Short Answer TypeName the two different categories of microbes naturally occurring in sewage water. Explain their role in cleaning sewage water into usable water.
Study the graph given below. Explain how oxygen concentration is affected in the river when sewage is discharged into it.
The diagram above is that of a typical biogas plant. Explain the seQ uence of events occurring in a biogas plant. Identify a, b and c.
The sequences of events occurring in a biogas plant are:
(i) Hydrolysis: Through hydrolysis the complex organic molecules are broken down into simple sugars, amino acids and fatty acids.
(ii) Acidogenesis: In this step further breakdown of the remaining components by acidogenic (fermentative) bacteria takes place.
(iii) Acetogenesis: In this step simple molecule obtained by acidogenesis phase are further digested by acetogens, to produce largely acetic acid as well as carbon dioxide and hydrogen.
(iv) Methanogenesis: In this step methanogens utilize the intermediate products of the previous stages and convert them into methane, carbon dioxide and water.
The parts of biogas plant:
The part labelled (a) is sludge
The part labelled (b) is a gas holder, and
The part labelled (c) is inlet to feed slurry
Name a free-living and a symbiotic bacterium that serve as bio-fertilizer. Why are they called so?
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