Application of Response Surface Methodology on Brewery Wastewater Treatment Using Chitosan as a Coagulant

Brewery wastewater (BWW) treatment seems to be challenging for conventional wastewater treatment processes. Hence, different processes (i.e., biological, physical, chemical, and advanced oxidation processes) have been investigated; however, reports on parametric optimization using statistical tools are scant. In this present study, the potential application of chitosan as a biopolymer coagulant in decontaminating BWW was investigated. Operating conditions were optimised using the central composite design in response surface methodology (RSM) with 16 experimental runs. The effect of process variables, i.e., pH (4-8), chitosan dose (2-4) g/L and contact time (15-45 min) on the removal of turbidity, total organic carbon (TOC), and orthophosphates were investigated. Experimental results obtained were statistically analysed using the analysis of variance (ANOVA) and second-order polynomial response predictive models as functions of input variables with a significant regression coefficient of R-2 > 0.95 at 95% confidence were obtained. At numerical optimum conditions of pH (8), chitosan dose (2 g/L), and contact time (43 min), validation experimental responses of 91% turbidity, 89% TOC, and 65% orthophosphate removals were obtained at a standard deviation of +/- 0.588, +/- 0.395, and +/- 3.603, respectively. The validation results at optimum conditions suggest that proper adjustment of pH, chitosan dose, and contact time is imperative for maximising the efficiency of chitosan in treating BWW. Moreover, the findings of the current study demonstrate that chitosan can be used as a viable bio-coagulant in BWW treatment prior to being discharged into water receiving bodies.