During secondary treatment, major part of activated sludge is pumped into tanks called

1.  Aerobic sludge digesters.

2.  Anaerobic sludge digesters.

3.  Primary sludge digesters.

4.  Settling tanks.

Which of the following in sewage treatment removes suspended solids?

1. Secondary treatment

2. Primary treatment

3. Sludge treatment

4. Tertiary treatment

1. A-3, B-1, C-2, D-4

2. A-3, B-1, C-4, D-2

3. A-1, B-4, C-2, D-3

4. A-3, B-4, C-1, D-2

Match the items in Column ‘A’ and Column ‘B’ and choose correct answer:   

The correct answer is:

1. i B, ii D, iii C, iv A     

2. i C, ii D, iii B, iv A

3. i D, ii A, iii B, iv C         

4. i C, ii D, iii A, iv A

Which one of the following pairs is wrongly matched?

1. Methanogens - Gobar gas

2. Yeast - Ethanol

3. Streptomycetes - Antibiotic

4. Coliforms - Vinegar

Select the correct group of biocontrol agents:

1. Nostoc, Azospirillum, Nucleopolyhedrovirus

2. Bacillus thuringiensis. Tobacco mosaic virus, Aphids

3. Trichoderma, Baculovirus, Bacillus thuringiensis

4. Oscilatoria, Rhizobium, Trichoderma