Chapter 22: Water Pollution:
Water pollution refers to the degradation of water quality. A pollutant is any biological, physical, or chemical substance that, in excess, is known to be harmful to other desirable living organisms. Water pollutants include heavy metals, sediment, certain radioactive isotopes, heat, fecal coliform, bacterial, phosphorus, nitrogen, sodium, other useful (even necessary) elements, pathogenic bacteria, and viruses. In some cases, a pollutant might not be harmful to some people, but is harmful to others, i.e. salty water. It might not harm most people, but others that are on a salt restricted diet, it could harm.
Today, the primary water pollution problem in the world is the lack of clean, disease free drinking water. Diarrheal disease is one of the top 10 deadliest infectious diseases—usually caused by cholera in drinking water. Fortunately, the U.S. has largely eliminated this because we treat drinking water, but this is not the case worldwide.
The quality of water determines its use. The major uses for water are agricultural, industrial processes and domestic (household uses). The water for domestic use must be free of substances that can have health: insecticides, pesticides, pathogens, and heavy metal concentrations. The water should be odorless, colorless, taste good and not damage plumbing or appliances. Industrial and agricultural water may require a range of qualities from distilled to reclaimed water.
Many different processes or materials pollute the water: ground and surface. All segments of society (urban, rural, industry, agricultural and military) may contribute to the water pollution. Most sources result from runoff, leaks or seepage of pollutants into surface or ground water. Pollutants can be transported by air and deposited in water.
An increasing population often results in the introduction of more pollutants in the environment as well as demands on the finite water resources. As a result, we can expect that the quality of drinking water will decrease. More than ¼ of drinking water systems in the U.S. have reported at least one violation of federal health standards. About 36 million people have been supplied water from systems that violated federal drinking water standards.
The US EPA has thresholds or limits on water pollution levels for some pollutants. Maximum
concentration standards have been set for more than 700 identified contaminants. Before we talk about pollutants, we need to briefly talk about Biochemical Oxygen Demand and Dissolved Oxygen needed for healthy aquatic ecosystems.
Biochemical Oxygen Demand: BOD:
When dead organic material decays, bacteria carry out this process with oxygen. If there is too much decay, a lot of oxygen is being used up; there is a decrease in the amount of oxygen in the body of water. The level can decrease so much that fish die. A stream with inadequate oxygen levels is considered polluted for these organisms that require dissolved oxygen above existing levels.
The most of oxygen required for biochemical decomposition process is known as the Biochemical Decomposition Process—Biochemical Oxygen Demand (BOD). The BOD is used in water quality management. The BOD is measured in a number of places to test for water quality.
When BOD is high, the dissolved oxygen is too low. The US EPA defines the threshold for water pollution in terms of dissolved oxygen content of less than 5 ug/liter of water. When raw sewage is introduced into a river or stream, there are three zones that are identified:
1) Pollution Zone: high BOD and low DO
2) Active Decomposition Zone: Do reaches its maximize value
3) Recovery zone: organic matter is gone. Oxygen can reenter the water.
All rivers/streams can cleanse themselves. The problem arises when there is too much organic matter to breakdown.
Waterborne Disease:
In the US, we don’t really think about contaminated drinking water. North America is not immune to outbreaks of waterborne diseases.
Outbreak in Milwaukee, WI:
April of 1993, in Milwaukee, WI, there was an outbreak of a disease with flu-like symptoms. This gastrointestinal disease is caused by Cryptosporidium (causes Cryptosporidiosis). About 400,000 of 1.6 million people got sick and about 100 people died. The parasite is resistant to chlorine and passed through the city’s water treatment plant. Source remains unknown. This caused some concern about the state of our drinking water. Recent tests suggest that 65-97% of the surface drinking water in the US have Cryptosporidium—needs to be removed by filtration.
Fecal Coliform:
Count fecal coliform bacteria in water as a standard measure and indicator of disease potential. The presence of this bacterium indicates the presence of fecal material from birds and mammals. These bacteria are usually harmless bacteria that are normal inhabitants of our intestines. They are present in all humans and animal waste. The threshold used by the EPA for swimming water is no more than 200 cells of fecal coliform bacteria per 100 ml of water. Water with any fecal coliform is unsuitable for drinking. E. coli (a type of fecal coliform bacteria) has been responsible for causing human illness and death. The treat of waterborne diseases in near coastal waters, as well as, lakes, and rivers is responsible for warnings and beach closing per year. In most cases, the identified bacteria are fecal coliform.
Outbreak in Wilkerton, Ontario:
May 2010, 5,000 people had the E.coli strain that was dangerous. It was found in the cow’s digestive system. The likely contamination was cow manure washed into water supply during heavy rains. The local public utilities know that the well supplying the town was contaminated, but didn’t report it immediately. By 5/26, 5 people died and more than 20 people were in intensive care. Best doctor’s advice: drink clean fluid and let it runs it course.
Nutrients:
Phosphorus and Nitrogen are the two important nutrients from sources related to land use. Forests have the lowest concentration of phosphorus and nitrogen in stream waters. Urban have a higher concentration of these two elements due to fertilizers, detergents, and products of sewage treatment plants. Often the highest concentration of P and N are found in agricultural areas. The sources are fertilized feed and feedlots. Over 90% of the total N added to the environment by human activity comes from agriculture. Medical Lake: An example: Summer of 1977
Phosphorus entered the lake, the algae grow, the top of the water was shaded and the alga below the surface was blocked to the sunlight…there was no photosynthesis. The algae below the surface died, no photosynthesis, no glucose, and no energy. The bacteria increased and utilized oxygen to decompose the dead algae. This decreased the oxygen even more. If the DO decreases to a certain level, the fish, bacteria and algae will die. The Ecosystem effect: there are interactions among the different species. Eutrophication:
Algae grow due to an increase in nutrients. The algae forms mats on the surface, which decrease the DO under the algae (blocks light and photosynthesis) which decreases DO. The algae at the lower level die. Bacteria and decomposers use oxygen to break down the algae which lowers the DO. When the DO drops to a certain level, the fish will die.
A lack that has a naturally high concentrations of the elements needed for life is called eutrophic. An oligotrophic lake has a low concentration of needed elements.
When eutrophication is accelerated by humans that add nutrients to the water, this is cultural
eutrophication. This is not restricted to lakes. There have been concerns about sewage from urban areas pumping into tropical coastal ocean water. This can affect the coral reefs. Some parts of the great barrier reef and the reefs around the Hawaiian Islands are being damaged due to eutrophication…algae will completely take over the coral.
The solution is pretty simple: reduce the nutrients by 1) Use phosphate free detergents
2) Control nitrogen rich run off from agricultural lands
3) Dispose of or reuse treated wastewater or use a more advanced treatment (use filters or other steps to remove the nutrients).
Oil:
Oil discharged into surface water (ocean), on land, and in rivers are major pollution problems. Exxon Valdez: Prince William Sound, Alaska:
3/24/1981, Supertanker Exxon Valdez ran aground on Bligh Reef South of Valdez in Prince William Sound, Alaska. A tank ruptured and lost 20,000 barrels of Alaskan Crude per hour and about 250,000 barrels (11 million gallons) of oil entered the sound. The oil loss could have been greater, but some oil was offloaded to another tanker. Because of the Exxon Valdez, the oil pollution act was passed in 1990. The oil was spilled on one of the most ecologically rich environments. There were a lot of fish, birds, and marine mammals were present in the sound. 13% of harbor seals, 28% of sea otters and 100,000-645,000 seabirds were lost due to the spills. Within three days, the wind blew the slick beyond the containment. Of the 11 million gallons spilled, 20% evaporated, and 50% deposited on the shoreline, 14% was collected by skimming and waste recovery.
Before the spill, people thought that the oil industry could clean up spills. After $3 billion, few people are satisfied with the clean up. There are disagreements on the methods of clean up. Instead of washing the oil off of rocks with a hose and hot water, you should allow the organisms under the rock to clean.
The long term effects of an oil spill is uncertain, we know that the effects of the spill can last for decades. Toxic levels of oil have been identified in Salt Marshes after 20 years.
If one hull is breeched then the other hull will still be intact. The next important step is to pump out the breeched tanker quickly. Once a spill occurs, we need to use floating barriers and skimmers to collect the oil at sea. We need to clean animals, birds and mammals. It is really important that these animals don’t ingest any oil. Once inside, you really can’t clean it and the mortality is high. The oil on the beaches may be picked up by absorbent material and disposing of the material might be tough.
Jessica: Galapagos Islands:
1/22/01, a small oil tanker, Jessica, made a navigational error and the small tanker ran aground on the Galapagos Islands. It spilled 100,000 gallons of diesel oil. The US responded with a coast guard ship that is designed to remove oil from the tanker. Some of the oil leaked out and injured birds, seals and other life. There was an oil slick that spread over 3,000 km2 of water. Winds and currents move it away from the Galapagos.
Sediment:
Sediments are rock and mineral fragments from 2mm in diameter to finer sand, silt and clay. By volume, sediment is our biggest pollutant. The sediment will choke streams. It will fill in lakes, reservoirs, ponds, canals, drainage ditches, and harbors. Sediment buries vegetation and is tough to remove. Sediment pollution 1) results from erosion (depletes land resources at one site) and 2) reduces the quality of the water resource.
Human activities affect the pattern, amount and intensity of surface runoff, erosion, and sedimentation. Streams in a forested area are really stable: little or no sedimentation. If the forest is converted to agricultural land, this will increase erosion and sedimentation. You need to apply conservation practices to decrease erosion. In urbanization, a large amount of sediment can be formed.
Reduction of sediment pollution in an urbanized area has been demonstrated in a Maryland study. They used a drainage area and measured it for 10 years. During the time of construction 3% of the area of the basin was converted, and the total urbanized land area in the basin was about 20%. At the end of the year of study, sediment pollution was a problem because of the amount of rainfall and type of soil.
A sediment control program reduced sediments by 35%. The program exposed a minimum amount, of land, used by natural topography, divided temporary protection for exposed land, minimized surface runoff from critical areas and trapped sediment at critical sites.
Acid Mine Drainage:
Acid mine drainage refers to high H2SO4 with water. The acid drains from coal, copper, lead, zinc… mines. Coal and rocks containing coal are associated with pyrite (fool’s gold). When pyrite combines with water and oxygen, it produces H2SO4. In addition, pyrite is associated with metallic sulfide deposits. These deposits also produce H2SO4. The acid produced when surface water or shallow groundwater runs through or moves into and out of mines or waste rock (tailings). If the acid rich water funs off into surface water, then pollution and ecological damage will occur. This acid rich water can also seep into groundwater.
Surface Water Pollution:
Pollution of surface water occurs when too much of an undesirable or harmful substance flows into a body of water, exceeding the ability of that body of water to remove the undesirable material, dilite it to a harmless concentration or convert it to a harmless form.
There are two categories of pollutants:
1) Point Sources: Distinct and confirmed: pipes from industrial or municipal sites that empty into surface water. Usually industrial waste is treated on site or has a permit. In older cities, most municipal point sources are the sewer systems.
2) Nonpoint Sources: Runoff. This is diffused and intermittent and is influenced by a lot of different factors: land use, climate, hydrology, topography, native vegetation, and geology.
Examples: runoff from streets or fields. This stuff can contain all sorts of pollutants: chemicals, sediments, metals….. It is difficult for you to monitor and control nonpoint pollution.
There are two approaches to dealing with surface water pollution: 1) Reduce the source
2) Treat the water to remove pollutants or convert them to forms that dispose safely.
Reducing at the source is environmentally preferable. The second method is used for a variety of issues, adding chlorine to the water to kill microorganisms and filtering out metals is what will usually happen. There are success stores: Thames River in London and Cuyhuga River in Cleveland.
Groundwater Pollution:
About ½ of all people in the US depend on groundwater for drinking water. People think that ground water is clean and pure, but groundwater can easily be polluted and the pollutants may be tough to recognize.
In the US, only a small portion of ground water is affected. It’s the growing population that puts pressure on water resources, which makes the problem worse. The extent of the problem is growing and
groundwater pollution becomes more common. For example: Atlantic City and Miami are cities that are threatened by polluted groundwater that are slowly migrating to wells.
It is estimated that 75% of the 175,000 known waste disposal sites in the US may be producing hazardous chemicals that are migrating into the groundwater resources. These chemicals may be
toxic/carcinogens…basically; we are conducting a large, long term experiment.
The hazard presented by a particular groundwater pollutant depends on several factors: concentration or toxicity of the pollutant in the environment and the degree of exposure of people/organisms to the pollutant.
Principles of Groundwater Pollution: An Example:
Example: Pollution for leaking buried gasoline tanks. These Tanks are regulated and many old tanks have been removed. These old tanks can leak. Clean up is very expensive. We can use microorganisms underground to help with the clean up (bioremediation). The pollution from leaking gas tanks emphasizes some important points about ground pollutants.
Some pollutants, like gas, are lighter than water and float on the groundwater.
Some pollutants have multiple phases: liquid, vapor and dissolved. Dissolved phases chemically can be with the groundwater.
The method used to treat or eliminate a water pollutant will take into account the physical and chemical properties of the pollutant and how these interact with the surface and groundwater.
Clean up of groundwater pollutants is expensive. Detected or undetected pollutants may cause environmental damage.
Ground water pollution often lacks oxygen. This will kill aerobic microorganisms. The breakdown of pollutants occurs in the soil about a meter or so below the surface.
Long Island NY: example:
2 counties of LI, Suffolk and Nassau, depend on the groundwater for water. There are 2 problems: 1) Intrusion of salt water and 2) shallow aquifer contamination. The salt water intrusion comes from the ocean, usually happens in coastal towns. Nassau uses water has drained the freshwater reserve. (Zone of Diffusion is the interface between the freshwater and saltwater.
Most services pressure in LI. The shallow aquifer pollution is associated with urban runoff. Landfills have been particularly problematic.
Wastewater Treatment:
The US has laws that water must be treated before being released back into the environment. Wastewater treatment, or sewage treatment, costs about $20 billion per year. The cost will only continue to increase. Conventional methods of wastewater treatment include septic tanks and centralized waste water treatment plants in cities.
Septic Tank Disposal Systems:
In many rural areas, there are no central sewage systems or waste water treatment facilities are available. Because not all land is suitable for the installation of a septic tank disposal system, there is a need to evaluate each site, which is required. It is called a “perk” test.
Basic parts of a septic tank:
Sewer lines from the house lead to an underground septic tank in the yard. The first tank is designed to separate the solids from liquids. You want bacteria to digest (biochemical change) and store organics through a period of detention and allow the clear liquid to discharge into the drain field. Through a series of pipes, treated sewage seeps into the surrounding soil. As the wastewater moves through the soil, it is further treated by the natural process of oxidation and filtering. By the time the water reaches a
freshwater source, the wastewater should be safe. Sewage absorption fields may fail. Why?
1) Failure to pump out the septic tank when filled with solids. 2) Poor soil drainage
Wastewater Treatment Plants:
Wastewater treatment occurs at specifically designed plants. Raw sewage is delivered to the plant
through sewer pipes. Following treatment, the wastewater is discharged into the surface water. The main purpose of treating waste is to decrease BOD.
Primary Treatment:
Incoming raw sewage enters the plant. The waste water passes through a series of screens. This removes the large floating organic matter. The sewage will enter the grit chamber: sand, small stones and grit are removed and disposed of. The sewage enters the primary sedimentation tank where the sediments settle to form sludge, which is removed to a digester for more processing. The primary treatment removes about 30-40% of the BOD which is usually solids and organic matter.
Secondary Treatment:
There are several methods for secondary treatment. We’ll be going over the most popular, the activated sludge method. Waste water from the primary sedimentation tank enters the aeration tank: wastewater is mixed with air and some sludge from the final sedimentation tank. The sludge contains aerobic bacteria which consumes organic material in the wastewater (BOD). Wastewater enters the final sedimentation tank. The sludge settles out. Some of this sludge will be used again in the aeration tank. Most of the sludge is removed and placed on the digester. The sludge in the digester is treated with anaerobic bacteria which degrades the sludge.
Methane gas is produced with the anaerobic digestion. The methane can be collected and burned as fuel or to fuel generators. The wastewater in the final sedimentation tank is chlorinated to kill
microorganisms, and then it is placed in a freshwater source. The secondary treatment removes about 90% of BOD.
The sludge is dried and disposed of in a landfill or placed in the soil to improve it. Can we remove heavy metals?
Advanced Wastewater treatment:
Add more steps to remove pollutants. Usually you would put the secondary wastewater through a series of filters: sand filters, carbon filters, and chemical filters which remove pollutants. The treated water can be placed in the freshwater source, used as irrigation (golf courses).
Chlorine Treatment:
Chlorine has been successful at killing pathogens. However, the treatment produces minute quantities of byproducts that have been identified as potentially hazardous to humans and other organisms. These byproducts may cause cancer.
Land Application of Wastewater:
Applying waste water to the land is an extension on the belief that waste is another resource. Wastewater renovation and conservation cycle:
The ideal land application system can be called Wastewater Renovation and Conservation Cycle. Here are the 3 major steps:
1) Return of wastewater after the primary treatment to crops via sprinkler or irrigation.
2) Renovation (natural purification) is done by slow percolating of wastewater into the soil. This will recharge the groundwater, after it had been filtered.
3) Reuse of the water: pump it from the ground or it reenters a stream.
A wastewater resource recovery plant is a plant that will treat water and produce resources: methane gas and ornamental plants/flowers that have a commercial value. Steps to this type of plant:
1) Waste water is run through filters which remove large objects. 2) Waste water undergoes anaerobic processing
3) Nutrient rich water flows over an inclined surface that contains plants. This process is supposed to clean the water to the same secondary treatment standard. Problems:
1) There has been a tremendous investment into the traditional wastewater treatment plants and people are familiar with how to operate them.
2) Economic incentives need to be provided for new techniques.
3) Not enough personnel are trained to design and operate a new type of wastewater treatment plant. Hopefully things will change.
Wastewater and wetlands:
Wastewater is being successfully added to natural and constructed wetlands. These wetlands are effective in treating the following water problems:
Municipal wastewater from primary or secondary treatment plants (BOD, pathogens, phosphorus, nitrate, suspended solids, and metals).
Storm water runoff (metals, nitrates, BOD, pesticides, and oils)
Industrial Wastewater (metals, acids, oils, solvents)
Agricultural Wastewater and runoff (BOD, nitrates, pesticides, suspended solids)
Mining Waters (metals, acidic water, sulfates)
Groundwater seepage from landfills (BOD, metals, oils and pesticides)
The treatment of wastewater through wetlands is attractive to communities that can’t afford a traditional wastewater treatment plant.
Louisiana Coastal Wetlands:
LA has abundant coastal wetlands, and is a leader in the development of wetlands to treat wastewater. The Nitrates and Phosphorus rich wastewater, when applied to the coastal wetlands, increases the
production of wetland plants, this will improve the water quality as these nutrients are used by the plants. This system will save about $40,000 per year.
Phoenix AZ, Constructed
Wetlands can be constructed in an arid region to treat the water quality. The one in Avondale, AZ cost $11 million dollars to build (1/2 the cost of a wastewater treatment plant). This wetland will remove nitrates from the water.
Water Reuse:
Inadvertent Water Reuse: Water is withdrawn, treated, used, treated, and returned to the environment, followed by further withdrawals and use. This type of water reuse is common for people living along a river.
Several risks are associated with inadvertent water reuse:
1) Inadequate treatment facilities and you may deliver contaminated water to downstream users. 2) Because the fate of all disease causing viruses during and after treatment is not completely
3) Every year, new hazardous chemicals are introduced to the environment. These chemicals are often difficult to detect. Their effects might be tough to evaluate.
Indirect Water Reuse: planned endeavor. Wastewater is applied to surface to recharge the ground water.
Direct Water Reuse: Treated wastewater is piped directly from the treatment plant to the next user. In these cases, water is used for industry, in agriculture, irrigation of golf courses, institutional grounds (University grounds), and parks. Resorts in Las Vegas, NV use a great deal of direct use water reuse for the fountains, canals, rivers and lakes.
Water Pollution and Environmental Law:
Environmental Law is a branch of law dealing with the conservation and use of natural resources and control of pollution. It is very important that we debate environmental issues and make decisions on how to protect our environment. Our local, state and federal laws address these issues.
1899 was our first environmental law called the Refuse Act: this protects navigable streams rivers, and lakes for pollution. Many federal laws have been passed with the purpose of cleaning up pollution and preventing the pollution from getting in the water.
1972, the Clean Water Act was passed. It was amended in 1977. In 1994, congress attempted to rewrite it. The purpose was to give industry more flexibility in choosing how to comply. Industry supported the amendment. Environmentalists hated it. Congress continues to debate laws—little has been resolved.
July 2000, President of the US approves new water pollution regulations aimed at protecting
