Process Performance of a Granular Single Bioreactor with Continuous Feeding and Intermittent Discharge Regime Treating Dairy Wastewater

In this study, granulated sludge synthesized in a sequence batch reactor (SBR) and then granulated sludge was transferred to continuous feeding and intermittent discharge (CFID) bioreactor. Two independent variables (air flow rate and hydraulic retention time (HRT)) were considered to optimize the process. Subsequently, long term performance (150 days) of the bioreactor was assessed by monitoring nine responses. The process optimization in CFID regime was performed using a central composite face-centered design (CCFD) and analyzed using response surface methodology (RSM). Based on obtained data, the optimum conditions were achieved at HRT of 7-8 h and air flow rate of 2-3.5 L/min. The CFID with granular sludge acted as a high rate bioreactor as the granular sludge could provide high MLSS concentrations (around 10000 mg/L)  in a bioreactor.