Desalinating a real hyper-saline pre-treated produced water via direct-heat vacuum membrane distillation

Yiming Liu; Jingbo Wang; Bongyeon Jung; Unnati Rao; Erfan Sedighi; Eric M V Hoek; Nils Tilton; Tzahi Y Cath; Craig S Turchi; Michael B Heeley; Y Sungtaek Ju; David Jassby

doi:10.1016/j.watres.2022.118503

Desalinating a real hyper-saline pre-treated produced water via direct-heat vacuum membrane distillation

Water Res. 2022 Jun 30:218:118503. doi: 10.1016/j.watres.2022.118503. Epub 2022 Apr 25.

Authors

Affiliations

¹ Department of Civil & Environmental Engineering, California NanoSystems Institute and Institute of the Environment & Sustainability, University of California Los Angeles (UCLA), Los Angeles, CA, United States.
² Department of Mechanical and Aerospace Engineering, UCLA, Los Angeles, CA, United States.
³ Department of Civil & Environmental Engineering, California NanoSystems Institute and Institute of the Environment & Sustainability, University of California Los Angeles (UCLA), Los Angeles, CA, United States; Energy Science & Distributed Resources Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
⁴ Department of Mechanical Engineering, Colorado School of Mines, Golden, CO, United States.
⁵ Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States.
⁶ Buildings & Thermal Science Center, National Renewable Energy Laboratory, Golden, CO, United States.
⁷ Department of Economics and Business, Colorado School of Mines, Golden, CO, United States.
⁸ Department of Civil & Environmental Engineering, California NanoSystems Institute and Institute of the Environment & Sustainability, University of California Los Angeles (UCLA), Los Angeles, CA, United States. Electronic address: jassby@ucla.edu.

PMID: 35500328
DOI: 10.1016/j.watres.2022.118503

Abstract

Membrane distillation (MD) is an emerging thermal desalination technology capable of desalinating waters of any salinity. During typical MD processes, the saline feedwater is heated and acts as the thermal energy carrier; however, temperature polarization (as well as thermal energy loss) contributes to low distillate fluxes, low single-pass water recovery and poor thermal efficiency. An alternative approach is to integrate an extra thermal energy carrier as part of the membrane and/or module assembly, which can channel externally provided heat directly to the membrane-feedwater interface and/or along the feed channel length. This direct-heat delivery has been demonstrated to increase single-pass water recovery and enhance the overall thermal efficiency. We developed a bench-scale direct-heated vacuum MD (DHVMD) process to desalinate pre-treated oil and gas "produced water" with an initial total dissolved solids of 115,500 ppm at a feed temperature ranging between 24 and 32 °C. We evaluated both water flux and specific energy consumption (SEC) as a function of water recovery. The system achieved a 50% water recovery without significant scaling, with an average flux >6 kg m^-2 hr^-1 and a SEC as low as 2,530 kJ kg^-1. The major species of mineral scales (i.e., NaCl, CaSO₄, and SrSO₄) that limited the water recovery to 68% were modeled in terms of thermodynamics and identified by scanning electron microscopy and energy-dispersive X-ray spectroscopy. In addition, we further developed and employed a physics-based process model to estimate temperature, salinity, water transport and energy flows for full-scale vacuum MD and DHVMD modules. Model results show that a direct-heat input rate of 3,600 W can increase single-pass water recovery from 2.1% to 3.1% while lowering the thermal SEC from 7,800 kJ kg^-1 to 6,517 kJ kg^-1 in an unoptimized module. Finally, the scaling up potential of DHVMD process is briefly discussed.

Keywords: Brine; Hyper-saline water; Membrane distillation; Mineral scale; Pre-treated produced water; Process modeling.

MeSH terms

Distillation* / methods
Hot Temperature
Membranes, Artificial
Vacuum
Water
Water Purification*

Substances

Membranes, Artificial
Water