Freshwater Part 3


Howdy! In this mini-lecture we will discuss types of fresh water pollution and wastewater treatment. After reading Chapter 15 and watching both
videos on freshwater resources or reading the transcripts that go with these videos,
you should be able to: * Distinguish between Point and Non-Point
Water pollution * Describe the major classes of water pollution
and propose solutions to each; and * Explain how we treat drinking water and
waste water Now we will consider freshwater pollution. Freshwater pollution can come from either
point sources or non-point sources. Point source pollution is a direct discharge
from a single location. Examples of point source water pollution are
industrial waste discharges and wastewater treatment plant discharges. Non-point source pollution is an indirect
discharge that comes from multiple sites over large areas. Examples of non-point source pollution are
pesticides used on lawns that runoff when it rains or the lawn is irrigated, fertilizer
or animal waste runoff from farms, and oil in stormwater runoff from city streets. Non-point-source pollution is the major source
of U.S. water pollution. Watershed management strategies are developed
and implemented at the regional and state level to help to minimize non-point source
pollution within the area. Figure 15.22 in your book provides examples
of both point and non-point sources of water pollution. The items on this figure that are confusing
are the abandoned mines, animal feed lots, and oil tankers or oil spills. Depending on the scale each of these could
qualify as either point or non-point sources. Many environmental scientists generally consider
animal feed lots to be a non-point source pollutant. Now we will examine the specific types of
freshwater pollution, namely nutrient, biological, toxic chemical, sediment, thermal, pathogens
and water borne diseases, oil, plastic, and pharmaceutical pollution. We have already discussed nutrient pollution
extensively, but I mention it here because it is one of the main types of aquatic pollution. The sources of nutrient pollution include
fertilizers on farms, lawns and golf courses and sewage. Nutrient pollution leads to eutrophication,
which can then cause hypoxic or anoxic conditions. Recall that hypoxic means very low levels
of oxygen and anoxic means no oxygen in the water. Nutrient pollution can be resolved by treating
wastewater, judicious application of fertilizers, use of phosphate-free detergents and building
vegetated buffers on the edges of water bodies. The vegetation in the vegetated buffer filters
nutrients in runoff before the runoff reaches the water body. Another type of water pollution is biological
pollution caused by human and animal waste, paper pulp and yard wastes. Wastewater from toilets, sinks, dishwashers,
washing machines and industrial processes is also a source of biological pollution. The particles suspended in wastewater decrease
dissolved oxygen through the process of bacterial decomposition. Developing countries have more problems with
this type of pollution than developed countries because developed countries have built wastewater
treatment plants to remove biological pollution from wastewater before it is discharged into
a stream. The best solution for biological pollution
is to help developing countries build wastewater treatment facilitates. Toxic chemicals are another source of water
pollution. This type of pollution comes from pesticides
petroleum products, and synthetic chemicals, as well as toxic metals, acid rain and acid
mine drainage. This type of pollution is harmful to both
the environment and human health. One solution for this type of pollution is
to implement more stringent regulations of industry, perhaps shifting from an “innocent
until proven guilty” philosophy to a “Precautionary Principal” philosophy of managing toxic compounds. Other options are to modify industrial processes
to eliminate or minimize toxic wastes produced and for consumers to influence the market
and industry through mindful purchasing of products that do not produce, support, or
include toxic compounds. Sediment pollution is another type of freshwater
pollution. This type of pollution is caused by clear-cutting,
mining and clearing land for a variety of uses. Soil will flow off the land if the land is
cleared but not covered with vegetation or some kind of erosion control product. This sediment is carried to streams and ponds
through runoff and consequently causes dramatic changes in the aquatic habitat. The sediment clogs up the stream making it
difficult for photosynthesis to occur, impairs organisms’ respiration and causes the stream
to fill in. The solution to this is to adopt soil best
management practices that keep soil in place following a disturbance. Additionally large-scale disturbance of vegetation
should be avoided and riparian vegetation should be preserved. One type of pollution that most people don’t
realize is a problem is thermal pollution. Thermal pollution is when the temperature
of a natural aquatic system is changed quickly and dramatically by some human or natural
cause. Typically thermal pollution is due to human
activities. For example, industrial facilities often build
a holding pond near their facility so that they can pull in the cold water into their
plant to cool down the machines they operate. When they are done with the water, they pump
it back into the holding pond. Organisms living in the water body will receive
a shock to their system because the water entering the pond is significantly warmer
than what they are accustomed and adapted to. Dams are another example of thermal pollution
because dams typically discharge cold water from the bottom of the reservoir into the
river downstream of the dam. The organisms in the stream therefore suddenly
have a much colder environment than they are used to. Thermal pollution, either hot or cold, can
kill or harm aquatic organisms. Pathogens and waterborne disease are a type
of water pollution caused by inadequately treated sewage and animal wastes. This type of pollution causes more human health
problems than any other type of water pollution. Disease that humans can contract from this
type of pollution include giardia, typhoid, hepatitis A, and dysentery. These diseases and pathogens can be prevented
by disinfecting water, treating wastewater, public education regarding waste management,
regulations that protect food, and cleaning up after domestic animals. Oil pollution comes from large catastrophic
spills, such as the Deepwater Horizon or Exxon Valdez, natural seepage, boat leakage, runoff
from city streets, and small spills that occur during transport and extraction. The largest oil spill in U.S. history occurred
in 2010 when the Deepwater Horizon drilling platform exploded in the Gulf of Mexico. This disaster killed 11, caused over 200 million
gallons of crude oil to spill into the Gulf of Mexico for 87 days, consequently polluting
the coasts of Texas, Louisiana, Mississippi, Alabama, and Florida. While this may seem depressing, the amount
of oil spills from tankers has decreased worldwide in the last 30 years. This is due to an emphasis on spill prevention
and response and the U.S. Oil Pollution Act of 1990. This act provided a 1 billion dollar prevention
and cleanup fund and required than any tankard shipping oil must have a double hull. The double hull is so that if the exterior
hull of the tanker is broken by impact with another object, then the interior hull of
the ship will still retain the oil. The U.S. Oil Pollution Act of 1990 was in
response to the 1989 Exxon Valdez oil spill, which at the time was the largest oil spill
in U.S. History. Net and plastic are also a significant source
of water pollution. Things like fishing nets, plastic bags and
bottles, fishing line, buckets, floats, and other plastic items dumped into water bodies
harm or kill wildlife. Furthermore, converging ocean currents accumulate
plastic trash and have cause a massive plastic island to form in the Pacific Ocean. This patch is called the Great Pacific Garbage
Patch and is twice the size of Texas. Plastic is harmful because mammals, seabirds,
and sea turtles eat plastic, thinking it’s food, or eat tiny particles of partially degraded
plastic. Consumption of plastic is toxic to organisms
and kills them. Solutions to this problem are reducing, reusing,
and recycling plastic. Some places, such as cities in California,
New York, Washington, Texas and Europe have actually banned the thin plastic bags used
in shopping. Additionally, in 2006 Congress passed the
Marine Debris Research, Prevention, and Reduction Act. This act sets aside 10 million dollars for
National Oceanic and Atmospheric Administration for implementation of a program that will
include mapping, identification, and impact assessments, removal and prevention activities,
research and development of alternatives to products posing threats to the marine environment,
and outreach activities. The final type of pollution you should be
aware of is pollution caused by pharmaceuticals. The three main routes by which pharmaceuticals
enter the environment are: 1. improper disposal of excess or unwanted pharmaceuticals
(i.e. flushing pharmaceuticals down the toilet or sink);
2. through patient excretion of pharmaceuticals and their metabolites. Metabolites are by-products created as they
pass through an organism’s system; and 3. wash-off of medicated lotions or creams during
bathing Pharmaceuticals can also enter the environment
through the medicines we give to livestock, domestic animals, fish in fisheries, and through
medical wastes or medicine manufacturing processes. Each of these routes ultimately results in
the pharmaceuticals being carried through municipal sewage lines to a local wastewater
treatment plant. As the majority of these facilities were not
designed to remove pharmaceuticals or their active metabolites, pharmaceutical compounds
are subsequently discharged into surface waters that receive treated wastewater from wastewater
treatment plants. Pharmaceuticals in the water pose little threat
to humans but they have very significant and well documented effects on wildlife, especially
aquatic organisms. For example, exposure of tadpoles to the medication
fluoxetine, also known as Prozac, has been shown delay of metamorphosis in frogs. The picture on the bottom left shows two tadpoles
after 57 of development in the lab. The tadpole on the right, which hasn’t developed
its limbs yet, was exposed to fluoxetine. Fluoxetine is used to treat depression and
obsessive compulsive disorder. Another example of effects of pharmaceuticals
on aquatic organisms is seen in the picture on the bottom right. This picture shows fathead minnows that were
exposed to estradiol. This is the medication that is in birth control. Estradiol, not surprisingly, acts as an endocrine
disruptor and feminizes male fish and other aquatic organisms. This can lead to reproduction problems. To prevent pharmaceutical pollution do not
flush your medications down the toilet or drain. Instead dispose of them through a community
pharmaceutical disposal event or dispose of them in your household trash if a disposal
event is not available. Now let us examine how we treat wastewater. Before the Clean Water Act, untreated sewage
was released into waterways. This caused oxygen depletion and contamination. In populated areas, municipal sewer systems
carry wastewater to wastewater treatment plants. Once there, the raw sewage first goes through
primary treatment to remove suspended solids. Primary treatment is accomplished by running
the wastewater through a series of progressively smaller screens. Secondary treatment follows primary treatment. During secondary treatment the wastewater
is stirred and aerated, allowing aerobic bacteria to degrade organic pollutants. Further treatment may remove particular pollutants. The tertiary treatment is the last treatment
as is used to disinfect and sterilize the water. This is accomplished using either chlorine
or ultraviolet light During wastewater treatment, solids are removed
from the water and disposed of. These solids are called Sludge. The sludge is sent to an anaerobic digester
for treatment. The gases produced from the anaerobic digester
can be used to generate electricity and the solids produced are called bio-solids and
they can be applied to farm fields as fertilizer. When the wastewater has gone through the entire
treatment process it is discharged into a local river, stream or ocean. This discharged treated wastewater is call
effluent. Alternatively, the effluent can be retained
and used as reclaimed water for irrigation or industrial purposes. People who live in rural areas, which are
not connected to a municipal wastewater treatment system, typically dispose of their sewage
through a septic systems. Septic systems are underground septic tanks
that separate solids and oils from water. The water drains into a field through perforated
pipes and microbes decompose pollutants in the water. The solid waste in the septic system is periodically
pumped out and sent to a landfill. We have learned a lot about how to clean our
wastewater in the last few decades. Long before we had wastewater treatment facilities,
wetlands were filtering pollutants from water. Environmental engineers and other trained
professionals now build artificial wetlands to clean wastewater. The microbes in the wetlands “polish” treated
wastewater and remove excess nutrients. The cleansed water is then released into waterways
or percolates underground. The U.S. has over 500 artificial or restored
wetlands. Releasing wastewater effluent into wetlands
can help restore marshes because nutrients in the wastewater can increase marsh grass
growth. Overall artificial wetlands improve water
quality and provide wildlife habitat and opportunities for education and recreations, such as bird
watching. We have an example of a constructed or artificial
wetland here in Texas. The Tarrant Regional Water District’s George
W. Shannon Wetlands and Water Reuse Project is a functional artificial wetland that will
soon serve as a water supply for the district. The entire system encompasses 2,000 acres
and also serves as a habitat to wildlife in the area. That concludes the second mini-lecture on
types of fresh water pollution and wastewater treatment. Please review the weekly outline and complete
the activities for this week per the schedule set forth in the outline. Thanks and Gig ‘Em.

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