Chapter 21: Water Pollution. April 14, 2014

Transcription

1 Chapter 21: Water Pollution April 14, 2014

2 April 14, 2014 Point Sources Nonpoint sources

3 April 14, 2014 Infectious Agents Types of Water Pollutants Oxygen-demanding wastes Plant nutrients Organic chemicals Inorganic chemicals Sediments Thermal

4 April 14, 2014 Infectious agents Bacteria, virus, protozoa, worms Diarrhea kills 1.9 million people/year (children) Fecal coliform bacteria

5 Dissolved Oxygen Content (DOC) April 14, 2014

6 April 14, 2014 Freshwater Streams natural dilution and biodegradation of waste overloaded or disrupted by damming, drought, water diversion Oxygen sag curve Biological oxygen demand = amount of DOC needed to break down organic waste in a given temperature and time period

7 Stream pollution Agriculture, industrial waste, untreated sewage Laws to increase waste water treatment plans and control point-source discharge Clean up success stories Case Study: Ganges River > Bathe, drink, religious ceremonies (cremation) April 14, 2014

8 Freshwater Lakes Dilution not effective: layers and little flow cultural eutrophication > Nitrates (NO3 - )and phosphates (PO4 3- ) > blooms (algae, cyanobacteria, duckweed) reduce productivity of phytoplankton decomposition depletes O2 content Input and output control methods? April 14, 2014

9 Groundwater 50% US population (95% rural) drink water fro groundwater Fertilizer, pesticides, gasoline, organic solvents April 14, 2014

10 April 14, 2014 Groundwater flows slowly (no dilution), low DOC (no decomposition), cold (slow decomposition) MTBE (Santa Monica, gasoline additive: carciongen) Arsenic (Carcinogen) Prevention cheaper than clean up

11 Ocean able to dilute, disperse, degrade large amounts of degradable pollutants (deep ocean) coastal areas most affected > Untreated sewage often dumped > threaten coastal ecosystems Runoff of sewage and agricultural waste results in algal blooms > release toxins > dead zones (hypoxia) April 14, 2014

12 Chesapeake Bay: Integrated Coastal Management Estuary received waste from huge drainage basin > industry waste > sewage treatment > agricultural and urban runoff > increased runoff from increased pavement Solution > integrated effort of citizens + government > land-use regulations > ban use of phosphate detergents > upgrade sewage plants > restore wetlands oysters April 14, 2014

13 April 14, 2014 Ocean Oil Pollution Accidents: Exxon Valdez (1989) spilled oil in to Alaska's Prince William Sound Runoff from urban/industrial runoff: waste oil, spilled, leaked, motor oil (oil change) Volatile organic hydrocarbons: kill organisms Floating oil: coats feathers and fur Heavy oil: sinks, smother bottomdwelling organisms

14 April 14, 2014 BP Oil Spill: Gulf of Mexico Oil rig in Gulf (Horizone) exploded Exposed pipeline > gushing oil out into ocean Accident? > combination of: reduced regulation failure to meet safety standards not enough monitoring? Immediate and long lasting effects > BP recently had moratorium on off shore drilling lifted > Still seeing effects of oil spill--oil and dispersants found along coast, wildlife suffering > Economy suffers

15 Clean up? Mechanical: floating booms, skimmer boats, pillows filled with feathers/hair Chemical: dispersants to spread oil out or sink Fire: burn surface oil Bacteria: bioremediation! April 14, 2014

16 April 14, 2014 *Side note: Clarification between organic waste and organic/inorganic chemicals Organic = things that are alive or once alive Organic waste = comes from plants/animals that are biodegradable Organic chemical = contains carbons (CH4, DDT- C14H9Cl5 Inorganic chemicals = no carbons (NO3-, Hg, Pb)

17 April 14, 2014 Pollution Prevention: Nonpoint sources Reduce soil erosion--vegetation (cover crops), less till, etc. Reduce use of fertilizer and pesticides > integrated pest management Reduce runoff > Bufferzones of vegetation > locate feedlots, waste sites away from sloped land, water, flood zones Reduce/reuse animal waste > natural gas (methane digester) > building material?

18 Pollution Prevention: Point sources Legislation > Water Quality Act States develop and set water quality standards for interstate waters Not enough to just set standards > Clean Water Act (amended in 1972) discharge permits > possible discharge trading policy? April 14, 2014

19 April 14, 2014 Sewage Treatment Septic tank (small scale, for a house) Oil/grease floats to top Solids fall to bottom: decomposed by bacteria Partially treated wastewater discharged in drainage field: filtered by soil Sludge/scum need to be taken out every few years

20 Sewage Treatment: Sewage treatment plants primary sewage treatment = physical process > screen-remove floating objects > grit chamber-allow sand/rocks to settle > settling tank-suspended organic solids settle out as sludge removes 60% suspended solids, 30-40% of oxygen-demanding organic waste April 14, 2014

21 April 14, 2014 Sewage Treatment: Sewage treatment plants secondary sewage treatment = biological process > aeration tank-aerobic bacteria remove 90% dissolved and biodegradable oxygen demanding organic waste > settling tank-settles out microbes (activated sludge tertiary treatment chlorination (safe?) > kills microbes

22 Sewage Sludge--contains bacteria, toxic chemicals, metals 9% --> compost for soil conditioner 36% --> biosolids for fertilizer 55% --> land fills or incinerated April 14, 2014

23 April 14, 2014 Ways to reduce sludge require industry to remove toxic and hazardous wastes from water before sending to sewage encourage elimination or reduced use of toxic chemicals composting toilet systems Using wetlands to treat sewage (wetland instead of septic tank) genetic engineering

24 April 14, 2014 Drinking Water: Water Purification Plants Reservoirs-improves clarity, increase DOC, allow particles to settle > filtration if necessary Purification plant > disinfection ozonation chlorination *Cheaper to protect watershed than build water purification Other additives: fluoride softener

25 Drinking Water in Developing Countries lack centralized water treatment systems Use: > Sun!-Heat + UV (plastic bottles) > Small, portale filters cloth LifeStraw nanofilters? > Water purification packets (Chemicals) April 14, 2014

26 Safe Drinking Water Act (1974) maximum contaminant levels not always met April 14, 2014

27 April 14, 2014 Safe Drinking Water Act and the Clean Water Act Who likes them? Who doesn't? What's the right solution?

28 Bottled Water Necessity in some parts of the world in US > some is just tap water (Dasani anyone?) > regulated by FDA and EPA standards (same as tap) FDA sets certain criteria for using words like "purified" or adding fluoride > April 14, 2014

29 April 14, 2014 Indirect Potable Reuse or "Toilet to Tap" Sewage --> Drinking Water Take effluent from sewage treatment center + further processing > filtration > reverse osmosis > disinfection (hydrogen peroxide, UV, chlorine) Natural processing > recharge basin > lakes/ponds > pumped into aquifer Percolation Pond in Anaheim, CA

30 April 14, 2014 Activity 1: (7 minutes) In groups of 4 discuss the following assigned topic about the Clean Water Act and Safe Drinking Water Act. Each group will then share with the class. 1. Summarize the essential components of the Clean Water Act. 2. Summarize the essential components of the Safe Drinking Water Act. 3. What are similarities between the two acts? 4. What are differences between the two acts? 5. What groups or individuals are interested in strengthening the two acts? What arguments would they make? 6. Who opposes the strengthening of the two acts or is fighting to weaken them? What arguments would they make? 7. What new components would you recommend adding to the acts and why?

31 April 14, 2014 Activity 2: (10 minutes) Diagram the water cycle, but incorporate human water use and treatment. *What aspects of sewage treatment, potable water purification, and "toilet to tap" mimic natural processes?

32 April 14, 2014