Response surface optimisation of a magnetic coagulation process for wastewater treatment via Box-Behnken

Abstract

In the wastewater treatment settings, conventional coagulants for wastewater treatment are becoming very complex with environmental concern. This necessitates the investigation for the use of magnetized rice starch as alternate coagulants. Herein, its application in the coagulation operational mechanism for decontamination of wastewater was investigated. The coagulation conditions were optimised via response surface methodology (RSM) based on a Box–Behnken design (BBD). Three operational parameters viz. coagulant dosage (2–4 g), settling time (15–30 min) and mixing rate (50–150 rpm) were investigated with their effects on turbidity and phosphate removal (at a wavelength of 880 nm) with 17 experimental runs by the BBD. Using the analysis of variance (ANOVA), the results obtained were analysed and quadratically modelled as a function of the input parameters with a significant regression coefficient (R2 > 0.96) at a 95% confidence level. At numerical optimum conditions of coagulant dosage (3.4 g), settling time (17.3 min) and mixing rate (103 rpm), 100% desirability treatability efficiency was attained with 100 distinctive conditional solutions. Interestingly, validation of the optimal condition revealed proper adjustment of the coagulant dosage and settling time can maximise the coagulation efficiency. Also, the findings demonstrated that the applicability of the magnetised rice starch in the wastewater settings can be used as a viable coagulant alternative.