Untreated Sewage is the Feces and Urine of Humans That Has Not Been Treated to Kill Disease

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  Untreated sewage is the feces and urine of humans that has not been treated to kill disease-causing organisms. Humans, like all warm-blooded animals, contain bacteria in their gut. If these bacteria get into another part of the body where it does not belong, then people can get sick. If untreated sewage was dumped into a pond the effects could be harmful on many levels. Nutrients in aquatic ecosystems are beneficial when in appropriate amounts at the appropriate times and places, but excessive nutrients in aquatic ecosystems are detrimental. Besides high levels of nutrients, sewage usually contains microorganisms that can be harmful to humans or wildlife. In ponds or lakes with swimming areas and a known or potential source of sewage, public health agencies may monitor the water for contaminants. The so-called fecal coliform bacteria count is a standard indicator of contamination and levels above a certain threshold can lead to a beach being closed until the fecal coliform count returns to acceptable levels. Primary treatment. This treatment removes large floating or suspended particles, heavier particles called grit (such as sand or gravel), and any excessive grease or oil from the sewage. A series of screens, grit chambers, and sedimentation tanks are used at this stage. If no further treatment is performed, the wastewater is disinfected by the addition of chlorine and discharged into a stream or a body of water. If further treatment is needed, the wastewater goes through the secondary-treatment step. Secondary treatment. The second step in the process uses aerobic microorganisms (bacteria that thrive in the air) to break down organic matter left in the sewage. The process — called biological oxidation — involves trickling  filters, activated sludge, and stabilization ponds. Unless tertiary treatment will be used, the wastewater is disinfected with chlorine and then discharged. Sludge remaining from the primary- and secondary-treatment processes is sent to a sludge digester for further processing. The digester relies on aerobic bacteria to break down volatile matter in the sludge over the course of two or three weeks. Methane, a by-product of this step, can be captured and used as a fuel source. The remaining sludge is incinerated, deposited in a landfill, or recycled as fertilizer or for use as a soil conditioner. The


Jul 23, 2017
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