A study of fixed-bed biofilm sequencing batch reactor for pollutant removal from agro-based industrial effluent
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Date
2008-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Water is one of the most vital components of the earth. It is not only essential for survival of animals and plants but also occupies a unique position in industrial development of nation. The agro-based industries consume considerable quantities of water during their processes and generate large volumes of effluents which ultimately pollute the environment. In present study, the raw and primary treated starch industry effluent from Riddhi Siddhi Gluco Biols (RSGB) Ltd., Pantnagar had been selected for pollutant load study and its mitigation by development of an appropriate technology. Sequential Batch Reactor (SBR) technology is basically a fill-and-draw activated sludge process. Fixed-bed Biofilm Sequencing Batch Reactors (FbSBR) used in present study is the modified version of SBR in which fixed media is used as support for biofilm formation under aerobic conditions with altering anoxic conditions. During the start-up operation, three 18 L bioreactors were operated in batch mode for 28 days with synthetic water solution for biofilm formation and substrate stabilization. After stabilization period of 28 days, these bioreactors were operated in continuous mode with 24 hr cycle/day. The type-A and B FbSBR were fed with raw and primary treated effluent respectively while control i.e. type-C with primary treated effluent. Experiments were conducted in four periods each having different anoxicaerobic hydraulic residence times (H anoxic = 3-12 hr and H aerobic = 6-15 hr) in order to determine the optimum HRT for highest pollutant removal. The total reaction time was kept constant at 18 hr for all operational periods. It was found that type-B FbSBR at HRT of H anoxic = 6 hr and H aerobic = 12 hr gave better removal efficiency for COD, BOD, TKN, total solids, total suspended solids, total dissolved solids, chloride and sulphate in comparison to the type-A and control. The experimental results indicated that anoxic and aerobic residence times in FbSBR significantly affected the system’s performance. Thus, in present study it was observed that FbSBR reduced the pollutants concentration, particularly organics and nitrogen more as compared to conventional sequential batch reactors (SBR). Therefore this technology can be considered as efficient and cost effective for the treatment of agro-based industrial effluent.
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