A New Membrane Based Treatment Process for Reclaiming and Reutilization of Produced Water
The objective of this work was to optimize the operation of a zeolite nanofiltration membrane (Zebrex, manufactured by Mitsubishi Chemical) to remove the organic compounds from produced water (PW) that cause fouling of the RO membranes. TDA Research worked to develop a new treatment process and carried out proof-of-concept demonstrations at bench-scale and in a 1 bpd prototype using simulated and actual PW received from different fields. The TRL was elevated to 6 at the successful completion of the project. The performance of the Zebrex membranes for separating target impurities (e.g. volatiles organics, polyaromatics, ketones, phenols, amides, phosphate esters, methanol, glycol, and organic acids) was evaluated. Various versions of the Zebrex membranes with different pore sizes and surface properties were tested to determine the best combinations to reject the widest possible range of hydrocarbons. Bench-scale experiments were conducted to assess the impact of temperature and salinity on performance, and we discovered that when operated in pervaporation mode, the ceramic nanofiltration membrane can reject both hydrocarbons and salts in a single process step, altogether eliminating the need for an RO membrane. Pervaporation mode requires heating of the inlet feed water and transport of the water across the membrane in the vapor phase. The pore size of the membrane selectively rejects all molecules larger than water, and the lack of a liquid concentration gradient prevents mass transfer of ions (salts) across the membrane. Produced water is filtered for total suspended solids using a mechanical filter, heated to 120-150°C, and delivered to the membrane shell at moderate pressure < 50 psig. Water is transported through each tubular membrane element in the vapor phase and collected under vacuum in a clean permeate plenum. The clean water is cooled, condensed, and collected for use. The retentate stream is recycled back to the inlet of the membrane to conserve sensible heat and further concentrate the rejected contaminates in a waste stream. The water recovery is dependent on the solubility of salts in the produced water. TDA demonstrated the performance of the proposed PW purification system, showing that the treated water was free of both salt and soluble organic compounds. A techno-economic analysis (TEA) was developed and a prototype system capable of processing 1 bpd of PW to fit-for-purpose water was designed. In BP2, the prototype was fabricated and reclamation of fit-for-purpose water at 1 bpd scale was demonstrated. The membrane life was evaluated for over 8,000 hours. Proof-of-concept tests were carried out using actual PW samples received from multiple basins in collaboration with operators from those regions. A design of the full-scale system with all auxiliary units was conducted. Finally, the overall process was optimized and the TEA was updated based on the prototype performance demonstrating economic viability with a treatment cost less than the target of $3/bbl.
- Research Organization:
- TDA Research, Inc.
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- FE0031853
- OSTI ID:
- 1975283
- Type / Phase:
- SBIR (Phase II)
- Report Number(s):
- TDA-R-2201-012-PhIIF; TDA-R-2201-012
- Country of Publication:
- United States
- Language:
- English
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