Effect of Different Hydraulic Retention Time (HRT) on Sulfate Reduction in Anaerobic Baffled Reactor

Design and Method: The anaerobic baffled reactor (ABR) is a modification of upflow anaerobic sludge blanket (UASB) reactor. A laboratory scale ABR was inoculated with an effluent of a full scale anaerobic digester located in Kayseri Wastewater Treatment Plant, Turkey. Before inoculation, the sludge was sieved to remove coarse materials. The ABR was 20 cm wide, 80 cm long, 20 cm deep and constructed from glass, with a working volume of 19 L. Reactor was divided into four equal 4.75 L compartments by vertical baffles, each compartment having down-comer and riser regions created by further vertical baffle. The lower parts of down-comer baffles were angled at 45 degrees in order to direct the flow evenly through the riser. Ethanol and sulfate are consumed as electron donor and electron acceptor, respectively. Sulfate, dissolved sulfide, pH, alkalinity and chemical oxygen demand (COD) have measured three times a week. Aim: There are varying structures and concentrations of sulfate compounds in natural waters. In addition, the amount of sulfate is higher in some industrial wastewaters In addition, some industrial wastewaters and natural waters. Due to rise energy costs of existing aerobic systems, anaerobic systems have gained importance as an economic alternative to wastewater treatment. So that, recent studies have focused on anaerobic treatment of wastewaters containing sulfate. Anaerobic baffled reactor (ABR) from anaerobic systems is a good strategy for the reduction of sulfate. However, many parameters that affect the performance of anaerobic treatment of wastewater containing sulfate are available. In this study, treatability wastewater containing high sulfate concentration investigated the effect of hydraulic retention times (HRT). Results: The performance of different hydraulic retention times (2; 1.5; 1; 0.5 day) were observed in ABR operated for 120 days. In working conditions of HRT is 2 days COD and sulfate removal efficiciency, respectively, were observed in 88% and 84% while in working conditions of HRT is 0.5 days these efficiencies were observed in 80% and 75%. Also the yield of sulfur formation under the same conditions had risen from 75% to 96% in last compartment. Inferences and Original Value: In this study, in anaerobic baffled reactor treatment of wastewaters with high sulfate concentration has proven to be a good alternative. Effluent sulfate and sulphur concentrations have not effected from varying hydraulic retention times.