Question

Explain the purpose for recycle flow in the high-rate trickling filter process.

Answer 1

High rate trickling filter are generally associated with increased H. R. T, incresed ventilation by reducing depth of filter. Because of which the contact time of biomass is less so lesser oxidation takes place. To overcome this drawback, recirculation is done i. e., returning a portion of treated or partially treated sewage to the treatment process.

The following are the advantages of recirculation

1. Uniform loading rate can be achieved.

2. Sewage gets diluted in this process.

3. Efficient B. O. D removal.

To further treat the nitrogenous matter, 2 stage filter is generally provided.