What can an operator do to reduce the effluent BOD of a Trickling Filter?

Raising the recirculation rate in a trickling filter system is an effective approach to reduce the effluent Biochemical Oxygen Demand (BOD). When the recirculation rate is increased, a larger volume of the effluent is returned to the filter. This practice enhances the contact between the wastewater and the biofilm on the filter media, providing more opportunities for the microorganisms to digest the organic material present in the influent.

As the microorganisms break down organic matter, the BOD in the effluent decreases. The increased flow of effluent being recirculated also helps maintain optimal conditions for microbial activity, such as moisture and nutrient exchange, further promoting the reduction of BOD levels.

In contrast, lowering the recirculation rate would minimize the interaction time between the effluent and the biofilm, likely resulting in higher BOD levels. Increasing the influent flow rate may not directly contribute to improving treatment efficiency and can overburden the system, leading to less effective treatment. Reducing sludge retention time could lead to the washout of active microorganisms, negatively impacting the capacity of the system to reduce BOD effectively.

Thus, raising the recirculation rate fosters an environment conducive to efficient organic matter breakdown, resulting in lower effluent B