Managing Water and Air Quality 81

Total Page:16

File Type:pdf, Size:1020Kb

Managing Water and Air Quality 81 CHAPTER 5 MManaginganaging wwaterater aandnd aairir qqualityuality his chapter builds upon the background provided in Chapters 2, 3 and 4 and Tprovides guidance relating to water and air quality management (risk management specifi c to certain microbial hazards is covered in greater detail in Chapter 3). The primary water and air quality health challenges to be dealt with are, in typical order of public health priority: • controlling clarity to minimize injury hazard; • controlling water quality to prevent the transmission of infectious disease; and • controlling potential hazards from disinfection by-products. All of these challenges can be met through a combination of the following factors: • treatment (to remove particulates, pollutants and microorganisms), including fi ltration and disinfection (to remove/inactivate infectious microorganisms); • pool hydraulics (to ensure effective distribution of disinfectant throughout the pool, good mixing and removal of contaminated water); • addition of fresh water at frequent intervals (to dilute substances that cannot be removed from the water by treatment); • cleaning (to remove biofi lms from surfaces, sediments from the pool fl oor and particulates adsorbed to fi lter materials); and • ventilation of indoor pools (to remove volatile disinfection by-products and radon). Controlling clarity, the most important water quality criterion, involves adequate water treatment, including fi ltration. The control of pathogens is typically achieved by a combination of circulation of pool water through treatment (normally requiring some form of fi ltration plus disinfection) and the application of a chemical residual disinfectant to inactivate microorganisms introduced to the pool itself by, for instance, bathers. As not all infectious agents are killed by the most frequently used residual disinfectants, and as circulation through the physical treatment processes is slow, it is necessary to minimize accidental faecal releases and vomit (and to respond effectively to them when they occur) and to minimize the introduction of bather-shed organ- isms by pre-swim hygiene. Microbial colonization of surfaces can be a problem and is generally controlled through adequate levels of cleaning and disinfection. The control of disinfection by-products requires dilution, selection of source waters without DBP precursors (may include water pretreatment if necessary), pre-swim showering, treat- ment, disinfection modifi cation or optimization and bather education. Figure 5.1 outlines the components and shows a general layout of a ‘typical’ pool treatment system. Most pools have a pumped system and water is kept in continuous 80 GUIDELINES FOR SAFE RECREATIONAL WATER ENVIRONMENTS llayoutayout SSafeafe WWater.inddater.indd 110202 224.2.20064.2.2006 99:57:13:57:13 Plant room Coagulant dosing (5.2) Strainer Pump Filtration (5.4) Water disinfection (5.3) alternative disinfection dosing point pH correction dosing (5.10.3) Surface water off-take Balance tank Swimming pool Treated water Dilution (5.5) and make-up water Bottom off-take Figure 5.1. Water treatment processes in a ‘typical pool’ (relevant section numbers are identifi ed in parentheses) circulation (see Section 5.6), with fresh water being added for dilution of materials that are not effectively removed by treatment and to account for losses (often referred to as make-up water). 5.1 Pre-swim hygiene In some countries, it is common to shower before a swim. Showering will help to remove traces of sweat, urine, faecal matter, cosmetics, suntan oil and other potential water contaminants. Where pool users normally shower before swimming, pool water is cleaner, easier to disinfect with smaller amounts of chemicals and thus more pleas- ant to swim in. Money is saved on chemicals (offset to some extent by the extra cost of heating shower water, where necessary). The most appropriate setup for showers (e.g. private to encourage nude showering, a continuously run or automatic ‘tunnel’ arrangement) will vary according to country, but pool owners and managers should actively encourage showering. Showers must run to waste and should be managed to control Legionella growth (see Chapter 3). The role of footbaths and showers in dealing with papillomavirus and foot infec- tions is under question. However, it is generally accepted that there must be some barrier between outdoor dirt and the pool in order to minimize the transfer of dirt into the pool. A foot spray is probably the best of the alternatives to footbaths. Where outdoor footwear is allowed poolside (e.g. some outdoor pools), separate poolside drainage systems can minimize the transfer of pollutants to the pool water. CHAPTER 5. MANAGING WATER AND AIR QUALITY 81 llayoutayout SSafeafe WWater.inddater.indd 110303 224.2.20064.2.2006 99:57:14:57:14 Toilets should be provided and located where they can be conveniently used before entering and after leaving the pool. All users should be encouraged to use the toilets before bathing to minimize urination in the pool and accidental faecal releases. If babies and toddlers (that are not toilet trained) are allowed in the pool facilities, they should, wherever possible, wear leak-proof swimwear (that will contain any urine or faecal release) and, ideally, they should have access only to small pools that can be completely drained if an accidental faecal release occurs. 5.2 Coagulation Coagulants (or fl occulants) enhance the removal of dissolved, colloidal or suspend- ed material by bringing it out of solution or suspension as solids (coagulation), then clumping the solids together (fl occulation), producing a fl oc, which is more easily trapped during fi ltration. Coagulants are particularly important in helping to remove the oocysts and cysts of Cryptosporidium and Giardia (Pool Water Treatment Advisorz Group, pers. comm.; Gregory, 2002), which otherwise may pass through the fi lter. Coagulant effi ciency is dependent upon pH, which, therefore, needs to be controlled. 5.3 Disinfection Disinfection is part of the treatment process whereby pathogenic microorganisms are inactivated by chemical (e.g. chlorination) or physical (e.g. UV radiation) means such that they represent no signifi cant risk of infection. Circulating pool water is disinfected during the treatment process, and the entire water body is disinfected by the application of a residual disinfectant (chlorine- or bromine-based), which partially inactivates agents added to the pool by bathers. Facilities that are diffi cult or impos- sible to disinfect pose a special set of problems and generally require very high rates of dilution to maintain water quality. For disinfection to occur with any biocidal chemi- cal, the oxidant demand of the water being treated must be satisfi ed and suffi cient chemical must remain to effect disinfection. 5.3.1 Choosing a disinfectant Issues to be considered in the choice of a disinfectant and application system include: • safety (while occupational health and safety are not specifi cally covered in this volume, operator safety is an important factor to consider); • compatibility with the source water (it is necessary to either match the disinfec- tant to the pH of the source water or adjust the source water pH); • type and size of pool (e.g. disinfectant may be more readily degraded or lost through evaporation in outdoor pools); • ability to remain in water as residual after application; • bathing load; and • operation of the pool (i.e. capacity and skills for supervision and management). The disinfectant used as part of swimming pool water treatment should ideally meet the following criteria: • effective and rapid inactivation of pathogenic microorganisms; • capacity for ongoing oxidation to assist in the control of all contaminants dur- ing pool use; 82 llayoutayout SSafeafe WWater.inddater.indd 110404 224.2.20064.2.2006 99:57:14:57:14 • a wide margin between effective biocidal concentration and concentrations re- sulting in adverse effects on human health (adverse health effects of disinfec- tants and disinfection by-products are reviewed in Chapter 4); • availability of a quick and easy measurement of the disinfectant concentration in pool water (simple analytical test methods and equipment); and • potential to measure the disinfectant concentration online to permit automatic control of disinfectant dosing and continuous recording of the values measured. 5.3.2 Characteristics of various disinfectants 1. Chlorine-based disinfectants Chlorination is the most widely used pool water disinfection method, usually in the form of chlorine gas, a hypochlorite salt (sodium, calcium, lithium) or chlorinated isocyanurates. While chlorine gas can be safely and effectively used, it does have the potential to cause serious health impacts, and care must be taken to ensure that health concerns do not arise. When chlorine gas or hypochlorite is added to water, hypochlorous acid (HOCl) is formed. Hypochlorous acid dissociates in water into its constituents H+ and OCl– (hypochlorite ion), as follows: HOCl ↔ H+ + OCl– hypochlorous hydrogen hypochlorite acid ion ion The degree of dissociation depends on pH and (much less) on temperature. Disso- ciation is minimal at pH levels below 6. At pH levels of 6.5–8.5, a change occurs from undissociated hypochlorous acid to nearly complete dissociation. Hypochlorous acid is a much stronger disinfectant than hypochlorite ion. At a pH of 8.0, 21% of the free chlorine exists in the hypochlorous acid form (acting as a strong, fast, oxidizing disin- fectant), while at a pH of 8.5, only 12% of that chlorine exists as hypochlorous acid. For this reason, the pH value should be kept relatively low and within defi ned limits (7.2–7.8 – see Section 5.10.3). Together, hypochlorous acid and OCl– are referred to as free chlorine. The usual test for chlorine detects both free and total chlorine; to determine the effectiveness of disinfection, the pH value must also be known. The chlorinated isocyanurate compounds are white crystalline compounds with a slight chlorine-type odour that provide free chlorine (as hypochlorous acid) when dis- solved in water but which serve to provide a source of chlorine that is more resistant to the effects of UV light.
Recommended publications
  • Water Quality Conditions in the United States a Profile from the 1998 National Water Quality Inventory Report to Congress
    United States Office of Water (4503F) EPA841-F-00-006 Environmental Protection Washington, DC 20460 June 2000 Agency Water Quality Conditions in the United States A Profile from the 1998 National Water Quality Inventory Report to Congress States, tribes, territories, and interstate commissions report that, in 1998, about 40% of U.S. streams, lakes, and estuaries that were assessed were not clean enough to support uses such as fishing and swimming. About 32% of U.S. waters were assessed for this national inventory of water quality. Leading pollutants in impaired waters include siltation, bacteria, nutrients, and metals. Runoff from agricultural lands and urban areas are the primary sources of these pollu- tants. Although the United States has made significant progress in cleaning up polluted waters over the past 30 years, much remains to be done to restore and protect the nation’s waters. Findings States also found that 96% of assessed Great Lakes shoreline miles are impaired, primarily due to pollut- Recent water quality data find that more than ants in fish tissue at levels that exceed standards to 291,000 miles of assessed rivers and streams do not protect human health. States assessed 90% of Great meet water quality standards. Across all types of water- Lakes shoreline miles. bodies, states, territories, tribes, and other jurisdictions report that poor water quality affects aquatic life, fish Wetlands are being lost in the contiguous United consumption, swimming, and drinking water. In their States at a rate of about 100,000 acres per year. Eleven 1998 reports, states assessed 840,000 miles of rivers states and tribes listed sources of recent wetland loss; and 17.4 million acres of lakes, including 150,000 conversion for agricultural uses, road construction, and more river miles and 600,000 more lake acres than residential development are leading reasons for loss.
    [Show full text]
  • 2021 Water Quality Report
    2021 WATER QUALITY REPORT 2021 WATER QUALITY REPORT CITY OF NEWARK: SOUTH WELL FIELD TREATMENT PLANT AIR STRIPPER BUILDING Annual Water Quality Report The Environmental Protection Agency (EPA) Newark meets or exceeds the water quality requires public water suppliers to provide standards of the Delaware Division of Public consumer confidence reports (CCR) to their Health Office of Drinking Water and the customers . These reports are also known as Environmental Protection Agency. The tables on annual water quality reports. The below report pages 4-6 of this report list those substances summarizes information regarding the sources found in our finished water during calendar year used (i.e. rivers, reservoirs, or aquifers), any 2020. detected contaminants, compliance and educational efforts. How the Water is Treated The City’s 317 million gallon reservoir provides a Drinking water, including bottled water, may At the Curtis Water Treatment Plant (CWTP), reliable source of raw water which can be treated reasonably be expected to contain at least small water from the White Clay Creek is clarified with and ready for drinking in times of heavy rain or amounts of some substances. The presence of alum and polymer and then filtered to remove drought. In an effort to keep sediment these substances does not necessarily indicate impurities. Chlorine is added to kill harmful accumulation in our water mains to a minimum, that water poses a health risk. In order to ensure bacteria and viruses. Finally, fluoride is added to we flush the entire system yearly. that tap water is safe to drink, the EPA prescribes the water to protect your teeth.
    [Show full text]
  • Evaluating Residential Indoor Air Quality Concerns1
    Designation: D7297 – 06 Standard Practice for Evaluating Residential Indoor Air Quality Concerns1 This standard is issued under the fixed designation D7297; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval. 1. Scope 2. Referenced Documents 1.1 This standard practice describes procedures for evaluat- 2.1 ASTM Standards:2 ing indoor air quality (IAQ) concerns in residential buildings. D1356 Terminology Relating to Sampling and Analysis of 1.2 The practice primarily addresses IAQ concerns encoun- Atmospheres tered in single-family detached and attached (for example, D1357 Practice for Planning the Sampling of the Ambient townhouse or duplex design) residential buildings. Limited Atmosphere guidance is also included for low- and high-rise multifamily D4861 Practice for Sampling and Selection of Analytical dwellings. Techniques for Pesticides and Polychlorinated Biphenyls 1.3 The IAQ evaluation procedures are comprised of inter- in Air views with the homeowner or resident(s) (including telephone D4947 Test Method for Chlordane and Heptachlor Residues interviews and face-to-face meetings) and on-site investiga- in Indoor Air tions (including walk-through, assessment, and measure- D5197 Test Method for Determination of Formaldehyde ments). For practicality in application, these procedures are and Other Carbonyl Compounds in Air (Active Sampler dividing into three separate phases. Methodology) 1.4 The procedures described in this standard practice are D5438 Practice for Collection of Floor Dust for Chemical aimed at identifying potential causes contributing to the IAQ Analysis concern.
    [Show full text]
  • Diffuse Pollution, Degraded Waters Emerging Policy Solutions
    Diffuse Pollution, Degraded Waters Emerging Policy Solutions Policy HIGHLIGHTS Diffuse Pollution, Degraded Waters Emerging Policy Solutions “OECD countries have struggled to adequately address diffuse water pollution. It is much easier to regulate large, point source industrial and municipal polluters than engage with a large number of farmers and other land-users where variable factors like climate, soil and politics come into play. But the cumulative effects of diffuse water pollution can be devastating for human well-being and ecosystem health. Ultimately, they can undermine sustainable economic growth. Many countries are trying innovative policy responses with some measure of success. However, these approaches need to be replicated, adapted and massively scaled-up if they are to have an effect.” Simon Upton – OECD Environment Director POLICY H I GH LI GHT S After decades of regulation and investment to reduce point source water pollution, OECD countries still face water quality challenges (e.g. eutrophication) from diffuse agricultural and urban sources of pollution, i.e. pollution from surface runoff, soil filtration and atmospheric deposition. The relative lack of progress reflects the complexities of controlling multiple pollutants from multiple sources, their high spatial and temporal variability, the associated transactions costs, and limited political acceptability of regulatory measures. The OECD report Diffuse Pollution, Degraded Waters: Emerging Policy Solutions (OECD, 2017) outlines the water quality challenges facing OECD countries today. It presents a range of policy instruments and innovative case studies of diffuse pollution control, and concludes with an integrated policy framework to tackle this challenge. An optimal approach will likely entail a mix of policy interventions reflecting the basic OECD principles of water quality management – pollution prevention, treatment at source, the polluter pays and the beneficiary pays principles, equity, and policy coherence.
    [Show full text]
  • Monitoring Water Quality & Quantity in Mining
    SURFACE & GROUNDWATER / ENVIRONMENT & ECOSYSTEMS DHI SOLUTION MONITORING WATER QUALITY & QUANTITY IN MINING Environmental monitoring - tailor-made! ENVIRONMENTAL MONITORING - THE KEY TO KNOWLEDGE SUMMARY Regardless of the project, monitoring is a crucial element of gaining knowledge CLIENT about environmental conditions. When it comes to monitoring water, it is essential The mining industry and associated to do this in an optimal way so as to provide only the necessary information, which companies can be used for specific actions. Too many monitoring programmes have been established with the aim to know everything, which eventually leads to enormous CHALLENGE amount of data but not knowledge. Assessment of water quality and quantity Water is linked to nearly every type of mining industry, whether as groundwater, Collect the right variables surface water coastal water, or process/wastewater and accordingly there is a Fulfill the regulations substantial need to assess water quality and quantity conditions in all phases of Ensure scientifically sound judgement of mining: exploration, operation/production and decommissioning. impacts We at DHI work with tailor-made monitoring, which enables the client to get all the SOLUTION relevant data - and only those. To provide tailor-made monitoring based on the relevant data Changes in water quality can Applying state-of-the-art technologies as lead to many types of impacts part of the monitoring and the mining industry unfortunately creates various VALUE such problems. One of the Optimisation of monitoring costs standard impacts comes from Fast delivery of data acid drainage of the mines or Easier compliance with permits the mine-tailing and has multiple impacts on not just the biology but also on water which is taken downstream for domestic or industrial use.
    [Show full text]
  • Modification of the Water Quality Index (WQI)
    water Review Modification of the Water Quality Index (WQI) Process for Simple Calculation Using the Multi-Criteria Decision-Making (MCDM) Method: A Review Naseem Akhtar 1 , Muhammad Izzuddin Syakir Ishak 1,2,*, Mardiana Idayu Ahmad 1 , Khalid Umar 3 , Mohamad Shaiful Md Yusuff 1, Mohd Talha Anees 4, Abdul Qadir 5 and Yazan Khalaf Ali Almanasir 1 1 School of Industrial Technology, Division of Environmental Technology, Universiti Sains Malaysia, Gelugor 11800, Pulau Pinang, Malaysia; [email protected] (N.A.); [email protected] (M.I.A.); [email protected] (M.S.M.Y.); [email protected] (Y.K.A.A.) 2 Centre for Global Sustainability Studies, Universiti Sains Malaysia, Gelugor 11800, Pulau Pinang, Malaysia 3 School of Chemical Sciences, Universiti Sains Malaysia, Gelugor 11800, Pulau Pinang, Malaysia; [email protected] 4 Department of Geology, Faculty of Science, University of Malaya, Petaling Jaya 50603, Kuala Lumpur, Malaysia; [email protected] 5 School of Physics, Universiti Sains Malaysia, Gelugor 11800, Pulau Pinang, Malaysia; [email protected] * Correspondence: [email protected] Abstract: Human activities continue to affect our water quality; it remains a major problem world- wide (particularly concerning freshwater and human consumption). A critical water quality index Citation: Akhtar, N.; Ishak, M.I.S.; (WQI) method has been used to determine the overall water quality status of surface water and Ahmad, M.I.; Umar, K.; Md Yusuff, groundwater systems globally since the 1960s. WQI follows four steps: parameter selection, sub- M.S.; Anees, M.T.; Qadir, A.; Ali indices, establishing weights, and final index aggregation, which are addressed in this review.
    [Show full text]
  • Water Quality Criteria
    Office of Water EPA 823 -B -17 -001 2017 Water Quality Standards Handbook Chapter 3: Water Quality Criteria The WQS Handbook does not impose legally binding requirements on the EPA, states, tribes or the regulated community, nor does it confer legal rights or impose legal obligations upon any member of the public. The Clean Water Act (CWA) provisions and the EPA regulations described in this document contain legally binding requirements. This document does not constitute a regulation, nor does it change or substitute for any CWA provision or the EPA regulations. Water Quality Standards Handbook Chapter 3: Water Quality Criteria (40 CFR 131.11) Table of Contents Introduction .................................................................................................................................................. 1 3.1 Water Quality Criteria ............................................................................................................................. 1 Toxic and Priority Pollutants ..................................................................................................................... 1 3.2 Forms of Water Quality Criteria .............................................................................................................. 4 3.2.1 Numeric Water Quality Criteria ....................................................................................................... 4 3.2.2 Narrative Water Quality Criteria .....................................................................................................
    [Show full text]
  • Water Quality and Biodiversity of Lønningsbekk Creek
    Lønningsbekk 2014 WATER QUALITY AND BIODIVERSITY OF LØNNINGSBEKK CREEK Group 6 Siri Vatsø Haugum Eihab Idris Eugene Kitsios Imelda Rantty Kåre Andreas Thorsen The University of Bergen BIO 300 UiB Group 6 : Siri Vatsø Haugum, Eihab Idris, Eugene Kitsios, Imelda Rantty, Kåre Andreas Thorsen 1 Lønningsbekk 2014 Table of Contents 1. Introduction………………………………………………………………………………….. 4 1.1 The environmental impact of concrete production……………………….. 4 1.2 Abiotic factors ………………………………………………………………………………. 5 1.3 Thermotolerant Coliform Bacteria ………………………………………………… 6 1.4 Phosphorus ………………………………………………………………………………….. 6 1.5 Benthic macroinvertebrates as ecological indicators …………………… 7 1.6 Aim of study 8 2. Materials and Methods ……………………………………………………………….. 9 2.1 Study area ……………………………………………………………………………………. 9 2.2 Sampling Procedures ……………………………………………………………………. 12 2.2.1 Thermotolerant Coliform Bacteria ………………………………………………… 12 2.2.2 Phosphorus…………………………………………………………………………………… 12 2.2.3 Temperature, conductivity, pH, dissolved oxygen, salinity and 13 velocity ………………………………………………………………………………………… 2.2.4 Creek Flow Rate …………………………………………………………………………… 13 2.2.5a Biodiversity …………………………………………………………………………………. 14 2.2.5b Laboratory investigations ……………………………………………………………. 14 2.2.5c Biodiversity analysis ……………………………………………………………………. 15 3. Results …………………………………………………………………………………………. 17 3.1 Thermotolerant Coliform Bacteria ………………………………………………… 17 3.2 Phosphorus ………………………………………………………………………………….. 18 3.3 Temperature, conductivity, pH, dissolved oxygen, salinity and 20 velocity ………………………………………………………………………………………….
    [Show full text]
  • Guidelines for Drinking-Water Quality FIRST ADDENDUM to THIRD EDITION Volume 1 Recommendations WHO Library Cataloguing-In-Publication Data World Health Organization
    Guidelines for Drinking-water Quality FIRST ADDENDUM TO THIRD EDITION Volume 1 Recommendations WHO Library Cataloguing-in-Publication Data World Health Organization. Guidelines for drinking-water quality [electronic resource] : incorporating first addendum. Vol. 1, Recommendations. – 3rd ed. Electronic version for the Web. 1.Potable water – standards. 2.Water – standards. 3.Water quality – standards. 4.Guidelines. I. Title. ISBN 92 4 154696 4 (NLM classification: WA 675) © World Health Organization 2006 All rights reserved. Publications of the World Health Organization can be obtained from WHO Press, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel: +41 22 791 3264; fax: +41 22 791 4857; email: [email protected]). Requests for permission to reproduce or translate WHO publications – whether for sale or for noncommercial distribution – should be addressed to WHO Press, at the above address (fax: +41 22 791 4806; email: [email protected]). The designations employed and the presentation of the material in this publication do not imply the expres- sion of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters.
    [Show full text]
  • 1.3 Wastewater and Ambient Water Quality · Understand the Quality, Quantity, Frequency and Sources of Applicability and Approach
    General EHS Guidelines [Complete version] at: www.ifc.org/ehsguidelines Environmental, Health, and Safety (EHS) Guidelines GENERAL EHS GUIDELINES: ENVIRONMENTAL WASTEWATER AND AMBIENT WATER QUALITY WORLD BANK GROUP 1.3 Wastewater and Ambient Water Quality · Understand the quality, quantity, frequency and sources of Applicability and Approach......................................25 liquid effluents in its installations. This includes knowledge General Liquid Effluent Quality.......................................26 about the locations, routes and integrity of internal drainage Discharge to Surface Water....................................26 Discharge to Sanitary Sewer Systems.....................26 systems and discharge points Land Application of Treated Effluent........................27 · Plan and implement the segregation of liquid effluents Septic Systems ......................................................27 principally along industrial, utility, sanitary, and stormwater Wastewater Management...............................................27 Industrial Wastewater .............................................27 categories, in order to limit the volume of water requiring Sanitary Wastewater ..............................................29 specialized treatment. Characteristics of individual streams Emissions from Wastewater Treatment Operations .30 may also be used for source segregation. Residuals from Wastewater Treatment Operations..30 Occupational Health and Safety Issues in Wastewater · Identify opportunities to prevent or reduce
    [Show full text]
  • Chapter 2 - WATER QUALITY
    Water Quality Monitoring - A Practical Guide to the Design and Implementation of Freshwater Quality Studies and Monitoring Programmes Edited by Jamie Bartram and Richard Ballance Published on behalf of United Nations Environment Programme and the World Health Organization © 1996 UNEP/WHO ISBN 0 419 22320 7 (Hbk) 0 419 21730 4 (Pbk) Chapter 2 - WATER QUALITY This chapter was prepared by M. Meybeck, E. Kuusisto, A. Mäkelä and E. Mälkki “Water quality” is a term used here to express the suitability of water to sustain various uses or processes. Any particular use will have certain requirements for the physical, chemical or biological characteristics of water; for example limits on the concentrations of toxic substances for drinking water use, or restrictions on temperature and pH ranges for water supporting invertebrate communities. Consequently, water quality can be defined by a range of variables which limit water use. Although many uses have some common requirements for certain variables, each use will have its own demands and influences on water quality. Quantity and quality demands of different users will not always be compatible, and the activities of one user may restrict the activities of another, either by demanding water of a quality outside the range required by the other user or by lowering quality during use of the water. Efforts to improve or maintain a certain water quality often compromise between the quality and quantity demands of different users. There is increasing recognition that natural ecosystems have a legitimate place in the consideration of options for water quality management. This is both for their intrinsic value and because they are sensitive indicators of changes or deterioration in overall water quality, providing a useful addition to physical, chemical and other information.
    [Show full text]
  • Lesson 2. Pollution and Water Quality Pollution Sources
    NEIGHBORHOOD WATER QUALITY Lesson 2. Pollution and Water Quality Keywords: pollutants, water pollution, point source, non-point source, urban pollution, agricultural pollution, atmospheric pollution, smog, nutrient pollution, eutrophication, organic pollution, herbicides, pesticides, chemical pollution, sediment pollution, stormwater runoff, urbanization, algae, phosphate, nitrogen, ion, nitrate, nitrite, ammonia, nitrifying bacteria, proteins, water quality, pH, acid, alkaline, basic, neutral, dissolved oxygen, organic material, temperature, thermal pollution, salinity Pollution Sources Water becomes polluted when point source pollution. This type of foreign substances enter the pollution is difficult to identify and environment and are transported into may come from pesticides, fertilizers, the water cycle. These substances, or automobile fluids washed off the known as pollutants, contaminate ground by a storm. Non-point source the water and are sometimes pollution comes from three main harmful to people and the areas: urban-industrial, agricultural, environment. Therefore, water and atmospheric sources. pollution is any change in water that is harmful to living organisms. Urban pollution comes from the cities, where many people live Sources of water pollution are together on a small amount of land. divided into two main categories: This type of pollution results from the point source and non-point source. things we do around our homes and Point source pollution occurs when places of work. Agricultural a pollutant is discharged at a specific pollution comes from rural areas source. In other words, the source of where fewer people live. This type of the pollutant can be easily identified. pollution results from runoff from Examples of point-source pollution farmland, and consists of pesticides, include a leaking pipe or a holding fertilizer, and eroded soil.
    [Show full text]