Ch. 22 Water Pollution

Oil Spills  Sources: offshore wells, tankers, pipelines and storage tanks  Effects: death of organisms, loss of animal insulation and buoyancy, smothering  Significant economic impacts  Mechanical cleanup methods: skimmers and blotters  Chemical cleanup methods: coagulants and dispersing agents

Solutions: Preventing and Reducing Surface Water Pollution Nonpoint Sources Point Sources  Reduce runoff  Buffer zone vegetation  Reduce soil erosion  Clean Water Act  Water Quality Act

StepsinWaterPurification Steps in Water Purification Water comes from the stream Settling pond - Al 2 (SO 4 ) 3 - ALUM – added, pulls clay particles downward Filtration - passing it through porous material (sand) Adsorption - use of Carbon to remove organic pollutants Biological oxidation - use of bacteria & microbes - oxygen helps the organisms grow & eliminate colloidal particles Disinfection - addition of Chlorine, Ozone, or UV to eliminate harmful pathogens Voluntary fluoride treatment & storage in water tower for drinking water

Technological Approach: Septic Systems  Require suitable soils and maintenance Household wastewater Perforated pipe Distribution box (optional) Septic tank Manhole (for cleanout) Drain field Vent pipe Nonperforated pipe Gravel or crushed stone Fig , p. 494

Technological Approach: Sewage Treatment  Mechanical and biological treatment Raw sewage from sewers Bar screen Grit chamber Settling tankAeration tankSettling tank Chlorine disinfection tank Sludge Sludge digester Activated sludge Air pump (kills bacteria) To river, lake, or ocean Sludge drying bed Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland Primary Secondary Fig , p. 494

Waste Water Treatment Primary –mechanical Secondary –biological

StepsinWastewaterTreatment Steps in Wastewater Treatment Wastewater - sanitary sewer pipes Pre-treatment - bar screen removes debris Primary 1. settling tank- (removes grit) 2: clarifier- (lets sludge settle while oil removed by skimmer)

Primary Treatment - Clarifier

PrimaryTreatmentOilSkimmer Primary Treatment (Oil Skimmer)

StepsinWastewaterTreatment Steps in Wastewater Treatment Secondary – 1: aeration tank – colloids & organics removed by hungry bacteria - aeration increases bacterial growth activated sludge 2: clarifier- lets activated sludge settle – some reused in aeration tank rest goes to anaerobic digester 3: disinfection- by Chlorine, Ozone, or sunlight in Wetland

Secondary TreatmentBiological Oxidation Aeration Tank) Secondary Treatment - Biological Oxidation (Aeration Tank)

Technological Approach: Advanced Sewage Treatment  Removes specific pollutants Effluent from Secondary treatment Alum flocculation plus sediments Activated carbon Desalination (electrodialysis or reverse osmosis) Nitrate removal Specialized compound removal (DDT, etc.) 98% of suspended solids 90% of phosphates 98% of dissolved organics Most of dissolved salts Recycled to land for irrigation and fertilization To rivers, lakes, streams, oceans, reservoirs, or industries Fig , p. 495

WastewaterTreatment Wastewater TreatmentTertiary Tertiary Removal of chemicals (P, N, etc) - not required! Anaerobic digester – sludge from primary/secondary treatment breaks down waste further disposed in a landfill/treated/used as fertilizer Water returned to the stream

After Anaerobic Digestion of Sludge & Activated Sludge - Uses After Anaerobic Digestion of Sludge & Activated Sludge - Uses Biogas – produced during anaerobic digestion - used as fuel Co-composting – combined post-consumer waste paper w/treated sludge decomposed by bacteria - use as fertilizer animal crops only Pasteurization – drying sludge in ovens kill pathogens pellets - sold as fertilizer

Technological Approach: Using Wetlands to Treat Sewage (1) Raw sewage drains by gravity into the first pool gravity into the first pool and flows through a long and flows through a long perforated PVC pipe into perforated PVC pipe into a bed of limestone gravel. a bed of limestone gravel. (3) Wastewater flows through another perforated pipe another perforated pipe into a second pool, where into a second pool, where the same process is repeated. the same process is repeated. (2) Microbes in the limestone gravel break down the sewage into break down the sewage into chemicals, that can be absorbed chemicals, that can be absorbed by the plant roots, and the gravel by the plant roots, and the gravel absorbs phosphorus. absorbs phosphorus. (4) Treated water flowing from the second pool is nearly free of second pool is nearly free of bacteria and plant nutrients. bacteria and plant nutrients. Treated water can be recycled Treated water can be recycled for irrigation and flushing toilets. for irrigation and flushing toilets. 45 centimeter layer of limestone gravel coated with decomposing bacteria First concrete poolSecond concrete pool Sewage Wetland type plants plants Treatedwater Fig , p. 497

Wetland Functions Disperses volume of flow moderates flow of water - less storm damage Recharge groundwater from surface water Removes sediment Removes excess organic nutrients - microbial decomposition Increased availability - limiting nutrients Creates ecosystem -habitat for animals

Emergent Wetlands dominated by perennial plants cattails, sedges & cordgrass – which are rooted in bottom sediments cattails, sedges & cordgrass – which are rooted in bottom sediments “emerge” above the surface of the water

Federal LAWS Protecting Wetlands Rivers & Harbors Act of Rivers & Harbors Act of establishes a program to regulate activities affecting navigation in US waters Food Securities Act of Food Securities Act of establishes rules for farmers concerning use of wetlands prior or since 1985 for farming. Duck Stamp Act of 1934 Duck Stamp Act of allocates funds for the acquisition of land for migratory birds Clean Water Act (Section 404) - Clean Water Act (Section 404) - establishes a program to regulate the discharge of dredged and fill material into water of the US

N. A. Wetlands Conservation Act - N. A. Wetlands Conservation Act - provides for voluntary action to create wetlands under a grant program Coastal Wetlands Planning, Protection, & Restoration Act - Coastal Wetlands Planning, Protection, & Restoration Act - to grant funds to coastal states to carry out coastal wetlands conservation projects. There are a number of regulations that give various agencies such as the EPA, the Army Corps of Engineers, and the US Department of Agriculture the power to oversee and implement regulations provided for by these Acts. Having several government agencies oversee different parts of these regulations creates friction and leaves gaps in the implementation of these regulations.

Wetland Mitigation If a construction project allows the destruction of a wetland (allowable by a permit from the Army Corps of Engineers) then another area of equal or larger size, has to be created as a new wetland. The lands are usually sold by private owners to corporations, that act as mitigators, for the purpose of restoring what was once a wetland or to create a new wetland.

Drinking Water Quality  Safe Drinking Water Act  Maximum contaminant levels  Bottled water 10 to 20 percent Greater than 20 percent Not tested Contaminated Probability Fig , p. 488