In septic tanks__________________?
(A) Free board of 0.3 m may be provided
(B) The baffles or tees are extended up to top level of scum
(C) The clear space between the baffle top and covering slab is about 7.5 cm
(D) All the above
The factor responsible for purification of sewage in river is________________?
(A) Hydrology
(B) Dissolved oxygen in water
(C) Temperature
(D) All the above
To maintain aerobic biological activity, the moisture content of the compost mass should be about_________________?
(A) 45 %
(B) 50 %
(C) 55 %
(D) 60 %
The pH value of sewage is determined with the help of_________________?
(A) Imhoff Cone
(B) Turbid meter
(C) Potentiometer
(D) None of these
The normal value of over flow rates for plain primary sedimentation tanks, ranges between________________?
(A) 25,000 to 35,000 litres/sqm/day
(B) 40,000 to 50,000 litres/sqm/day
(C) 50,000 to 60,000 litres/sqm/day
(D) 80,000 to 100,000 litres/sqm/day
Which one of the following statements regarding septic tanks is wrong ?
(A) A gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided
(B) The outlet invert level is kept 5 to 7.5 cm below the inlet invert level
(C) The minimum width of septic level is 90 cm
(D) The depth of tank is kept equal to its width
In areas where rainy season is limited to a few months, the type of sewerage system recommended is__________________?
(A) Combined system
(B) Partially separate system
(C) Separate system
(D) None of these
In areas where light rains are uniformly distributed throughout the year, the type of sewerage system to be adopted is_______________?
(A) Separate system
(B) Combined system
(C) Partially combined system
(D) None of these
5 days-biochemical oxygen demand (BOD5) is taken at a temperature of_________________?
(A) 0°C
(B) 15°C
(C) 20°C
(D) 25°C
Pick up the in-correct statement from the following?
(A) Manholes are provided in sewer pipes at suitable intervals
(B) Catch basins are generally provided in sewers for carrying drainage discharge
(C) Inlets are generally provided in all sewers
(D) None of these