how is sewage treated
Answers
Answer:
Sewage treatment is the process of removing contaminants from waste water by physical, chemical, or biological methods. Treated wastewater or effluent should be safer for the environment than the untreated waste.
Sewage treatment involves 3 stages.
1. Primary treatment
This involves settling down of heavy solids by holding the sewage in a tank in a quiescent stage. The lighter solids , oil and grease will float to the surface. The settled and floating materials are removed from the tank. The remaining liquid is subjected to secondary treatment.
2.Secondary treatment
This involves biological treatment of the waste for the removal of dissolved and suspended biological matter. For this process we use sewage treatment plants. Secondary treatment is performed by indigenous, aquatic microorganisms in a managed aerobic habitat. These microbes consume biodegradable , soluble organic contaminants and increase in their biomass. Filter beds, Rotating biological contactors, activated sludge, membrane bioreactors, aerobic granulation, surface aerated lagoons, constructed wetlands etc. are various types of secondary treatment.
3.Tertiary treatment
Treated wastewater should be disinfected chemically or physically before discharging it into a wetland, stream, river, or any other water body. It may be used for irrigation of a golf course, green way or park and agricultural purposes. It can also be used for ground water recharge. These are known as recycling of water.
Explanation:
Answer:
1. 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.
2. Secondary treatment remove dissolved and suspended biological matter
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