Q.1.
Percentage of bacterial load that can be removed from water by the process of plain sedimentation is about
Q.2.
The type of sewer which is suitable for both combined and separate system is
Q.3.
The dissolved oxygen level in natural unpolluted waters at normal temperature is found to be of the order of
Q.4.
The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is
Q.5.
The maximum permissible limit for fluoride in drinking water is
Q.6.
Sludge volume index is defined as the ratio of
Q.7.
Cleaning is done by (i) Scraping and removal in filters slow sand (ii) Back washing in slow sand filters (iii) Scraping and removal in filters rapid sand (iv) Back washing in rapid sand filtersThe correct answer is
Q.8.
The amount of coagulant needed for coagulation of water increases with (i) Increase in turbidity of water (ii) Decrease in turbidity of water (iii) Increase in temperature of water (iv) Decrease in temperature of waterThe correct answer is
Q.9.
The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about
Q.10.
Which of the following retards the self purification of stream?
Q.11.
Sewage treatment units are normally designed for
Q.12.
The polluted water is one which
Q.13.
Activated carbon is used for
Q.14.
Generally the detention period for grit chambers is kept as
Q.15.
In a BOD test, 1.0 ml of raw sewage was diluted toml 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
Q.16.
Sewerage system is usually designed for
Q.17.
The biochemical treatment of sewage effluents is essentially a process of
Q.18.
The minimum and maximum diameters of sewers shall preferably be