Welcome to kashibiology.com In the previous post we have learned about the role of Microbes in Antibiotics Production.

This Post open the understanding, Significance of Microbes in Sewage or Wastewater treatment.

As we know that in present scenario, water pollution is a very big challenge for all the  government in the world, our society as well as our ecosystem, because every living organism needs water for its survival.

Availability of clean water is the right for every human being as well as other organisms.

Water plays an essential role in our body. Even the origin of life also takes place in water, if we see from an evolutionary point of view.

Nowadays a large amount of sewage water or municipal wastewater or domestic wastewater is disposed of in our water bodies especially in the rivers.

Therefore our aquatic bodies as well as rivers are heavily polluted. The consequences of water pollution are the spread of a large number of water borne diseases as well as harmful effects on aquatic plants and animals.

It also reduces the percentage of dissolved oxygen which is intake by aquatic organisms for respiration.

We often hear and see in newspapers in a pond a large number of Fish mortality or death take place due to the lack of oxygen.

All these due to the increasing water pollution day by day.

In this article we shall learn and understand the system that how we treat or clean the sewage to reduce its pollution level by using the microbes and then dispose in our aquatic bodies to minimize the water pollution.

Treatment of sewage or wastewater as well as industrial wastewater from different processing industries is also treated in sewage treatment plants and after the treatment the wastewater or treated water is disposed of in aquatic bodies.

Some important questions

What is the sewage?

What is the treatment of sewage?

What are the steps of sewage treatment?

What is the BOD value?

What is the Activated Sludge?

All these points will be understood in this post.

What is Sewage

Any wastewater from the house or from different industries is called sewage or wastewater.

The municipal wastewater or domestic wastewater is considered as sewage which contains large amounts of organic as well as inorganic matter along with non soluble solid particles. In sewage large amounts of pathogenic microbes are also present.

Sewage Treatment

Sewage treatment is a process in which Sewage or wastewater is treated in sewage treatment plants (STP) under different steps to reduce or minimize sewage pollution level.

Steps of Sewage Treatment

Sewage or wastewater treatment take place under the following steps in the sewage treatment plant.

• Primary or Physical treatment
• Secondary or Biological treatment 
• Tertiary or Chemical treatment.

Primary or Physical Treatment

The primary treatment includes sequential filtration and sedimentation. First of all the sewage is passed by filters which are of different sizes.

The insoluble and floating debris such as plastics, clothes, brick particles and other solid particles etc. are filtered out.

The filter is then passed in a settling tank and filter is allowed to sediment.

After this the floating debris is called supernatant and the remains settle down waste sediments.

The supernatant is known as effluent which is used in secondary treatment and the sediment can be used as fertilizer.

Secondary or Biological Treatment

In the secondary treatment it or biological treatment microbes’ aerobic microbes are used in the oxidation of sewage to reduce the pollution level of wastewater.

After the primary treatment the obtained effluent is transferred to an aeration tank where it is oxidized by aerobic bacteria and fungi to decompose dissolved organic matter in the effluent.

During the oxidation of effluent the microbes grow enormously and form flocs. These are the mesh-like structures in which bacterial colonies are associated with fungus filaments.

The treatment of effluent done until its BOD value reduces. If the value of BOD reduces then it is the indication that the level of pollution decreases in the effluent.

While growing these aerobic bacteria and Fungi they consume the major part of organic matter present in the effluent.

After the secondary treatment the treated water or effluent is generally disposed of to the aquatic bodies.

Biological Oxygen Demand (BOD)

It is the amount of oxygen required by microbes during the oxidation of organic matter dissolved in sample wastewater.

Polluted water or waste water normally treated till the value of BOD is reduced.

The BOD value test helps us to measure the amount of oxygen uptake by microorganisms during oxidation of organic matter present in the sample water.

The value of BOD helps us in understanding how much organic matter dissolved in the wastewater.

If the value of BOD is high then the sample water or the wastewater has more organic matter or it is more polluted and vice versa.

Activated sludge

After the secondary treatment the value of BOD is significantly reduced no the treated effluent is transferred into another settling tank.

In this tank the microbial flocs are allowed to settle down as sediment. The settled down sediments are called activated sludge because this contains a large number of aerobic microbes.

A small amount of activated sludge for the introduced in aeration tank as a starter for inoculums for secondary treatment.

Anaerobic Sludge Digester

The major part of activated sludge is passed into another large airtight tank which is called anaerobic sludge digester.

As the name indicates there is no oxygen supply during the digestion of activated sludge. Here anaerobic microbes or bacteria (such as Methanogens) grow and digest the Flocs in the sludge.

During the digestion of sludge these anaerobic microbes produce Biogas.

Biogas is a mixture (methane, carbon dioxide, hydrogen sulphide etc.) of gases. Due to its inflammatory nature Biogas can be used as a source of energy like in lightning as well as cooking.

River Action Plan

Due to increasing untreated sewage disposal in major rivers is the main cause of river water pollution.

The government of India has initiated Ganga action plan and Yamuna Action Plan to save our rivers.

The ministry of environment and forest has started this plan to construct a large number of sewage treatment plants (STP). Therefore only treated sewage discharged in these rivers.

Most of the metro cities or major cities in the world are located near the river or sea.

And we know due to increasing urbanization very large quantities of sewage are produced. Therefore a large number of sewage treatment plants are needed.

Conclusion

In this post we have learned how microbes, especially bacteria play an important role in the Treatment of millions liter’s of sewage or wastewater release across the world.

This approach has been used for more than a century now, in most of the cities in the world. Till time there is no man made technology has been developed which take place microbial treatment of sewage.

Hope you like the post and understand the concept of sewage treatment buy microbes.

If you have any suggestion or found any mistake in the post please update us by comment.

Thanks for reading this post.