Recirculation Factor in Low Rate Trickling Filter

The recirculation factor in a low rate trickling filter is a measure of the ratio of the volume of recirculated effluent to the volume of influent wastewater. It is also known as the recirculation ratio or the recirculation rate. The recirculation factor is an important operational parameter that affects the performance of the trickling filter in terms of organic removal efficiency, hydraulic loading rate, and biomass growth.

Definition of Recirculation Factor

The recirculation factor is defined as the ratio of the volume of effluent recycled back to the top of the trickling filter to the volume of influent wastewater applied to the filter. Mathematically, it can be expressed as:

Recirculation Factor = Qr / Qi

where Qr is the flow rate of recycled effluent and Qi is the flow rate of influent wastewater.

Importance of Recirculation Factor

The recirculation factor plays a crucial role in determining the hydraulic and biological characteristics of the low rate trickling filter. It affects the distribution of wastewater across the filter media, the contact time between the wastewater and the biomass, and the thickness and activity of the biofilm on the media.

Optimal Recirculation Factor

The optimal recirculation factor for a low rate trickling filter depends on various factors such as the nature and strength of the wastewater, the type and size of the filter media, the hydraulic loading rate, and the environmental conditions. Generally, a recirculation factor of 0.5 to 1.5 is recommended for most applications.

Answer

Therefore, the correct answer is option 'B' which means the recirculation factor in a low rate trickling filter is 1.