M8D1 Microbes and the Environment
Scenarios 1: Characterize the differences among untreated, primary-treated, and secondary-treated sewage and compare and explain the effects of dumping each type on the eutrophication of a pond and a fast-moving river.
Answer 1: The general idea of wastewater treatment plants is to decrease the biochemical oxygen demand (BOD) and chemical oxygen demand (COD) in the runoff into the lakes and streams, and do so by meeting the standards of the state and federal government. The purpose of the treatment plants is to feed oxygen and organic waste to bacteria and other microorganisms (Cooke, n.d.). The untreated sewage waters frequently contain high levels of organic matter from industrial, agricultural wastes and from human wastes. It is a necessity to get the organic matter removed by the process of waste water treatment. Pathogens like bacteria, protozoa and viruses are all in the untreated water (Untreated Sewage, 2014). The primary sewage treatment removes 25-35%of the BOD that is present in particulate form and thus there will be a slight increase in dissolved oxygen. In this treatment, particulate material is reduced by screening, precipitation of small particulates, and settling in basins or tanks. The resulting solid material is usually called sludge (Tortura, 2013, p. 789). Secondary sewage treatment promotes the biological transformation of dissolved organic matter to microbial mass and carbon dioxide. They remove 75-95% of the BOD and many bacterial pathogens are removed by this process which will ultimately increase dissolved oxygen. Under some toxic conditions, the dissolved organic matter will be transformed into additional microbial biomass plus carbon dioxide. When the microbial growth is completed, under ideal conditions microbes will aggregate and form a stable structure which can then be removed (Cooke, n.d.). When the untreated waste is dumped into a pond or fast-moving river, there is less dissolved oxygen and the waste content is
Answer 1: The general idea of wastewater treatment plants is to decrease the biochemical oxygen demand (BOD) and chemical oxygen demand (COD) in the runoff into the lakes and streams, and do so by meeting the standards of the state and federal government. The purpose of the treatment plants is to feed oxygen and organic waste to bacteria and other microorganisms (Cooke, n.d.). The untreated sewage waters frequently contain high levels of organic matter from industrial, agricultural wastes and from human wastes. It is a necessity to get the organic matter removed by the process of waste water treatment. Pathogens like bacteria, protozoa and viruses are all in the untreated water (Untreated Sewage, 2014). The primary sewage treatment removes 25-35%of the BOD that is present in particulate form and thus there will be a slight increase in dissolved oxygen. In this treatment, particulate material is reduced by screening, precipitation of small particulates, and settling in basins or tanks. The resulting solid material is usually called sludge (Tortura, 2013, p. 789). Secondary sewage treatment promotes the biological transformation of dissolved organic matter to microbial mass and carbon dioxide. They remove 75-95% of the BOD and many bacterial pathogens are removed by this process which will ultimately increase dissolved oxygen. Under some toxic conditions, the dissolved organic matter will be transformed into additional microbial biomass plus carbon dioxide. When the microbial growth is completed, under ideal conditions microbes will aggregate and form a stable structure which can then be removed (Cooke, n.d.). When the untreated waste is dumped into a pond or fast-moving river, there is less dissolved oxygen and the waste content is
References: Cooke, R. L. (n.d.). Lesson 1: Wastewater Treatment. Mountain Empire Community College. Retrieved from http://water.me.vccs.edu/courses/env108/Lesson1_print.htm Muir, P. (2012, October 29). Eutrophication. Retrieved from http://people.oregonstate.edu/~muirp/eutrophi.htm Tortora, G., Funke, B., Case, C. (2013). Microbiology: An Introduction. 11th Ed. Pearson. www.pearsonhighered.com Untreated Sewage. (2014). Untreated Sewage. Retrieved from http://www.worstpolluted.org/projects_reports/display/63