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
Aerobic biological oxidation ponds used for the purification of polluted water
A Destroys/removes pathogen from the sewage
B Is not very effective for nonbiodegradable substances (e.g. ABS) containing effluents
C Destroys/removes pathogen much more effectively if the sewage is chlorinated
D All of the above
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 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
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
Radioactive substances present in the polluted water stream can be removed by
A Biological oxygen treatment
B Coagulation and filtration
C Adsorption in ion exchange materials
D None of these
How the biological oxygen demand gets affected with the increased presence of organic matter in water?
A the oxygen demand increases
B the oxygen demand decreases
C the oxygen demand remains unchanged
D none of the mentioned

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