Pick out the correct statement.
BOD of raw municipal sewage may be in the range of about __________ mg/litre.
Irradiation of water by ultraviolet light of suitable wavelength is commonly used for disinfection of water in
When the concentration of SO2 in air is greater than __________ ppm, it gives a pungent smell.
Presence of a certain minimum quantity of flourine is desirable in potable water to prevent
Pick out the wrong statement.
Which of the following is not an air pollutant ?
Presence of high concentration of ozone and smog in atmospheric air causes the
Algae growth in water is controlled by
__________ is removed from water by lime-soda process.
Most of the bacteria in sewage are
Shouting by a man at his full voice corresponds to a voice level of about __________ decibels.
Which of the following is the most major constituents of air pollutants ?
Carbonaceous particles having size less than 1 μm are called
__________ substances present in sewage are removed in grit chamber during sewage treatment.
The type of bacteria which is active in trickling filter during biological treatment of sewage is the __________ bacteria.
Presence of dissolved impurities of __________ is responsible for the red brownish color of water.
TLV of aldrin in public water supply system is about __________ μg/litre.
A gas is termed as non-toxic, if its maximum permissible concentration (TLV) ranges from __________ ppm.
Removal of __________ is accomplished by aeration of water.
Green house effect is accentuated by
Thermal pollution due to excessive heat & temperature in the working place causes
High concentration of carcinogenic hydrocarbon pollutants in atmospheric air causes
World environment day is observed every year on the 5th of
The major reason of hydrodynamic noise (i.e., noise resulting from liquid flow) is