Feasibility of sequential anaerobic-aerobic integrated settler-based biofilm reactor for onsite treatment of domestic wastewater

Abstract

The present study investigates the applicability of sequential anaerobic aerobic integrated settler-based biofilm reactor (SAABR) for the onsite treatment of domestic wastewater. The main aim of the study is to overcome the inherent flaws in an anaerobic system as well as enhancing the effluent quality by means of aerobic post-treatment. The sequential system consisted of an anaerobic settler is followed by two biofilters, anaerobic as well aerobic in series. The first biofilter is anaerobic and the second one is aerobic. The system was run on two hydraulic loading conditions (steady and non-steady flow) with a 24-hour hydraulic retention time (HRT) for the anaerobic system and a 2-hour HRT of aerobic filters. It was found that the performance of the system at steady flow stood at 93.9 ± 2.6, 93.3 ± 1.8, 91.2 ± 4.2, 75.8 ± 3.8 and 98.7 ± 1.1% in terms of total suspended solids (TSS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN) and faecal coliform (FC), respectively while at non-steady flow, it decreased slightly. The Field Emission Scanning Electron Microscope (FESEM) showed the presence of anaerobic bacteria in the system. The system is able to overcome the major flaws of the anaerobic systems and able to deliver high effluent quality. The study demonstrated that the sequential system can be a sustainable alternative for the onsite treatment of domestic wastewater, particularly in rural areas of the developing countries like India.