Download Lecture - Water Pollution

Chapter 22
Water Pollution
Overview of Chapter 22
o Types of Water Pollution
• Sewage
• Disease-causing agents
• Sediment pollution
• Inorganic plant and algal nutrients
• Organic compounds
• Inorganic chemicals
• Thermal pollution
o Water Quality Today
o Improving Water Quality
o Laws Controlling Water Pollution
Types of Water Pollution
o Water pollution
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o Major water pollution issue globally
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o Eight categories
• Sewage, disease-causing agents, sediment pollution, inorganic plant and algal nutrients, organic
compounds, inorganic chemicals, radioactive substances, and thermal pollution
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Sewage
o The release of wastewater from drains or sewers
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o Causes 2 serious environmental problems:
• Enrichment
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Increase in Biological Oxygen Demand (BOD)
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Sewage
Sewage- Eutrophication
o Oligotrophic
• Unenriched, clear water that supports small populations of aquatic organisms
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Sewage- Eutrophication
o Eutrophic•
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Disease-causing Agents
o Infectious organisms that cause diseases
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o Common bacterial or viral diseases:
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Disease-causing Agents
o Monitored by testing for presence of E. coli in the water via a fecal coli form test
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Sediment Pollution
o Excessive amounts of suspended soil particles
o Problems
• Limits light penetration
• Covers aquatic animals and plants
• Brings insoluble toxins into waterways
Inorganic Plant and Algal Nutrients
o Chemicals such as nitrogen and phosphorus that stimulate the growth of plants and algae
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o Sources:
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o Causes:
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Inorganic Plant and Algal NutrientThe Dead Zone
o Chemicals that contain carbon atoms
• Natural examples:
• Human-made examples:
Organic Compounds
Inorganic Chemicals
o Contaminants that contain elements other than carbon
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o Do not degrade easily
o Lead
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o Mercury
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Radioactive Substances
o Contain atoms of unstable isotopes that spontaneously emit radiation
o Sources
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Thermal Pollution
o Occurs when heated water produced during industrial processes is released into waterways
o Organisms affected
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o Two Types of Water Pollution
o -Point Source Pollution
Water Quality Today
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o -Non-point Source Pollution
• Pollutants that enter bodies of water over large areas rather than being concentrated at a
single point of entry
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Ex:
o Agriculture is leading source of water pollution in US
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o Almost all streams and rivers are polluted with agricultural pesticides
Municipal Water Pollution
Industrial Wastes in Water
o Different industries generate different pollutants
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o Many industries recover toxins before they go into the waste stream
Case-In-Point Green Chemistry
Groundwater Pollution
Water Pollution in Other Countries
o Lake Maracaibo, Venezuela
• 10,000 oil wells tap lake bottom
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Water Pollution in Other Countries
o Po River, Italy
• Similar to Mississippi River
• Pollutants:
• >16 million Italians depend on the river for drinking water
• Pollution is high
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o Ganges River, India
Water Pollution in Other Countries
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Ganga Action Plan initiated by government
Improving Water QualityPurification of Drinking Water
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In US most municipal water supplies are treated
Collected from water or reservoir
Treated
Improving Water QualityPurification of Drinking Water
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Purification of Drinking Water
o Chlorine Dilemma
• Chlorine kills disease causing organisms
• Chlorine
• Peru stopped using chlorine
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• Prevents tooth decay
• Linked to cancer, kidney disease
o Primary treatment
Municipal Sewage Treatment
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o Secondary treatment
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o Sewage Sludge
Municipal Sewage Treatment
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o Tertiary treatment
• Advanced wastewater treatment methods that are sometimes employed after primary and
secondary treatments
• Reduce phosphorus and nitrogen
• Municipal Sewage Treatment
Individual Septic SystemSeptic Tank
Individual Septic SystemDrain Field
Laws Controlling Water Pollution
o Citizen Watchdogs to Monitor Pollution
o Safe Drinking Water Act (1974)
• Set uniform federal standards for drinking water
• Maximum contaminant level
o Clean Water Act (1972)
• EPA sets up and monitors National Emissions Limitations
• Effectively improved water quality from point sources
Laws that Protect Groundwater
o Safe Drinking Water Act
o Resource, Conservation and Recovery Act