Statistical analysis of treatment of rice mill wastewater using the aerobic inverse fluidized bed biofilm reactor (AIFBBR)

Abstract

Among the different industries, the ricemill industry is identified as one of the major polluting industries because of the large amounts of effluents generated and variations in the concentration of its constituents. The current experimental study aimed to investigate the treatment of ricemill (simulated) using the aerobic inverse fluidized bed biofilm reactor (AIFBBR). Box–Behnken design (BBD) based statiscal response surface methodology (RSM) was used for the current AIFBBR-ricemill treatment system. For the evaluation of the RSM process through the BBD technique, three input variables: Influent COD (800–3200 mg/L), HRT (12–24 h), and % bed volume (15 − 45), and two output variables: %COD and %TOC removal, were selected. The effect of these chosen variables was verified by conducting 15 experiments in a multivariate system for the AIFBBR-ricemill treatment system. The quadratic polynomial models yielded a regression coefficient (R2) of 0.99 (for both COD and TOC) when the experimental data were fitted to it, which indicates the model's suitability for the process. The precision and efficiency of the model were visualized using the ANOVA and lack of fit test. The system has witnessed the maximum COD (88.95%) and TOC (95.68%) removal at optimum parameters of 2804.27 mg/L of influent COD, 23.79 h of HRT, and at a % bed volume of 44.94. Along with the COD and TOC, parameters such as nutrients (NH4+-N, PO43--P, and NO3--N), phenol, and lignin were also monitored in the present study.