Wastewater treatment is cover under sewage treatment because in wastewater we purify wastewater as in Sewage contains human and animal waste and pollutants ,effluent. Sometime it contains storm water also.
Wastewater disposed as municipal or commercial wastes and be treated under sewage treatment plants. Wastewater contains both residential and industrial waste to treat. Differentiating solid and liquid waste from the sewage and treat the remaining liquid and make it safe for surroundings and reusable is called “Wastewater treatment” . In wastewater there are three processes called 1) Chemical, 2) Physical and 3) Biological. Considering which type of effluents are in wastewater, process can be apply .
Residential waste is like municipal sewage, remaining waste of house holds, sludge coming from dirty area etc. It contains only grey water .To treat this needs low rate treatment. It tends to be lower in coast and less maintenance. For this We just required physical and biological process. Filtration and clarification which are in physical process of wastewater treatment, can use for this type of wastewater.
Industrial waste contains effluents coming from industry, chemical sludge ,Toxins coming from pharmaceuticals .It contains black water. It is high rate treatment contains high cost and high maintenance. It requires pretreatment which is not full treatment in industry just remove pollutants before it discharge from industry. Pretreatment consist physical process, and for removal of effluents and toxin , Chemical and Biological process apply. For Biological process biological treatment units are use this process is called Activated sludge process.
Physical Process:-
Removal of physical substance from the sludge called physical process. It involves filtration, clarification ,sedimentation and aeration. Now Removal of solids settles which are in base is called Sedimentation .Whenever heavy solids go at the bottom, to discard them from wastewater become easy. To increase oxygen in the remaining waste and contaminated water is called Aeration. Passing water through filters and separate solid and liquid part of waste is called Filtration. These all processes are done by physically so its called Physical Process.
Chemical Process:-
Taking out the existence of contaminants from the wastewater is called Chemical Process. To purify water ,most used treatment is considered to be chlorination. To decompose water and remove bacteria from the waste water, chlorine is most usable chemical. It is a strong oxidizing chemical. By the oxidation we can purify water and make it reusable by controlling the bacteria growth, and for that we can also use agent like ozone.
It is widely use in industrial area and some times it is used in municipal sewage also. In industry PH control and neutralization is also necessary. Carbon is use for this process because of its adsorption property.
Making wastewater biochemically decomposed and stabilizing it called Biological Process. This process makes use of bacteria and other microorganisms which are in waste water. It categories in Aerobic and Anaerobic. An aerobic process we have oxygen presence ,and by the bacteria it transform in to CO2.In anaerobic process the sludge is fermented in considered temperature without O2.
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