Question

A wastewater has a BOD5 of 410 mg/L and is to be treated by a completely mixed type activated sludge process. The flow is 2 MGD. The rate constant is0.226

L/g MLVSS-hr/ The MLSS concentration is 3000 mg/L and the MLVSS content is 75% of the MLSS. The sludge density index is 9000 mg/L. If the residence time inside the reactor is 7h, what will be the effluent BOD5 concentration coming out of the biological reactor?

Fig: 1