BEM 4351 – Environmental Technology Unit 3 Questions Answered

Explain what a point source is in regards to water pollution.

Point source pollution refers to any particular identifiable pollution source from which pollutants are discharged. Point source discharges pollutants from distinct conveyances. Point source can include factory or ship smokestack, ditch or pipe.  

Discuss the roles of pathogenic organisms, inorganic chemicals, and sediment in water pollution.

Pathogenic micro-organisms are essential biological pollutants which are responsible for various human water borne diseases which include dysentery, cholera, hepatitis, and typhoid infections. Pathogen contamination that includes viruses, protozoa, and bacteria poses a serious threat to water resources. There is also pathogens transport to groundwater from surface water which increases the groundwater vulnerability.  Pathogens that include viruses are of much less quantity in water compared to protozoa and bacteria and majority can possibly reach groundwater via porous matrices of soil. Inorganic substances contain by far the highest percentage of drinking water chemical contaminants. Inorganic substances are in greatest quantity as natural processes consequences though a number of essential contaminants are present due to man’s activities.

Read also Clean Water Act

Some most significant inorganic chemicals originate from plumbing material where water is passed. Inorganic chemical contaminants are the most significant determinants of suitability to the consumer, impacting color, taste and scale deposition on fittings and pipes (Fawell, 1993). Sediment is the loose sand, silt, clay and other particles of soil that settle at the bottom of a water body. Sediment can originate from soil erosion or from animals and plants decomposition. Wind, ice and water help carry these particles to streams, lakes and rivers. Sediment impacts the aquatic life sometimes where by high volume of sediments chock coral reefs, seagrass beds and other sensitive habitats of the sea.  Sediments also silt the water bodies sometimes forming sediments rocks.

Why is thermal pollution a contributor to water pollution?

Thermal pollution is regarded as sudden decrease or increase in the natural water body temperature which might be pond, ocean, river, or lake by human influence. This usually takes place when a facility or plant takes in water from natural resources, alters the temperature through heating or cooling it using machines and puts it back to its natural source. Thermal pollution by heating the water oxygen reduces oxygen in water impacting the composition of the ecosystem. Organisms and fish adapted to specific temperature range can die due to abrupt water temperature change or thermal shock.  The change of oxygen content and altering of temperature which impact water organisms is what makes thermal change of water to be regarded as pollution (Nathanson & Schneider, 2014).

How do sediment basins and channel stabilization help reduce erosion?

Sediment basins and channel refers man-made structure at agricultural operations, construction sites, and other unsettled regions to offer temporal pools for runoffs which permit sediment to settle prior to discharging of runoff water into a landscape, stream or river. Sediment basins trap sediment as well as other coarse materials, preventing soil erosion. Basins and channels help in slowing down runoff flows giving time for eroded soil to settle down and to discharge the water at a slow pace back to the river or close natural water body (Nathanson & Schneider, 2014).

Explain how streams “self-purify.”

A river is capable of purifying itself using complex physical, chemical and biological processes. The river is involved in biological processes of self-purification through total decomposition of organic matters by bacteria, fungi and other microorganisms, and through the utilization of various functional biological filters. The stream also goes through chemical processes that include photochemical, hydrolysis, and oxidation among others and physical processes that include aeration, evaporation, adsorption and sedimentation. All these process assist in stream self-purification (Fisenko, 2006). 

Why does dissolved oxygen “sag”

Dissolved oxygen sags when the biological contaminants need oxygen to decompose and hence reducing the amount of dissolved oxygen in the water for aquatic life. During this stage, oxygen demand is higher than the supply since the waste also needs to be supplied with high content of oxygen to enhance the decomposition process. This results to continuous decrease of dissolved oxygen, causing sag (Nathanson & Schneider, 2014).

Discuss seasonal stratification of lakes including why there is a “fall overturn” and a “spring overturn.

A lake develops vertical stratification due to differences in density between bottom and surface waters. These differences in density can be as a result of biological, chemical or physical processes. The most common form of seasonal stratification in lakes is initiated by the surface water differential heating, making the surface water to be buoyant and less dense above denser colder water. Introduction of water containing saline variation from those of the lake can as well result to impart stratification. Also salts production by processes of biological decomposition can in addition create differences in density, thus causing lake stratification. During stratification fall overturn or spring overturn can be experienced. Fall overturn happens when upper surface of water cools turning to be denser that water in lower surface. As a result, water in upper surface sinks. During the sinking process, the nutrients move up while the dissolved oxygen moves down.  In spring overturn oxygen dissolved from the surface shifts to deep water while there is release of nutrients created through decomposition to the surface (Bade, 2005).

Explain how hydraulic fracturing can lead to groundwater pollution.

Hydraulic fracturing refers to the process of natural gas or oil extraction by use of fracking fluids to inject wells containing toxic chemicals, sand, and water, at very high pressure. Freshwater is injected in hydraulic well, and contaminated water is left on the well after the extraction process. IN case the well is not properly constructed, the contaminated water can infiltrate to other underground water sources causing contamination. In addition, the water may manage to spill off and join other surface water sources by joining the runoffs (Nathanson & Schneider, 2014).

Read also Types of Sources of Environmental Pollution And Effects of Environmental Pollution on Human and Ecosystem Health

 Discuss the typical differences in treating surface water versus groundwater for drinking water

Generally surface water contains a lot of contaminants compared to groundwater. Therefore, the two types of water are treated differently. Ground water is first tested for E. coli and other physical and chemical characteristics which include salinity and radioactivity. Retesting should be done in case of any modification in water quality based on color, taste and odors.  The adapted water treatment system should be guided by the types of identified contaminants. UV disinfection can be used to kills protozoa, viruses and bacteria in water. Filtration should be done to eliminate specific maters from the water. Chlorine disinfection should then be done to treat water over harmful giardia, viruses and chemical. On the contrary surface water is first coagulated where positive charges are introduced in the water to neutralize dirt negative charges in the water. This is followed by sedimentation where sediments are settled at the bottom of the supply of the water.  Filtration is then done where the clean water from sedimentation stage is passed through filtration system eliminate dissolved particles that include chemicals, viruses, parasite and dust.  The water is then disinfected using chloramine or chlorine so as to kill the remaining viruses, bacteria, and parasite and to safeguard water from germs (CDC, 2015).

List one health effect of too much exposure to each of the following: nitrate, selenium, and benzene.

Excessive exposure to selenium can result to organs damage. It can also result to development of diabetes, increase risks of development of selenium toxicity which characterized by fatigue,, nausea, irritability, hair loss, and nail inflammation. Excessive exposure to selenium can also result to blood clotting issues, facial flushing, lightheadedness, tremor, and muscle tenderness. Excess exposure to nitrate can resulted to acute methemoglobinemia, hypotension, increased risks of complications during pregnancy, increased danger of developing diabetes mellitus and has also been identified as a carcinogen. Benzene has been documented as a carcinogen and hence high exposure to benzene can increase the risk of developing cancer. Benzene can as well result to genetic defects, while repeated or prolonged exposure can result to organs damage (Nathanson & Schneider, 2014).

A sedimentation tank for water treatment is designed to have a detention time of four hours. If the flow rate entering the tank is 20 ft3/s, what is the tank volume required in cubic feet?

Detention time = volume /Flow rate

Volume = detention time x flow rate

1 hour -60minutes

1minutes -60 seconds

60mins – 3600 seconds

So 1 hour – 3600 seconds and thus 4 hours = 14400 seconds

Volume = 14400 x 23 ft/s

=331200 ft3

Explain the coagulation / flocculation process including when and why it is used.

The flocculation refers to process employed when there is a high turbidity level in water or when liquids must be separated from solids. Flocculation is effective in removing colloidal material, solids and color and reducing turbidity from water. Flocculation involves four main steps that include coagulation where chemical coagulants are input in water with intention of destabilizing finely divided materials and colloidal making them to start aggregating. This is followed by flax mixer where water with coagulant chemicals is mixed forcefully and quickly to ensure the chemicals are distributed evenly in the water. This is followed by flocculation which starts through a gentler, slower mixing which brings the fine particles created in coagulation step into contact with one another. The speed changes in every compartment and the entire phase takes 30 to 45 minutes. The last stage is clarification where clarifiers with basins or tanks hold wastewater or water for enough time to permit settling of floc; bacteria and impurities clumps bound together in a cluster, as well as other suspended materials at the bottom. This stage ensures removing all forms of sediments, particles, color, natural organic matter and oil (Filtronics, 2012).  

If a rapid sand filter is to be operated at 2 gpm/ft2 (gallons per minute per square foot of surface area), what filter surface area (in square feet) is required to treat 200,000 gpd (gallons per day)?

Surface loading rate, gpd/ft2 = flow, gallons/day/ surface area, ft2

1 day = 24 hours

I hour = 60 minutes

24 hours = 1440 minutes

1 minutes – 2gp/ft2

1440 minutes – 2880gp/ft2

SLR = 2880 gpd/ft2

2880gpd/ft2 = 200000/surface area

Surface area= 200000/2880

surface area = 69.44 ft2

Discuss the chlorination process.

Chlorination refers to the process of adding chlorine to drinking water to kill germs and disinfect it. In this process chlorine compounds that include solid calcium hypochlorite and sodium hypochlorite or chlorine itself can be added at the right dose in water. The compound is mixed in water and spread all through resulting to destruction of germs without causing harm to the water user (Nathanson & Schneider, 2014).

Explain the lime-soda method of water softening.

Precipitation of chemicals is one of the most common techniques employed to soften water. Calcium hydroxide also known as lime is one of the most common chemicals used in water softening. Lime is utilized to eliminate chemicals which yield to carbonate hardness. When lime is added into the water the calcium hydroxide combines with hardness causing chemical compound creating calcium carbonate precipitation or magnesium carbonate precipitation, softening the water (Nathanson & Schneider, 2014).

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