Synthesis and application of polyacrylamide grafted magnetic cellulose flocculant for wastewater treatment

Abstract

A continuous presence of organic loads in palm oil mill wastewater treatment plants has lately risen as a major issue. This situation shows that coagulation-flocculation process should be overhauled in removing micro-size particles from palm oil mill effluent. Therefore, a direct flocculation process was proposed as pre-treatment to remove total suspended solid (TSS), turbidity, chemical oxygen demand (COD) and colour. In this study, a new polyacrylamide grafted onto magnetic cellulose extracted from oil palm empty fruit bunch (PAM-g-mcOPEFB) was successfully synthesised by using a microwave assisted synthesis method. The physical and chemical properties of PAM-g-mcOPEFB was characterized by using Fourier transform infrared spectroscopy, vibrating sample magnetometer, zeta potential and elemental analysis. A jar test method was employed to perform direct flocculation. The flocculation studies have been evaluated on anaerobically treated palm oil mill effluent suspension. Important parameters including flocculants dosage, pH of solution and settling time were varied to study the effects of these independent variables. For grafting synthesis study, the highest grafting percentage was achieved at 155.25%. It was observed that the best condition for the reduction of TSS, turbidity, COD, and colour were achieved at flocculants dosage of 1.5 g/L, pH of 8.0 and settling time of 30 minutes. Under this condition, the reduction of TSS, turbidity, COD, and colour was 82.97%, 88.62%, 53.23% and 91.76%, respectively. Prepared PAM-g-mcOPEFB also showed better performance when compared with cellulose, magnetic cellulose (mcOPEFB), polyacrylamide, and alum. In conclusion, direct flocculation by utilizing PAM-g-mcOPEFB can possibly be one of the best alternative flocculants to remove small particles of organic matters in palm oil mill treatment plants due to its simplicity and environmentally friendly method.