Application of response surface methodology (RSM) for optimisation of COD, NH3–N and 2,4-DCP removal from recycled paper wastewater in a pilot-scale granular activated carbon sequencing batch biofilm reactor (GAC-SBBR)

In this study, the potential of a pilot-scale granular activated carbon sequencing batch biofilm reactor (GAC-SBBR) for removing chemical oxygen demand (COD), ammoniacal nitrogen (NH3–N) and 2,4-dichlorophenol (2,4-DCP) from recycled paper wastewater was assessed. For this purpose, the response surface methodology (RSM) was employed, using a central composite face-centred design (CCFD), to optimise three of the most important operating variables, i.e., hydraulic retention time (HRT), aeration rate (AR) and influent feed concentration (IFC), in the pilot-scale GAC-SBBR process for recycled paper wastewater treatment. Quadratic models were developed for the response variables, i.e., COD, NH3–N and 2,4-DCP removal, based on the high value (>0.9) of the coefficient of determination (R2) obtained from the analysis of variance (ANOVA). The optimal conditions were established at 750 mg COD/L IFC, 3.2 m3/min AR and 1 day HRT, corresponding to predicted COD, NH3–N and 2,4-DCP removal percentages of 94.8, 100 and 80.9%, respectively.

► A pilot-scale GAC-SBBR was setup and operated in a real wastewater treatment plant. ► Optimisation of the pilot plant for recycled paper wastewater treatment was studied. ► RSM using CCFD was used to optimise HRT, AR and IFC. ► Quadratic models have been developed for the response variables. ► The optimum operating conditions were established using RSM.