Related Questions

Bacterial aerobic oxidation of polluted water in biological oxidation ponds is done to purify it. Presence of bacteria helps in
A Coagulation and flocculation of colloids
B Oxidation of carbonaceous matter to CO2
C Nitrification or oxidation of ammonia derived from breakdown of nitrogeneous organic matter to the nitrite and eventually to the nitrate
D All of the above
Biological oxidation ponds remove organic matters present in the polluted water by
A Using the activities of bacteria and other micro organisms
B Aerobic oxidation
C Both A & B
D Neither A nor B
A. some towns in Bangladesh are polluted B. All polluted towns should be destroyed C. Town Dhaka should be destroyed D. Town Dhaka is polluted E. Some towns in Bangladesh should be destroyed
A BDE
B BAE
C ADE
D CDB
Each question consists of five statements following by options consisting of three statements put together in a specific order. Choose the option which indicates a valid argument, that is, where the third statement is a conclusion drawn from the preceding two statements. A.Some towns in Bangladesh are polluted .B.All polluted towns should be destroyed.C.Town Dhaka should be destroyed.D.Town Dhaka is polluted.E.Some towns in Bangladesh should be destroyed
A BDE
B BAE
C ADE
D CDB
The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological decomposition of sewage, is known
A Bio-Chemical Oxygen Demand (B.O.D.)
B Dissolved Oxygen (D.O.)
C Chemical Oxygen Demand (C.O.D.)
D None of these
The amount of chemical coagulant added for treatment of polluted water __________ with increase in temperature of the polluted water to be treated.
A Decreases
B Increases
C Remains constant
D May increase or decrease ; depends on the chemical characteristics of polluted water
Lagoons used for purification of polluted water
A Are large shallow artificial lakes also known as clarification lakes, maturation ponds or oxidation ponds
B Use micro-organisms/bacteria in presence of dissolved oxygen
C Gives an excellent final effluent (with 3 to 4 lagoons arranged in series) having suspended solid
D All of the above
In sewage treatment, the detention period allowed for oxidation ponds ranges from __________ weeks.
A 1 to 2
B 4 to 5
C 9 to 10
D 15 to 20
The detention period for oxidation ponds is usually kept as
A 48 hours
B 24 hours
C 10 to 15 days
D 3 months
Coal mines drainage waste water (acidic in nature) results from the earth's water percolating through the voids created in coal bed during mining. This polluted water which either drains out naturally to water courses or are removed before starting the mining is
A Neutralised by alkali treatment
B Left as such without any treatment
C Diluted with fresh water to reduce its acidity
D None of these

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