A PILOT-SCALE STUDY ON PVA-GEL BASED MBBR FOR SEWAGE TREATMENT

Abstract

Since last decade, wastewater treatment technology has been improved in order to get higher removal efficiencies and to meet stringent effluent regulations. However, from a global perspective, wastewater treatment is facing a large number of challenges, especially in case of nutrient removal and hence resulting in concern for finding new technologies as well as modification and boosting the existing treatment processes in order to achieve better organics and nutrient removal efficiency. In this direction, biological nutrient and organic removal in biofilm processes have shown a potential advantage in comparison to existing treatment facilities like activated sludge processes. Moving Bed Biofllm Reactors (MBBRs) integrate advantages of both AS and fixed film process. MBBR process is an incessant flow process which uses moving carrier elements for providing sites for sessile biomass growth besides suspended biomass which permits greater biomass inventory in reactor. These processes have been reported giving higher organic and nutrient removal efficacies. The present study intends to assess a moving bed biofilm system for removal of organics and nutrients from actual municipal wastewater. The study was carried out at pilot scale. The pilot MBBR was based on PVA-gel (Poly Vinyl Alcohol hydrogel) carrier procured from Kuraray, Japan. The process condition variables were Hydraulic Retention Time (HRT) and temperature. The intluent was actual pre-treated domestic wastewater. The study was carried out in two phases at Jalandhar, Punjab and Srinagar. J&K. The first phase of study included optimisation of pilot and to evaluate the potential of media for removal of organics from municipal wastewater. The treatment scheme included two aerobic tank in series followed by a sedimentation tank. The results demonstrated high organic matter removal and almost complete nitrification with a HRT of 3.75 hours at ambient temperature. The second phase of study included optimisation of pilot and evaluating the potential performance of carrier for nutrient removal at low temperature conditions for real sewage. The treatment scheme included two aerobic tanks and one anoxic tank with PVA media in series followed by a clarifier. The results demonstrated not only nitrogen removal but also good organic removal efficacy even at the sub-zero (freezing) temperature conditions.