Enhanced Degradation of the Substrate Using Modified Upflow Anaerobic Sludge Blanket Reactor–Static Granular Bed Reactor Series with Varying Hydraulic Retention Time at Lab Scale

Abstract

The performance of a modified upflow anaerobic sludge blanket (MUASB) reactor with a modified three-phase separator and a rope matrix, combined with SGBR in series was analyzed for the treatment of synthetic wastewater. The performance of the reactor series in terms of chemical oxygen demand (COD) removal was evaluated by varying the operational hydraulic retention times (HRT) from 12 to 30 h. The optimum HRT for the reactor series was found to be 24 h, with a corresponding organic loading rate (OLR) of 8 kg COD/m3/day. The maximum overall COD removal of the reactor series of 98.75% ±0.62% was obtained with the corresponding overall biogas production of 0.339%±0.01 m3/kg CODdigested. The reactor series was found to be stable during the operational period in terms of volatile fatty acids (VFAs)/alkalinity ratio. The analytical hierarchy process was used for choosing a better treatment option among the alternatives based on the selected criteria. MUASB–static granular bed reactor (SGBR) series was found to be superior to the MUASB and the SGBR individually based on COD removal. The payback period for the reactor series was calculated to be 8 years (approximately). The MUASB-SGBR series was found to be robust, stable, and economical, with better performance in terms of COD removal.