Energy recovery from produced water via reverse Electrodialysis: The role of heavy metals and soluble organics on process performance

Produced water (PW) is the largest by-product of oil and gas exploration, drilling and processing. PW salinity ranges from highly dilute solutions to saturated brines. This study investigates the potential use of salinity gradient power (SGP) for energy harvesting from PW generated from oil and gas exploration and processing. The study aims to evaluate the efficiency of reverse electrodialysis (RED) technology for harvesting SGP from PW and its dependence on various parameters such as feed concentration gradients, compositions, temperature and flow rate, as well as the presence of heavy metals and dissolved organic matter. Fourier transform infrared spectroscopy (FTIR) was used to study the interaction of phenol, nickel and zinc with the RED ion exchange membranes and their impact on power production. The study also explores the feasibility of utilizing the SGP of mixing PW streams for operating treatment processes such as nanofiltration (NF) and reverse osmosis (RO). According to our findings, when two PW streams with salinities of 150 g/L and 1 g/L are mixed, a maximum power output of nearly 8 kWh bbl(-1) of PW can be achieved using 1000 cells and an active membrane area of 0.25 m(2). Overall, this study provides valuable information for further research and development of RED technology for sustainable energy generation and management of PW by-products. Indeed, the energy extracted from the PW may be utilized to lessen the cost of its treatment and pave the way for its use in sustainable farming and landscaping.