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Chapter 17: Water Pollution and Its Prevention. The DEAD ZONE… WHY????

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Presentation on theme: "Chapter 17: Water Pollution and Its Prevention. The DEAD ZONE… WHY????"— Presentation transcript:

1 Chapter 17: Water Pollution and Its Prevention

2 The DEAD ZONE… WHY????

3 It is unreasonable to use vital water resources to receive pollutants and then expect those resources to continue to provide us with their usual bounty of goods and services.

4 Key Topics Discussed this Chapter: 1.Water Pollution 2. Eutrophication 3. Sewage Management and Treatment 4. Public Policy

5 Pollution: The presence of a substance in the environment that because of its chemical composition or quantity prevents the functioning of natural processes and produces undesirable environmental and health effects. 17.1: Water Pollution


7 Air Particulates Acid-forming compounds Photochemical smog CO2 CFCs Categories of Pollution

8 Pollution Essentials: Not deliberate; mostly the result of an essential activity like crop production, transportation, energy production Pollution problems have gotten worse due to the rapid population increase and the greater demands for energy More materials are now non- biodegradable making them resistant to the breakdown by detritus feeders

9 Undesirable Environmental Alterations Caused By Pollution:

10 Problems caused by Pollution: -Hazy Air -litter -impact on ecosystems (death) -contaminated water supplies -impacts on human health (cancer & other illnesses) -ozone depletion


12 Actions to Required to Reduce Pollution Problems: 1.Identifying the materials causing the pollution problem 2.Identify the Source 3.Develop and Implement Control Strategies 4. Avoid the pollution altogether

13 Strategies for addressing Pollution: A technology transition from pollution-intensive economic production to environmentally benign processes.


15 Water Pollution: Point Sources: Involve the discharge of substances from factories, sewage systems, power plants and underground coal mines and oil wells *Easier to identify, monitor and regulate than non-point sources*

16 Non-Point Pollution: agricultural run-off, storm water drainage, atmospheric deposition *Harder to identify because they are poorly defined and scattered over broad areas*


18 How to Control Water Pollution?? 1.Reduce or remove the sources 2. Treat the water so as to remove pollutants or convert them to harmless forms


20 4 Basic Types of Water Pollutants: 1.Pathogens (disease causing viruses, bacteria & other parasitic organisms, protozoans) *Even after symptoms of the disease disappear, an infected person or animal can still harbor populations of the organism thus acting as a carrier* Giardia Protist V. Cholera bacterium Roundworms

21 Public Health is at RISK! The Ganges River in IndiaUsed for drinking, washing, sewage disposal

22 Building a Pit Latrine in Nepal Squat Toilet or Pit Latrine in Gambia

23 Public Health Measures Needed to Prevent Disease: 1. Disinfection of public water supplies 2. Improving hygiene and sanitation 3. Sanitary collection of wastes and treatment of sewage

24 Poor Sanitation and Waste Disposal Plague Bangladesh

25 2. Organic Wastes (human and animal wastes, leaves, grass clippings, food scraps, etc) Decomposition of organic matter can lower the amount of oxygen in the water thus killing organisms. (ie Dead Zone)

26 3.Chemical Pollutants Inorganic Chemicals: heavy metals (lead, mercury, cadmium, nickel, etc); acids from mine drainage (sulfuric acid) and acid precipitation (sulfuric and nitric acids); road salts (sodium and calcium chlorides) Organic Chemicals: Examples-petroleum products, pesticides, PCBs, cleaning solvents and detergents

27 4.Sediments (soil and silt) from erosion -Material, such as clay, can settle and smother animals by clogging gills and feeding structures -smother the eggs of fish -bed load of silt and sand is gradually washed along the bottom, burying and smother bottom dwellers; prevent the reestablishment of aquatic plants


29 Six Major Points of Soil Erosion and Sediment 1.Croplands 2.Deforested Areas 3.Overgrazed Rangelands 4.Construction Sites 5.Surface Mining 6.Gulley Erosion

30 When is water considered polluted? The concentration of the pollutant must be the primary concern.

31 National Recommended Water Quality Criteria : Established the critical maximum concentration (CMC) Safe Water Drinking Act: Established the maximum contaminant levels (MCLs) National Pollution Discharge Elimination System: Issues permits that regulate discharges from wastewater treatment plants Total Maximum Daily Load: Evaluate all sources of pollutants entering a body of water

32 Of our rivers, lakes and estuaries are not meeting water quality standards!!

33 Trophic means feeding; eutrophic means well nourished This process has NEGATIVE results on aquatic ecosystems! Creates hypoxic zones devoid of oxygen!


35 Different Kinds of Aquatic Plants Benthic plants: grow attached to, or are rooted in, the bottom of a body of water (ex: common aquarium plants, sea grasses) SAV (submerged aquatic vegetation; light must penetrate for the plants to flourish; get nutrients from the bottom

36 Phytoplankton: consist of numerous species of photosynthetic algae, protists, and cyanobacteria. They live suspended in water and are found wherever light and nutrients are available. As nutrient levels increase phytoplankton can grow more prolifically making the water more turbid, thus shading the SAV. Factoid! Phytoplankton are the base of aquatic food chains!!


38 Oligotrophic bodies of water have lower nutrient levels. As an oligotrophic body of water becomes enriched with nutrients numerous changes begin to take place and eutrophication can take place.

39 Oligotrophic Characteristics: 1. high dissolved oxygen 2. low bacterial decomp 3. high light penetration 4. lots of benthic plants 5. lower numbers of phytoplankton 6. lower water temp 7. lower water turbidity 8. lower nutrient concentrations 9. higher species diversity 10. good aesthetic qualities (pretty) 11. good for recreation 12. lower BOD (biological oxygen demand) 13. less decomposition 14. less sediments (clear)


41 An abundance of phytoplankton begin to flourish and shade the SAV. Excess algae dies and the shaded SAV decays. Decomposition depletes the dissolved oxygen suffocating other aquatic life thus creating a hypoxic zone.

42 Combating Eutrophication!

43 Four Methods used to combat eutrophication & problems caused MethodProblems Caused 1.Herbicide treatmentsPhytoplankton resistance 2.AerationExpense 3.Harvesting algaeExpense/grows back quickly 4.Drawing water downKills rooted aquatic plants *Key is to reduce long term flow of nutrients and sediments and to identify major non-point and point sources***

44 Where do the excess nutrients and sediments come from??? 1. Agriculture/forestry 2. Urban/Suburban run-off 3. Sewage effluents

45 7 Best Management Practices for Controlling Eutrophication: 1.Banning of phosphate detergents 2.Upgrade sewage treatment plants 3.Control agriculture and urban run-off 4.Control sediments from construction and mining sites 5.Control stream erosion 6.Protect wetlands 7.Control air pollution Stream Erosion

46 Collecting Animal Wastes in a Pond and recycling them is a good way to prevent Eutrophication!


48 Before the late 1800s the general means of disposing of human excrement was the outdoor privy. Seepage contaminated drinking water & caused disease. Before Louis Pasteur discovered sanitation practices and germ theory was widely accepted, people thought that diseases were caused by the odors! London Cholera Outbreak

49 The First Sewage Treatment Plants in the US were built around They were constructed to treat the outflow before it entered the receiving waterway. Storm Drains: collects and drains run-off from precipitation Sanitary Sewer Line: receives waste water from sinks, toilets and tubs

50 The Pollutants in RAW SEWAGE Raw Sewage is being dumped into a river in Bangkok.

51 What is RAW SEWAGE? Flushings from toilets Collection of wastewater from all other drains in homes and buildings Most of what goes down the sewer drains is water Raw Sewage is about 1,000 parts water for every 1 part waste – 99.9% water to 0.1% waste Communities of 10,000 persons will produce 1.5 – 2.0 million gallons of wastewater every day

52 What is in Raw Sewage 1. Debris and grit 2. Particulate organic matter 3. Colloidal and dissolved organic matter 4. Dissolved inorganic matter 5. Pathogens 6. Heavy metals, pesticides, and various other t toxic compounds

53 Four Major Categories of Pollutants in Raw Sewage and an Example of Each: CategoryExample 1.Debris & Grit plastic bags 2.Particulate organic materialfood waste 3.Colloidal or organic materialfeces 4.Dissolved inorganic materialsnitrogen

54 Most of the developing world is still plagued by lack of sanitary water and sewage treatment facilities thus causing high infectious disease rates. An African Village

55 Removing Pollutants from Sewage Preliminary Treatment: removal of debris and grit; screen out debris and settle the grit; raw sewage flows through a bar screen and debris will be mechanically raked from the screen and taken to an incinerator. After passing through the screen, the water flows through the grit chamber in which the velocity is slowed to permit the grit to settle Fig A Raw sewage moves from the grit chamber to primary treatment, where sludge is removed and the clarified water then proceeds to secondary treatment (here shown as activated sludge treatment).

56 2. Primary Treatment - particulate organic matter removed by primary clarifiers ; the flow is slow; organic material settles to the bottom and the fatty or oily material floats to the top where it is skimmed off the surface. All the material that is removed is referred to raw sludge and must be treated separately. See page 481 text figure

57 Fig B In primary treatment sludge is removed and the clarified water then proceeds to secondary treatment. Raw sewage moves from the grit chamber to primary treatment, where sludge is removed and the clarified water then proceeds to secondary treatment.

58 3. Secondary Treatments - colloidal and dissolved inorganic matter removed by trickling filter systems or activated sludge systems (also called the biological treatment because it uses organisms that are natural decomposers) Fig C Raw sewage moves from the grit chamber to primary treatment, where sludge is removed and the clarified water then proceeds to secondary treatment (here shown as activated sludge treatment).

59 The Activated Sludge System is the most common secondary-treatment (activated sludge is a mixture of detritus-feeding organisms) Fig The secondary treatment, activated sludge process may be modified to remove nitrogen and phosphate while at the same time breaking down organic matter.

60 Biological Nutrient Removal (removal of dissolved inorganic material) Uses parts of the nitrogen and phosphorus cycles.

61 4. Biological Nutrient Removal - dissolved inorganic matter removed by bacterial denitrification and bacterial uptake of phosphorus a. Can also be done inorganically by using chemical processes ·Lime causes phosphate to precipitate as insoluble calcium phosphate ·Ferric chloride causes phosphate to precipitate as insoluble ferric phosphate b. Removal of the dissolved inorganic matter is not standard treatment though it is becoming more common

62 What Do We Do with the Sludge that Remains? 1. Most sludge is disposed of in landfills or spread on land a. These practices are diminishing (but need more public pressure to continue) · Sludge is difficult to handle in landfills · Spreading can result in water pollution, and · Sludge is nutrient rich organic material that can be used as organic fertilizer ·

63 Treatment of Sludge: Sludge is about 98% water; 2% organic material Three Sludge treatment methods are: anaerobic digestion, composting, and pasteurization Dewatering treated sludge: Sludge which is 98% water may be dewatered by means of belt presses, as shown in figure a. The liquid sludge is run between rollers so that much of the water is pressed out. The resulting sludge cake is a semisolid humus-like material that may be used as organic fertilizer.

64 Milwaukee, Wisconsin has a rich sludge that results from the brewing industry. The city bags and sells the pellets throughout the country as organic fertilizer.

65 Alternative methods for extracting wastewater nutrients: *septic systems *using effluents for irrigation * Reconstructing wetlands Rural homes may lie outside of the municipal system therefore, on-site treatment systems are required. Septic tanks must be pumped out every 3-5 yrs

66 Many on-site systems fail causing sewage to back up into homes! Septic System Failure destroys homes and can be traced to groundwater pollution!

67 How to prevent septic system back-up: 1.Routine cleanings (3-5 yrs) 2.Do not dispose of items down the drain (i.e coffee grounds, cat litter, diapers, grease, feminine hygiene products, pesticides, paint, gasoline, household chemicals) 3.Maintain your system with regular inspections 4.Keep heavy equipment & vehicles off your system and leeching field 5.If you have a garbage disposal system, disable it because the added materials will shorten the lifespan of the system!

68 Public Policy: 1899Rivers and Harbors Act 1948Water Pollution Control Act 1972Clean Water Act 1972Marine Protection, Research and Sanctuaries Act 1974Safe Water Drinking Act 1977Clean Water Act Amendments 1987Water Quality Act 1996Safe Water Drinking Act Amendments **see table pg 487

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