Using biofilter aerobic reactor for optimizing the hydraulic loading rate in nitrification process for tofu-manufacturing wastewater management

The working anaerobic reactor in the tofu-manufacturing industry generates wastewater as the effluent which contains high organic nitrogen, the largest pollutant to the surrounding irrigation system of tofu-manufacturing industries. To minimize the environmental problems, this type of wastewater requires a waste management strategy that can transform organic nitrogen from ammonia into nitrate through the nitrification pathway. This study aimed at optimizing the hydraulic loading rate (HLR) of tofu-manufacturing wastewater nitrification employing an aerobic biofilter reactor. The liquid waste was collected from the active hybrid upflow anaerobic sludge blanket reactor of the tofu-manufacturing industry located in Polonia Medan, Indonesia. Using laboratory-standardized techniques, the waste was characterized based on the suspended solids, volatile suspended solids, chemical oxygen demand (COD), ammonia, and nitrate. The result indicated that higher HLR was ineffective for ammonia and COD removals. Treating the wastewater using a biofilter reactor resulted in a brownish-yellow color, suggesting the success of the treatment. The elevation of nitrate content from 55.06 mg/L in the influent to 190.25-225.25 mg/L in the effluent suggests an effective nitrification process. Moreover, the optimizing HLR up to 38 hours at 0.1397 m3/m2 is considered the best condition for operating a biofilter reactor for the nitrification process of tofu wastewater treatment. Finally, effective HLR for nitrification using an aerobic biofilter reactor significantly reduces the danger of environmental pollution from the tofu-manufacturing industries through ammonia and COD minimization.