water pollution Guided notes
Water Pollution Notes
POINT SOURCE POLLUTION
- comes from a specific source, like a pipe
- factories, industry, municipal treatment plants
- can be monitored and controlled by a permit system
- is pollution associated with storm water or runoff
- NPS pollution cannot be traced to a direct discharge point such as a waste water treatment facility
- Examples: oil and grease from cars
- fertilizers
- animal waste
- grass clippings
- Septic systems
- sewage and cleaners from boats
- household cleaning products
- litter
- NPS pollutants build up on land surfaces during dry weather
- atmospheric deposition
- Fertilizer applications
- Animal waste
- Automotive exhaust/ fluid leaks
- Pollutants are washed off land surfaces during precipitation events (storm water runoff)
- storm water runoff will flow to lakes and streams
- imperviousness increases runoff
- Land use changes impact build up
- roads, rooftops, parking lots, and other hard surfaces that do not allow storm water to soak into the ground
- "predominant American vegetation"
- fish and wildlife
- recreational water activities
- commercial fishing
- tourism
- drinking water quality
- sediment: soil particles transported from their source
- Biochemical Oxygen Demand (BOD): oxygen depleting material
- leaves
- organic material
- Toxics: pesticides
- herbicides
- fungicides
- insecticides
- metals (naturally occurring in soil, automotive emissions/ tires)
- lead
- zinc
- mercury
- petroleum hydrocarbons
- nutrients: various materials that become dissolved and suspended in water
- nitrogen
- Phosphorus
- Bacteria/Pathogens: originating from pets, water fowl, and failing septic systems
- thermal stress: heated runoff, removal of stream-side vegetation
- Debris: litter and illegal dumping
- sediment
- nutrients
- pathogens
- pesticides
- Worldwide, the amount of land under irrigation has been increasing.
- Whether from aquifers or surface bodies of water, the majority of the freshwater we use for irrigation is lost before it ever reaches the crops.
- Inefficient “flood and furrow” irrigation, in which fields are liberally flooded with water that may evaporate from shallow standing pools, accounts for 90% of irrigation worldwide.
- Over-irrigation leads to water logging and salinization, which affects 1/5 of farmland today and reduces world farming income by $11 billion.
- Unfortunately, huge amounts of groundwater are being used up for little gain; because of the dry climate and inefficient irrigation methods.
- flood irrigation
- wasteful
- center pivot, low pressure sprinkler
- low-energy, precision application sprinklers
- Drip or tickle irrigation, micro irrigation
- costly; less water waste
- Most nutrients in water come from organic matter (leaves, waste, etc.)
- Nutrients are an essential part of any aquatic ecosystem, but when slow-moving waters contain too much, they are eutrophic.
- Eutrophication= build-up of organic matter in water causing algal blooms
- Outcomes:
- Decreased sunlight
- Decaying matter uses oxygen
- Suffocation/Fish Kills :(
- Humans act as a catalyst by adding excess nutrients to the soil
- Main culprits= phosphates from fertilizers and cleaning agents
- Human activity can also cause thermal pollution
- It can take hundreds to thousand of years for contaminated groundwater to cleanse itself of degradable wastes.
- Non degradable wastes (toxic lead, arsenic, fluoride) are there permanently.
- Slowly degradable wastes (such as DDT, PESTICIDE) are there for decades.
- Groundwater has low flow rates, few bacteria, & cold temps - all slow down recovery time
- Average recycling time for groundwater = 1400 years
- surface water generally more polluted
- Groundwater harder to clean up
- Clean Water Act – surface water
- 1972 – make water swimmable and fishable by regulating point sources
- 1977 and 1987 – storm water runoff
- Section 404 – requires permit for draining, dredging, filling wetlands
- Mitigation banking
- Safe Drinking Water Act (1974) – monitors levels of contaminants in groundwater
SEWAGE VS. SEPTIC NOTES
STEP 1 IN THE WASTE WATER TREATMENT PROCESS
Primary Treatment: removes 40-50% of the solids
SECONDARY TREATMENT
DIGESTERS
Primary Treatment: removes 40-50% of the solids
- Removal of Solids
- Chunks of debris, sticks, sand, etc… get caught on the bar screens as the sewage enters the plant.
- next it goes into the grit chamber sand, grit and heavy solids settle to the bottom
SECONDARY TREATMENT
- 85-90% of pollutants are removed
- is aeration- microorganisms and oxygen are mixed with the waste water, air speeds the growth of the bacteria which eat the waste matter.
- Secondary Sedimentation- solids clump together (activated sludge) and settle out for reuse in the aeration tanks.
DIGESTERS
- The purpose of sludge treatment is to destroy the pathogens
- Huge tanks in which the sludge is stored to allow it to continue to decompose (15-30 days)
- Aerobic digestion (treatment) consists of continuously pumping compressed air into a tank
- Anaerobic bacteria present in the waste convert much of the waste materials to carbon dioxide and methane (natural) gas
- Burn it in specially designed plants to prevent air pollution
- a source of methane for powering small power plants
- bury it in approved landfills
- septic system
- The septic tank is a settling tank where sewage from the house is stored temporarily so that solid materials settle to the bottom of the tank to form sludge, while grease floats to the top to form a scum layer.
- The scum and sludge must be periodically removed from the septic tank by simply pumping them out.
- The absorption field is frequently a network of drain lines (pipes with holes in them) that carry wastewater from the septic tank and apply it to the soil.
- The size of the absorption field varies from site to site, but most are small enough to fit in a backyard and cover and area between 400 and 800 ft 2.
- Although effluent can be applied to the surface of any soil, not all soils are able to absorb and purify waste water.
- Soils that can be used for waste disposal are permeable, deep, well drained (not waterlogged) and are not on a steep slope.
- Do:
•Inspect your tank for signs of sludge buildup.
•Pump your tank every 2-3 years.
•Keep a grease can handy.
•Protect your system from vehicles and encroaching trees and shrubs.
•Install water saving devices to conserve water.
•Use non-toxic cleaning products such as baking soda to scrub toilets, or boiling water to help clear clogged drains. - Don't:
•use a garbage disposal - it adds 50 % more solids to your system.
•pour automotive oil, cooking oil, grease or paint or paint thinner down the drain.
•drive vehicles over the septic system/fields.
•plant bushes or trees over the leach field.
•use too much water, especially during rainy, wet seasons when the ground is saturated.
•use drain cleaners and other toxic chemical products.
•use chemical or biological septic system cleaners which can plug up leach fields and ruin your system.
WASTE WATER TREATMENT ACTIVITY
dAMS AND DIVERSIONS OF WATER NOTES
PROS AND CONS OF HYDROPOWER
What are the effects of water diversion?
- PROS: dams are relatively inexpensive to operate
- yet, they are very expensive to build
- Dams generate clean power
- hydropower is renewable and doesn't emit greenhouse gases or other air pollutants
- Dams improve quality of life
- prevent flooding, create jobs, and provide cheap electricity, irrigation, and drinking water
- CONS: dams alter river habitats in many ways
- upstream: flooding
- downstream: not enough water
- natural cycles are disrupted
- flood plains don't receive nutrients from sediments because they get trapped behind dams
- temperature of the water is changed
- aquatic populations go extinct
- dams prevent anadromous dish from laying eggs
- In the US, the era of large dam construction is probably over
- not so in developing countries (Brazil, China, India)
- micro-hydropower: electricity produced in a small stream without having to build a big dam
- much cheaper to build
- can be used in remote areas
What are the effects of water diversion?
- water diversion projects bring water to areas that need it
- central Arizona Project Aqueduct- brings water from the Colorado River to dry areas of Arizona, multiple uses (drinking water, recreation, power, etc.)
- we divert- and deplete- surface water
- people have long diverted water to farm fields, homes, and cities
- The once mighty Colorado River has been extensively dammed and diverted
- What water is left after all the diversions comprises hust a trickle into the Gulf of California
- on some days, water does not reach the gulf
- diversion has drastically altered the river's ecology
- once the fourth largest lake on Earth
- it has lost more than 80% of its volume in just 45 years
- the two rivers leading into the Aral Sea were diverted to irrigate cotton fields
- Consequences of a shrinking sea
- 60,000 fishing jobs are gone
- pesticide-laden dust from the lake bed is blown into the air
- the cotton cannot bring back the regions economy
- people may have begun saving the northern part of the Aral Sea
WILL WE SEE A FUTURE OF WATER WARS?
- fresh water depletion leads to shortages, which can lead to conflict
- 261 major rivers cross national borders
- water is a key element in hostilities among Israel, Palestinians, and neighboring counrties
- Many nations have cooperated with neighbors to resolve disputes