Sewage Treatment

Human health and environment are mainly affected by direct disposal of industrial and human effluents into the natural resources without any treatment.  The sewage treatment is necessary to reduce the toxicity of sewage and maintain a safe and healthy environment, as well as promote human welfare.

Sewage Treatment Process

Sewage contains a huge amount of organic matters which are toxic. Microorganisms are widely used in the sewage treatment plant for removing this toxic organic matter. Sewage or wastewater treatment plant consists of two stages.

  • Primary Treatment

It involves the removal of large or small sized components in the wastewater through physical processes.

  • Biological Treatment:

Aerobic microorganisms are inoculated into the sewage treatment plant. These microbes utilize the organic components of the sewage and reduce the toxicity. This can be measured by BOD (Biological oxygen demand).

After the biological treatment, the sludge is pumped from the treatment plant into a large tank. This large tank consists of anaerobic bacteria which lead to the digestion of sludge. During digestion, biogas is produced and it is used as an energy source. Hence, Sewage treatment plant design and sewage management play a crucial role in the maintenance of human welfare.

Energy generation

Microorganisms which are involved in the production of energy are called as microbial fuel cells. Microbial fuel cells are used to generate a variety of energy sources like biogas and electricity. Agricultural waste, manure, and domestic wastes are used as raw materials for the generation biogas. Biogas generation is done in the large concrete tank which is called as biogas plant.

Biomasses (Biowastes) are collected at the biogas plant and the slurry is fed. Biomasses are rich in organic matter. Some of the bacteria can grow anaerobically inside the biogas plant. These bacteria can digest the biomasses which are present in the slurry and sewage. During digestion, a huge amount of mixture of gases is released inside the tank. The mixture of these gases is called as biogas. Biogas is removed from the biogas plant through a separate outlet.

Microbial fuel cells are also used to generate electricity from wastewater. Microbial fuel cells utilize the organic matter from the wastewater treatment plant. During digestion, organic matters are converted into the simple molecule and release the carbon dioxide and electrons. Those electrons are absorbed by the electrode and used as the source of electricity.

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Practise This Question

Which kind of garbage is not converted into compost by red worms?