A. Aeration is continued till stability
B. Aeration is done with an admixture of previously aerated sludge
C. Sludge is activated by constant stirring
D. Water is removed by centrifugal action
Related Mcqs:
- The moisture content of sludge is reduced from 90% to 80% in a sludge digestion tank. The percentage decrease in the volume of sludge, is_______________?
A. 25 %
B. 50 %
C. 10 %
D. 5 % - In a sludge digestion tank if the moisture content of sludge V1 litres is reduced from p1 % to p2 % the volume V2 is____________________?
A. [(100 + P1)/(100 – P2)] V1
B. [(100 – P1)/(100 + P2)] V1
C. [(100 – P1)/(100 – P2)] V1
D. [(100 + P2)/(100 – P1)] V1 - The sludge does not contain waste water from_________________?
A. Bath rooms
B. Wash basins
C. Kitchen sinks
D. Toilets - The rate of accumulation of sludge in septic tanks is recommended as____________________?
A. 30 litres/person/year
B. 25 litres/person/year
C. 30 litres/person/month
D. 25 litres/person/month - In a sludge tank, the gas mainly produced, is_________________?
A. Oxygen
B. Nitrogen
C. Hydrogen
D. Carbon dioxide - In normal conditions, the period for sludge digestion, is_______________?
A. 10 days
B. 20 days
C. 30 days
D. 60 days - Sludge banks are formed if sewage is disposed of in____________________ ?
A. Rivers
B. Seas
C. Lakes
D. None of these - The digested sludge from septic tanks, is removed after a maximum period of__________________?
A. 3 years
B. 3.5 years
C. 4 years
D. 5 years - The rate of accumulation of sludge per person per year, is_______________________?
A. 10 litres
B. 15 litres
C. 20 litres
D. 25 litres - pH value of sludge during alkaline regression stage, is__________________?
A. More than 7
B. Less than 7
C. Less than 6
D. More than 6
