micro-chap37

micro-chap37 - CHAPTER 36 WASTE WATER TREATMENTS Water...

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CHAPTER 36 WASTE WATER TREATMENTS Water treatment standards are designed to prevent infections from bacteria, viruses, and protozoa. Coliform bacteria o Inhabit the intestinal tract of humans and animals in large numbers. Presence in drinking water indicates fecal contamination o Coliform counting filtration until 1905 to reduce turbidity leading to treatment with chlorine. Water samples can be passed through selective media such as: EMB which select for coliform bacteria. Filtration helped to eliminate most cases of waterborne illness and chlorine almost completely eliminated. Wastewater from domestic or industrial sewage cannot be discarded into lakes and streams. Sewage is liquid effluent contaminated with fecal materials. Complete wastewater treatment involves physical, chemical and biological treatments to remove or neutralize contaminants. Wastewater enters a treatment plant and effluent (treated) water is suitable to release into surface waters. Some industries must pre-treat their waste before sending to a publically owned water treatment plant. Goal of wastewater treatment is to reduce organic and inorganic materials in wastewater to a level that no longer supports microbial growth and eliminate other potentially toxic materials. The efficiency of treatment is a reduction in the Biochemical Oxygen Demand – relative amount of dissolved oxygen consumed by microorganisms to completely oxidize all organic and inorganic matter in a waste sample. The more oxidizeable material in water, the more oxygen required to break it down, ie the higher the BOD. Primary wastewater treatment o Uses only physical separation methods to remove solid and particulate matter. Uses gates and screens and then allows effluent water to settle to the floor in order to remove additional solids. Anoxic Secondary wastewater treatment
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o Involves a series of digestive fermentative reactions carried out by various anaerobic bacteria. Breaks down insoluble organic matter in large enclosed tanks called bioreactors. *figure o Major reactions in anoxic secondary wastewater treatment of sludge o Complex polymers monomers fermentation Acetate H 2 + CO 2 Aerobic Secondary Wastewater Treatment o Uses digestive reactions carried out by microorganisms under aerobic conditions to treat wastewater with low levels of organic materials. o Aerated in large tank by oxidizing organisms o Trickling filter – spray onto rocks containing biofilm that breaks it down o Activated sludge Tertiary Wastewater Treatment
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o The effluent is chlorinated before released to surface water. Disinfection also done by UV radiation or ozone. Done after secondary. Trickling filter mimics what occurs naturally to clean rain water as it filters down
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This note was uploaded on 11/16/2010 for the course BIO 3317 taught by Professor Fentisel during the Spring '10 term at Temple.

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micro-chap37 - CHAPTER 36 WASTE WATER TREATMENTS Water...

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