Cross-Flow Microfiltration of Industrial Oily Wastewater: Experimental and Theoretical Consideration

Microfiltration of industrial oily wastewater was performed using polyamide membrane. A rectangular cross flow membrane cell was used for the experiments. Effects of different operating parameters such as transmembrane pressure drop and Reynolds numbers on the steady state permeate flux and oil rejection was investigated in detail. Initial oil concentration in the industrial oil-water emulsion was found to be 192mg/L with average oil droplet range size 0.01 to 47 mu m. The treated industrial oily water was characterized in terms of electrical conductivity, total dissolved solids (TDS), and chemical oxygen demand (COD). It was observed that the steady state permeate flux increased with transmembrane pressure drop and Reynolds numbers. The oil concentration in permeate was found to be around 4.5mg/L, after treatment, which was lower than the permissible discharge limit. The results showed that microfiltration was an efficient and ecologically suited technology for the treatment of industrial oily wastewater. The cross flow velocity was considered in both laminar and turbulent regimes. A model was proposed by combining of Brownian diffusion and shear-induced diffusion to predict the steady state permeate flux data at different Reynolds numbers and different transmembrane pressure drops.