Freshwater Pollution Guided Notes
|
Water Pollution
Point-source and Non-Point Source pollution
Point -source pollution- comes from a specific source, like a pipe. Factories, industry, municipal treatment plants. Can be controlled and monitored by a permit system.
Non-point source pollution- NPS pollution is associated with stormwater or runoff. NPS pollution cannot be traced to a direct discharge point such as a watewater treatment facility, making it hard to control or measure. Can include oil or grease form 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 rain. Stormwater runoff will flow into lakes and streams
Impacts of NPS- fish and wildlife, recreational water activities, commercial fishing, tourism, drinking water quality
Pollutants found in runoff- sediments, biochemical oxygen demand (BOD, oxygen depleting material, leaves, organic material) , toxics ( pesticides, metals, lead, petroleum), debris (litter and illegal dumping) , nutrients ( nitrogen and phosphorus), Bacteria and pathogens ( pets, waterfowl, failing septic tanks), thermal stress ( heated runoff, removal of streamside vegetation)
Most of these can be sourced from residential areas.
Inefficient Irrigation- 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. Flood and furrow is SUPER ineffective. We can cut water waste in irrigation with by decreasing flood irrigation (wasteful), center pivot, low pressure sprinkler, low-energy, precision application sprinklers, or drip or trinkle irrigation (microirrigation, costly, but less water waste)
Eutrophication- 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. Build-up of organic matter in water causing algal blooms is eutrophication. Outcomes: decreased sunlight, decaying matter uses oxygen, suffocation (kills fish). Humans act as a catalyst by adding excess nutrients to the soil, mostly from fertilizers. Human activity can also cause thermal pollution
It can take hundreds to thousands of years for contaminated groundwater to cleanser itself of degradable wastes. Non-degradable wastes are there permanentaly. Slowly degradable wastes (such as DDT) are there for decades. Groundwater has slow flow rates, few bacteria, and cold temps.- all slow down recovery time. Avg. recycling time for groundwater- 1400 years
Clean water act- surface water
1972- make water swimmable and fishable by regulating point sources
1977-1987- 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
Point -source pollution- comes from a specific source, like a pipe. Factories, industry, municipal treatment plants. Can be controlled and monitored by a permit system.
Non-point source pollution- NPS pollution is associated with stormwater or runoff. NPS pollution cannot be traced to a direct discharge point such as a watewater treatment facility, making it hard to control or measure. Can include oil or grease form 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 rain. Stormwater runoff will flow into lakes and streams
Impacts of NPS- fish and wildlife, recreational water activities, commercial fishing, tourism, drinking water quality
Pollutants found in runoff- sediments, biochemical oxygen demand (BOD, oxygen depleting material, leaves, organic material) , toxics ( pesticides, metals, lead, petroleum), debris (litter and illegal dumping) , nutrients ( nitrogen and phosphorus), Bacteria and pathogens ( pets, waterfowl, failing septic tanks), thermal stress ( heated runoff, removal of streamside vegetation)
Most of these can be sourced from residential areas.
Inefficient Irrigation- 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. Flood and furrow is SUPER ineffective. We can cut water waste in irrigation with by decreasing flood irrigation (wasteful), center pivot, low pressure sprinkler, low-energy, precision application sprinklers, or drip or trinkle irrigation (microirrigation, costly, but less water waste)
Eutrophication- 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. Build-up of organic matter in water causing algal blooms is eutrophication. Outcomes: decreased sunlight, decaying matter uses oxygen, suffocation (kills fish). Humans act as a catalyst by adding excess nutrients to the soil, mostly from fertilizers. Human activity can also cause thermal pollution
It can take hundreds to thousands of years for contaminated groundwater to cleanser itself of degradable wastes. Non-degradable wastes are there permanentaly. Slowly degradable wastes (such as DDT) are there for decades. Groundwater has slow flow rates, few bacteria, and cold temps.- all slow down recovery time. Avg. recycling time for groundwater- 1400 years
Clean water act- surface water
1972- make water swimmable and fishable by regulating point sources
1977-1987- 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 and Septic
First in your house, then in sewer pipes, then a waste treatment facility
Primary Treatment- removes 40%-50% of solid waste
1. Removal of solids- chunks of debris, sticks, sand, etc with heavy bar screens as sewage enter the plant
Grit Chamber- silts settle to the bottom to filter the water, but grease floats to the top
Primary Sedimentation Tank- smaller particles settle; scrapers collect the solid matter plus scum or grease floating on the top
Secondary Treatment- removes 85% - 90% of pollutants are removed
1. Aeration- micro-organisms and oxygen are mixed with the waste water. Air speeds the growth of the bacteria which eat the waste matter
2. Solids stick together (activated sludge) and settle out for reuse in aeration tanks
3. Chlorine is added as a disinfectant before the wastewater leaves the plant to fill disease-causing organisms
Sludge is either incinerated , used in agriculture, or thrown in a landfill
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)
If you aren't connected to a sewer, you have a septic tank.
•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 ft2.
•Although effluent can be applied to the surface of any soil, not all soils are able to absorb and purify wastewater.
•Soils that can be used for waste disposal are permeable, deep, well drained (not waterlogged) and are not on a steep slope.
•In N. C., state law requires that all soils pass an inspection before a septic system is installed on any property.
Primary Treatment- removes 40%-50% of solid waste
1. Removal of solids- chunks of debris, sticks, sand, etc with heavy bar screens as sewage enter the plant
Grit Chamber- silts settle to the bottom to filter the water, but grease floats to the top
Primary Sedimentation Tank- smaller particles settle; scrapers collect the solid matter plus scum or grease floating on the top
Secondary Treatment- removes 85% - 90% of pollutants are removed
1. Aeration- micro-organisms and oxygen are mixed with the waste water. Air speeds the growth of the bacteria which eat the waste matter
2. Solids stick together (activated sludge) and settle out for reuse in aeration tanks
3. Chlorine is added as a disinfectant before the wastewater leaves the plant to fill disease-causing organisms
Sludge is either incinerated , used in agriculture, or thrown in a landfill
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)
If you aren't connected to a sewer, you have a septic tank.
•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 ft2.
•Although effluent can be applied to the surface of any soil, not all soils are able to absorb and purify wastewater.
•Soils that can be used for waste disposal are permeable, deep, well drained (not waterlogged) and are not on a steep slope.
•In N. C., state law requires that all soils pass an inspection before a septic system is installed on any property.
Field Trip!
Wastewater Treatment Activity*
Resources
Please review the following resources to answer the questions that follow.
Wastewater Treatment for Youngsters (Ages 8 to 80)
http://www.metrocouncil.org/Wastewater-Water/Publications-And-Resources/ES_kids_book-pdf.aspx
What Can You Do to Protect Local Waterways? U.S. Environmental Protection Agency http://www.epa.gov/npdes/pubs/centralized_brochure.pdf
What Happens After the Flush U.S. Environmental Protection Agency, The Family Handyman Magazine http://www.epa.gov/npdes/pubs/what_happens_after_the_flush.pdf
background
Think about the things that enter the wastewater system from a typical home: human waste; soap, detergents, and cleaning products from drains and washing machines; food items from garbage disposals; and anything people pour down the sink drain. How is this material removed so that the water can be safely returned to the environment and used again? The answer depends on where you live. If your home is not serviced by a public sewer system, your wastes are treated with a septic system. If your home is connected to a public sewer system, the water goes to a local wastewater treatment plant.
Click on Blue Plains Virtual Tour: http://esa21.kennesaw.edu/activities/ww-treatment/ww-tour-dc/blue_plains.swf
Since we were not able to visit a wastewater treatment plant, this website provides an interactive “virtual tour” of a wastewater treatment facility. It allows you to control the direction of the tour by selecting steps using the aerial view of the plant. Follow the numbered steps, clicking on the thumbnail images to enlarge and reading the associated text as you progress and answer the following questions.
Wastewater Treatment: Sequence of Events: Put the steps in the wastewater treatment process listed below in the right order.
Air is mixed vigorously into tanks with wastewater effluent (4)
Chlorine or bleach is added to the wastewater effluent (5)
Sand and grit are removed from the wastewater effluent (1)
Bacteria are settled out of wastewater effluent (3)
Oils ad greases float to the surface of wastewater effluent (2)
* Adapted from: Environmental Science Activities for the 21st Century
Resources
Please review the following resources to answer the questions that follow.
Wastewater Treatment for Youngsters (Ages 8 to 80)
http://www.metrocouncil.org/Wastewater-Water/Publications-And-Resources/ES_kids_book-pdf.aspx
What Can You Do to Protect Local Waterways? U.S. Environmental Protection Agency http://www.epa.gov/npdes/pubs/centralized_brochure.pdf
What Happens After the Flush U.S. Environmental Protection Agency, The Family Handyman Magazine http://www.epa.gov/npdes/pubs/what_happens_after_the_flush.pdf
background
Think about the things that enter the wastewater system from a typical home: human waste; soap, detergents, and cleaning products from drains and washing machines; food items from garbage disposals; and anything people pour down the sink drain. How is this material removed so that the water can be safely returned to the environment and used again? The answer depends on where you live. If your home is not serviced by a public sewer system, your wastes are treated with a septic system. If your home is connected to a public sewer system, the water goes to a local wastewater treatment plant.
- What happens in preliminary treatment at a wastewater treatment plant? The dirty water passes through a bar screen. The bar screen takes the large objects out of the water.
- What happens to large objects found in the wastewater? They are placed on a conveyor belt and placed in a dumpster to be later taken to a landfill.
- What is a grit chamber and how is it used? A grit chamber is long narrow tanks that are designed to slow down the flow and pass grit through screens so that solids will settle out of the water.
- Primary treatment removes 50% of the pollutants in wastewater.
- What happens to solids such as grease and oil? Skimmed from the top of the tank and pumped into incineration.
- What happens to the sludge in primary treatment? It is pumped to the Dewatering and Incineration process . The sludge is pumped into a centrifuge and the water is spun out of the sludge , dewatering it and leaving it dry enough to burn. When it is finally dry enough to burn, it is conveyered to a large incineration.
- What happens in secondary treatment? Air is pumped into the water to create an environment in which bacteria or "bugs" can live
- What are some examples of microorganisms used in secondary treatment? Vorticella, Paramecium, Tokophrya, Activated Sludge Floc, and Philodina
- What happens to the remaining dirt? It sinks and is pumped out
- What happens to the remaining water? (Discuss the role of chlorine in your answer) The remaining water is pumped into chlorine contact channels. The chlorine enters the waste stream through the yellow pipes. Chlorine is added to help clean the water and kill the germs
- What is the final process of wastewater treatment? The clean water is pumped through the gates that control the flow of water back into nature
- According to the U.S. EPA, what does it mean to “flush responsibly”? What items should you never put down the drain in your house?" Flush Responsibly" means Don’t pour household products such as cleansers, beauty products, medicine, auto fluids, paint, and lawn care products down the drain. Properly dispose of them at your local household hazardous waste facility. Wastewater treatment facilities are designed to treat organic materials, not hazardous chemicals. If you pour hazardous chemicals down the drain, they might end up in your local rivers, lakes, and coastal waters.
- What did people do with their waste before we had sewer systems and septic tanks? When did the Federal government start to mandate that wastewater be treated before being returned to rivers, lakes and the ocean? People would just dump waste into the streets . The government started to mandate that wastewater be cleaned in the 1970s when the Clean Water Act came into place.
Click on Blue Plains Virtual Tour: http://esa21.kennesaw.edu/activities/ww-treatment/ww-tour-dc/blue_plains.swf
Since we were not able to visit a wastewater treatment plant, this website provides an interactive “virtual tour” of a wastewater treatment facility. It allows you to control the direction of the tour by selecting steps using the aerial view of the plant. Follow the numbered steps, clicking on the thumbnail images to enlarge and reading the associated text as you progress and answer the following questions.
Wastewater Treatment: Sequence of Events: Put the steps in the wastewater treatment process listed below in the right order.
Air is mixed vigorously into tanks with wastewater effluent (4)
Chlorine or bleach is added to the wastewater effluent (5)
Sand and grit are removed from the wastewater effluent (1)
Bacteria are settled out of wastewater effluent (3)
Oils ad greases float to the surface of wastewater effluent (2)
- Anything you flush down the toilet will eventually show up at the wastewater treatment plant. Let’s say you accidentally drop a small towel down the toilet. What device is likely to catch the towel at the plant, and what would be its ultimate destination if this occurred at the Blue Plains plant?
- Why is the wastewater effluent treated with chlorine, bleach, or ultraviolet light after secondary treatment?
- Describe how the organic solids collected in the wastewater treatment plant are processed after collection, and list their final destinations at the profiled plant.
- Both nitrogen and phosphorus can occur in large concentrations in wastewater effluent. Why is this a potential problem? Describe, the approaches taken at the Blue Plains plant to deal with nitrogen and phosphorus removal prior to the release of the effluent into the environment.
* Adapted from: Environmental Science Activities for the 21st Century
Dams and Diversions
Hydropower (Dams)
1. Relatively inexpensive to operate once they are built
2. Generate clean power
3. Improves quality of life- prevent flooding, create jobs, and provides cheap electricity, irrigation, and drinking water
4. Alters river habitats in many ways , upstream-flooding, downstream- not enough water
5. Natural cycles are disrupted
6. Temperature of water is changed ( most of the time hotter)
7. Aquatic specices can go extinct , prevents anadromous fish from laying eggs.
In the US,the era of large dam construction is probably over, but not in developing countries
Micro-hydropower- electricity produced in a small stream without having to build a big dam
Water Diversions
Brings water to areas that need it, ex. aqueducts
We divert - and deplete- surface water
Diversion has drastically altered the river's ecology
Water Wars?- Freshwater depletion leads to shortages, which can lead to conflict. 261 major rivers cross national borders.; Water is a key element in hostilities among countries in the Middle East, but many countries (typically with similar gov'ts and belief systems) have made agreements to resolve disputes
1. Relatively inexpensive to operate once they are built
2. Generate clean power
3. Improves quality of life- prevent flooding, create jobs, and provides cheap electricity, irrigation, and drinking water
4. Alters river habitats in many ways , upstream-flooding, downstream- not enough water
5. Natural cycles are disrupted
6. Temperature of water is changed ( most of the time hotter)
7. Aquatic specices can go extinct , prevents anadromous fish from laying eggs.
In the US,the era of large dam construction is probably over, but not in developing countries
Micro-hydropower- electricity produced in a small stream without having to build a big dam
Water Diversions
Brings water to areas that need it, ex. aqueducts
We divert - and deplete- surface water
Diversion has drastically altered the river's ecology
Water Wars?- Freshwater depletion leads to shortages, which can lead to conflict. 261 major rivers cross national borders.; Water is a key element in hostilities among countries in the Middle East, but many countries (typically with similar gov'ts and belief systems) have made agreements to resolve disputes