Zero Liquid Discharge of Ultrahigh-Salinity Brines with Temperature Swing Solvent Extraction

Abstract

Zero liquid discharge (ZLD) of hypersaline brines is technically and energetically challenging. This study demonstrates ZLD of ultrahigh-salinity brines using temperature swing solvent extraction (TSSE), a membrane-less and nonevaporative desalination technology. TSSE utilizes a low-polarity solvent to extract water from brine and then releases the water as a product with the application of low-temperature heat. Complete extraction of water from a hypersaline feed, simulated by 5.0 M NaCl solution (≈292 g/L TDS), was achieved using diisopropylamine solvent. Practically all of the salt is precipitated as mineral solid waste and the product water contains <5% of NaCl relative to the hypersaline feed brine. Consistent ZLD performance of high salt removals and product water quality was maintained in three repeated semibatch TSSE cycles, highlighting recyclability of the solvent. The practical applicability of the technique for actual field samples was demonstrated by ZLD of an irrigation drainage water concentrate. This study establishes the potential of TSSE as a more sustainable alternative to current thermal evaporation methods for zero liquid discharge of ultrahigh-salinity brines.

Solute displacement in the aqueous phase of water–NaCl–organic ternary mixtures relevant to solvent-driven water treatment

“…The existence of an LL boundary provides an added potential for water selective solvent extraction. [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] To account for the phenomenon of liquid phase separation in the conceptual models, solubility limits were imposed for the aqueous phase in eqn (1) to describe a partially-miscible organic solvent, thereby superimposing a liquid-liquid phase equilibria Fig. 5 Ternary phase diagrams examining the aqueous-rich phase of water-NaCl-MOS for: (A) DMF when plotted monomolecularly and as a dimer; and (B) alcohols, acetone and MOS that exhibited a LL boundary in addition to a LS boundary.…”

“…The organic phase will selectively extract water from a brine inducing further precipitation of a salt. This water-selective extraction [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] is a mechanism distinct from FP. Several conceptual and mathematical models have been developed to describe FP, but those models ignore these distinct mechanisms, thereby oversimplifying the process.…”

Molecular Simulation of High-Salinity Brines in Contact with Diisopropylamine and Tripropylamine Solvents

“…Dipropylamine (DPA) was found to have a high salt rejection rate and efficient water recovery. 18 Also, Boo et al 19 for extracting water from high-salinity brines, with total dissolved solids as high as ∼292 g/L.…”

Thermodynamics of solvent-driven water extraction from hypersaline brines using dimethyl ether

“…Solvent-driven water extraction (SDWE) has the potential to efficiently desalinate highlysaline feed streams up to saturation using a partially water-miscible solvent [21][22][23][24][25][26][27][28][29][30][31][32]. In SDWE, the saline feed stream is contacted with an extraction solvent, typically an organic compound, in a liquid-liquid separator (LLS) forming two distinct liquid phases.…”