The Effect of Organic Matter on Heavy Metals Removal from Simulated Wastewater using a Reverse Osmosis Membrane Process

Abstract The reverse osmosis (RO) technique is an effective method for producing potable water. It is commonly employed in water treatment facilities because of its lower cost and simplicity compared to other methods. The main challenge to the RO process is fouling, which leads to higher operating pressure, flux decline, and shortened membrane life. In this study, different simulated wastewater samples were used as feedwater to a lab‐scale RO membrane system to investigate the effect of organic matter on the removal of heavy metals. In addition, the effect of individual salts, heavy metals, and oil on scaling formation was studied. Experimental data showed that when various pollutants were added to the feedwater, the permeate flux dropped from 142.86 LMH to 45.91 LMH, and the percentages of rejection for Na + , Ca +2 , Mg +2 , Cu +2 , Cr +3 , and oil were 96.56 %, 87.5 %, 95.5 %, 100 %, 100 %, and 99.96 %, respectively. The Scanning Electron Microscope (SEM) images showed a thin fouling layer that partially covered the membrane surface where the feedwater contained only NaCl salt. In contrast, it showed a thick layer of organic fouling that entirely covered the membrane surface when the feedwater contained all the other contaminants. Moreover, the Atomic Force Microscopy (AFM) showed that when oil was added to the feedwater, numerous pores were plugged and the surface roughness of the fouled membrane was reduced to 0.91 nm. Overall, the findings showed that oil in the feedwater enhanced the removal percentages of salts and heavy metals because the removal efficiency exceeded 96 %. Furthermore, Cr +3 and oil were observed to reduce the permeate flux by 43 % and 49 %, respectively.