Microbes in Sewage Treatment

Sewage treatment plans are a huge treatment mechanism to remove and dispose of the microbes and organic matter from the waste and municipal polluted water. Most microbes are pathogenic and toxic and can cause harmful effects in plant and animal physiology. Sewage treatment plants help make them less polluted, pathogenic-free and increase the Biochemical oxygen demand (BOD) in water which decreases the mortality period of water organisms. Some heterotrophic microbes help in the process, which is naturally present in sewage water. This sewage treatment is managed in two stages:-

Primary treatment

Primary treatment is responsible for removing physical particles, which can be large or small, by the process of filtration and sedimentation. In the initial step filtration, floating debris is removed, and in the second step, sedimentation grit (soil or small pebbles). The remaining components of solids that settle down are known as primary sludge, and the supernatant forms the primary effluent. Some proportions of primary effluent are required for secondary treatment; therefore, it is removed.

Secondary treatment

This treatment process requires more time than primary treatment. It involves the active participation of living microbes; therefore, it is called a biological process. The primary effluent is poured into large Aeration tanks for constant mechanical agitation, and oxygenic air is passed. This helps the growth of aerobic microbes in water into Flocs ( combinative masses of bacteria and fungi to form mesh-like structures). The aerobic growth of microbes reduces the Biochemical oxygen demand of water. After reduction of BOD, they are passed into the settling tank where Flocs are required to sediment and are called activated sludge. A small quantity of activated sludge called Inoculum is pumped back into the aeration tank, and the remaining part is transferred into the anaerobic sludge digesters. In the anaerobic sludge digesters, anaerobic bacteria digest the aerobic bacteria and fungi from the sludge, producing biogas. Biogas is a useful inflammable gas that contains methane, hydrogen sulfide, and carbon dioxide secondary treatment.

Tertiary treatment

Tertiary treatment aims at giving final polishing treatment before discharge and reusing wastewater. It removes phosphorus and nitrogen from the wastewater after secondary treatment. Chlorination removes soluble iron, magnesium, and sulfur from the wastewater. The other tertiary treatment methods include precipitation, oxidation and reduction, biological processes, adsorption, and membrane separation. The final effluent, free from pathogenic microbes and least polluted is finally released into natural water bodies like rivers, streams, and ponds. 

Use of Sewage Treatment Plans 

• Makes water less polluting and safe for water-living organisms.
• Increases the BOD of water. 
• Decreases mortality period of water living organisms.
• Helpful for recycling water.
• Improves the life of major rivers of our country. 
• Prevent water from biomagnification and save flying creatures. 
• Prevent water from natural aging. 

Conclusion

In the whole treatment process, microbes are used to make water that is most harmful to least harmful. Therefore, some microbes are helpful in human welfare. The sewage treatment method is useful in treating massive quantities of water at a time. Due to the increase in population and urbanization, sewage is produced in large quantities. To cope with this issue, the Ministry of Environment and Forests has established Ganga Action Plan and Yamuna Action Plan to cope with this issue.