A sustainable approach for industrial wastewater treatment using pomegranate seeds in flocculation-coagulation process: Optimization of COD and turbidity removal by response surface methodology (RSM)

Abstract

In this study, we presented a sustainable approach for industrial wastewater treatment through flocculation-coagulation process by using pomegranate seed powder as a novel natural alternative to the conventional chemical flocculants and coagulants. Pomegranate seeds are non-toxic, safe, locally available and free of charge as food-waste. The performance of Pomegranate seeds in treatment of paper recycling wastewater (PRWW) was optimized using response surface methodology (RSM) in terms of pH, dosage and settling time. The ZP, FTIR, EDX, XRD, BET and SEM analyses were performed for characterization of the flocs and flocculation-coagulation mechanism. The maximum removals of 87 % and 98 % were achieved for chemical oxygen demand (COD) and turbidity, respectively, under the optimum condition of Pomegranate seed dosage of 2391.91 mg/L, pH of 10.37 and settling time of 25 min (R2 = 0.988). According to the ZP analysis, adding pomegranate seeds increases the ZP of the PRWW from −11.7 mV to an isoelectric point (ZP ~ 0 mV) which results in particles coagulation through charge neutralization mechanism. The characterization analyses revealed that pomegranate seeds contain polysaccharides, proteins and fatty acids compounds that enable particles flocculation via inter-particle bridging mechanism. The findings of this study proved that pomegranate seed powder can be considered a promising, environmentally friendly and effective coagulant-flocculant agent for industrial wastewater treatment.