Guide for Management of Waste Stabilisation Pond Systems in South Africa

Guide for management of waste stabilisation pond systems in South Africa Philip de Souza & Unathi Jack TT 471/10 GUIDE FOR MANAGEMENT OF WASTE STABILISATION POND SYSTEMS IN SOUTH AFRICA Report to the Water Research Commission by Philip de Souza and Unathi Jack on behalf of Emanti Management (Pty) Ltd WRC REPORT NO. TT 471/10 NOVEMBER 2010 Obtainable from Water Research Commission Private Bag X03 Gezina, 0031 The publication of this report emanates from a project entitled Status Quo Assessment of Wastewater Ponding Systems (WRC Project No. K5/1657). DISCLAIMER This report has been reviewed by Water Research Commission (WRC) and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the WRC, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. ISBN: 978-1-4312-0034-4 Set No. 978-1-4312-0037-5 Printed in the Republic of South Africa ii EXECUTIVE SUMMARY It is understood that the health of a community is significantly influenced by its water quality. The appropriate management of water systems, both the natural resource and municipal water services, is a critical requirement in municipal services provision. PURPOSE OF THE GUIDE This guide has been developed with the purpose of providing assistance in terms of: Planning for construction of an appropriate wastewater treatment system and determining what is appropriate Management to understand what to expect from the contractors and/or consultants in designing a waste stabilisation ponds system Good operations and maintenance of waste stabilisation ponds system Possible re-use of treated wastewater from waste stabilisation ponds system Upgrading waste stabilisation ponds system. This guide can be used in conjunction with the following Water Research Commission (WRC)/Department of Water Affairs and Forestry (DWAF) guides: DWAF (2004) General Authorisation Permissible Utilisation and Disposal of Treated Sewage Effluent, Department of Health under reference 11/2/5/3: 30 May 1976 “South African water quality guidelines – agricultural use” DWAF 1993 “South African water quality guidelines – industrial use” DWAF 1993 Handbook for the operation of wastewater treatment works (2006) by Frik Schutte All other references at the end of the document A guide for operations and maintenance of waste stabilisation ponds system also developed. WHO SHOULD USE THIS GUIDE? The guide has been developed in such a way that it will assist the wastewater management team to answer the following questions: Is a waste stabilisation pond system appropriate for us? What do we need to consider when designing a waste stabilisation pond system? Once we have constructed a waste stabilisation pond system, how do we operate and maintain the system? Is the treated wastewater in the waste stabilisation pond system suitable for re-use purposes? How do we prevent and respond to typical system failures? What options are available if we need to upgrade or refurbish the waste stabilisation pond system? iii ACKNOWLEDGEMENTS The following persons and organisations are thanked for their contribution to this project. Financial Support Water Research Commission Members of the Reference Team <ul style="display: flex;"><li style="flex:1">Dr Heidi Snyman </li><li style="flex:1">Water Research Commission </li></ul>University of Pretoria Umgeni Water Prof At Pretorius Dr Paul Gaydon Mr Andrew Lucas Dr Johan van der Merwe Ms Corrine de Kock Eastern Cape DWAF Free State DWAF Free State DWAF WSAs involved Eastern Cape Mpumalanga Free State : Maletswai, Senqu, Buffalo City, Inkwanca, Great Kei : Emalahleni : Dihlabeng, Kopanong, Letsemeng, Mantsopa, Mohokare, Naledi, Tokologo, Nketoane iv TABLE OF CONTENTS EXECUTIVE SUMMARY................................................................................................................ iii PURPOSE OF THE GUIDE ........................................................................................................... iii WHO SHOULD USE THIS GUIDE? .............................................................................................. iii ACKNOWLEDGEMENTS.............................................................................................................. iv TABLE OF CONTENTS.................................................................................................................. v LIST OF FIGURES......................................................................................................................... vi LIST OF TABLES.......................................................................................................................... vii ABBREVIATIONS........................................................................................................................ viii 1. BASIC CONSIDERATIONS FOR DESIGN OF A WASTEWATER TREATMENT WORKS ................................................................................................................................... 1 2. SELECTING AN APPROPRIATE WASTEWATER TREATMENT SYSTEM ........................ 3 2.1 Wastewater treatment facility efficiency ............................................................................. 3 2.2 Wastewater treatment facilities economic considerations.................................................. 5 2.3 Indicative operations and maintenance cost .................................................................... 14 3. TYPES OF WASTE STABILISATION PONDS..................................................................... 16 3.1 Anaerobic ponds............................................................................................................... 18 3.2 Facultative ponds ............................................................................................................. 18 3.3 Aerobic ponds................................................................................................................... 18 4. WASTE STABILISATION PONDS DESIGN CONSIDERATIONS....................................... 20 4.1 Pond lining........................................................................................................................ 20 4.2 Pond shape and depth ..................................................................................................... 21 4.3 Pond topography .............................................................................................................. 23 4.4 Pond inlet and outlet......................................................................................................... 23 4.5 Pond hydraulic considerations.......................................................................................... 24 4.6 Pond location.................................................................................................................... 26 4.7 General............................................................................................................................. 26 5. MANAGEMENT OF TREATED EFFLUENT......................................................................... 27 5.1 Environmental consideration ............................................................................................ 27 5.2 Agriculture......................................................................................................................... 29 5.3 Industrial use of treated wastewater................................................................................. 30 6. TYPICAL FAILURES AND TROUBLESHOOTING.............................................................. 31 Causes of failing waste water ponds and possible remedial actions........................................ 31 6.1 Lining ................................................................................................................................ 31 6.2 Inlets and outlets .............................................................................................................. 32 6.3 Receiving ponds............................................................................................................... 33 6.4 Fencing............................................................................................................................. 34 6.5 Supervision and Maintenance .......................................................................................... 34 6.6 Algal removal.................................................................................................................... 34 6.7 Odour control.................................................................................................................... 36 6.8 Handling excess flows...................................................................................................... 36 6.9 Process controllers health ................................................................................................ 37 6.10 Environmental Safety: Monitoring and evaluation of pond system performance............ 38 7. UPGRADING PONDS ........................................................................................................... 39 7.1 Additional technologies used to improve ponds............................................................... 39 REFERENCES .............................................................................................................................. 42 APPENDIX A................................................................................................................................. 44 APPENDIX B................................................................................................................................. 47 APPENDIX C................................................................................................................................. 49 APPENDIX D................................................................................................................................. 58 vLIST OF FIGURES Figure 1: Decision support model with respect to community size and discharge standards :................................................................................................................................................ 7 Figure 2: Decision support model with respect to land availability for plant site: (Golder Associates Africa and Zitholele consulting draft report prepared for WRC and DWAF, 2006)........................................................................................................................................... 8 Figure 3: Decision support model with respect to operational support and resources: (Golder Associates Africa and Zitholele consulting draft report prepared for WRC and DWAF, 2006).. 9 Figure 4: Decision support model with respect to maintenance support and resource: (Golder Associates Africa and Zitholele consulting draft report prepared for WRC and DWAF, 2006)............. 10 Figure 5: Decision support model with respect to existing treatment infrastructure: (Golder Associates Africa and Zitholele consulting draft report prepared for WRC and DWAF, 2006) 11 Figure 6: Capital Investment Cost Curves for Integrated Ponds Treatment Plants: (Golder Associates Africa and Zitholele consulting draft report prepared for WRC and DWAF, 2006)13 Figure 7: Capital Investment Cost curves for the Activated Sludge and Trickling Filter Treatment systems: (Golder Associates Africa and Zitholele consulting draft report prepared for WRC and DWAF, 2006).................................................................................................... 14 Figure 8: Indicative O&M costs for Integrated Ponds and Polishing Wetlands: (Golder Associates Africa and Zitholele consulting draft report prepared for WRC and DWAF, 2006)......................................................................................................................................... 15 Figure 9: Indicative O&M costs for Activated Sludge and Trickling Filter Plants: (Golder Associates Africa and Zitholele consulting draft report prepared for WRC and DWAF, 2006)......................................................................................................................................... 16 Figure 10: Detailed waste stabilisation ponds configurations ............................................................. 17 Figure 11: Simple waste stabilisation ponds configurations................................................................. 17 Figure 12: Photographs showing lining in ponds.................................................................................. 21 Figure 13: Illustration of a pond ............................................................................................................ 23 Figure 14: Various pond inlets.............................................................................................................. 24 Figure 15: A waste stabilisation pond system discharging to the environment.................................... 29 Figure 16: Lining issues........................................................................................................................ 32 Figure 17: Illustration of pond flow configuration.................................................................................. 32 Figure 18: Inlet issues .......................................................................................................................... 33 Figure 19: Receiving pond issues ........................................................................................................ 33 Figure 20: Safety issue s....................................................................................................................... 34 Figure 21: U-shaped pipe for algae collection (Gaydon, 2008)............................................................ 35 Figure 22: Algal issues ......................................................................................................................... 35 Figure 23: Sludge removal issue s........................................................................................................ 37 Figure 24: Staff safety issues ............................................................................................................... 37 Figure 25: Illustration of integrated facultative pond............................................................................. 39 Figure 26: Baffled pond ........................................................................................................................ 40 Figure 27: Integrated waste stabilisation ponds system ...................................................................... 40 vi LIST OF TABLES Table 1: Characteristics of typical wastewater treatment systems (Mara, 1976; UNEP, 1997 and Qasm, 1998)............................................................................................................................................ 4 Table 2: Variation of design volumetric COD loading on, and COD removal in anaerobic ponds (Mara, 2005)...................................................................................................................................................... 22 Table 3: Wastewater limit values applicable to discharge of wastewater into a water resource.......... 28 Table 4: Wastewater limit values applicable to irrigate with wastewater.............................................. 30 Table 5: Senses Characteristics in waste stabilisation ponds (Federation of Canadian Municipalities and National Research Council, 2004 and Gaydon presentation, 2008).............................................. 38 vii ABBREVIATIONS COD : Chemical Oxygen Demand EPA : Environmental Protection Agency FC RBC : Rotating Biological Contactor SS : Suspended Solids : Faecal Coliform viii GLOSSARY Aerobic Anaerobic Desludge : a biological process which occurs in the presence of oxygen : a biological process which occurs in the absence of oxygen : the process of removing sediment by draining and cleaning Discharging : is a process where treated wastewater is discharged of Effluent Grit : treated wastewater flowing out of the wastewater treatment system : solid material contained in raw wastewater (e.g. sand, gravel, food waste etc) Infiltration Influent : the process of water entering soil :untreated wastewater – the wastewater that flows into a wastewater treatment system Inlet Lining : opening providing a means of entrance/intake of the untreated wastewater : a protective covering that protects an inside surface of the pond to avoid leaching Nightsoil : human excreta collected intentionally Organic load : amount of Chemical Oxygen Demand (COD) per unit volume or area per unit of time; usually expressed as [kg/m3/day] or [kg/m2/day] Outlet : opening providing a means exit of the treated wastewater Overflow : flows or runs over the top or banks Overloaded : loaded past/exceeds capacity of the treatment system Ponds : are described as relatively shallow bodies of wastewater contained in an earthen basin Septage Screenings : material removed from any part of an individual sewage disposal system : the fine or coarse material removed by the screens at the inlet of the wastewater treatment system Screens Scum : a device with openings, generally of uniform size, that is used to retain course solids found in wastewater : filmy layer of slimy matter that forms on or rises to the surface of a pond. Scum is known to be a form or type of algae Sludge : semisolid material deposited during the treatment of wastewater <ul style="display: flex;"><li style="flex:1">ix </li><li style="flex:1">x</li></ul><ul style="display: flex;"><li style="flex:1">1. </li><li style="flex:1">BASIC CONSIDERATIONS FOR DESIGN OF </li></ul>WASTEWATER TREATMENT WORKS AAn understanding of the nature of wastewater (i.e. raw wastewater) is fundamental for the design of appropriate wastewater treatment works. Effluent quality is the most important factor in choosing a wastewater treatment technology. Facilities are permitted to meet certain effluent water quality standards, depending on the water quality of the receiving waters. The ideal wastewater treatment system should satisfy the following criteria (Metcalf and Eddy, 2003; Marais, 1966) Health criteria – pathogenic organisms should not be spread either by direct contact with wastewater or indirectly via soil, water or food. The treatment system chosen should achieve a high degree of pathogen destruction. Cost criteria – capital and running costs should not exceed the community’s ability to pay. The financial return from reuse is an important factor in this regard. Ecological criteria – in cases when the wastewater cannot be reused, the discharge of effluent into surface water should not exceed the self purification of the recipient water. Operational criteria – the skills required for the routine operation and maintenance of the wastewater treatment system components should be available locally or are such that they can be acquired with only minimum training. Reuse criteria – the wastewater treatment process should yield a safe effluent for reuse, preferably for aquaculture and/or agriculture purposes. Nuisance criteria – No part of the system should become odour offensive. Cultural criteria – the methods chosen for wastewater collection, treatment and reuse, should be compatible with local habits and social practice. This is dependent on issues such as location of the system, cultural value of the area etc.

Guide for Management of Waste Stabilisation Pond Systems in South Africa

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