Related Questions

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
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
The detention period in coagulation tanks is usually kept as
A 1 to 2 minutes
B 30 to 45 minutes
C 2 to 6 hours
D 2 to 6 days
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
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
Generally the detention period for grit chambers is kept as
A 1 minute
B 5 minutes
C 24 hours
D 12 hours
The detention period for plain sedimentation water tanks, is usually
A 4 to 8 hours
B 8 to 16 hours
C 16 to 24 hours
D 24 to 36 hours
A survey was conducted among the students of Khulna University to find out how many forms of physical exercise usually swam, 25% said they usually did jogging, 20% said they played cricket, 15% said they usually played football and 20 respondents said they did not take any form of exercise. From the above findings it can be concluded that.
A The student of khulna University do not usually take physical exercise.
B No respondent took more than one form of exercise.
C The method of data collection was not valid.
D Some of the respondents took more than one form of exercise.
Four subjects ---physics, Chemistry, Mathematics and Biology ---were taught in four consecutive periods of one hour each starting from 8.00 a.m. At what time was the chemistry period scheduled? 1. Mathematics period ended at 10.00 a.m, which was preceded by Biology. 2. Physics was scheduled in the last period. 3. Mathematics period was immediately followed by Chemistry.
A Only 1
B Only 2
C Only 2 and 3
D Only 1 and either 2 or 3
The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally
A Less and more
B Less and less
C More and less
D More and more

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