Question

What are the unit problems that may occur in biological wastewater treatment plants?

for example, sludge swelling, cause and solution. Please explain and write 4 problems and solutions.

#environmental engineering

Answer 1

The unit problems that may occur in wastewater treatment plants are as follows:-

1. Ponding problem :- in trickling filter when voids of medium particles gets choked and water does not pass due to the growth of algae and fungi due to excessive nutrients present in waste water. The surrounding gets flooded and ponding problem occurs.

To avoid this nutrients level should be less in waste water and algicides and fungicides like CuSo4 should be used and filter should be cleaned properly.

2. Odour problem :- when distribution of waste water is not continuous i.e intermittent or it gets stranded at one location due to obstruction in path then odour problem occurs. It occurs in oxidation pond, trickling filter etc.

To avoid it waste water supply should be continuous and obstruction. Proper cleaning should be done at regular intervals.

3. Sludge Bulking:- it occurs in secondary sedimentation tank after activated sludge process due to the formation of filamentous micro organisms due to low nutrient content, high sludge age or low F/M ratio ( less than 0.3 per day ).

To avoid it Chlorination should be done in secondary sedimentation tank or nutrient content is increased such that BOD5 : N2 : P ratio is 100:5:1.

4. Fly Nuissance :- it is a problem in which excessive flies are grown in waste water due to growth of larva or eggs of insects when the waste water is stagnant. It reduces the rate of removal. Occurs mostly in trickling filter when medium particles gets clogged.

To avoid it DDT is applied over the medium.

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