Optimization of coagulation-flocculation process in the treatment of wastewater from the brick-manufacturing industry

Brick manufacturing is a water-intensive industry that uses water, mainly potable, as a major raw material in its production process. It is therefore imperative that the wastewater generated by this industry is effectively treated for reutilization. There is limited study on how wastewater from the brick-manufacturing industry can be sustainably managed. Hence, this study was conducted to optimize treatment of wastewater generated by the brick manufacturing industry, employing coagulation-flocculation techniques. Commercially available flocculants, namely slightly anionic polyacrylamide (nPAM), anionic polyacrylamide (aPAM), cationic polyacrylamide (cPAM) and poly diallyldimethylammonium chloride (PDADMAC) were screened using the jar test procedure. The one-factor-at-a-time (OFAT) method was used to optimize the process. The nPAM gave optimal performance based on turbidity and suspended solids removal. Results of the evaluations showed an optimal dose of 0.8 mg L⁻¹ at a pH range of 7.2–7.4 and mixing speed of 200 rpm for 5 minutes, followed by 50 rpm for 15 minutes. Both turbidity and total suspended solids removal was approximately 98% at the optimal condition. This study has demonstrated that optimized coagulation-flocculation can produce treated water of high quality that can be reused to reduce mains water consumption and hence contribute to the industry's sustainability.