Performance evaluation of anaerobic baffled reactor and filter for treating medium-strength wastewater using natural sludge growth and different hydraulic retention times

Abstract

The purpose of this study is to evaluate and compare the efficacy of an anaerobic baffled reactor (ABR) and an anaerobic filter (AF) in treating medium-strength wastewater under natural sludge growth conditions and different hydraulic retention times (HRT) of 12h and 24h. The ABR reactor has five compartments with a total capacity of 71 L, whereas the AF reactor with 70% sponge bio-media has five compartments with a total volume of 51 L. Both reactors required 13 weeks to achieve steady-state without adding sludge seeds during the startup phase. During that period, total suspended solid (TSS) removal was 80-90% in the AF and only 60-70% in the ABR. Furthermore, the average COD removal in the AF was determined to be 50-60% and 70-80% under HRT of 12h and 24h, respectively, but the ABR in these conditions could only accomplish 40-50%. To conclude, the AF reactor running under 24h HRT performs better than other conditions. In this case, it is due to the presence of 70% sponge bio-media in each compartment, which plays an important role in retaining suspended particles in the system. Furthermore, the initial attachment of sludge to sponge media may enhance the active microorganisms in the reactor, resulting in increased COD removal through organic digestion.