Sewage Water Treatment Plant Methods
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Sewage treatment refers to the process of eliminating contaminants from wastewater, mainly from household sewage. For the majority of cities, the sewer system will also hold a component of industrial effluent to the sewage treatment plant which has typically received pretreatment at the factories themselves to decrease the pollutant load. If the sewer system is a mixed sewer then it will also contain urban runoff (stormwater) to the sewage treatment plant.
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To make wastewater admissible for reuse or for returning to the environment, the concentration of contaminants must be lowered to a safe level. Here are some of the treatment methods in sewage water treatment plants. Read more great facts on sewage ejection pump, click here.
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Mechanical Treatment
Primary or mechanical treatment is intended to get rid of gross, suspended and floating solids from raw sewage. It involves screening to trap solid objects and sedimentation by gravity to eliminate suspended solids. This level is also called as "mechanical treatment", even though chemicals are frequently employed to speed up sedimentation process. Primary treatment can decrease the BOD of the incoming wastewater by 20-30 percent and the total suspended solids by some 50-60 percent. Primary treatment is generally the first level of wastewater treatment. A lot of the modern wastewater treatment plants in industrialized countries have begun with primary treatment, and have then built up to other treatment stages as wastewater load has increased, as the need for treatment has developed, and as more resources have become accessible. For more useful reference regarding sewage treatment plants, have a peek here.
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Secondary Treatment
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Secondary or chemical treatment is an aerobic process. The liquid from the primary treatment has dissolved and particulate biological components. This is continuously converted into clean water by employing native, water-borne aerobic micro-organisms and bacteria which consume the pollutants. In a lot of cases, this effluent is sufficiently clean to discharge directly into rivers.
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Disinfection
Disinfection typically necessitates the injection of a chlorine solution at the head end of a chlorine contact basin. The chlorine dosage is dependent on the strength of the wastewater and different elements, but dosages of 5 to 15 mg/l are typical. Ozone and ultra violet (uv) irradiation can also be employed for disinfection but these techniques of disinfection are typically used. Chlorine contact basins are generally rectangular channels, with baffles to avert short-circuiting, intended to offer a contact time of approximately 30 minutes. Nonetheless, to fulfill advanced wastewater treatment requirements, a chlorine contact time of not less than 120 minutes is occasionally necessary for particular irrigation functions of reclaimed wastewater. Please view this site http://sciencing.com/waste-water-treatment-plant-work-4896800.html for further details.