Microbes in Human Welfare Test - 5

Treatment of waste water is done by the heterotrophic microbes naturally present in the sewage. This treatment is carried out in two stages: primary treatment and secondary treatment.

The masses of bacterium associated with fungal filaments to form mess like structure is called flocs. Flocs are used to remove organic wastes from waste water.

Biological Oxygen Demand is the amount of oxygen that would be consumed if all the organic matter in one liter of water are oxidized by bacteria. it is used as indicator of water pollution. More the value of BOD higher the water polluted.

Biogas is mixture of gases like methane, hydrogen and oxygen. It is produced by anaerobic breakdown of biomass like animal dung, animal wastes etc. It is used as fuel in rural areas.

Anaerobic bacteria are used in water treatment process during which marsh gas is produced. This gas have pungent smell and highly flammable.

Secondary treatment of sewage is also called biological treatment because in this treatment aeration of sewage water is done that increase the microbes that decompose the organic materials in sewage water.

Spirulina is an Algae found in water. It is unicellular and rich in proteins. It is used as single cell protein as substitute of plant or animal protein.

Anaerobic decomposition of biomass like cow dung release biogas. This biogas contains mainly methane gas and can be used as fuel for cooking and lighting.

Biological oxygen demand is the amount of oxygen required to completely decompose the organic waste present in one liter of water by bacteria. High value of BOD shows that water is highly polluted.

Activated sludge treatment is a step in sewage treatment in which a part of decomposer bacteria present in wastes is recycled into the starting of treatment to maintain bacteria.