Purification of oil produced water using ceramic membrane: an experimental and response surface model analysis

The treatment of produced water remains a pressing challenge in the oil and gas sector, given its complex mixture of dispersed oil, dissolved organics, salts, and suspended solids. In this study, we examined the performance of a ceramic α-Al₂O₃ membrane (50 nm pore size) under cross-flow operation for real produced water, across a practical range of pressures (1.3–7 bar) and temperatures (25–45 °C). Unlike many previous investigations that relied on synthetic emulsions or limited operating windows, this work uniquely combines real-field oily water testing with response surface modeling (RSM) and Sobol sensitivity analysis to disentangle the relative roles of pressure and temperature.

The membrane achieved oil-in-water (OIW) rejection between 78 % and 99.99 %, reducing concentrations to as low as 0.15 ppm. Turbidity rejection consistently exceeded 96 %, while TOC and COD reductions ranged from 30 to 60 % and 0.36–62 %, respectively. Permeate flux reached up to 150 L m⁻² h⁻¹, with apparent permeability values between 150 and 210 L m⁻² h⁻¹·bar⁻¹, and recovery peaked at 91 %. Sensitivity analysis identified pressure as the dominant operating parameter, whereas temperature introduced competing effects of viscosity reduction and fouling enhancement.

These results provide evidence that ceramic membranes can offer reliable separation performance for untreated produced water, while the integration of RSM and Sobol analysis delivers a novel quantitative framework for optimizing operating conditions. The study highlights both the opportunities and trade-offs of deploying ceramic membranes at scale, offering insights directly relevant to regulatory compliance and water reuse strategies in oilfield applications.