Optimization of Coagulation–Flocculation Process for Organic Load Reduction in Latex Industry Wastewater Using Response Surface Methodology (RSM)

Abstract :

Wastewater generated from glove manufacturing industries, particularly latex-containing effluents, is challenging to treat due to the presence of refractory organic compounds, stable colloids, and various chemical additives. This study aimed to optimize the chemical coagulation–flocculation process to reduce the organic load of such wastewater using Response Surface Methodology (RSM). Three coagulants—aluminum sulfate (alum), ferric chloride (FeCl₃), and polyaluminum chloride (PAC)—were evaluated in combination with auxiliary coagulants, including lime and a polymeric polyelectrolyte (polyacrylamide). The experimental design was carried out using a Central Composite Design (CCD) comprising 26 experimental runs, with COD selected as the key performance indicator. The results showed that PAC outperformed the other coagulants in COD removal efficiency. Under optimal conditions, the combination of PAC, lime, and polyacrylamide achieved more than 89.5% COD removal, with respective concentrations of 211.5 mg/L (PAC), 41.5 mg/L (lime), and 2.1 mg/L (polyacrylamide), resulting in a residual COD concentration of approximately 183 mg/L. ANOVA results indicated that both the linear and quadratic effects of PAC, as well as its interaction with lime, were statistically significant (P < 0.01), and the second-order model demonstrated a strong fit with a high F-value. Overall, the combined use of PAC, lime, and polyacrylamide proved to be an effective, economical, and reliable method for the advanced treatment of latex-containing wastewater, potentially enabling compliance with discharge standards and facilitating reuse in agriculture.

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