DSST Environment-Humanities DANTES II

Where screening fits into wastewater treatment

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Where "screening" fits into wastewater treatment Screening is part of the pre-treatment phase. Screening is when influent sewage water is strained to remove all large objects carried in the sewage stream.
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Know the EPA minimums for wastewater treatment, as well as all of the steps in wastewater and potable water treatment. Pretreatment – Screening and grit removal. Primary treatment - consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. The settled and floating materials are removed and the remaining liquid may be discharged or subjected to secondary treatment. Secondary treatment removes dissolved and suspended biological matter. Secondary treatment is typically performed by indigenous, water-borne micro-organisms in a managed habitat. Secondary treatment may require a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment. Tertiary treatment is sometimes defined as anything more than primary and secondary treatment. Treated water is sometimes disinfected chemically or physically (for example by lagoons and microfiltration) prior to discharge into a water source. Sludge is dealt with the secondary treatment phase when it becomes activated sludge. Its then treated for disposal using anaerobic, aerobic or other means. The ocean water pollutant that is the most damaging Oil (Petroleum) Be familiar with the Chernobyl nuclear plant meltdown The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine (then in the Ukrainian Soviet Socialist Republic, part of the Soviet Union). It is considered the worst nuclear power plant accident in history and is the only level 7 event on the International Nuclear Event Scale. Subsidence – Sinkholes Subsidence sinkholes form gradually where the overburden is thin. The dissolving limestone is replaced by sand granules that fall into the depression and fill the holes. They appear as a concave depression in the ground. Subsidence sinkholes are usually only a few feet in diameter and depth because the development of the cavities in the limestone is retarded since they are filled with clay and sand. Lakes are formed from these sinkholes. Ecological Succession (Primary and Secondary Succession) Primary Succession begins in areas where no soil is initially present Secondary Succession begins in areas where soil is already present Know what nonpoint source pollution is.
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This is defined as water pollution affecting a water body from different sources, such as polluted runoff from agricultural areas draining into a river, or wind-borne debris blowing out to sea. NPS may derive from many different sources with no specific solution to rectify the problem, making it difficult to regulate. It is the leading cause of water pollution in the United States today, with polluted runoff from agriculture the primary cause.
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