A. 5-10 years
B. 15-20 years
C. 30-40 years
D. 40-50 years
Related Mcqs:
- Sewage treatment units are designed for_______________?
A. maximum flow only
B. minimum flow only
C. average flow only
D. maximum and minimum flow - 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 - A pipe conveying sewage from plumbing system of a single building to common sewer or point of immediate disposal is called________________?
A. house sewer
B. lateral sewer
C. main sewer
D. submain sewer - 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 - 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 - The characteristics of fresh and septic sewage respectively are____________________?
A. acidic and alkaline
B. alkaline and acidic
C. both acidic
D. both alkaline - The specific gravity of sewage is_______________?
A. much greater than 1
B. slightly less than 1
C. equal to 1
D. slightly greater than 1 - The chemical most commonly used to increase speed of sedimentation of sewage is_______________?
A. sulphuric acid
B. copper sulphate
C. lime
D. sodium permanganate
