Experimental and Techno-Economic Analysis of Polybenzimidazole Thin-Film Membranes for Efficient Pervaporation Desalination of Produced Water

Abstract

Produced water is a massive wastewater source generated by hydraulic fracturing during oil and gas extraction. Due to high salinity (3000 to >300,000 mg/L) and presence of organic (≤1000 mg/L) impurities, thermal- or membrane-based separation processes of produced water are very expensive and challenging. Elevated temperature membrane desalination processes can efficiently treat high-salinity produced water containing organic impurities, provided thermo-chemical robust membrane materials are developed. Here, a highly selective and dense polybenzimidazole (m-PBI) thin-film membrane was extensively evaluated with a simulated brine, representative of brine produced from the San Juan basin, and a real brine obtained from the Permian Basin to demonstrate its thermo-chemical robustness for the treatment of high-salinity produced water. The membrane showed extremely high stability in the brine solutions at elevated temperatures approaching 200 °C and 99.9% salt and organic rejection, producing high-purity distillate. A detailed techno-economic analysis was carried out for a multistage PBI membrane-based pervaporation process using experimentally obtained data scaled to industrial membrane thicknesses. A minimum cost of $3.49 m^–3 was calculated for an 18-stage pervaporation system to treat produced water, which is 50% lower than that compared to commercial brine concentrator technology for produced water treatment. More efficient elevated temperature pervaporation desalination is achieved by higher operating temperatures enabled by the thermo-chemical durability of the PBI membranes providing opportunities for efficient heat recovery.