Treatment of waste oil/water emulsion by ultrafiltration and ion exchange

The present work investigates the treatment of waste drawing oil which is a high-strength waste oil/water emulsion commonly used in the cable and wire industries. Semi-batch ultrafiltration (UF) and ion exchange processes were employed to treat the waste oil/water emulsion. Experiments were conducted to examine the performance characteristics of the UF membranes of hydrophilic and hydrophobic types and of different pore sizes. Ion exchange treatment using synthetic strong acid cationic and strong base anionic resins was used as the polishing step to further lower the permeate COD and copper concentration and to improve the turbidity and conductivity. The test results have shown very good performances of combined UF and ion exchange processes. The water quality of permeate from the combined treatment processes has been consistently excellent which permits direct discharge or can be considered for re-use. An economic evaluation and a simple flow chart of the treatment system are also presented to show its advantage over the current practice of waste drawing oil disposal.