The performance and phase separated characteristics of an anaerobic baffled reactor treating soybean protein processing wastewater

A laboratory-scale anaerobic baffled reactor (ABR) with four compartments using soybean protein processing wastewater as organic loading rates (OLRs) was investigated for the performance and phase separated characteristics. It was found that the chemical oxygen demand (COD) removal efficiencies were 92–97% at 1.2–6.0 kg COD/m3 d feeding. The dominated species, propionate and butyrate, were found in the 1st compartment. Acetate was dominated in the 2nd compartment and then decreased in the 3rd and 4th. Meanwhile, 93% volatile fatty acids (VFAs) were removed in the 3rd and 4th compartments. In the 1st compartment, biogas revealed carbon dioxide (CO2) and hydrogen (H2). The highest H2 yield was found in the 2nd compartment, thereafter decreased from the 2nd to 4th which corresponded to the increased of the methane (CH4) yield. It indicated that the proper anaerobic consortium in each separate compartment was developed along with substrate availability and specific environmental conditions.