Turbidity of raw water is a measure of

Aerobic bacterias

If 2% solution of a sewage sample is incubated for 5 days at 20°C and depletion of oxygen was found to be 5 ppm, B.O.D. of the sewage is

If the diameter of sewer is 225 mm, the gradient required for generating self cleansing velocity, is

Assertion (A) : Discharging the effluents from the oxidation ponds just up stream of lakes or reservoirs is undesirable.

Reason (R) : The discharged algae get settled in the reservoirs and cause anaerobic decomposition and other water qualities.

The width of a rectangular sewer is twice its depth while discharging 1.5 m/sec. The width of the sewer is

Pick up the correct statement from the following :

In olden days the type of section adopted in trunk and out fall sewers was

For the survival of fish in a river stream, the minimum dissolved oxygen is prescribed

Self-cleansing velocity is