Small-Scale Operation of an Integrated Anaerobic Baffled Reactor and Biofilter: Factors Affecting Its Performance

Abstract

This study aims to evaluate the effect of factors influencing the performance of a small-scale operating wastewater treatment plant (WWTP) integrating anaerobic baffled reactor (ABR) and biofilters with temperature fluctuations in the psychrophilic–mesophilic range. Over nine months of monitoring, the overall removal efficiencies for total chemical oxygen demand (TCOD), soluble chemical oxygen demand, particulate chemical oxygen demand, total suspended solids, ammonia nitrogen (NH3–N), and phosphorus (P) were 92%, 82%, 98%, 98%, 49%, and 31%, respectively, on average. The ABR’s TCOD removal efficiency (57%) was about 20% lower than the simulated efficiency using the Bremen Overseas Research and Development Association (BORDA)’s ABR design model, implying that temperature fluctuation and intermittent wastewater flow are possibly the factors that most affect performance. Although it was lower than the expected efficiency, the global performance of the system is supported by the significant contribution of horizontal and vertical gravel biofilters. The effluent quality complies with the local standard for wastewater discharge, except for the high content of nitrogen and phosphorus concentrations, which can be used for crop irrigation. To improve the WWTP performance, we recommend using a primary settler considering the use of a chemically enhanced solid separation process to avoid overloading organic solids in the ABR operation.