Study and evaluation of the characteristics of saline wastewater (brine) produced by desalination and industrial plants.

Desalination and industrial plants all around the world generate large amounts of saline wastewater (brine). The discharge of brine from facilities poses a severe environmental threat, while at the same time, the opportunity to recover resources is being lost as discharged brine is rich in valuable metals that could be recovered as salts/minerals. To this aim, this study presents and analyzes for the first time the characteristics of different brine effluents (from industries such as desalination, oil and gas production, petrochemical, aquaculture, pharmaceutical, textile) to prevent environmental pollution and to recover valuable resources (i.e., salts, minerals, metals, chemicals) enabling the concept of waste-to-resource (circular water economy model). The results revealed that the common salinity values in brine effluents range from 0.5 to 150 g/L, while the only exception is the produced water from the oil and gas industry (up to 400 g/L). Brine effluents from all sectors contain sodium, chloride, calcium, and potassium ions in high concentrations, while the production of common salts such as NaCl, CaCl, and MgCl from brine can be economically profitable. Besides common ions, precious metals such as lithium, rubidium, and cesium are present in low concentrations (<25 mg/L); however, their extraction from brine effluents can be significantly profitable due to their very high sale price. The treatment and valorization of brine can be implemented by the hybridization of membrane-based, chemical, biological, and thermal-based technologies/processes in minimal and zero liquid discharge (MLD/ZLD) systems.