Chemically enhanced primary treatment of municipal wastewater; Comparative evaluation, optimization, modelling, and energy analysis

Abstract

Wastewater treatment plants (WWTPs) are intended to be transformed from energy consumers into sources of energy. In this paper, we considered chemically enhanced primary treatment (CEPT) and conventional primary sedimentation treatment (CPST) reactors in the treatment of raw municipal wastewater, and their performance in terms of performance, sludge and methane production, and energy content. The optimization factors of coagulant (alum (AlSO4)), coagulant aid (polyelectrolyte), sedimentation time, and pH were analyzed by the response surface method (RSM). The results of the CPST reactor indicated that the TS, VS, TSS, VSS, and COD removal rates were 60%, 43%, 69%, 8.96%, and 45%, respectively. Meanwhile, the CEPT reactor was able to remove a high percentage of all pollutants (94.99% TS, 50.79% VS, 98.92% TSS, 95.40% VSS, and 95.70% COD) under optimum operation conditions, including a sedimentation time of 150 min, pH 7.9, coagulant aid 2.5 mg/L, and coagulant 106.2 mg/L.