3 - General description of the state of the sewerage system:
3.3.3.3.1 - Northern Port Louis The sewer network consists of earthern ware, vitrified clay, ductile iron and PVC. The system was designed as a separate system but is now subject to heavy infiltration. It was constructed in the 1880’s and is quite old and subject to numerous sewer blockages
3.3.3..3.2 - Baie du Tombeau The sewerage system is quite new, construction having been completed in mid -2002. It consists of UPVC and VC gravity sewer.
3.3.3.4 - Types of wastewater treated: Domestic and Industrial
Quantity of wastewater treated:
From Northern Port Louis: 15, 000 m3/day From Baie du Tombeau 9, 000 m3/day
Total wastewater treated: 24, 000 m3/day
Design Capacity: 35, 000 m3/day Quantity untreated: NIL (m3/day) 3.3.3.5 - Description of the treatment plant
3.3.3.5.1 - Types of preliminary treatment (if any): Screening: 50mm manually raked coarse screen followed by 12mm mechanically raked fine screen Grit Removal: Flat bottom detritus tank
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3.3.3.5.2 - Description of operational units and processes of the main treatment facility:
The effluent from the Northern Port Louis undergoes preliminary treatment through coarse and fine screens and grit removal before being pumped to the Baie du Tombeau WWTP.
At Baie du Tombeau WWTP, the inlet channels are provided with coarse, manually raked screens The primary effluent is discharged into the ocean through a long sea outfall at a depth of 30 m and at a distance of 1km beyond the lagoon, whereby it undergoes marine treatment.
Marine treatment is a natural treatment process which uses the assimilative capacity of the sea, the physical mixing and dispersive effects in the sea, dilution effects, disinfection by the sun’s ultraviolet light and the natural die-off rate of bacteria to achieve acceptable water quality criteria in the coastal zone. The physical process consists of a headworks to provide a minimum standard of pretreatment and a long sea outfall pipe to discharge the effluent through a diffuser at a suitable location offshore.
3.3.3.5.3 - General description of the state of the treatment plant: Newly constructed plant, operational since 2003
3.3.3.6 - Point of discharge Through long sea outfall
3.3.3.7 – Influent and Effluent Characteristics
The treatment plant was commissioned in February 2006. During the period August 2005 to September 2006, 211 samples (at inlet and outlet) were collected and analysed. The range of values for inlet and outlet for the different parameters are shown in Table 3.14 below.
3.3.3.8 – Discussion of performance of Baie du Tombeau WWTP
The Baie du Tombeau WWTP has been designed to treat wastewater to a preliminary level only, with the main aim of reducing suspended solids and BOD. The reduction of the concentration of other parameters is brought about by the dispersive and dilution effects of the sea. The results in Table 3.14 show that SSV (suspended solids by volume) were below the permissible limits for all samples analysed. The BOD was mostly compliant with the required standard.
Oil & Grease are quite high but it is observed that this is the case for all the other municipal WWTPs.
The Baie du Tombeau WWTP is therefore performing as designed and is achieving the required effluent characteristics for discharge into the ocean.
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Table 3.14– Influent and Effluent Characteristics for Baie du Tombeau WWTP
Parameters Units Range Std. for Effluent Discharge Outlet into Ocean Temperature oC 25.5 - 32 40 pH 6.5 – 7.8 5 – 9 Conductivity µS/cm 1238 - 3562 - Turbidity NTU 2.0 - 250 - SSV ml / l 2.0 - 55 300 TSS mg / l 216 – 2180 - TDS mg / l 128 -524 - COD mg / l 197 - 2156 750 BOD mg / l 66 - 287 250 Chloride mg / l 101 - 518 - Ammonia – N mg / l 0.08 - 181 - Nitrate – N mg / l 0.05 - 303 - Reactive phosphorous mg / l 2.8 - 14 - Oil & Grease mg / l 8.8 – 10 470 20 Detergents mg / l 1.3 – 2.5 - Total Coliforms MPN/ 100 ml FC MPN/ 100 ml Heavy Metals Aluminium mg / l 0.126 – 0.63 - Arsenic µg / l 0.445 – 8.38 200 Cadmium µg / l 0 – 0.048 20 Chromium (Total) µg / l 0 – 0.046 500 Cobalt mg / l 0.007 – 0.063 - Copper mg / l 0 – 0.09 - Iron mg / l 0.55 – 62.5 - Lead mg / l 0.012 – 0.196 2 Lithium mg / l 0 – 0.006 - Manganese mg / l 0.062 – 0.615 - Molybdenum µg / l 2.26 – 6.25 - Nickel mg / l 0 – 0.044 2 Selenium µg / l 3.77- 48.9 - Vanadium µg / l 7.12 – 16.9 - Zinc mg / l 0.01 – 4.47 10
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3.3.4 – The Montagne Jacquot WWTP
3.3.4.1 -Location of the treatment facility Town: Pointe Aux Sable District: Black River Distance from the sea shore: 1km 3.3.4.2 - Specification of sewerage system Southern Port Louis Lower B. Bassin-Coromandel Length of sewers: 91 km 31 km Minimum diameter: 160 mm 200 mm Maximum diameter: 600 mm 400 mm Population served by the sewerage system: N.A N.A
3.3.4.3 - General description of the state of the sewerage system:
3.3.4.3.1 - Southern Port Louis The sewer network consists of earthern ware, vitrified clay, ductile iron and PVC. The system was designed as a separate system but is now subject to heavy infiltration. It was constructed in the 1880’s and is quite old and subject to numerous sewer blockages
3.3.4.3.2 – Lower Beau Bassin - Coromandel The sewerage system was commissioned in1994. It consists of UPVC gravity sewer. The sewer system is very performing and there are hardly any blockages recorded.
3.3.4.4 - Types of wastewater treated: Domestic and Industrial
Quantity of wastewater treated:
From Southern Port Louis: 27, 000 m3/day From Lower Beau Bassin - Coromandel 8, 000 m3/day
Total wastewater treated: 35, 000 m3/day
Design Capacity: 48, 000 m3/day Quantity untreated: NIL(m3/day) 3.3.4.5 - Description of the treatment plant
3.3.4.5.1 - Types of preliminary treatment (if any): Screening: 2x 65mm manually raked coarse screens followed by 2x 6mm rotating drum screens Grit Removal: 4 primary sedimentation tanks
3.3.4.5.2 - Description of operational units and processes of the main treatment facility:
The effluent from Southern Works (Fort Victoria PS) and from Pointe aux Sable PS undergoes preliminary treatment through coarse and fine screens and grit removal before being pumped to the Montagne Jacquot WWTP.
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At Fort Victoria, the raw wastewater undergoes screening through 2 Nos. 60mm & 2 Nos. 19mm mechanically raked bar screens and grit removal through a grit detritor. At Pointe aux Sable, the raw water undergoes only screening through 1 No. 60mm and 2 Nos. 19mm mechanically raked bar screens. The flow is measured at both pumping stations by means of magnetic flow meters.
Processes at Montagne Jacquot:
Preliminary Treatment At Montagne Jacquot, the influent undergoes screening through 2 Nos. 65mm mechanically raked coarse screens followed by 2 Nos. rotating drum screens of 6mm aperture. The influent then undergoes grit removal through a vortex type grit trap. The screenings and grit from the screening and grit removal processes is disposed of in landfill at Mare Chicose.
Primary Sedimentation The wastewater undergoes primary sedimentation through four Nos. primary clarifiers. Polymer is added to the primary sedimentation process from a nearby inlet building.
Disinfection The effluent from the primary sedimentation undergoes disinfection with chlorine in chlorine contact tanks.
Flow Measurement The flow from the chlorine contact tanks is measured by means of an ultrasonic flow meter.
Disposal The final effluent is discharged into the ocean through a long sea outfall at a depth of 30 m and at a distance of 1km beyond the lagoon, whereby it undergoes marine treatment.
Sludge Treatment The primary sludge is pumped into sludge holding tanks and is thickened by means of two picket fence thickeners. It is then pumped to two sludge dewatering filter belt presses with lime addition and the primary sludge is dewatered to 28% solids.
Sludge Disposal A sludge conveyor directs the dewatered sludge to skips/trucks and the cake is disposed of in landfill at Mare Chicose.
The Montagne Jacquot WWTP flow process diagram is shown at ANNEX 3.13.
3.3.4.5.3 - General description of the state of the treatment plant: Newly constructed plant, operational since15 January 2007
3.3.4.6 - Point of discharge Through long sea outfall
3.3.4.7 – Influent and Effluent Characteristics
The influent and effluent characteristics, based on the average values of four sets of samples taken on 24, 25, 26 and 27 January 2007 are shown in Table 3.15 below.
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Table 3.15– Influent and Effluent Characteristics for Montagne Jacquot WWTP
Parameter Unit Inlet Outlet Stds for Discharge into Ocean Temperature 0C 26.3 25 40 pH 7.21 7.37 5 – 9 Colour Hazen 763 781 Conductivity µS/cm 2.37 2.1 TSS @ 1050C mg / l 129 59 TDS mg / l 875 1110 COD mg / l 379 372 750 BOD mg / l 99 717 250 Chloride mg / l 919 609 Reactive mg / l 2.02 1.75 Phosphorous Oil & Grease mg / l 10 7.8 20 Total Coliform MPN/100ml E.coli MPN/100ml
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3.4 – Overview of Most Important Wastewater Producing Enterprises
3.4.1 – Industrial Activities
Details of the most important industrial enterprises in Mauritius are given at ANNEX 3.14.1
Industrial activities in Mauritius involve mainly textile dye-houses, breweries and soft drink bottling plants, dairy processing plants, food canning plants slaughterhouses and laundries. It can be noted that the industries discharge effluents that conform to the relevant Standards for discharge into the sewer network.
Dye-house effluents are not heavily loaded, in terms of COD, for discharge into sewers. Generally, only pre-treatment such as screening, primary sedimentation and pH adjustment are required. Organic dye-stuffs are used and the results of analysis show that heavy metals are not an issue. Conductivity is generally high due to uses of salts such as sodium sulphate in the dyeing processes.
Slaughter houses, breweries and dairy processing plants produce effluents with high COD and generally need secondary treatment for reduction of COD.
Industrial effluents discharged to the sewer network are well managed as the industries are licensed under the Wastewater (Standards for discharge of Industrial Effluent into a Sewer Network) Regulations 2004. The industries need to submit monthly reports with records of water consumption and results of analysis of treated effluent. A monitoring exercise is also carried out whereby the industries are visited at last one a year to check whether the conditions of the licence are still valid and whether the industry practices good housekeeping. The Wastewater Laboratory also takes independent samples for analysis at least once a year.
3.4.2 – Coastal Hotels
Details of the coastal hotels having a wastewater treatment plant is at ANNEX 3.14.2
According to the Public Health Act of 1991, all hotels having more than 75 rooms need to have a wastewater treatment plant. In Mauritius, technologies used in wastewater treatment for hotels consist of activated sludge systems and septic tank followed by RBC units. Recently one hotel has been constructed with constructed wetland for wastewater treatment. These hotels re-use the treated wastewater for irrigation of golf courses and lawns. Almost all the hotels apply chlorination for disinfection.
In terms of the key parameters, namely COD, BOD, TSS, Nitrate and faecal coliforms, the quality of treated effluents used for irrigation in the hotel sector is quite satisfactory. The Wastewater Laboratory of the WMA regularly samples and analyses the coastal effluents which are also required to submit monthly results of analysis performed by private laboratories.
Mauritius is experiencing a major boost in the tourist industry whereby some 900,000 tourists are expected by the end of 2007. The aim is to reach a target of 2 million tourists by 2020. Many major coastal hotels and tourist resorts are under construction and the number and complexity of hotel wastewater treatment plants is expected to increase drastically in the next years. Monitoring will need to be reinforced so as to preserve the natural resources that constitute main assets of the tourism industry
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3.4.3 – Agricultural Activities
Pig rearing is the most polluting agricultural activity in Mauritius. A survey carried out by the AREU in 2003 showed that there are about 480 pig breeders all around the island, rearing some 13, 000 pigs annually. The local pig meat production accounts for 35% of the annual average consumption. The pig farming industry in Mauritius has slowly evolved from the early 70s’ from a traditional mode of operation to a semi-industrial base.
The pig industry has flourished due to many incentives and facilities granted by the Government to give a push to this activity. Over the years, the pig industry has given rise to severe pollution as it was carried out in an unprofessional way, characterized by poor husbandry practices and improper disposal of wastes. Pig wastes are characterized by high COD, TSS and phosphates and nitrates which are washed into ground water resources. Run-off arising from indiscriminate dumping of wastes finds its way into local water bodies which become overloaded with nutrients, potassium, trace heavy metals, salts, viruses, bacteria and other micro-organisms and sediments. Monitoring of boreholes (meant for potable water) revealed contamination of borehole water in regions where pig breeding activities are carried out. High nitrate level in potable water can cause a number of diseases such as ‘Blue baby’ syndrome, spontaneous abortions in humans, and methemoglobnemia in animals. Environmental risks include algal blooms, loss of bio-diversity due to excess nitrogen deposition, acidification and green house effect.
A large number of pig sties discharge their wastewater indiscriminately into the environment. Other sties dispose of liquid wastes as follows: 24% through surface water drains, 62% in absorption pits, 3% in septic tanks and 2% in the public sewers.
Several attempts to treat pig wastes have been made in the past as follows:
● In 1983/84, two horizontal digestors (each of a capacity of 70 m3 biogas per day) were set up as pollution control plant for piggeries at Albion Prime Farms.
● A biogas plant was installed on one large farm at St. Martin for treatment of pig wastes but is presently not in use.
● A polyethylene tube digestor was installed for demonstration purposes at Calebasses on pig farm at Calebasses for treatment of pig wastes and biogas produced was used for cooking by one household. It is no longer in operation.
● An Integrated Farming System (IFS) was set up at Union Sugar Estate during 1995-1997 jointly by a group of sugar estates and the Mauritius Research Council (MRC). The operation has since been operated on a full fledge basis.
Lately, anaerobic-cum-aerobic systems have been implemented to treat pig waste. The system comprises of the Underflow Anaerobic Sludge Blanket (UASB) followed by aerated basins. This technology has been implemented at:
The Integrated Farming System at Union Ducray The wastewater treatment plant consists of a UASB digestor, sedimentation tank, shallow basin as well as fish pond. The treated effluent complies with the Guidelines for Discharge of wastewater into the ocean. Bassin Requin, St. Martin and Albion Prime Farm
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The technology adopted is the partial IFS, based on anaerobic and aerobic treatment whereby the waste is treated by the UASB digestor, sedimentation tank and shallow basin. The treated effluent at Bassin Requin does not comply with the Effluent Standard for discharge onto land (NEL 2001). The St. Martin plant is yet to be monitored. No satisfactory results have been obtained at Albion Prime Farms and the management has decided to phase out the farming activity and concentrate on the processing of meat.
As regards disposal of pig wastes in Rodrigues, most breeders scrape the solid, which is either stacked on site or placed in pits dug in the ground and subsequently used as fertilizer. As such very little liquid waste is produced and is disposed mainly through surface drains.
Recognizing the need to regulate the pig industry, a Technical Advisory Committee under the aegis of the Ministry of Environment was set up in 2001to highlight the main problems of the industry in a policy paper on pig farming. The policy paper highlighted recommendations on several aspects of pig farming pertaining to the scale of activity, husbandry practices, wastewater disposal system and legislation. Consequently, wastewater treatment facilities were constructed at Bassin Requin and St. Martin and a new Pig Regulation has been drafted.
The policy paper also recommended that a more in-depth study be undertaken on all issues pertaining to the pig industry. Since there had been little emphasis on waste treatment facilities, another Technical Advisory Committee was set up in 2004 to make recommendations on ways and means to efficiently treat and dispose of solid and liquid waste generated from pig farming activities. The methods of pig wastes management studied comprised of:
● Spreading of slurry on agricultural fields This was not found as an appropriate method of pig waste disposal especially due to socio- cultural acceptance.
● Anaerobic and aerobic treatment of liquid wastes The TAC reported that the anaerobic-cum-aerobic treatment using UASB digestor is a proven technology and recognized to be a viable method of treating pig waste.
● Composting of solid wastes The TAC has found out that composting could be an appropriate option to dispose of pig wastes. Weaknesses include limited amount of solid waste generated, labor intensive scraping required, accessibility of lorries to the pig farms, modification required to husbandry practices and initial investment.
Conclusion The TAC recommended that solid should be collected and treated separately from the effluent. Composting and anaerobic-aerobic treatment have been selected as the two most appropriate technologies to be adopted in the local context.
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3.5 – Major rivers draining water into the ocean
Most town centers and their immediate suburbs as well as some localities are provided with road drains which drain surface water into the numerous tributaries and rivers which criss-cross Mauritius. As stated in Section 3.1.1 above, there are 25 major rivers and 21 minor ones in Mauritius. Most of the rivers spring from the Central Plateau and flow radially to the sea. Due to the steep topography of the island and its relatively small size, precipitation from all over the island reaches the sea within a few hours. Catchment areas vary from 3 to 166 km2, with most of the rivers being perennial. Water flow in streams and rivers may vary from a few liters per second to more than 500 m3/s, during heavy rains and cyclones.
The different rivers and catchment areas of Mauritius is shown on Map at ANNEX 3.15. The annual flow of the major rivers and their catchment areas is given in Table 3.17 below.
Table 3.16: Annual flow of major rivers
River Catchment area Period Annual volume (Mm3) (km2) Average Maximum Minimum Citronniers 172.7 1995-2004 3 6 1 Des Anguilles 32.6 1995-2004 40 55 12 Dragon 11.1 1995-2004 13 17 3 Tabac 22.8 1994-1999 10 13 4 La Chaux 63.4 1995-2004 53 67 7 Grand River 165.7 1995-2004 111 146 25 South East Grand River 113.4 1990-2004 29 79 0 North West Black River 31.1 1987-1995 8 23 0 Seche 45.6 1996-2004 41 63 8
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3.6 – Standards for Assessment of Performance of Wastewater Treatment Plants
Different National Environmental Guidelines, Standards and Regulations exist under the EPA 2002 for the discharge of effluents into different media. These Standards, which represent maximum values of concentration of different relevant parameters, are used in the design of wastewater treatment plants and to ensure that the treatment plants perform as per design.
The relevant Regulations are:
Standards for Effluent for use in Irrigation: Environment Protection (Standards of Effluent for Use in Irrigation) Regulations 2003
Standards for Effluent discharge into the Ocean: Environment Protection (Standards for Effluent Discharge) Regulations 2003.
Standards for Effluent discharge onto land, into watercourse or into a water body: Environment Protection (Standards for Effluent Discharge) Regulations 2003
These Regulations have been discussed in Chapter 2 and the different Standards are given below in Tables 3.17, 3.18, and 3.19
Table 3.17 - Environment Protection (Standards for Effluent Discharge) Regulations 2003
Parameter Unit Permissible limits
Temperature 0C 40 pH - 5 – 9 Floatables mm 6 Biochemical Oxygen Demand (BOD5) mg / l 250 Chemical Oxygen Demand mg / l 750 Suspended Solids mg / l 300 Cadmium µg / l 20 Chromium (VI) µg / l 100 Chromium, (Total) µg / l 500 Cyanides (as CN-) µg / l 100 Lead mg / l 2 Nickel mg / l 2 Zinc mg / l 2 Total Mercury µg / l 10 Arsenic µg / l 200 Total pesticides mg / l 1 Oil & Grease mg / l 20
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Table 3.18 - Environment Protection (Standards of Effluent for Use in Irrigation) Regulations 2003
List Parameter(1) Unit Standards pH - 5-9 A Colour - Not objectionable Biochemical Oxygen Demand mg / l 40 Chemical Oxygen Demand mg / l 120 Suspended Solids mg / l 45 Chloride mg / l 250 Sulphate mg / l 500 Nitrate-N mg / l 20 B Total Dissolved Solids mg / l 2000 Sodium Adsorption Ratio (SAR) - < 6 Aluminium mg / l 5 Arsenic µg / l 100 Beryllium mg / l 0.10 Boron mg / l 0.75 Cadmium mg / l 0.01 Chromate Chromium mg / l 0.10 Cobalt mg / l 0.0 5 Copper mg / l 0.2 Fluorine mg / l 1 C Iron mg / l 5 Lead mg / l 2 Lithium mg / l 2.5 Manganese mg / l 0.2 Molybdenum µg / l 10 Nickel mg / l 0.02 Mercury mg / l 0.02 Selenium µg / l 20 Vanadium µg / l 100 Zinc mg / l 2 Total Pesticides mg / l 0.025 D Oil&Grease mg / l 10 Detergents mg / l 5 Faecal Coliforms(2) MPN/ 1000(3) E 100ML Intestinal Nematodes(2) MPN per 100 ml Arithmetic <= 1 mean no. of eggs per Litre
Notes: (a) (1) : A 95% compliance limit will be accepted based on the series of samples taken in a year.
(b) (2) : Prohibited for crops to be eaten raw.
(c) (3) : 200 faecal coliforms MPN/100ml for public lawns such as hotel lawns, which the public have direct contact.
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Table 3.19 - Environment Protection (Standards for Effluent Discharge) Regulations 2003
Parameter Unit Maximum permissible limits Land/Underground Surface water courses Total Coliform MPN per 100 ml - < 400 E. Coli MPN per 100 ml < 1000 < 200 Free Chloride mg / l - 0.5 Total Suspended Solids (TSS) mg / l 45 35 Reactive Phosphorous mg / l 10 1
Colour - Not objectionable Temperature 0C 40 pH - 5-9 Biochemical Oxygen Demand mg / l 120 (BOD5) Chemical Oxygen Demand (COD) mg / l 40 Suspended Solids mg / l 750 Chloride mg / l 750 Sulphate mg / l 0.002 Sulphide mg / l 1 Ammoniacal Nitrogen mg / l 10 Nitrate as N mg / l 25 Total Kjeldahl Nitrogen (TKN) mg / l 1 Nitrite as N mg / l
Aluminium mg / l 5 Arsenic mg / l 0.1 Beryllium mg / l 0.1 Boron mg / l 0.75 Cadmium mg / l 0.01 Cobalt mg / l 0.05 Copper mg / l 0.5 Iron mg / l 2.0 Lead mg / l 0.05 Lithium mg / l 2.5 Manganese mg / l 0.2 Mercury 0.005 Molybdenum mg / l 0.01 Nickel mg / l 0.1 Selenium mg / l 0.02 Sodium mg / l 200 Total Chromium mg / l 0.05 Vanadium mg / l 0.1 Zinc mg / l 2 Oil & Grease mg / l 10 Total Pesticides mg / l 0.025 Total organic halides mg / l 1 Cyanide (as CN-) mg / l 0.01 Phenols mg / l 0.5 Detergents (as LAS*) mg / l 15
* Linear Alkylate Sulphonate
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3.7 - Sludge Management in Mauritius
In Mauritius, all the sludge produced in wastewater treatment plants is disposed of in landfill at Mare Chicose. The sludge treatment at the different wastewater treatment plants has been discussed in Section 3.3 above. A summary of the sludge management for the four major wastewater treatment plants and three important treatment works at Roche Bois, Fort Victoria and Pointe aux Sable is given in Table 3.20 below:
Table 3.20: Sludge Management in Mauritius
WWTP Type of Monthly Treatment Disposal Sludge Production (Tonnes) St. Martin Primary & 600 • Picket Fence Thickener Secondary for Primary Sludge
• Belt thickeners for Secondary Sludge
• Anaerobic Sludge Digestion + Centrifugal Sludge Dewatering for Primary and Secondary Sludge
Grand Baie Primary & 10 Centrifugal thickening Secondary Baie du Tombeau Primary 10 Nil Montagne Jacquot Primary 400 Belt Press Thickening
To Land Fill at Mare Chicose Land ChicoseFill Site To Mare Land Fill at Roche Bois PS Primary 25 Nil
Fort Victoria PS Primary 15 Nil
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3.8 – Re-use of Wastewater and Sludge in Mauritius
3.8.1 – Re-use of Wastewater
Re-use of treated wastewater in agriculture in Mauritius is presently limited to urban and industrial wastewater from the Plaines Wilhems District being treated to tertiary level at the St. Martin wastewater treatment plant (WWTP) and sold to the Irrigation Authority for irrigation of sugarcane fields in the western part of the island.
The Grand Baie WWTP which was put into operation in 2004 also treats wastewater to tertiary level. The treated effluent is presently being disposed of through borehole injection but the quality of treated effluent achieved is well within the required standards for irrigation. The plant receives mainly domestic effluent as there are hardly any industries within the catchment. The treated effluent could potentially be used for irrigation provided a potential buyer is available. The plant is presently treating about 1, 200m3 of effluent per day and the final design capacity is 3, 500m3 per day.
There are also at present about 45 coastal hotels that are treating their wastewater and re-using for irrigation of lawns and golf courses. Most of these hotels make use of either activated sludge process or septic tanks followed by RBC. The volume of wastewater treated in coastal hotels is of the order of 10, 000 m3 per day.
Some industries, such as soft drink bottling plants also include water recycling in their processes.
3.8.1.1 - Reuse of treated wastewater for agriculture from the St. Martin WWTP
Presently, about 35, 000 to 40, 000 m3 of wastewater is treated daily, this represents 58% of the first stage design capacity of the plant. The final design capacity, after a future second stage extension, is of the order of 87, 000 m3 per day. One major advantage stems from the fact that the irrigation canals to which the St.Martin WWTP discharges treated effluent passes in the vicinity of the plant. No additional heavy investment has therefore been required for constructing the necessary infrastructure to convey the treated effluent to the irrigation network. This has been instrumental during the feasibility studies of the St. Martin WWTP, for adopting the re-use scenario for irrigation
3.8.1.1.1- Treated Effluent Quality
The treated effluent quality based on average value of daily analyses for the month of November 2006 was given in Table 3.13 above. It can be noted that the treated water is of superior quality when compared to the Environment Protection (Standards of effluent for use in irrigation) Regulations 2003.
Heavy metal content is negligible, as can be expected as there are no industries using significant amounts of heavy metals as raw material. Only one galvanizing plant has been identified as an industry using heavy metals within the catchment area of the St. Martin WWTP. Even though there are a number of textile dye-houses, all of them use organic dye stuffs as chrome dyeing has been banned under the Dangerous Chemicals Control Act 2004.
Pesticides and Detergents values are very low and microbiological quality is quite good for irrigation of crops that will not be eaten raw.
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The treated effluent does have some color due to the presence of dyes in the raw influent. This has been the only deterrent and has required extensive negotiations and explanations for the treated effluent to be accepted for irrigation of sugarcane fields.
3.8.1.1.2 – Suitability of St. Martin WWTP effluent for irrigation.
The suitability of the St. Martin WWTP effluent for irrigation has been assessed by various studies, (Soulie, 1996, Cadillon and Lancer, 1996 and BRL, 1997).
The BRL report concluded that water from St. Martin WWTP would be suitable for irrigation, provided a sufficient degree of treatment can be provided to meet recommended effluent standards, and provided a dilution factor of 1: 1 can be provided to reduce the salinity and sodium absorption ratio to an acceptable level. The salinity and sodium content of the effluent is relatively high due to industrial wastewater discharges, and particularly the use of sodium sulphate in textile dye-houses. The 1:1 dilution ratio was recommended so as to meet FAO recommended water quality parameters for irrigation based on the type of soil present in the area to be irrigated:
Conductivity < 1, 500 µS/cm Sodium Absorption Ratio < 6
The average water quality of La Ferme Canal was reported (Cadillon and Lancer, 1996) to exhibit conductivity of the order of 342 µS/cm.
The dilution factor required was calculated on the basis of limited data collected during October 1996, which showed the conductivity of the wastewater to be of the order of 1890 µS/cm, with a SAR of 11. This dilution was recommended so as to avoid long term build up of salinity in the soils over a period of years.
However, the results of analysis available for the months of June to December 2006 show that the conductivity of the raw influent and the final treated effluent were in the range 900-1000 and 830- 890 µS/cm respectively.
3.8.1.1.3 – Description of Irrigation System
The area under cultivation in the Western Coastal Plain is approximately 6, 300 hectares. About 3, 500 ha are irrigated, of which some 2000 ha are irrigated with river water and ground water resources, while only 1, 500 ha are irrigated with water from a canal system. There is an extensive irrigation network fed by two main canals, La Ferme and Magenta, which bring water from La Ferme and Magenta Dam respectively.
The majority of the area is cultivated with sugarcane but vegetables such as potatoes, tomatoes onions and ground nuts are also cultivated, either by small planters, or by intercropping with the sugarcane.
The Medine Sugar Estate is the dominant planter with 45.5% of the total area, and 60.4 % of the irrigated area.
The types of irrigation used comprise surface flooding, overhead centre pivots and drip systems.
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Water flowing along both La Ferme and Magenta canals is abstracted at various points by the planters along the route. Each planter has an allocation depending on the size of the irrigation area. The allocation is controlled by a Water Users Association (WUA) which meets each month to review reservoir levels and decide the appropriate allocation. These are controlled by a V- notch and gate on each abstraction point. The WUA controls releases by adjusting the gates, each of which is locked and cannot be adjusted by the farmers.
3.8.1.1.4 – Irrigation Water Potential from St. Martin WWTP effluent
In the past, due to water shortages in the reservoirs, the allocation had to be reduced by the same proportion to each farmer. During water shortages, it had been reported that the small planters suffer more severe water shortages than the larger plantations. The Irrigation Authority had expressed the wish to see the smaller planters benefit from additional water.
Additional treated effluent from St. Martin WWTP provided direct to the canals makes it possible to retain more water in La Ferme reservoir and prevents the need for reducing the allocation during the dry season.
The Western Coastal agricultural zone comprises 17, 000 ha of cultivable land, but at present only 6, 300 ha of this are cultivated (3, 500 ha under irrigation) due to the prevailing soil water deficit. Uncultivated areas are mostly used for pasture. Thus there is a high potential for expanding the irrigation area.
A model developed by SIGMA Ove Arup to determine irrigation demand for each month of the year, depending on climatic factors, soil characteristics and crop factors, has shown that the mean soil moisture deficit is greatest during the months of May and October. The model has provided a gross water requirement of 14, 000 m3/ha per annum assuming 15% losses in the irrigation canals (BRL 1997).
Thus, at full design stage, i.e at 87, 000 m3/d DWF, the St. Martin WWTP effluent could provide sufficient water to irrigate approximately 85% of the 1, 500 ha area formerly irrigated from the canals.
3.8.1.1.5 – Sale Agreement between the Wastewater Management Authority and the Irrigation Authority
The mechanism for the sale of effluent from the St. Martin WWTP for irrigation has been set up by means of an Agreement between the Wastewater Management Authority (WMA) and the Irrigation Authority (IA)
3.8.1.2 – Re-use of Wastewater as Cooling Water
A major solid waste incineration has been proposed near the St. Martin WWTP Negotiations are on-going between the WMA and the promoters for the sale of 3, 000 m3/day of treated effluent from the St. Martin WWTP.
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3.9 – Status of Sanitation in Rodrigues
Investigations carried out during the elaboration of the Sewerage Master plan revealed that only 9% of the Rodrigues population possess cistern flushed toilets, and this was mostly in Port Mathurin. Daily water consumption is estimated at 600m3 in Port Mathurin. There is therefore no sewerage network in Rodrigues and on-site wastewater disposal is practiced This is mainly due to the fact the piped water supply is not well developed and water resources are scarce. Even in the main urban area, Port Mathurin, there is no 24 hr potable water supply. 78% of the population were using pit latrines while the rest did not have any sanitary installations.
Upon request of the RRA for technical assistance, a mission was undertaken in August 2006 in Rodrigues by the author of this report. It was observed that most of the dwellings in Port Mathurin make use of cesspits and that no major problems are encountered by the residential houses though many houses discharge their sullage water directly into road and surface water drains which eventually discharge into the sea. However, public buildings and collective buildings like the market, hospital, and major commercial buildings and hotels, do have problems with on-site disposal, most probably due to the clayey nature of the soil and possibly due to undersizing of systems.
The Works Division of Rodrigues possesses one wastewater carrier which is used to pump wastewater principally from these public, commercial buildings and some private hotels. It is estimated that about 30 to 40 m3 of wastewater are carted away every day. The wastewater is discharged at a communal wastewater disposal system situated at Roche Bon Dieu.
The communal disposal system at Roche Bon Dieu consists of two septic tanks of about 15m3 and each connected to a leaching field of surface area of 300 m2. The wastewater is discharged directly into receiver manholes, without any screening facility, which direct the wastewater into the septic tanks. The effluent from the bottom of the leaching fields is collected by drainage pipes and is allowed to drip down the coast for about 1.5 km before reaching the lagoon.
It was found that the septic tanks were completely filled with sludge up to the outlet pipe level. The septic tanks also contained large amounts of stone, domestic waste, syringes and other hospital waste. The septic tanks and the leaching fields were severely clogged.
Recommendations made under the mission included short term, medium term and long term measures.
Short term measures included urgent desludging, cleaning, as well as some remedial works to defective piping systems and replacement of inappropriate fittings as required.
In the medium term some additional units such as a screening device and filter box are required to protect the septic tank and leaching field from foreign bodies and sludge/suspended solids respectively.
As long term measure, it was recommended that the quantity and quality of final effluent be monitored to decide whether further treatment, by means of a constructed wetland, is required before channeling the final effluent through a piping system from the existing treatment location to the coast and final infiltration of the effluent in the sand at more than 30 m from high water
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3.10 – Conclusions
Sanitation is well managed in Mauritius. Priority has been given to sewer the most urbanized parts of the island where high concentration of individual cesspits could lead to deterioration of ground water resources. Four major wastewater treatment plants have been built and treat wastewater to the required norms. Industries and coastal hotels are well managed. The low cost housing estates where the poorer segment of the population resides are given high priority by the Government by ensuring that sanitation infrastructure is upgraded to decent conditions. However, on-site sanitation practices need to be revisited, especially in terms of regulatory and enforcement aspects. Management of pig wastes also needs to be improved.
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Chapter 4 – Assessment of Existing MWW Management Practices and Methods
4.1 - Assessment of existing MWW management practices and methods
4.1.1 – Political Commitment
The policy of the Government of Mauritius in the broad environment sector is spelt out in the Environment Protection Act 2002, which declares that it is an Act that will:
“provide for the protection and management of the environmental assets of Mauritius so that their capacity to sustain the society and its development remains unpaired and to foster harmony between quality of life, environmental protection and sustainable development for the present and future generation; more specifically to provide for the legal framework and the mechanism to protect the natural environment, to plan for environmental management and to co-ordinate the inter-relations of environmental issues, and to ensure the proper implementation of governmental policies and enforcement provisions necessary for the protection of human health and the environment of Mauritius.”
In pursuing the above, the following objectives reflect the policy of the GoM in the wastewater sector:
•to halt and reverse the trend of wastewater pollution on the island and its coastal zone, •to improve health and sanitary conditions of the population •to provide the technical, legal, institutional and financial framework necessary for sustainable development of the sector.
Since the NEAP 1, the GoM has been committed to ensure that necessary funding sources are identified and that projects under the NSP are implemented.
Necessary legislation has been enacted to provide the regulatory framework for pollution abatement through the EIA process, development of water quality standards, identification of Enforcing Agencies and setting up of environmental laboratories.
A parastatal organization, the WMA has been set up, equipped with the necessary technical, legal, institutional and financial framework necessary for sustainable development of the sector The responsibility to achieve the above objectives lies primarily with Central Government, which through the Ministry of Public Utilities, has delegated its responsibilities with respect to the wastewater sector to the Wastewater Management Authority. The two most important legislations of relevance are the Environment Protection Act (EPA) 2002 and the Wastewater Management Authority Act 2000. The latter legislation defines a clear mandate for the responsibilities and obligations of the WMA in the wastewater sector. These include:
•Project management for implementation of projects in the National Sewerage Programme with a view to provide sewerage facilities to priority areas as identified under the NSP.
• The management of the operation and maintenance of existing sewerage infrastructure.
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• The control of domestic and industrial effluent discharges into public sewers and into the environment in compliance with the effluent standards contained in the Regulations under the WMA Act 2000 and the EPA 2002.
4.1.2 – Institutional Structure
The WMA Act 2000 confers the whole responsibility for the wastewater sector to the WMA. The WMA is responsible for: • Project Management of all feasibility studies, detailed design, consultancy supervision and Works contracts for extending the sewer network nationally and for construction of public wastewater treatment plants. • Operation and Maintenance of all public sewer networks in Mauritius. • Pollution Control by way of approval of wastewater management schemes of all proposed infrastructural development, issue of effluent discharge permits, post-monitoring through inspections, visits and effluent sampling and analyses. • Securing the generation of revenue, mainly through tariff, so as to ensure self-sustainability. • Advise the GoM and other institutions on all matters relating to the wastewater sector.
The existing organization structure advocates a lean and thin organization geared to the efficient operation of an entity providing services. It is structured to make large use of outsourcing for many of the Authority’s functions. The organization structure relies heavily on a highly qualified and skilled executive team and key posts at the top level of the organization backed by technical managers, engineers and technicians to ensure supervision of all the outsourcing contracts.
Thus, the New Works Division undertakes the project management of all consultancy and works contracts for capital works while the Operation and Maintenance Division is responsible for the operation and maintenance of wastewater treatment plants and pumping stations. The House Connection Unit is responsible for provision of house connections through works contracts. The Pollution Control and Monitoring Department gives formal approval for all infrastructural and industrial development while monitoring compliance of all treatment facilities with prescribed norms.
4.1.3 – National Strategy in Provision of Sanitation and Wastewater Treatment
Mauritius has followed the trend of many developing countries in that the water sector has been highly developed compared to the wastewater sector. Indeed huge investments have been made in the water sector over the past 30 years with the result that more than 98% of the population has access to safe drinking water. Piped water supply covers 95% of the population, with some 280,000 domestic connections. Potable water costs USD 0.15 per m3 for the first ten cubic metres and gradually increases to USD 0.8 per m3 for the next 150m3. This, coupled with a good standard of living, has favoured the use of cistern-flush toilets throughout Mauritius, pit latrines being used by only about 2% of the population.
The strategy of the GoM under the NSP has been to provide sewerage to those urban areas with heavy population density as identified under the Sewerage Masterplan. Presently 25% of the population has been provided with sewerage facilities. The remaining 73% of the population make use of on-site disposal systems consisting of cesspits and septic tanks followed by absorptions systems in the relative proportions of 7 : 3. The objective of GoM is to provide sewerage facilities to 50% and 80% of the population by the years 2015 and 2030 respectively.
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The great majority of the population has therefore access to basic sanitation. No gender issues exist regarding fetching of water or safe access to sanitation to women since piped water is available in the home and all toilets are also located in the house itself. The GoM is essentially a service provider and the traditional Supply-driven wastewater management approach is usually adopted. Consulting engineers were appointed to prepare the Sewerage Masterplan which identified the areas which needed to be sewered.
Consulting engineers are also appointed for all major feasibility and detailed design studies associated with sewerage infrastructure. Conventional waterborne sewerage infrastructure and activated sludge process based wastewater treatment plant are normally advocated.
Formerly only street sewers were built under sewerage projects and it was left to the house owners to build their house sewers and connect to the mains sewer at their own costs. Presently, the GoM has decided to provide house sewers free of charge and under the most recent projects, house sewer is provided under the same contract as for the provision of street sewers.
The strategy for wastewater treatment has been to direct all effluent from large existing sewered areas to four major treatment plants. Some low-cost housing estates which urgently required sewerage infrastructure due to failing on-site disposal systems have also been provided with treatment plants.
The possibility of re-use of wastewater for irrigation and the re-use of sludge as soil conditioning has been assessed in all feasibility studies for the four main treatment plants. Treated effluent from the St. Martin WWTP is being sold for irrigation of sugar cane fields in the western part of the island. At the Grand Baie WWTP, the treated effluent can be sold for irrigation provided a potential buyer is available.
Feasibility studies for the Baie du Tombeau and Montagne Jacquot WWTPs revealed that re-use of the treated effluent would not be economically viable in the immediate future but in the design and construction of these WWTPs provision has been to accommodate secondary treatment at a later stage when service levels would render the re-use of the treated effluent economically viable.
Laboratory analyses and further studies are still on-going at the Agricultural Research Extension Unit of the Ministry of Agro – Industry and by the Mauritius Sugar Industry Research Institute for the feasibility of applying secondary sludge as soil conditioner.
4.1.4 - Long term Strategy for Provision of Sewerage Facilities
The National Sewerage Masterplan 1994 identified priority sewerage projects which had to be implemented within a timeframe of 10 years. These projects involved the most heavily populated regions of the country and the National Sewerage Programme can be considered to have been implemented with a delay of 3 years. Thus both local and international financing was secured to ensure that those areas most likely to be under environmental threat, due to discharge of domestic and industrial effluents, were provided with sewerage networks and wastewater treatment plants. At the same time, feasibility studies for the different major sewerage projects made in-depth studies into the possibilities of reuse of treated effluent in agriculture. Reuse of effluent has been adopted where it was proved feasible, examples being treated effluent from the St. Martin WWTP and the Grand Baie WWTP. In other cases where reuse of treated effluents did not prove feasible
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One of the key components of the National Sewerage Programme is the rehabilitation and extension of wastewater facilities in low cost housing estates so as to improve the access of the poor to suitable sanitation. About 158 low cost housing estates were constructed in the period 1960 – mid 1980’s to provide shelters to nearly 100, 000 inhabitants who became homeless following severe cyclones during that period. Since the provision shelters were top priority and because of limited funds, adequate sanitation infrastructure was missing. The on-site sanitation facilities provided such as cesspits became overloaded and failed over the years.
During the years 1990 to 1999, Phases I and II of the rehabilitation of sewerage infrastructure took place and comprised 28 low cost estates. The Extension of Phase II project was carried out during the years 2003/2005, and around 1500 houses were connected to the public sewer system.
The Phase III project is on-going and concerns nine estates, located across the island and comprises 2200 households. The population from the low income group who will benefit from the project is estimated at around 11, 000.
Feasibility studies for Phase IV are on-going and concerns the provision/rehabilitation of sewerage infrastructure on a further 27 CHA and low cost housing estates scattered over the island.
The provision of proper sewerage facilities in these low cost estates will contribute to abate the wastewater pollution and environmental degradation mainly due to overflowing cesspits and will greatly reduce health hazards to the inhabitants, particularly with regard to waterborne diseases.
The WMA will derive substantial benefits from the project as this will facilitate operation and maintenance activities and consequently increase the willingness to pay for improved wastewater infrastructure. The WMA will also benefit from an increase in its revenue due to an increase in its number of customers.
4.1.5 – Stakeholder Involvement
The Central Government, through the Ministry of Public Utilities, is responsible for the wastewater sector and one of their main tasks is to ensure that capital sewerage projects are implemented.
International funding agencies have been largely involved in financing the capital sewerage projects and now that international funding is mainly through budgetary support, the wastewater
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Main institutions involved in water resources management such as the Central Water Authority, the Water Resources Unit, the Ministry of Agro-Industry and the Ministry of Fisheries operate within their established institutional and legal set-up, while overall policies regarding water management are defined by the parent Ministry, the Ministry of Public Utilities.
Other institutions such as the Ministry of Public Infrastructure and Ministry of Lands and Housings interact with the WMA through meetings and correspondences for the purpose of obtaining specific approvals on wastewater projects and developments.
The role of the industrial sector is to ensure that the quality of industrial effluents is within required norms by complying with existing monitoring programmes.
4.1.6 – Private Sector Participation
Private Sector Participation in the wastewater sector involves outsourcing of engineering services including feasibility studies, detailed design and works supervision. Major works contracts are outsourced to international and local private contractors through competitive bidding. Cesspool emptying services is also outsourced to a list of private cesspool emptyers duly registered with the WMA.
4.1.7 – Financing Mechanisms
The 1998 Sector Policy Letter stressed the need for financial sustainability in the wastewater sector. To that effect, the WMA was established as a corporate body to provide facilities and services in the wastewater sector and to charge such wastewater taxes as are necessary to cover the costs of those provisions.
The wastewater charges applied to WMA’s customers is based on the volume of water consumed, with different rates for domestic and non-domestic tariff.
The WMA is remunerated by GoM for managing the implementation of the Capital Projects at 2% of the Capital expenditure incurred during the financial year. This project management fee will continue as long as capital projects will be implemented.
The WMA also provides miscellaneous services related to the wastewater sector like cesspool emptying, which is charged on actual expenditure basis. The sale of treated effluent from the St. Martin WWTP has generated revenues amounting to MUR 2.2 million for the year 2005/06.
According to the Sector Policy Letter, GoM retains ownership of the sector’s assets. The GoM policy does not regard it as possible, or desirable, to attempt to recover the full cost of provision of the services through wastewater charges to the user. The wastewater tariffs, although proposed by the WMA, are subject to approval by the GoM. Tariffs are expected to cover the O&M costs of the facilities, depreciation of the assets and a contribution to debt service, subject to the affordability criterion that combined water and wastewater tariffs are not expected to exceed 5% of household income.
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Capital projects are normally funded through loans and grants from international funding agencies, which are topped up from National Budget.
Provisions exist in Regulations for industrial effluents for application of Polluter Pays Principle.
4.1.8 – Technological Options
Sanitation in Mauritius can be summarized into two main technologies, waterborne sewerage for collection and transportation, activated sludge process for wastewater treatment and on-site disposal such as cesspits and septic tank systems for unsewered regions.
There are a few wastewater treatment plants using the RBC technology, especially on coastal hotels.
Other treatment technologies include anaerobic treatment and physico-chemical treatment for some industrial effluents.
Constructed wetlands and pond treatment systems are land intensive and, since Mauritius is a small island where land has high value, these have not been applied for large communities. Recently, however, this technology has been adopted for wastewater treatment by a major coastal hotel.
No other low-cost technologies such as dry sanitation and small bore diameter sewer are applied.
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4.2 – Assessment of Existing Constraints in MWW Management Practices and Methods
4.2.1 – Public Awareness
The supply driven approach of potable water provision over the past 30 years has not been followed by a corresponding development of the sanitation sector and the introduction of water education at national level. It is desirable to impart the general public with the necessary notions of water conservation, need to protect our environment for future generations and understand that wastewater collection treatment and disposal is not only the responsibility of government and that payment for this service is essential.
Although collection ratio for wastewater is high, rates being relatively affordable, the general public needs to understand the reasons and basis of such a charging system so as to enhance and encourage commitment to participate fully in the process.
Although sanitation rates high on the agenda of the Government, it still requires to be fully appreciated by other stakeholders such as practicing professionals and other governmental organizations.
The main technologies applied on a national basis are waterborne sanitation, conventional activated sludge process wastewater treatment. This results in high costs of investment in sewerage infrastructure. Anaerobic treatment systems other sanitation technologies are not popular and there is no incentive to apply such technologies which may have a much lower capital and operation & maintenance cost, whilst providing scope for wastewater valorization.
Pond systems and constructed wetlands are not popular due to large land requirements and relatively highland value on a small island.
On-site sanitation techniques consist mainly of cesspits, irrespective of soil hydrogeology.
4.2.2 – Policy and Commitment
The policy and commitment of the Government in the wastewater sector has been mainly dictated by: • providing waterborne sewerage infrastructure in urban regions with high population density. • Improvement of access of the poor to suitable sanitation. •Strengthening the WMA with adequate legal status, human resources and tariff structure •Promulgation of environmental laws and regulations, development, monitoring and enforcement of environmental standards for effluent discharge. •Setting up of environmental laboratories and enforcing agencies.
4.2.3 – Extension of wastewater facilities
The extension of waterborne sewerage linked with high technology wastewater treatment involves extensive financial mobilization which, in the long run, may not favor financial sustainability and the sector will finally require government subsidies for sustenance. The potential of low-cost technologies and/or alternative technologies should therefore be envisaged.
Since most efforts have been geared towards provision of waterborne sewerage, on-site sanitation has lagged behind. The passing of Regulations for wastewater on-site disposal will ensure that
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Proper legislation and enforcing mechanism for on-site disposal systems is necessary since a great majority of the population will still be using this technology for a long time, more so that 40% of our potable water resources come from ground water.
4.2.4 – WMA Institutional Structure
A scrutiny of the WMA Act 2000 reveals that the whole responsibility of the wastewater sector, including regulatory aspects for private sewerage systems, falls under the responsibility of the WMA. Such a large umbrella of responsibilities would normally require extensive human resources and competencies in various fields, unless responsibilities are out-sourced. The present institutional set-up advocates a lean and thin organization, consisting of technical managers, engineers and technicians to ensure supervision of the outsourcing contract, since the organization is structured to make large use of outsourcing for many of the Authority’s functions.
This set-up is appropriate for the New Works Division and the Operation and Maintenance Division where most activities are readily outsourced to engineering consulting firms and private consulting firms. The legal set-up for undertaking capital sewerage works and operation & maintenance of public sewerage infrastructure is defined through the two contracts signed between the WMA and the Ministry of Public Utilities, namely the Convention de Maîtrise d’Ouvrage Déléguée and the Contrat de Délégation. Financial remuneration for carrying out these activities are provided under the first contract by way of a 2% project management fee and by provision under the WMA Act 2000 that the WMA can raise tariff to finance its activities.
4.2.4.1 – Regulatory, monitoring and enforcement aspects
Certain activities pertaining to regulatory, monitoring and enforcing aspects are being carried out by the Pollution Control & Monitoring Division. Regulatory, monitoring and enforcement aspects regarding industrial and commercial effluents, EIA exercises, approval of all proposed infrastructural development, monitoring of WMA owned treatment plants, attending to complaints regarding effluent overflows island wide, provision of technical advice on wastewater issues to other governmental organizations require extensive human and financial resources. A reasonable number of competent and well trained staff is also required for such activities. Thus engineering technicians may require specific training, especially in wastewater treatment process, operation & maintenance aspects of sewerage infrastructure, cleaner production for industrial sector and on-site sanitation.
4.2.4.2 – Project Management
Since a recent past, capital sewerage projects have been managed by civil engineers. These sewerage projects have one consultancy contract component and several works contract component and these usually involve international consulting and contracting firms. Major projects usually span over more than five years. The WMA has adapted with the increasing complexity of projects by ensuring that a full fledge project team is in place for an efficient management of projects.
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4.2.4.3 – Operation and Maintenance
Before being transformed into the present parastatal organization, the then Waste Water Authority was the sole organization dealing with all aspects of wastewater. All operation & maintenance of sewerage networks, cesspool emptying services and house connections were performed in-house. Private consultants and contractors were only involved for studies, design and construction of major sewerage infrastructure. This led to the development of specific skills such as construction of manholes which could be found within the organization.
With increasing out-sourcing and less in-house operation and maintenance, these skills may be lost.
4.2.5 – Existing Legislation for Effluent Discharge
Existing legislation under the EPA 2002 and the WMA Act 2000 address the regulatory, monitoring and enforcement aspects for discharge of effluents.
4.2.5.1 – EIA / PER Undertakings
Many undertakings require an EIA or PER Licence prior to implementation. Under existing procedures, the Promoter is required to submit his EIA or PER Report to the Ministry of Environment which distributes these to the various organizations so as to obtain their views/approval. A joint site visit, attended by the different public organizations, is organized by the Ministry of Environment which also organizes EIA and PER meetings before issuing the EIA or PER Licences.
Due to Government’s concern to facilitate business, a time limit of about 4 weeks is normally imposed for the public organizations to submit their views to the MoE. However, in many cases, EIA / PER reports submitted by promoters do not contain the relevant information necessary to assess the quantity and quality of effluents to be produced and the treatment processes proposed. In case of on-site disposal, necessary hydro geological soil reports are rarely submitted. In such cases, the WMA has to request for missing/additional information. Due to the large number of EIA/PER reports submitted (average 500 per year) and limited number of trained engineers deadlines for submission of views to the MoE are not always respected.
4.2.5.2 – Building and Land Use Permit
Under recent Regulations all infrastructural development requires a Building and Land Use Permit (BLP) from the relevant Municipal or District Council. All development within sewered areas require a clearance from the WMA in order to obtain the BLP. Such a clearance will normally state whether the proposed development should be connected to the public sewer network or whether on-site disposal is required. The Planning Guidelines do not specificically indicate the type and size of development for which a WMA clearance is required. When on-site disposal systems fail and cause overflows, the WMA is called upon to investigate and propose remedial measures. The number of such complaints islandwide sent to the WMA is increasing and is a subject of much concern as the concerned department is not staffed to handle such a number of complaints.
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4.2.5.3 – Enforcing Agencies for Effluent Discharge
Under the EPA 2002, the Ministry of Public Utilities is responsible for enforcing environmental legislation related to inland waters and effluents. This Ministry has delegated this responsibility to the Water Resources Unit which is mandated to licence all industries discharging effluents into water courses.
The Central Water Laboratory carries out regular water quality monitoring of raw water and of treated potable water that it delivers to the public. This laboratory also undertakes ad-hoc monitoring of quality of effluents from industries upon request from other institutions.
The enforcement for environmental legislation concerning the quality of drinking water rests with the Ministry of Health and QL which also possesses its own water quality laboratory.
The Ministry of Environment, by virtue of its mandate for policy making and quality conservation of water bodies and overall planning and regulation of inland and coastal waters, also carries out ad-hoc monitoring of inland water quality and quality of effluent from industries and coastal hotels.
The Wastewater Laboratory of the WMA carries out regularly sampling and analyses of effluent from public wastewater treatment plants, industries connected to the sewer network and coastal hotels.
The Ministry of Agro-Industry is responsible for coastal water quality and carries out regular sampling and analysis of coastal waters.
Although co-ordination between the different institutions takes place through meetings and committees, the legislation and responsibilities is fragmented and overlapping among various institutions involved in the exploitation and monitoring of water resources.
4.2.6 – Interaction between different actors in the water sector
The water sector is under the umbrella of the State through the Ministry of Public Utilities. It is managed by different parastatal organizations such as the Central Water Authority, the Water Resources Unit and the Wastewater Management Authority. Such sectoral delegation of duties allows the different tasks to be allocated more specifically but requires greater co-ordination, especially when cross-sectoral decisions need to be taken.
There also exists a number of legislations which regulate the activities and responsibilities of different organizations relating to the water sector. These include:
The Ground Water Act 1970 which established a licensing system in prescribing that no person can abstract, divert, obstruct or use groundwater without a licence from the Central Water Authority. The licence can be suspended or revoked for any person who is likely to alter the composition or quality of the groundwater.
The Rivers and Canals Act 1863 is the first piece of legislation to regulate the protection and use of watercourses and man-made canals in Mauritius. The Act specifically provides that all rivers and streams in Mauritius are public property and water from these
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The Public Health Act 1925 and its further amendments empower the Sanitary Authority to call for the removal of a nuisance that can exist in a watercourse, stream, canal, pond, reservoir that for any cause would be in such a state to be injurious or dangerous to public health.
The Central Water Authority Act 1971 (CWA Act 1971) established the Central Water Authority (CWA) as the sole undertaker for the supply of water for domestic, commercial and industrial purposes throughout Mauritius. This Act empowers the CWA to prepare plans for the conservation, utilization, control and development of water resources. The CWA may also disconnect the supply of water to any consumer that discharges polluted water into the ground and surface waters.
The Irrigation Authority Act 1979 was passed to establish the Irrigation Authority and provide the agricultural water sub-sector with a legal framework.
The Wastewater Management Authority Act 2000 (WMA Act 2000) enacted in 2001 empowers the WMA to monitor, supervise, manage and carry out wastewater works, control the discharge of industrial wastewater and prevent the discharge of toxic and other wastes into the wastewater system, and to levy taxes and charge expenses. The Act recommends the promotion of re-use of treated wastewater.
4.2.7 – Financing Options The WMA, though designed to operate as an autonomous body, operates like many public authorities. Thus, costs for investments, operation and maintenance outstrip capacities to ensure full cost recovery. The relevant impediments stemming from this mode of operation are as follows:
•The WMA does not have wholly autonomous status as its decisions, such as the raising of tariffs, are subject to the approval of GoM.
As the actual tariffs are relatively low, not reflecting the actual cost of collection, treatment and disposal, there is no incentive from the public and from the industrial sector to consume less water and to control pollution.
• Although the Wastewater (Standards for Discharge of Industrial Effluent into a Wastewater System) Regulations 2004 in already in force since 01 January 2005 and 153 industries have already been licensed, the surcharge tax, for which provision is made in the Regulations, has not yet been applied as the mechanisms for its implementation are being reinforced.
•The wastewater sector is not presently linked to other sectors whose activity may cause considerable effect to the environment. The potential of such sectors, like the tourism sector, could be exploited to finance the wastewater sector. Opportunities that public-private partnerships can bring in assisting local government in initial financing and operation wastewater management infrastructure should also be exploited.
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• Conventional high technology wastewater treatment and waterborne sewerage has so far been adopted in Mauritius for most capital projects. Financial sustainability may not be attained in the next few years, especially considering the cost of operation & maintenance of new treatment plants. If these technologies continue to be adopted, the financial sustainability of the WMA may be even more at stake.
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4.3 – Recommendations for improved MWW management practices and methods
4.3.1 – Pubic Awareness and Sensitization Campaign It has been recognized worldwide that improvements in water management cannot be accomplished by technical or regulatory measures only. These need to be complemented by awareness and education initiatives. A fundamental change in behaviour and attitude is required to develop a new water-use ethic in society. Such fundamental change cannot be brought overnight but needs to be planned effectively.
During the Regional Consultations on Values-based Water Education for Asia and the Pacific held in Manilla from 29 November to 2 December 2003, the Water for Asian Cities (WAC) Programme was developed as a collaborative initiative of UN-HABITAT, the Asian Development Bank and countries of the region. The programme supports the implementation of the water and sanitation related Millenium Development Goal and targets in Asian cities, specifically promoting pro-poor governance, water demand management, increased attention to environmental sanitation; and income generation for the poor linked to water supply and sanitation. The programme seeks to achieve this by mobilizing political will, raising awareness through advocacy, information and education; training and capacity building; by promoting new investments in the urban water and sanitation sector; and by systematic monitoring of progress towards MGDs.
The programme is based on four specific approaches that can be adapted and applied in the Mauritian context to bring about a new water-use ethic. These approaches are:
• Engaging policy level officers and decision makers so as to mobilize political will and commitment to promote policy, regulatory and tariffs reforms, cross-cutting across different public institutions.
• Strengthening capabilities at the national, regional, institutional and municipal level for integrated urban water management. The capacity of existing institutions would need to be strengthened while a network of experts and institutions would need to be established.
• Promoting integrated urban water management through demonstration projects, focusing on income generation for the urban poor, demand management and environmental sanitation. Selected projects would need to be undertaken to demonstrate the integrated approach and its benefits. • Creating a new ethic amongst children and communities through value-based Water Education. This should include capacity building for value-based water education in schools by developing teacher training guides and conducting training of trainers, establishing water education classrooms in pilot schools and community water education, promoting water value based education through the curriculum. The Mauritius College of the Air could be the appropriate institution for developing such projects for schools as well as television programmes for community water education. This institution could work in close collaboration with public water institutions while the support of the private sector can be sought to finance the programme. Partnerships should be established between schools and the water sector by establishing water and sanitation class rooms with the support of water providers and developing value-based teaching materials, including water quality and quantity audits. Value-based water education in schools is an essential part of a national sensitization programme as children and youth are the best ambassadors to bring long term attitudinal change. Parents can then best be influenced by educating their children.
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Public awareness and sensitization can also be undertaken by distributing leaflets with utility bills, publicity campaigns sponsored by the private sector and television programmes. Public awareness campaigns can help to make customers aware of their water use patterns, give them advice on how to change those patterns and provide estimation of costs and savings associated with water conservation measures.
4.3.2 – Creating an enabling environment at national and local levels
Internationally, central government utilities have not been successful, especially in the sanitation sector. Thus, the global trend has been to encourage delegation of responsibilities to the local level. Such an approach gives the flexibility to the local authorities to decide whether to outsource to the private sector and to choose their own financing mechanisms.
However the context of Mauritius is different in that it is a small country with a relatively small population. In fact, its population of around 1.3 million inhabitants can be smaller than the population of many cities internationally. About 40% of the population is concentrated in five urban towns, 16.6 % is concentrated in 15 large villages and the remaining 44.4 % is scattered all over the island. Sewerage networks usually cut across municipal boundaries and, due to the steep topography, centralized wastewater treatment plants are situated near the coast, away from the urban centers they serve. Furthermore, presently only 25% of the population is sewered.
In such a context, it is best for Mauritius to have a central organization for sanitation, as it is the case now. If operation and maintenance of sewer networks were delegated to the local authorities, sewerage tax raised would obviously be allocated to these institutions. However, such sewerage tax is vital for the sustainability of the WMA. Also, the island being relatively small, it is quite easy for the WMA, with a few regional sub-offices, to access and maintain the existing sewer networks.
The WMA is the organization for wastewater management responsible for strategic planning, policy and regulatory aspects of the sector. However, regarding the issue of on-site disposal, it is believed that it would be more appropriate for the relevant enforcement aspects to be delegated to the local authorities since the existing institutional set-up of the WMA does not allow it to assume such a role, especially as regards control and enforcement. On the other hand, the local authorities do possess the required inspectorate cadre for inspection of building infrastructure during construction. These inspectors are each one responsible for a specific area and make regular visits. It would be therefore more appropriate to make use of the existing set-up within the local councils and reinforce it with appropriate training and incentives.
Thus, while policy and regulatory aspects of on-site disposal would rest with the WMA, approval and inspection of construction for proposed buildings would rest with local authorities. Proper legal set-up, as well as necessary Regulations for the design and construction of on-site disposal systems needs to be implemented. Required training of local authorities’ technical staff should be prepared and implemented, either by the WMA or by an appointed consultant, under the supervision of the WMA. Such a delegation of responsibilities will only be feasible after the implementation of the public awareness and sensitization campaign stated in the previous section so as to mitigate obvious opposition from these municipal/district councils.
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4.3.3 – Integration of water supply and sanitation with pollution prevention and control
The on-going and future sewerage projects provide the necessary mechanism for proper collection, transportation, treatment and disposal of wastewater and thus ensure the protection of human and ecosystem health. The necessary mechanisms, in terms of EIA Licences and Building Permits, regulate the quality of treated effluents that are allowed to be generated from proposed infrastructural and industrial development. Enforcing Agencies, armed with different Regulations under the EPA 2002, ensure monitoring of treated effluents from different activities and also monitor the quality of different water bodies. Reuse of treated effluent in irrigation is seriously studied under each major sewerage project and is applied if found viable.
In Mauritius, therefore, water supply and sanitation are not restricted to taps and toilets. However, a number of operating mechanisms need to be fine tuned.
Regarding EIA applications and Building Permits, relevant guidelines and procedures need to be developed to inform promoters and designers how to prepare and submit proper reports, including all relevant information pertaining to the wastewater management aspect of the project. This will minimize the amount of additional or missing information usually requested by the WMA and will allow processing of applications within the required timeframe.
In the monitoring exercises carried out by different Enforcing Agencies and their relevant laboratories, a synergy of laboratories would be desirable. Hence a national monitoring programme, involving all public laboratories, would ensure that there is no unnecessary repetition of work, enable more efficient sharing of information and data, more co-coordinated use of resources and would provide a global picture of the wastewater situation in the country.
4.3.4 –Integration of urban water supply and sanitation management systems
4.3.4.1 - Private Sector Participation (PSP) in the Water & Wastewater Sector
A study was undertaken in 2003 for the reform of the water and sanitation sectors with a view to improving the overall performance of the utilities through the enlistment of Private Sector Participation.
4.3.4.2 - Utility Regulatory Authority Act (URA Act)
A Utility Regulatory Authority Act (URA) has been passed and stands yet to be proclaimed.
4.3.5 –Long Term Approach in Wastewater Management
As discussed in Section 4.1.4, provision of sewerage facilities to highly populated urban areas and improvement of access of the poor to suitable sanitation has been planned over an extended time frame and has been implemented stepwise. The Second Sewerage Masterplan is expected to plan the provision of sewerage facilities to rural areas. The issues of public awareness and sensitization as well as proper policy and institutional planning for on-site disposal systems require a long term planning as from now since the success of these two projects will have a strong bearing on the sanitation sector in Mauritius over the years.
4.3.6 – Use well-defined time-lines, and time-bound targets and indicators
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The overall performance and progress of the wastewater sector is monitored by a series of key performance indicators. These are: • Annual Capital Expenditure under NSP expressed as a percentage of approved budget • Annual Increase in Domestic and Non-Domestic House Connections with respect to set target • WMA financial sustainability expressed as Tariff Revenue Collection Ratio • No. of Industrial Discharge Permits issued annually to industries • Improvement of access of poor to sanitation (No.of inhabitants concerned under relevant projects) • Implementation Capacity of WMA expressed by award of 2 major contracts annuallyand number of post-monitoring site visits to industries.
Well-defined time-lines, and time-bound targets and indicators will need to be devised to monitor the progress achieved in the Public Awareness and Sensitization Exercise and Policy and Institutional Review for on-site sanitation.
4.3.7 – Selection of appropriate technology
The major capital projects have till presently favoured waterborne sewerage followed by conventional activated sludge systems. These technologies are appropriate for highly urbanized areas in the Mauritian context. On-site sanitation is not recommended for the high population densities encountered and is definitely not appropriate for industrial zones found within the urban areas. Low-cost sanitation systems such as constructed wetlands or pond systems have high land requirements and may thus not appropriate for large populations as Mauritian is a small country where land has high value.
Under the Wastewater (Standards for Discharge of Industrial Effluent into Wastewater System) Regulations 2004, it is ensured that industries apply required pre-treatment and thus abate pollution at source before discharge to public sewers. However cleaner production should be encouraged to ensure that best production techniques and raw materials are used to produce less polluting effluents.
The possibility of reuse of treated effluents in agriculture is seriously studied under all major wastewater projects. Right incentives should be introduced to encourage industries to reuse their treated effluents.
Concerning rural villages with a much lower population density feasibility studies should also consider the use of low-cost technologies, with the necessary cost benefit analysis. Such low-cost technology can involve constructed wetlands, pond systems or small bore diameter sewers.
4.3.8 – Apply demand-driven approaches
As discussed in Section 4.3.2, and considering the specificity of Mauritius as being a small country, it is better to have a central organisation responsible for the sanitation sector. However, it has been shown that the management of on-site sanitation should preferably rest with the local authorities. As such the issue of making choices from a wide range of financial and management options does not arise.
From a technological point of view, different options should be carefully assessed. As discussed in the above section, these options would involve:
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• Conventional waterborne sewerage followed by activated sludge systems and final disposal being sub-surface or into water courses. • Conventional waterborne sewerage systems followed by pond systems and final disposal being sub-surface or into water courses.
• Small bore diameter sewer systems followed by filtration systems and constructed wetlands and final disposal being sub-surface or into water courses.
Feasibility studies with cost benefit analysis should be undertaken for the different options, considering reuse of effluent in irrigation so that reliable information is available for decision making. Planners should also be involved so as to consider long term development around the project area so that sewerage infrastructure is planned accordingly.
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Chapter 5 – Review Existing Technologies used for MWW Management
5.1 – Overview of existing technologies in Mauritius
5.1.1 – Summary of wastewater technologies
In Mauritius, 25% of the population is connected to the public sewerage system and the rest use on-site sanitation. About 50% of the population makes use of cesspits for disposal of black water from toilets while grey water is disposed of in individual soakaways. About 23% of the population makes use of proper septic tanks followed by absorption systems for disposal of all their wastewater. The remaining 2% of the population make use of pit latrines.
5.1.2 – Methods of collection for sewer systems
All sewerage systems in Mauritius consist of conventional separate systems. Due to the sharp topography, gravity sewers are normally adopted, with minimal pump stations. The Grand Baie Sewerage network is an exception since the drainage area is relatively flat and 12 pumping stations have been constructed. These conventional sewer systems transport wastewater to activated sludge process treatment plants.
In areas where industries are present, pollution prevention at source is applied, since industries must be licensed to discharge industrial effluents which meet the required norms for public sewers. The norms ensure that no damage is caused to the sewers by noxious effluents and also that receiving treatment plants can operate at the pollution load for which these were designed.
In some recently approved Integrated Resort Schemes (IRS), small bore diameter sewers have been recommended, especially due to the very hilly nature of the terrain. In these cases, the villas will be provided with conventional individual septic tanks and the overflow from the septic tanks will be transported by small bore diameter sewers to wastewater treatment plants using rotating bio-contactors. The final treated effluents will be used for irrigation of lawns and gardens. An IRS project may consist of up to 350 luxury villas which will normally be sold at the cost of USD 25 million per unit. There will certainly be a Syndic in place for the whole management of all infrastructures when in service. These projects are actually in the phase of construction.
5.1.3 – Overview of on-site industrial wastewater treatment
The level of treatment required by industries depends on the nature of the industrial activities and on the receiving body. In the case of industries discharging to the public sewer network, either through direct connection or by carting away effluent through wastewater carriers, the level of treatment required is less stringent than for industries located outside sewered areas and discharging directly to water courses. This is due to the fact that sewer networks convey wastewater to public WWTPs where the level of treatment required for discharge into the environment is provided.
5.1.3.1 – Industries discharging industrial effluent to the sewer network
The main industries consist of textile dyehouses, breweries, wineries and distilleries, slaughter houses, food processing plants, dairy production plants, soft drink plants and fish processing plants.
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5.1.3.1.1 – Textile Dyehouses
Textile dyehouses effluents do not contain high amounts of organic matter and the COD level is typically in the range of 500 – 900 mg/l, while the limit for discharge into sewers is 1, 500 mg/l. Therefore, no biological treatment is normally required for dye house effluent discharges into the public sewer network. Heavy metal concentrations are well within standards and sometimes below detectable limits. Due to use of sodium sulphate and ammonium chloride in dyeing processes, the levels of sulphate and chloride tend to be high, as well as electrical conductivity.
Dye house effluents tend to have a high pH, especially for cotton dyeing, high temperatures and high levels of suspended solids due to presence of fluffs. The types of pre-treatment applied to dyehouse effluents consist therefore of screening for removal of cloth rags, foreign solids and pumice stone, in the case of stone dyeing. A balancing tank is normally required to lower temperature and adjust pH by acid addition. Primary sedimentation is provided by means of primary sedimentation tank for removing suspended solids which consist of wool or cotton fibres and fluff, as well as powdery products arising from the friction action between the pumice stones.
5.1.3.1.2 – Breweries
Breweries effluents contain high levels of organic matter and suspended solids due to the use of yeast for fermentation. Preliminary treatment consists usually of coarse screening followed by fine screening through rotating drum filters and biological treatment consisting of either activated sludge process or anaerobic treatment process of the UASB reactor type, both of which are highly efficient in the removal of organic content of effluents.
5.1.3.1.3 – Slaughterhouses
Blood from slaughterhouses is usually collected to be sold for processing of animal feed. Effluent from slaughterhouses has a high COD level due to the presence of residual blood. In addition, effluents from chicken slaughterhouses contain high amounts of solids such as intestines parts and feathers. Preliminary treatment requires efficient screening devices for removal of such solid wastes. Grease treatment is also required due to high levels of grease in the effluent. Grease traps are normally provided but these fail rapidly if there is no regular maintenance. Ideally, dissolved air flotation should be provided to enhance flotation of the grease and removal by a rotating skimming arm. The primary effluent is usually treated using physico-chemical treatment, but such treatment processes are quite costly, especially considering purchasing of chemicals from abroad. Such treatment also does not remove excess TKN.
5.1.3.1.4 – Dairy production plants
Due to the use of fermentation products for the production of yoghurt, effluents from dairy production plants tend to have high COD values, high suspended solids, high oil & grease, high TKN and sodium content. Treatment processes usually involve fine screening using rotating drum screens, dissolved air flotation units for removal of oil & grease and biological treatment consisting of sequential batch reactor, (SBR), for abatement of COD.
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5.1.3.1.5 – Soft Drink Plants
Effluents from soft drink plants have high COD values due to extensive use of sugars and colorants. Such effluents usually undergo biological anaerobic treatment of the UASB type, after having undergone coarse and fine screening through rotating drum screens.
5.1.3.1.6 – Fish processing plants
Fish processing plants usually involve tuna processing, converting into chunks and canning with brine. The effluents have therefore a high suspended solid content due to pieces of tuna in suspension. COD values also tend to be high due to high load of organic matter. Extensive screening and sedimentation is usually required for removal of coarse matter and suspended solids. Biological treatment consisting of either activated sludge or anaerobic treatment would normally be recommended, but in one case, the industry has been wrongly induced to install a treatment plant based on physico-chemical treatment, which does not yield the required effluent quality.
5.1.3.2 – Industries discharging effluents directly to the environment
Industries discharging effluents directly to the environment consist of textile dyehouses, brewery and sugar factories. Treated effluents are discharged either to the lagoon, to open drains leading to water courses or directly to water bodies.
Textile dyehouse effluents undergo the usual primary screening processes, primary sedimentation, temperature and pH balancing and, finally, biological treatment consisting of either activated sludge process or sequential batch reactor. In some cases, the effluent is further refined by undergoing pond treatment consisting of facultative and maturation ponds and the final effluent is re-used in agriculture.
Breweries effluents undergo activated sludge treatment process before discharge into canals leading to water courses.
Sugar factories usually make use of biological treatment consisting of activated sludge process to treat effluents which contain high level of organics.
5.1.4– Existing wastewater treatment technologies for public systems
All public wastewater systems convey wastewater to wastewater treatment plants which are essentially activated sludge systems with, or without biological nutrient removal. The main wastewater treatment plants have been discussed in detail in Chapter 3.
5.1.4.1 – Treatment Processes
Preliminary and primary treatment processes usually involve mechanically raked screens followed by grit and grease removal. A dissolved air flotation unit is usually used where bubbled air enhance flotation of grease which are raked, together with scum, into a hopper and discharged into special containers for carting away at landfill site. Primary sludge is thickened using picket fence thickeners and is also carted away at landfill site.
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Secondary treatment consists of activated sludge process with, or without, biological nutrient removal. Secondary sludge from final clarifiers is thickened either by belt press or by centrifugation. The thickened sludge is disposed of at landfill. In the case of the St. Martin WWTP, the sludge is digested to produce methane for power generation.
Tertiary treatment consists of disinfection with chlorine or by ultraviolet light.
5.1.4.2 – Existing disposal modes of treated effluent
Treated effluent from the St. Martin WWTP is used for irrigation of sugarcane fields. In the case of Grand Baie WWTP, the effluent is presently being disposed of by borehole injection. For the Baie du Tombeau and Montagne Jacquot WWTPs, the effluent is disposed of through long sea outfall.
Regarding the five minor WWTP, the treated effluent is disposed of into land through leaching fields, except for the case of Vuillemin WWTP which discharged treated effluent onto land.
5.1.5 – On-Site Disposal Systems
5.1.5.1 – Cesspit systems
Cesspits are usually used for the disposal of wastewater from toilets only. These consist of an excavation of dimensions 3m x 3m x 3m deep covered by a concrete slab. The effluent gets absorbed into the surrounding earth through the bare sides of the excavation. In some cases interlocking block wall with spaces between the blocks have been provided with a view to prevent collapse of the sides of the excavation into the cesspit. The faecal matter undergoes anaerobic decomposition.
In regions of good soil permeability and low water table, the cesspit can stay into operation for more than 30 years without requiring any emptying. This further strengthens the general public attitude of “out of sight, out of mind” towards sanitation.
Grey water from kitchen sink, wash hand basins, baths and washing machines are normally disposed of into individual soakaways.
5.1.5.2 – Septic tank systems
5.1.5.2.1 – Individual septic tank systems
On an individual household basis, septic tanks of 3m3 capacity, providing for at least 2 days retention time, are recommended. Septic tanks are recommended to be built of reinforced concrete but some people make use of reinforced blockwall for reasons of economy. Fiberglass septic tanks, manufactured locally, are also available on the market and are quite popular.
In the past, the septic tank effluent was disposed of in absorption pits of dimensions 3m x 3m x 3m, irrespective of the hydrogeological characteristics of the soil. Since recently, the use of leaching fields is recommended in regions of high water table, while ensuring that the invert level of the leaching field is at least 1.2 m above the highest level of water table to be encountered.
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5.1.5.2.2 – Communal Septic Tank Systems
In the period 1993 to 2002, most government housing projects located outside sewered areas have been provided with conventional waterborne sewerage systems where all domestic wastewater is collected and conveyed to a communal septic tank followed by adsorption pit or leaching field.
5.1.5.3 – Design Guidelines for On-Site Disposal
Design guidelines for on-site disposal systems have been developed by the Ministry of Housing and Lands in consultation with the WMA. The same guidelines have been incorporated in the Planning Guidelines for Urban Authorities.
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5.2 – Description of existing technologies and constraints in MWW
5.2.1 – Building of local expertise
Activated sludge process has been adopted for most public wastewater treatment plants in Mauritius. The WMA is organizing on-the job training with he help of process experts so as to build in-house expertise for its young engineers. This will ensure that WWTPs can be properly operated and maintained by in-house staff.
5.2.2 – Zoning Aspects
Industrial development is not limited to dedicated industrial zones. It would definitely be more advantageous for industries to be located in a sewered region since the level of pre-treatment required for discharge to public sewers is less stringent and consequently less costly. Intensively wet industries located in unsewered regions have to install wastewater treatment plants at heavy costs to try meeting effluent quality requirements.
5.2.3 – Collection Systems
Due to poor surface water drainage some people connect their surface waters illegally to the public sewer systems. In times of heavy rain, this contributes to surcharge of sewers and overflows of public manholes. Pumping stations are also required to pump beyond their normal design frequency and public wastewater treatments are overloaded and need to be bypassed, thereby discharging untreated effluent to the environment.
It is foreseen that this state of affair will continue until a proper drainage network is provided to allow people to evacuate surface water from their premises.
5.2.4 – Operation and Maintenance of Wastewater Treatment Plants
The O& M of small WWTPs had been outsourced to contractors in the past. The newly formed Mechanical & Electrical Section, consisting of electrical, mechanical engineers and technical officers are being trained in process engineering and instrumentation. With the training of WMA staff in process engineering, it is expected that WMA will be proficient in the O & M of these plants in the near future.
5.2.5 – On-site systems
Septic tanks followed by absorption systems can be very efficient for domestic wastewater treatment. Faecal matter undergoes anaerobic decomposition in septic tanks where typical treatment results in BOD reduction of 30-40% and suspended solids reduction of 50-65%. Ammonia concentrations increase slightly due to the breakdown of proteins while microbiological quality is not improved. Oil and grease is removed as the septic tank also acts as a grease trap.
The septic tank effluent is then absorbed into the soil via an absorption pit or leaching field. The soil filters, treats and carries away the effluent into the ground water safely. Microbiological quality is greatly enhanced by the filtration treatment. Leaching fields provide a much more treatment than absorption pits. Since the leaching pipes are buried at a distance of less than 1m,
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The water table should be at some distance, usually 1 to 1.2m, from the bottom of the absorption systems to ensure that effluents are fully treated before reaching the water table.
Soils with percolation values less than 6mm/hr are considered as impermeable while soils with percolation rates higher than 500mm/hr will not provide adequate treatment as the effluent will just drip through without time for adequate treatment. In this case, it is possible to reconstitute the soil by importing soil with adequate permeability.
Most development requiring a clearance from the WMA and located outside sewered regions are provided with on-site disposal systems such as septic tanks followed by absorption pits or leaching fields. Soil reports providing information in the depth of the water table, the description of the soil strata, percolation test results and other relevant data such as presence of water bodies, are crucial for assessing the suitability of the site for on-site disposal. This is also important for a proper sizing and design of the on-site disposal system. Presently, this soil report is requested by the WMA on a case-to case basis, depending on the nature, size and location of the development. However, these requirements could best be incorporated in a proposed Regulations for on-site disposal.
5.2.6 – Low-cost sanitation systems and constraints
5.2.6.1 - Pit Latrines
Pit latrines are simple and effective if constructed and maintained properly. These consist of an excavation in the ground covered by a hard (concrete) surface. It must be provided with a vent pipe with fly screen. The faecal matter undergoes composting and fluids are limited to urine. Since this is a dry sanitation process, there are no effluents than can travel down to the water table. Pollution is limited and contained within an immediate layer of soil in contact with the faecal matter.
Pit latrines were in general use in Mauritius till the1960’s when potable water coverage was not well developed.
Later, the provision of piped water system to almost 99% of the population and a relatively good standard of living has favored the use of cistern-flush toilets. These can usually be located within the main dwelling unit and does not pose odor problems. On the other side, pit latrines need to be located away from the main dwelling unit, thereby causing more inconvenience for usage and less security, especially at night. These can also cause odor. Pit latrines are also considered to reflect much lower standards of living and belonging to the past when piped water system was not available, housing units were much more modest and people were much poorer. For these reasons, traditional pit latrines and ventilated improved pit latrines are not popular in the Mauritian context.
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5.2.6.2 – Composting Toilets
Composting toilets could have been an appropriate on-site technology in Mauritius for sites with high water table. These are dry toilets where faecal matter and urine are collected in a black metal container. In hot climates, the container gets heated; the urine evaporates and dissipates up a chimney which extends well above the building to avoid any odor nuisance to users. The elevated temperature enhances microbiological activity and the faecal matter is composted. Every year or so, the container is opened and the composted faecal matter is spaded out and can be applied as manure in agriculture.
However, culturally, a great majority of the population make use of water for anal cleansing. This is not appropriate for composting toilets to which no water should be added. Furthermore, the general attitude of considering any system related to or resembling pit latrines as belonging to the past is not in favor of the use of composting toilets in Mauritius.
5.2.6.3 – Septic tanks followed by absorption systems
The relatively high cost of construction of septic tanks, absorption pits and leaching fields, as well as the cost and concern of desludging a septic tank every three years or so, is a deterrent to the use of such systems It is relatively easier and cheaper for people to build a cesspit. Moreover, the cesspit may not require any desludging for over 30 years, compared to septic tanks.
It is also the legitimate will of every citizen to possess his own house and plot of land. However Mauritius is a small island where land is costly. Many people inherit a small plot of land from their parents, after division between heirs, and other people tend to buy small plots of land according to their financial capability. The minimum plot size allowed for residential development is of the order of 83.56 m2. In such cases there can hardly exist enough space to accommodate a septic tank and absorption pit, less even so a leaching field. Cesspits are usually used. People tend to make the maximum usage of their plots of land and it is not uncommon to find cesspits located under the floor of their houses. For recent land-subdivision projects, recommendations of the WMA regarding type of on-site disposal systems have to be incorporated in the title deeds and it is noted that educated people of the younger generation are more prone to follow these recommendations.
5.2.6.4 – Waste Stabilization Ponds
Waste stabilization ponds are efficient, reliable and sustainable. The advantages result from their simplicity. These require relatively low capital investment when flat land is available at reasonable price. Ponds are easily maintained, can absorb shock loads, and produce stabilized sludge that can be used in agriculture. Mechanical equipment and associated power requirements is not required to aerate or mix the sewage. Pond systems can remarkably remove BOD, nutrients and pathogens. They can easily be scaled down to small scale applications. Consequently, pond systems are very attractive for remote towns and villages in tropical countries. Due to their low operation and maintenance requirements, these are relevant in places where a shortage of skilled personnel exists.
The major disadvantages of ponds are their large area requirements (2-5m2 /PE), the high algal content of the effluent making it inappropriate for use in drip irrigation systems, evaporation losses, the potential odor and mosquito nuisance and the sensitivity of algae to toxic matter present in raw municipal sewage.
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Pond systems usually consist of anaerobic, facultative and maturation ponds in series and make use of natural treatment processes. Anaerobic ponds are normally used to reduce the strength of raw sewage by enhancing the settling and biodegradation of particulate organic solids by anaerobic digestion. Typical removal efficiencies for TSS range between 50-70% and BOD removal rates range between 30-70% depending on temperature. A 1 log unit faecal coliform reduction can be achieved as large fractions of coliforms are adsorbed to particulate matter. A good amount of helminth and nematode eggs reductions can be achieved by providing settling opportunities.
Facultative ponds which are usually 1 to 2.5m deep are divided into an aerobic surface and an anaerobic bottom layer. Oxygen produced by algal photosynthesis in the top layer is used for decomposition of organic matter in deeper layers by heterotrophs. As long as algae can provide oxygen in excess of the demand by the heterotrophic bacteria, aerobic conditions will prevail in the ponds, aerobic degradation will proceed and odor nuisance will be prevented. Filtered BOD values range from 20 to 60 mg/l while TSS levels vary from 30 to 150 mg/l. Facultative ponds are normally followed by maturation ponds to further polish the effluent.
Maturation ponds are shallow ponds in which an active biomass is maintained throughout the entire depth of the system so that during the day time large amounts of oxygen are produced. Further stabilization of organic matter and nutrient removal is accomplished mainly through aerobic bacteria, while pathogen destruction is realized through a complex interaction of various mechanisms including light-induced mortality, pH induced mortality, starvation induced mortality, adsorption/sedimentation, dilution and mixing and predation. Faecal coliform and virus die-off rates may reach 3 to 4 log units. Cysts and ova of intestinal parasites settle to the pond bottom and eventually die-off.
The major application for maturation ponds is to polish or upgrade facultative ponds effluents and achieve substantial reductions to allow safe use of the effluents in agriculture or aquaculture. Maturation ponds can be combined with aquaculture by filling the last ponds with floating macrophytes. Thus biomass is generated and the incidence of algal TSS in the effluent is reduced.
Pond systems have been used in the past in Mauritius at the St. Martin WWTP and for some isolated localities such as Richelieu Housing Estates. However, with rapid population growth and poor maintenance, the ponds became rapidly undersized and produced poor quality effluents. The major disadvantages of ponds are their large area requirements (2-5m2 /PE), the high algal content of the effluent making it inappropriate for use in drip irrigation systems, evaporation losses, the potential odor and mosquito nuisance and the sensitivity of algae to toxic matter present in raw municipal sewage. The need to provide an impermeable layer to the bottom of the ponds so as to protect the water table from seepage may also end in prohibitive construction costs.
Land development around existing residential areas can cause pond systems to become sources of odor and mosquito nuisance
Mauritius being a small country, pond systems will not be appropriate for large urban populations due to excessive land requirements. As an illustration, based on an average land requirement of 3.5m2/PE and a projected population of 322, 860 for St. Martin WWTP for the year 2015 ( St. Martin Sewage Treatment Plant Extension – Detailed Study Report) the total land requirement for a pond treatment system, excluding industrial effluents, is of the order of 113 hectares.
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The advent of mechanized treatment systems such activated sludge systems has outclassed pond systems as an outdated technology.
5.2.6.5 – High Rate Algal Ponds
In case maturation ponds are designed to optimize the production of algae, they are commonly called high rate algal ponds (HRAP). HRAP are only feasible for effluents mainly with soluble organic matter. Algal growth in these ponds tends to be high, producing an effluent with high TSS, unless algal separation is provided. For this reason HRAP are not routinely used for domestic wastewater treatment.
5.2.6.6 – Wetland Systems
A wetland is a complex assembly of water, substrate, plants (vascular and algae), litter (primarily fallen plant material), invertebrates (mostly insect larvae and worms) and an array of microorganisms (most importantly bacteria). Wetland systems use water-tolerant plant species and shallow, flooded or saturated soil conditions to provide various types of wastewater treatment. The mechanisms that contribute to wastewater treatment involve:
• Settling of suspended particulate mater • Filtration and chemical precipitation through contact of the water with the substrate and the litter. • Chemical transformation • Adsorption and ion exchange on the surface of plants, substrate, sediment and litter • Breakdown, transformation and uptake of pollutants and nutrients by micro-organisms and plants • Predation and natural die-off of pathogens
Settleable organics are removed in wetland systems by deposition and filtration. Attached and suspended microbial growth is responsible for the removal of soluble organic compounds, which are degraded aerobically and anaerobically. The oxygen required for aerobic degradation is supplied directly from the atmosphere by diffusion or oxygen leakage from the macrophyte roots into the rhizosphere. The uptake of organic matter by the macrophyte is negligible compared with biological degradation.
The major removal mechanisms of organic nitrogen are the sequential processes of ammonification, nitrification and denitrification. Nitrogen is also taken up by plants, incorporated into the biomass and released back as organic nitrogen after decomposition. Other nitrogen removal mechanisms involve volatization and adsorption.
Wetland systems are capable of absorbing new phosphorous loadings and in appropriate conditions can provide a low-cost alternative to chemical and biological treatment. Phosphorous interacts strongly with wetland soils and biota, which provide both short-term and long-term storage of this nutrient.
Constructed wetland mimic the optimal treatment conditions found in natural wetlands but provide the flexibility of being constructed at almost any location and can be used for the treatment of primary and secondary wastewaters.
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Constructed wetlands include free water surface wetlands and sub-surface wetlands.
In free water surface wetlands, , water flows over the soil surface from an inlet point to an outlet point or, in a few cases, is totally lost to evapotranspiration and infiltration within the wetland. Plants used include free-floating macrophytes, floating leaved, bottom-rooted macrophytes, floating mats and submerged macrophytes.
Subsurface flow treatment wetlands are usually soil based or gravel based. This technology is usually limited to low flow rates. Horizontal flow systems and vertical flow systems exist. In the horizontal flow system, wastewater is fed in at the inlet and flows slowly through the porous medium under the surface of the bed in a more or less horizontal path until it reaches the outlet zone.
Vertical flow systems are composed of a flat bed of gravel topped with sand. The liquid is dosed on the bed in a large batch, flooding the surface. The liquid then gradually drains vertically down the bed and is collected by a drainage network at the bottom.
Plants usually used in subsurface flow constructed wetland systems include common reed, reed canary grass, and sweet mannagrass.
Free water surface wetland system have the disadvantage that it encourages mosquito breeding and rodents and is more prone to odor nuisance.
Constructed wetlands are a cost-effective and technically feasible approach for the treatment of wastewater for the following reasons: • Wetlands can be less expensive to build than other treatment options • Operation and maintenance expenses are low • Operation and maintenance require only periodic, rather than continuous, on-site labor • Wetlands are able to tolerate fluctuations in flow • Wetlands are able to treat wastewaters with low organic load (too low for activated sludge) • They facilitate water reuse and recycling
Constructed wetlands are not applied in Mauritius for wastewater treatment due to lack of information. For one recent project involving the construction of a five star hotel, the consultants have proposed a constructed wetland system for wastewater treatment. One disadvantage for the use of wetland systems in Mauritius is the large land requirement, Mauritius being a small country.
5.2.6.7 – Trickling Filters
Trickling filters are attached growth systems and consist of a bed of highly permeable media surrounded by a tight wall. Crushed rock, gravel, lava stone or plastic media can be used. Presettled wastewater is distributed uniformly over the top of the filter bed by a rotating distributor and trickles down through the bed. The effluent is collected at the perforated under drain bottom. As wastewater flows as a thin film over the filter the biodegrable organic matter gets in contact with the biofilm attached to the media and is degraded. Air, and hence oxygen, is allowed to enter the filter to enhance aerobic metabolism of heterotrophic and autotrophic microorganisms. Adsorption and biodegradation causes the biofilm thickness to increase. Hydraulic forces exerted by the surface loading rate control the wash out of the biofilm layers from the filter.
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Trickling filters have a low capital investment cost, low energy requirements, low sludge production rates, are simple to operate and have a low running cost. The secondary sludge is easily thickened and dewatered.
However trickling filters will have a poor performance if high quality effluent is required and the potential for nitrogen and phosphorous removal is low. Process control is hardly possible and the performance is seasonal as it is strongly affected by temperature. The potential risks for mosquito breeding, odour nuisance and filter clogging is high.
Low rate trickling filters can have BOD removal efficiency of the order of 85%. A fair degree of nitrification can be achieved at the bottom part of the filter, where autotrophic nitrifiers might find suitable substrates, high oxygen and low BOD levels.
Denitrification can only be achieved if the nitrified effluent is recycled over the filter. From practice in moderate climates a maximum of 20 – 35% TKN can be nitrified by trickling filters if aerobic and anaerobic conditions can be balanced within the biofilm. This is however very difficult to achieve and control in practice. Generally, low rate trickling filters are not economically feasible for large-scale applications above 100, 000 PE.
With high rate trickling filters nitrification hardly takes place. The TKN levels in the effluent might be between 20-40 mg/l. This can inhibit fish life, disturb the oxygen balance of surface waters, induce eutrophication, and create nitrate pollution of ground water aquifers. High rate trickling filters can become environmentally feasible only if applied with additional treatment for nutrient removal. A trickling filter system was in operation in Mauritius at the Kennedy Housing Estate but it has recently been decommissioned as the housing estate has been connected to the public sewer system.
Trickling filters may not be appropriate in Mauritius if high quality effluent with biological nutrient removal is required.
5.2.7 – Conventional systems
5.2.7.1 – Activated Sludge Systems
Activated sludge wastewater treatment consists of suspended growth systems where wastewater is intensively mixed with oxygen and microorganisms to accelerate biodegradation processes. Activated sludge systems are the most widely applied compact technology for wastewater treatment. It has a fair degree of operational flexibility allowing the plant operator to adjust the process conditions in such a way that the treatment plant cultivates and accumulates a series of microbial populations performing a wide range of various pollutants. In particular its capability to incorporate biological nutrient removal makes it a very attractive technology for effluent discharge onto surface water sensitive to eutrophication. Sludge recycle from secondary clarifiers to the aeration tank ensures that a bacterial population is maintained to degrade the organic load applied. BOD removal efficiencies can be as high as 95%. Biological nitrogen removal can be achieved at specific sludge age threshold values that ensure that nitrification occurs and creating anoxic conditions to enhance denitrification. The overall process of nitrification-denitrification ensures that nitrates are converted to molecular nitrogen.
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Phosphorous can be removed by either physico-chemical treatment or by biological phosphorous removal processes. Physico-chemical removal involves addition of aluminium sulphate or ferric chloride to enhance precipitation of aluminum phosphate of ferric phosphate. The following options can be applied: • Pre-precipitation in the primary clarifier • Simultaneous precipitation in the aeration tank • Post precipitation in the final clarifier Disadvantages of physico-chemical P removal are the investment cost involved, the varying chemical dosage needed with the fluctuating incoming sewage and the production of chemically contaminated sludges which may be difficult to dispose of.
In biological phosphate removal, activated sludge is alternatingly exposed to anaerobic and aerobic conditions; poly-phosphate accumulating bacteria can increase the phosphorous binding capacity of the sludge. In particular, Acinetobacter species can perform this enhanced phosphorous uptake by storing substantial amounts of polyphosphates in their cells during unfavorable anaerobic conditions. In aerobic phase, this poly – P can immediately be used to initiate biomass synthesis. In that way substantial amounts of phosphorous can be removed from the wastewater via the excess sludge removal. Final mean effluent P concentrations less than 2 mg/l can be achieved.
The main disadvantages of activated sludge systems are their high capital and operation costs as power is required to maintain aeration, and large amounts of sludge are produced. Sludge must be dewatered and thickened by either belt press or centrifugation and is usually disposed of at landfill sites or used as soil conditioner in agriculture. It can also be applied on sludge drying beds. The sludge can also be digested to produce methane gas that can be used for power generation. Activated sludge systems are the main systems used for public wastewater treatment plants in Mauritius.
5.2.7.2 – Extended aeration systems
In extended aeration systems, wastewater is treated in one reactor only instead of using a grit chamber, a primary settling tank, an aeration basin, and a final settling tank as in activated sludge treatment plants. The numerous recirculation flows required for biological nutrient removal are also avoided.
The average sludge age is high enough for simultaneous BOD removal, biological N and P removal and sludge stabilization. Due to the high degree of endogenous respiration, the sludge production is low. The sludge is well stabilized and needs just dewatering at drying beds. A very high BOD removal efficiency (>95%) can be achieved and overall nitrogen removal can be over 80%. The overall process is very reliable due to hydraulic buffering capacity. However overall energy requirements are very high.
The operational regime of such treatment is very simple, the grit chamber and primary sedimentation tank are omitted, the need for recirculation is reduced, and separate sludge stabilization is not required. As a consequence, the capital cost of treatment by extended aeration can be substantially reduced. The wastewater can be brought directly into the aeration tank where at various locations anaerobic, anoxic and aerobic conditions are created to enable all biomass species to perform their duties for BOD, and biological N and P removal.
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About 20-25% more land and oxygenation capacity are required for extended aeration when compared to conventional activated sludge systems but this is offset by their simplicity and low operational caretaking. This can be interesting for regions where operational caretaking is not easily ensured, due to either financial constraints or due to limited skills available.
Extended aeration systems have not been used in Mauritius for public wastewater treatment.
5.2.7.3 – Anaerobic Treatment Processes
Anaerobic treatment processes involve the anaerobic digestion of organic matter by the combined action of a wide range of microorganisms. Four distinct stages can be recognized in the breakdown of biomass to methane:
(i) Hydrolysis. In this stage complex, non-dissolved materials are split into less complex dissolved compounds by exo-enzymes excreted by fermentative bacteria. The products of hydrolysis can pass through the cell wall and membrane of the fermentative bacteria. (ii) Fermentation or acidification: Here, the dissolved compounds are converted in the cells of the fermentative bacteria into a series of simple compounds that are excreted again. The main products of this stage are volatile fatty acids, alcohols, lactic acid, CO2, H2, NH3 and H2S as well as new bacterial biomass. (iii) Acetogenesis: In this stage fermentation products are converted into acetate, hydrogen, carbonate as well as new bacterial biomass. (iv) Methanogenesis: In this last step, hydrogen, carbonate, formate, and methanol are converted into methane, CO2 and new cell material.
Anaerobic reactors include contact process, anaerobic filter, UASB reactor and fluidized bed reactor.
The main advantages of anaerobic treatment technology include: no power requirement as no aeration is required, less volumes of sludge as compared to activated sludge systems and the production of methane which can be used for power generation.
Anaerobic technology focuses on the removal of organic and suspended matter only. In order to comply with effluent discharge standards post-treatment of anaerobic effluents is frequently needed. Post-treatment can include waste stabilization ponds, aquaculture systems with duckweed ponds, conventional mechanized technology such as activated sludge, trickling filter or rotating bio-disc.
Anaerobic technology has not been used so far in Mauritius for municipal wastewater treatment probably due to over popularity of activated sludge systems and lack of information about such systems.
5.2.7.4 – Rotating Biological Contactor
Rotating biological contactors (RBC) use fixed film processes which rely on attached microbial growth on rotating disc surfaces. Through continuous rotation, the media carries a film of wastewater into the air where oxygen is transferred through the liquid film surface. Both oxygen and organic substrate materials diffuse through the liquid film where they are consumed for growth and respiration. Typically RBC units are put in series to enhance plug flow conditions.
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This is to ensure high BOD removal. Full scale treatment plants can include 3-5 stages for BOD removal only while the number of stages can go beyond 6-8 in case additional nitrification is required.
RBCs are an attractive engineering alternative for low cost wastewater treatment because it is energy conservative and produce an effluent quality comparable, or even better than secondary effluents of trickling filters. Furthermore these are easy to operate and provide a good quality effluent, provided the operator properly and regularly performs the duties of inspecting the equipment, testing the influent and effluent, observing the media, maintaining the equipment and taking corrective action when necessary. In Mauritius, RBC systems are extensively used by coastal hotels, as a treatment process to primary treated effluents from septic tanks.
5.2.8 – Preliminary and Primary Technologies
• Screens Preliminary treatment is normally provided ahead of main treatment processes so as to remove coarse and solid matter that can cause physical damage (wear/tear) to pumps, weirs and aerators. Screens and racks are provided to remove coarse foreign matter. Screens can be classified as fine, medium or coarse screens. Fine screens can achieve a significant degree of coarse solids removal, but rapidly get clogged. Coarse screens are used for pre-screening, and as protective and safety device. In treatment plants with large capacity, a double set of screens is often used; the first one being a coarse screen, the second a fine screen. In terms of operation, screens can be divided into manually operated screen or mechanically driven screens. To prevent any nuisance from collecting rakings comminution or grinding can be applied whereby the retained coarse solids are reduced to particles with diameter less than 20 mm and transferred to the primary settling tanks. Odour and fly nuisance often found around the deposition of rakings are thus reduced.
Rakings are usually disposed of at landfill sites.
Rotary drums and wedge wire screens use perforated or slotted sheet metal screens or wire mesh with openings less than 1mm, these are hardly used in sewage treatment but mostly for industrial effluent on-site pre-treatment.
Screening systems are normally provided at the inlet works of all mechanized wastewater treatment plants and therefore coarse and fine screen, manually or mechanically raked, are provided at all public wastewater treatment plants in Mauritius
• Grit removal Domestic sewage also contains heavy inert materials called grit. Removal of the grit ahead of primary settlers help in preventing wear and tear of pumps and other mechanical equipment, reduce deposit formation and consequently clogging in downstream unit operations and transport pipes, and finally avoid inert accumulation in primary sludge (it then eventually will deposit as a thick sand layer in the sludge digester).
The object of grit removal systems is to discretely settle heavy sand particles with a diameter greater than 0.2mm. Grit removal systems include open channel grit removal, flat bottom detritus chamber, aerated grit chambers and hydro-cyclone.
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In open channel grit chambers the degree of grit settling is largely decided by the overflow rate. A critical overflow rate is applied whereby sand particles with diameter in excess of 0.2 mm are removed while organic solids are retained in suspension. This is realized by selecting a critical horizontal velocity that is below the scouring velocity of grit particles to prevent their re- suspension, but that creates enough turbulence and scouring to prevent settling of grit particles.
Open grit removal is simple in design and operation and is therefore frequently applied in small treatment facilities.
Flat bottom detritus chamber are usually used for large treatment plants (> 100, 000 PE). A rotating grit scraper at the bottom of the chamber brings the grit to a collection pit at the periphery of the grit chamber. From there the grit washing device further transports and separates sand particles from the lighter organic suspended solids.
A major disadvantage is that organic decomposable matter is also retained with the heavy grit. Disposal of this mixture by dumping can spread unpleasant odours, attract flies, and make this sight rather unhealthy and bad looking.
In aerated grit chambers a helical flow pattern is created by air diffusion at one side of the grit chamber. The organic particles remain in suspension, while the heavy sand and grit particles settle to the bottom. Aerated grit chambers are only recommended at large scale treatment works (over 150, 000 PE), where aeration is provided by diffused air bubbles. One disadvantage is that stripping of volatile (odorous) compounds may need a full covering of the grit removal unit to reduce its odour emission.
Sand removal can also be accomplished by generating centrifugal forces to sand particles in hydro-cyclones. Such systems are compact but their short lifetime, head losses involved and energy requirements make them rather expensive for large works. The efficiency of the hydro- cyclone can be high as a more constant flow and composition of the feed is assured. Their use is more feasible for small flows. Therefore they are commonly applied on primary sludge where sand is separated from the primary sludge prior to its further processing in sludge digesters.
In Mauritius, flat bottom detritus tank is used on small works while aerated grit chamber is used on major municipal wastewater treatment plants for grit removal.
Primary Sedimentation aims at removing suspended organic solids from wastewater by settling so as to reduce the load to the subsequent biological treatment units. Primary settling of suspended solids basically is of the flocculant type, meaning that the following parameters affecting the design are the flow rate, the settling characteristics of the suspension and the required removal rates. Rectangular and circular settling tanks are commonly used while other configurations include Dortmund tanks, Imhoff tanks, the clarigester and the tilted plate separator. Circular settling tanks are mostly used for primary sedimentation in Mauritius, while tilted plate separator is used in a few industries for on-site treatment.
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5.3 – Recommendations for Appropriate Technology
5.3.1 – Differentiation between natural treatment and conventional treatment systems
The fundamental difference between natural wastewater treatment systems and conventional systems is based on the source of energy that predominates in these. Conventional treatment processes depend largely on degradation of naturally occurring, biological pollutants. These processes are contained in basins and are driven by forced aeration or mechanical mixing. The sizes required for biological transformations can be decreased considerably compared with the area required for the same processes occurring in the natural environment because of the energy intensity induced.
Natural treatment systems require the same amount of energy input as conventional biological treatment systems for the same amount of pollutant to be degraded, however the source of energy is different in natural systems. Natural systems are driven by renewable, naturally occurring energies including solar radiation, the kinetic energy of wind, the chemical-free energy of rainwater, surface water and groundwater, and the storage of potential energy in biomass and soils. Natural treatment systems are land-intensive, whereas conventional treatment systems are energy-intensive.
Land availability, proximity with zones of development and urban planning are among the factors of prime importance in deciding the type of technology that will prevail in any region.
5.3.2 – Justification for existing centralized systems
Mauritius is a small country where the majority (about 56.6 %) of the population is concentrated in 5 major urban centers and 15 large villages. The remaining 44.4 % of the population is found in villages scattered all over the island. Also, due to the interconnectivity of rivers and aquifers, all activities occurring in the main land can affect the lagoon.
Under the National Sewerage Masterplan sewerage facilities have been provided to the most densely urban parts of the island and main treatment systems adopted have been activated sludge systems with biological nutrient removal and re-use of treated effluent in irrigation. These systems have quite a high capital and operation and maintenance costs. The same effluent quality could have been obtained by using low cost treatment; however these treatment technologies such as pond systems or constructed wetland are highly land intensive, with land having a high value in Mauritius.
Land development patterns in Mauritius also indicate that zones around the periphery of urban centers are being developed at an increasing pace. Natural treatment systems would restrict the development of such zones because of potential odour, mosquito and unaesthetic problems.
The presently sewered urban areas in Mauritius also contain a number of polluting industries whose effluents might inhibit the action of microorganisms and ecosystems at work in natural systems.
The necessary expertise is presently being built up in process engineering and instrumentation for the operation & maintenance of mechanized systems. There is also more flexibility for process control which is of prime importance as the treated effluent is sold for irrigation.
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The St. Martin WWTP, the Baie du Tombeau WWTP and the Montagne WWTP are designed for flows of 87, 000 m3, 35, 000 m3 and 48, 000m3 respectively. These WWTPs cater for the most populated districts of Port Louis and Plaines Wilhems with population densities of the order of 3000 to 3500 capita/km2.
For these reasons, the existing centralized systems, consisting of conventional activated sludge or conventional primary treatment, are more appropriate than natural systems for wastewater treatment for urban centers with large population and high population density.
5.3.3 – Recommended systems for future projects
The National Sewerage Programme under the Sewerage Master plan – 1994 will be completed with the second stage of the Plaines Wilhems Sewerage Project. The two urban districts of Port Louis and Plaines Wilhems will then be fully sewered as well as regions covered under the West Coast Sewerage Project, Pailles-Guibies Sewerage Project and Grand Baie.
The priorities of the second Sewerage Masterplan will then be to provide sewerage facilities to the fifteen major villages in Mauritius. As discussed in Chapter 3, these major villages have populations ranging from 10, 000 to 22, 000 inhabitants. These villages are densely populated and are located throughout the districts. These are not parts of major conurbations and other residential developments are scattered all over the island. Due to high population density, the need for a centralized sewerage system is justified. However each major village, by virtue of their geographical distributions, will require a separate treatment system.
As discussed above, pond systems are not appropriate due to their large land requirements, need to provide impermeable bottom surfaces at high costs, odor and mosquito nuisances and unaesthetic look. Constructed wetland systems cannot be applied to populations of such magnitude.
On the other hand, activated sludge WWTP have a high capital and O & M costs, require close monitoring and produce high amounts of biological sludge which need to be further treated, transported and disposed of.
Extended aeration systems could therefore be explored as suitable wastewater treatment technology for the major villages. The system is simple, robust and not highly mechanized. It does not require close supervision and monitoring, it produces effluent of very high quality, with biological nutrient removal. The resulting effluent easily meets the required norms for irrigation and the wastewater management scheme can incorporate re-use in irrigation. Well stabilized sludge is produced in smaller quantities, thus the cost of sludge treatment, dewatering, transportation and disposal is avoided. The stabilized sludge can readily be used in agriculture.
5.3.4 – Technology to be explored - Anaerobic Reactors (UASB Type)
The UASB anaerobic treatment reactor is simple, less reliant on mechanical parts and can easily achieve double the organic matter removal rates of conventional primary treatment (60% to 75% BOD5 removals) at a fraction of the construction and O&M costs. UASB process also produces substantially lower quantities of sludge, thereby reducing sludge treatment, transport and disposal costs. In case higher effluent quality is required polishing options can be added such as facultative lagoons and trickling filters.
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Based on recent construction of medium-sized UASB facilities in Curitiba, Brazil, (serving populations greater than 200, 000), costs ranging from USD 30 to USD 40 per habitation have been estimated. (Sandino et al 2004). This compares favorably to the USD 80 to USD 100 cost per habitation considered typical for a conventional secondary treatment plant.
However the anaerobic nature of the process brings a high potential for hydrogen sulphide generation.
UASB treatment technology can easily be scaled down for small communities and should be assessed in future feasibility studies for sewerage projects in Mauritius.
5.3.5- Other Residential Areas
The urban districts and the major villages contribute to 56.6 % of the population. The remaining 44.4 % is scattered in villages all over the island. For villages with population densities more than 1000 capita per km2, extended aeration systems can also be considered. About 19 village council areas are concerned.
Villages with population density less than 1000 capita per km2, not located along the coast, with no high water table and soils of reasonably good permeability do not pose significant risks for ground water or lagoonal water pollution. It is recommended that proper individual on-site disposal systems such as conventional individual septic tanks followed by absorption pits be used for such villages. 103 village council areas in total have population densities less than 1000 capita per km2
It is recommended that regions with problems of high water table or impermeable soils be provided with small bore diameter sewers. Each building should be provided with an individual septic tank and the effluent form the septic tanks be channeled by small bore diameter sewers to a suitable location where sand filtration treatment can be applied. In the case of smaller communities, additional nutrient removal can be applied by constructed wetlands, while for larger communities, polishing can be applied by the use of trickling filters or RBC, before final disposal into water bodies or water courses. Alternatively, the treated effluent may be disposed of by infiltration in the soil if a suitable site can be found nearby.
5.3.6 – Coastal Villages
Coastal villages use primarily individual cesspits for wastewater disposal. Areas with tourist activity have a considerable number of restaurants, small hotels and secondary homes which also mostly make use of cesspits. Due to the very permeable nature of sandy soil found in coastal areas, it is obvious that effluents percolate to the lagoon. Thus, while the attention is focused on providing wastewater facilities to central urban areas, the use of improper on-site disposal systems in coastal areas may be a more serious source of diffuse pollution.
Although it may be difficult to prove that lagoons are getting polluted from those cesspits, the future potential outcome of such a source of pollution should not be overseen. An appropriate method of wastewater collection, treatment and disposal should be devised.
Such coastal villages could be too small and set too widely apart to seriously consider providing a central sewerage system. Moreover these coastal regions tend to be flat and may not favor gravitational flow.
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An appropriate individual on-site disposal system which can also provide some nutrient removal should therefore be considered so as to limit risks of eutrophication in the lagoon.
The only system that can be recommended is an individual septic tank followed by sand filter and individual constructed wetland.
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Chapter 6 – Lessons learnt and ‘best practices’ from projects on MWW Management
6.0 – Introduction
The success of a project depends on several factors that need to be critically assessed at feasibility study stage and findings plugged in at design and implementation stage.
Thus projects that have been prepared while bearing in the necessary human resources, expertise and other back-up support required, existing policy and institutional framework, decision making process and, most important, involvement of all other stakeholders, are liable to proceed smoothly.
6.1 – Selection of Consultant
The starting point of most major wastewater projects is the recruitment of a Consultant for undertaking the necessary feasibility studies, detailed design, tender exercises for recruitment of Works Contractor and supervision of works. The recruitment of an experienced firm of Consultant, with key personnel having the prerequisite experience for the type of studies to be undertaken, as well as a well drafted Contract Agreement, with terms of reference with a reasonable level of detail and conditions of contract applicable to the local context and reasonably defending the interests of both parties, is essential for the successful implementation of any project.
6.1.2 – Drafting of Tender Documents and Terms of Reference
Terms of Reference should be drafted to a level of detail sufficient to convey the exact requirements of the Client. Particular attention should be drawn to establishment of existing services, traffic management issues and acquisition of wayleaves as these can lead to major time overruns during construction.
In built checks and specific clauses should be inserted in tender documents and conditions of contract so as to ensure that all required services are undertaken by the Consultant and to the required quality. Terms used should be defined with precision to ensure that all parties have the same understanding and same expectations.
Reasonable timeframes should be provided for deliverables and penalties imposed to ensure prompt responses. Deliverables also should be accurately defined so as to ensure quality.
Realistic periods for payment after submission of payment certificates should be allowed. Time taken for internal as well as external processes to effect payment should be properly assessed so that no claims can be made for delayed payments.
It is customary to allow international consultants to submit tenders in association with sub- consultants, usually local consulting firms. The tender documents should ensure that key personnel are mainly from the international.
It may also be necessary to impose that key personnel submit statements with their original signatures, certifying that they will be available for the assignment if the contract is awarded to their firm. This will ensure that key personnel proposed in technical proposals are indeed
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6.2 – Securing of Funds
Major wastewater projects require extensive financial resources which are usually provided in the form of loans from international funding agencies. Funding for consultancy services are usually secured first and negotiations to fund works contract are sometimes on-going while consultancy services have already been undertaken. It may sometimes be appropriate not to go for a single Feasibility – detailed design – tendering exercise – works supervision contract but break the consultancy services in separate contracts for feasibility studies, detailed design and tender exercise and supervision of works contract so as to avoid time and cost overruns due to works unavoidable delays in works contracts.
6.3 – Involvement of Other Stakeholders
Major wastewater projects normally involve different stakeholders including the general public, the media and other public institutions. These actors must be brought in at the very inception stage so as to identify possible hurdles to project implementation and the requirements and expectancy of the different stakeholders. Regular meetings should be held before and after the start of the works with the different stakeholders so as to inform them about the nature and progress of the works. The assistance of the media should be sought for a better communication with the general public. Local committees representing residents should also be invited so as to smoothen relations and help in problem solving
6.3.1 – Wayleave issues
Wastewater projects usually involve construction of plant and laying of pipes over privately owned land or roads under the responsibilities of public authorities. It is essential to identify all plots of land where permanent wayleave will be required. For major projects, this may involve the full time involvement of a land surveyor to ensure that all procedures for obtaining permanent wayleaves are started at the earliest possible. Delays in securing permanent wayleaves will result in claims for delays from the Contractor.
6.3.2 – Traffic Management
Pipe laying works in congested traffic areas undoubtedly leads to severe traffic disruption unless carefully planned. Traffic management authorities and the police should be brought in as early as possible so that their views and advice can be taken into consideration. In some cases, a traffic impact assessment is necessary. The public authorities can also advise how best all parties can collaborate during the implementation phase. A Public Relations Division can also help smoothen relations and solve problems amicably with members of the public
6.3.3 – Public Awareness
Sewerage works normally constitute major disruptions, such as high noise levels, dust emanation, blockage of entrances to private dwellings, damage to water pipes, electrical and telephone cables, to the life of the public. Commercial and industrial enterprises can also be affected by loss of potential customers.
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Public awareness should start early, at inception stage, and continue during works. The public should be made aware why these works are necessary, what benefits they will derive from same, so that their cooperation can be sought. Safety of the general public can also best be assured and the works can better be planned while limiting the potential discomfort to the public and residents.
6.3.4 – Interaction with public institutions
Interaction with public institutions at inception stage is essential so as to be informed about their different requirements, exigencies and approval. Procedures can be pre-arranged and contacts established so that approvals are obtained promptly and do not result in unnecessary delays.
Information about existing underground services can be obtained beforehand and supplied to the Contractor so as to eliminate the delays that can be encountered in locating existing services at construction stage.
6.4 – Internal and External Processes for Approval
Internal and external processes for approval of tender evaluation reports, design reports, payment certificates, variations and claims should be carefully assessed to minimize time and cost overruns.
External processes involve parent Ministries, Ministry responsible for finance, Central Tender Boards and other Ministries whose input are relevant to the works being carried out. Regular contacts and meetings should be ensured between officers of the different institutions so as to cut down time for the approval process.
6.5 – In –house capacity to handle major projects
Major wastewater projects usually involve international consulting and contracting firms with extensive resources and back-up support. Public institutions should ensure that they possess the required resources and technical staff experienced in wastewater works, project management and with previous exposure to the different situations that can be encountered.
Usually, a project team led by an experienced Project Manager, backed by a team of engineers and technicians, is responsible for major projects. Legal advice and advice on financial matters should be readily accessible.
Technical staff experienced in the design and operation & maintenance of wastewater infrastructure should be available so as to critically assess designs and modifications proposed by consultants and contractors.
6.6 – O & M facilities and commissioning
Wastewater projects such as construction of sewerage networks, pump stations and wastewater treatment plants should contain necessary provisions for availability of expertise necessary for the operation and maintenance immediately after construction and during the commissioning period. Training of local personnel should be given priority so as to ensure either taking over in case of in-house O & M or proper supervision of contractors in case of service contracts.
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6.7 – Use of equipment & material from abroad
In case equipment and material from abroad are used in construction works, it should be ensured that sufficient spare parts are purchased along with the construction contract. It should also be ensured that required expertise is available locally for necessary repairs. It may be necessary to incorporate necessary training of local technicians within the construction contract.
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Chapter 7 – Mechanisms for Domestication of Regional Guidelines
7.1 – Mechanisms for Domestication
The applicability of the ten keys for local and national actions on municipal wastewater is discussed in Table 7.1 below
Table 7.1: Applicability of the ten keys for local and national actions on municipal wastewater
10 keys Applicable Not Comments Applicable
1. Secure political commitment and domestic Political commitment to develop the wastewater sector is financial resources √ obvious from the progress made over the past fifteen years, institutionally, legally, and in terms of extension of sewer networks and pollution abatement 2. Create an enabling environment at national AND The specificity of Mauritius requires a central local levels √ organization responsible for sewerage infrastructure and general policy while general responsibility for on-site sanitation would best rest with local authorities 3. Do not restrict water supply and sanitation to taps The necessary mechanisms, in terms of EIA Licenses and and toilets √ Building Permits, Enforcing agencies, armed with relevant Regulations, ensure quality of treated effluents from different activities and quality of water bodies. 4. Develop integrated urban water supply and Government has taken steps to reform the water and sanitation management systems also addressing √ sanitation sectors with a view to improving the overall environmental impacts performance of the utilities through the enlistment of Private Sector Participation 5. Adopt a long term perspective, taking action step- Provision of sewerage facilities to highly populated urban by-step, starting now √ areas and improvement of access of the poor to suitable sanitation has been planned over an extended time frame and has been implemented stepwise 6. Use well-defined time-lines, and time-bound The overall performance and progress of the wastewater targets and indicators √ sector is already monitored by a series of key performance indicators
7. Select appropriate technology for efficient and The specificity of Mauritius in terms of size, cost-effective use of water resources and consider √ demographical distribution and large water coverage ecological sanitation alternatives restricts sanitation to centralized systems and on-site systems. There is no significant scope for ecological sanitation from a socio-cultural and land use standpoint 8. Apply demand-driven approaches √ Ditto
9. Involve all stakeholders from the beginning and Most stakeholders are already involved on wasteweater ensure transparency in management and decision- √ projects. These include the public, media, industrial making process sector, funding agencies and other governmental institutions. A public awareness campaign can significantly improve stakeholder involvement 10. Ensure financial sustainability Existing tariff structure and planned increases aim at √ improving the financial sustainability of the WMA in terms of recovery of Operation & Maintenance costs and Depreciation costs. Tariff should regularly be raised to improve the financial sustainability of the WMA.
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7.2 – Opportunities for Domestication
The following factors listed below favor the domestication of the Regional Guidelines. These factors have been analysed in the previous chapters.
● Strong political commitment and support to develop the wastewater sector ● Strong interest of international donors to fund the wastewater sector ● Clear policy and Masterplan for the wastewater sector ● Existing environmental and wastewater legal framework ● Existence of public laboratories with sophisticated equipment ● Existing institutional set-up and enforcing agencies to control and monitor discharge of effluents to the environment
7.3 – Impediments for Domestication
The following factors listed below are required for the domestication of the Regional Guidelines. These factors have also been analysed in the previous chapters.
● Improvement of public and stakeholder awareness ● Specificity of Mauritius does not encourage ecotechnologies and demand – driven approaches ● Training of technicians and professionals for the wastewater sector ●Improvement of institutional capacity to implement and enforce Regulations under Environmental Protection Act and Wastewater Act ●Enhanced capacity for analysis of effluents ● Promulgation of Regulations and enforcing mechanism for on-site disposal systems ● Improved synergy between public laboratories involved in analysis of effluents
7.4 – National Mechanisms, Strategies and Policies that can be used to internalize the Regional Guidelines on MWW Management
7.4.1 – White Paper on National Environment Policy of July 2006 The White Paper prepared by the Ministry of Environment defines the new National Environmental Policy of the Republic of Mauritius and is based on a review of key environmental issues, challenges and opportunities that are specific to the national context. It takes into consideration evolving patterns on the socio-economic scene as well as constraints that Mauritius has to face as a Small Island Developing State. The new policy will be mainly implemented through the revision National Environment Strategy and Action Plan which is actually being undertaken by an International Consultant.
A number of commitments taken in the White Paper can be translated into actual strategies and policies in the updating of the NES which will further strengthen the internalization of the Regional Guidelines.
7.4.1.1 – Commitment through the White Paper The White Paper recognizes that: ● The integration of environmental responsibility at all levels is a necessary for an active environmental policy. ● Mauritius needs an environmentally conscious society where each citizen has the responsibility and duty to protect the environment.
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●it is important to have more active participation of major stakeholders in decision-making and project implementation. ● environmental education plays an important part in building a culture of environmental responsibility in Mauritius. The emphasis on environmental education needs to be strengthened through review of curricula and promotion of co-curricular and extra-curricular activities.
● Policy must also cater for the needs of cooperation at all levels as environmental policy making is more and more being considered from a regional and international perspective. Transboundary issues such as management of hazardous wastes, trade and environment aspects are addressed in various conventions to which Mauritius is party to. This policy shall ensure that the provisions contained in the various Multilateral Agreements are implemented in synergy and that appropriate linkages are created to avoid duplication. As a member of the World Trade Organization, Government will ensure that environmental and trade policies are mutually supportive.
7.4.1.2 – Guiding Principles of the White Paper The Policy is based on certain guiding principles, among which the following are of particular relevance in the internalization of the Regional Guidelines:
I – Human Beings are at the Centre of Environmental Sustainability Every person has a right to a clean and healthy environment
II – Environmental Stewardship All citizens shall have a responsibility and duty to protect the environment.
III – Maintaining basic Ecological Integrity The diversity, health and productivity of our eco-systems will be maintained and managed well.
IV – Sustainability Sustainable Development shall be the preferred development paradigm and Government shall ensure that environmental concerns are mainstreamed in economic and social development.
V – Precautionary Principle Where there are credible threats of serious or irreversible damage to key environmental resources, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.
VI - Polluter Pays Principle Government shall adopt the required measures and instruments to encourage the rational use of environmental resources. Polluters shall have to bear the consequences of their activities.
VII – Use of appropriate technology The use of appropriate (environmentally – friendly) technology is a strategic consideration.
VIII – Preventive Approach The strategy for precaution of environmental pollution threat is based on the principle of control at source. The following hierarchy shall apply:
(i) Avoidance of pollution generation, i.e. activities aimed at the reconstruction of manufacturing and consumption practices to reduce the burden of pollutants through Cleaner Production.
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(ii) Recycling i.e. re-circulation of materials and resources; recuperation of energy, water and raw materials from wastes and utilization of wastes to reduce emissions into the environment; and
(iii) Treatment and disposal
IX – Science and Knowledge Government shall promote the use of best science and data for the effective decision making. This information shall be accessible and understood by all stakeholders. Traditional knowledge shall also be given due recognition and be fully utilized.
X – Partnerships Real commitment to safeguard the environment can be taken when all stakeholders play their role fully. Government shall strengthen collaboration and partnership with all stakeholders and incorporate their input in decision making.
XI – Decentralization Local Authorities will gradually be empowered to address environmental issues more effectively at local level.
XII – Environmental Education and Awareness The Mauritian population, especially children and youth, will be educated and sensitized on environmental issues with a view to involve them in conservation, protection and management of the environment.
XIII – Environmental Governance and Accountability Transparence, accountability and good environmental governance practices will be cornerstones of our environmental policies.
XIV – Global Code of Conduct International and regional agreements and treaties pertaining to environmental management will be fulfilled. Regional and international cooperation will complement national processes and capacity.
7.4.1.3 – Environmental Policy Instruments Policy tools will be diversified to provide more flexibility, reduce costs of enforcement and stimulate innovation. Effective implementation of NEP (2006) will be supported by the following instruments:
● Voluntary Agreements, Codes of Conduct and Practices – Schemes whereby actors (usually industry) take firm commitments to improve their environmental performance beyond existing legal requirements.
● Legal and Institutional Instruments – imposing obligations with respect to target actors and gradual decentralization of environmental protection activities and provide the right environment for implementation.
● Enforcement and Monitoring Systems – The establishment of an efficient system for the inspection of compliance to environmental laws and the establishment of a monitoring system to evaluate the effectiveness of policies.
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● Financial Support Programmes – Innovative financing mechanism will be devised for investment in cleaner technology, demonstrative programmes, projects and environmental audits in Small and Medium Enterprises. The potential of the Clean Development Mechanism in infrastructural developments will be investigated.
● Capacity Building and Research – Research projects aimed at the implementation of sustainable development is supported. Programmes to upgrade the capacity of key stakeholders to implement the policy.
● Market – based or Economic instruments – to provide incentives to change the behavior of producers and consumers.
●Environmental Education – An essential goal of environmental education should be inspiring the desire to act for the cause of environmental protection. To educate the children and Youth as future custodians of environment.
● Information and Awareness Raising – Collection and dissemination of environmental information is an essential part of environmental policy.
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Sector Policy Letter, 1998
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