A. aerobic bacteria only
B. algae only
C. dual action of aerobic bacteria and anaerobic bacteria
D. sedimentation
Related Mcqs:
- Facultative bacteria are able to work in________________?
A. presence of oxygen only
B. absence of oxygen only
C. presence as well as in absence of oxygen
D. presence of water - In a BOD test, 1.0 ml of raw sewage was diluted to 100 ml and the dissolved oxygen concentration of diluted sample at the beginning was 6 ppm and it was 4 ppm at the end of 5 day incubation at 20°C. The BOD of raw sewage will be___________?
A. 100 ppm
B. 200 ppm
C. 300 ppm
D. 400 ppm - The main disadvantage of oxidation pond is that________________?
A. large area is required for construction
B. maintenance and operation cost are high
C. BOD removal is very low
D. none of the above - Which of the following sewers is preferred for combined system of sewage ?
A. circular sewer
B. egg shaped sewer
C. rectangular sewer
D. none of the above - Most suitable section of sewer in separate sewage system is________________?
A. rectangular section
B. circular section
C. standard form of egg shaped sewer
D. modified egg shaped section - The relative stability of a sewage sample, whose dissolved oxygen is same as the total oxygen required to satisfy BOD, is______________?
A. 1
B. 100
C. infinite
D. zero - If the sewage contains grease and fatty oils, these are removed in_________________?
A. grit chambers
B. detritus tanks
C. skimming tanks
D. sedimentation tanks - When there is no recirculation of sewage, then recirculation factor is_______________?
A. 0
B. 1
C. infinity
D. none of the above - Sewage treatment units are designed for_______________?
A. maximum flow only
B. minimum flow only
C. average flow only
D. maximum and minimum flow - The chemical most commonly used to increase speed of sedimentation of sewage is_______________?
A. sulphuric acid
B. copper sulphate
C. lime
D. sodium permanganate
