Test: Digestion Of Sludge, Sludge Digestion Tank

Explanation: The sludge digestion process consists of acid fermentation, acid regression and alkaline fermentation.

Explanation: The digested sludge is free from pathogenic bacteria. It has the behavior of rich humus soil.

Explanation: The range of BOD of supernatant liquor in a sludge digestion process is between 2000 and 3000 ppm. It is a form of sludge that is obtained in the sludge digestion process.

Explanation: The pH value in Alkaline fermentation stage is 7.5 whereas in Acid regression and Acid fermentation stage, the pH>7, having the least in acid fermentation stage.

Explanation: The residual energy in aerobic digestion is very less in comparison to anaerobic digestion.

Explanation: The color of digestive sludge is black. It has an inoffensive odor.

Explanation: Anaerobic digestion is a low energy process which contains low amount of biomass and where both facultative and anaerobic bacteria solubilize the organic matter.

Explanation: The maximum and minimum temperature at which thermophilic microorganisms remain active in sludge digester are 60^oC and 40^oC respectively.

Explanation: In two stage sludge digester, the partially digested sludge is obtained in primary tank, whereas digested sludge is obtained in the secondary tank along with supernatant liquor.

Explanation: High rate digesters are used when the capacity of tank is 4 million litres per day. Complete mixing and uniform feeding of raw sludge takes place in high rate digesters.