Question

Explain the steps involved in the sewage treatment.

Answer 1

The sewage treatment consists of three processes:

1) Primary treatment: In this process, the effluent or the sewage flows through huge tanks called the primary sedimentation tanks.

• In these tanks, the sludge settles down while grease and oil float on the surface and are removed.
  
• These tanks have scrapers that continuously push the sludge that is collected, towards the hopper in the base of the tank
  

2) Secondary treatment: In this process, the biological waste from human waste, soap, food waste, and detergent are substantially degraded.

• Most of the municipal sewage water treatment plants treat the sewage that is settled through the aerobic process.
  
• The effluent after the primary treatment has dissolved biological matter is then converted into clean water by making use of the bacterial and waterborne aerobic micro-organisms that absorb the pollutants.
  
• The effluents from this process are clean enough to be discharged into the rivers.
  

3) Tertiary treatment: This is the final stage of filtration where the effluent is treated further to its best quality before being discharged to the environment.

• The tertiary treatment has to ensure very high standards of treating the effluents to be cleaner than the stream or river water.
  
• It reduces the phosphorous and ammoniacal nitrogen.