A new concept to concentrate seawater up to 200 g/kg for producing vacuum salt using a reverse osmosis (RO) system hybridized with an electrodialysis (ED) system is presented. The RO system operates up to pressures of 120 bar and concentrates seawater up to 120 g/kg with the ED system concentrating RO brine to 200 g/kg. A parametric analysis to minimize the specific cost of brine concentration was conducted. Parameters varied were: the degree of RO-ED hybridization, ED current density, electricity prices and water prices. Optimal hybrid RO-ED designs reduced brine concentration costs by 33-70 % over standalone ED systems, with revenue generated from water co-production further subsidizing costs by 1-6 %. Optimizing ED current density reduced costs the most. Including a crystallizer, the total reduction in production cost over a standalone ED-crystallizer system was 19-55 %, with the production cost for a typical case being $111/tonne-salt. The proposed RO-ED-crystallizer (REC) systems were found to be techno-economically feasible in Cyprus, Japan, Kuwait, Saudi Arabia, and the USA. At a road transportation distance of 735 km, REC based seawater vacuum salt was competitive with conventional vacuum salt. REC systems may open up the potential of small-scale decentralized salt production.

There is an increasing need for the desalination of high concentration brine (>TDS 35,000 ppm) efficiently and economically, either for the treatment of produced water from shale gas/oil development, or minimizing the environmental impact of brine from existing desalination plants. Yet, reverse osmosis (RO), which is the most widely used for desalination currently, is not practical for brine desalination. This paper demonstrates technical and economic feasibility of ICP (Ion Concentration Polarization) electrical desalination for the high saline water treatment, by adopting multi-stage operation with better energy efficiency. Optimized multi-staging configurations, dependent on the brine salinity values, can be designed based on experimental and numerical analysis. Such an optimization aims at achieving not just the energy efficiency but also (membrane) area efficiency, lowering the true cost of brine treatment. ICP electrical desalination is shown here to treat brine salinity up to 100,000 ppm of Total Dissolved Solids (TDS) with flexible salt rejection rate up to 70% which is promising in a various application treating brine waste. We also demonstrate that ICP desalination has advantage of removing both salts and diverse suspended solids simultaneously, and less susceptibility to membrane fouling/scaling, which is a significant challenge in the membrane processes.

Despite its attractive features for energy saving separation, the performance of forward osmosis (FO) has been restricted by internal concentration polarization and fast fouling propensity that occur in the membrane sublayer. These problems have significantly affected the membrane performance when treating highly contaminated oily wastewater. In this study, a novel double-skinned FO membrane with excellent anti-fouling properties has been developed for emulsified oil-water treatment. The double-skinned FO membrane comprises a fully porous sublayer sandwiched between a highly dense polyamide (PA) layer for salt rejection and a fairly loose dense bottom zwitterionic layer for emulsified oil particle removal. The top dense PA layer was synthesized via interfacial polymerization meanwhile the bottom layer was made up of a zwitterionic polyelectrolyte brush - (poly(3-(N-2-methacryloxyethyl-N,N-dimethyl) ammonatopropanesultone), abbreviated as PMAPS layer. The resultant double-skinned membrane exhibited a high water flux of 13.7 ± 0.3 L/m2.h and reverse salt transport of 1.6 ± 0.2 g/m2.h under FO mode using 2 M NaCl as the draw solution and emulsified oily solution as the feed. The double-skinned membrane outperforms the single-skinned membrane with much lower fouling propensity for emulsified oil-water separation.

A zero brine discharge seawater desalination concept integrating reverse osmosis (RO), electrodialysis (ED) and crystallizer into a single system (REC) is presented. Analytical models were used to optimize parameters and minimize water production costs. Parameters varied were: the ratio of seawater to RO brine in the ED diluate channel, ED current density, ED diluate outlet salinity, electricity and salt prices, and RO recovery by adding high pressure RO (HPRO). Using only RO brine instead of only seawater in the ED diluate channel reduced water production costs by 87% from 27 to 3.5 $/m 3 while increasing salt production costs 26% from 135 to 170 $/tonne-salt. The former was best for brine minimization, and the latter for salt production.Optimizing ED current density reduced REC costs by another 14% to 3.0 $/m 3 while increasing specific energy consumption 26% to 12.7 kWh e /m 3 , corresponding to a Second Law efficiency of 18%. Adding an HPRO stage was uneconomical as it increased specific costs 21%. A salt price of 104.5 $/tonne-salt will justify the cost of adding an ED-crystallizer. REC systems may be economically feasible in parts of the Middle-East. Producing other products such as Mg(OH) 2 or Br 2 may further improve economics. , "Cost and energy needs of RO-ED crystallizer systems for zero brine discharge seawater desalination," Desalination, online

Carbon-based nanocomposite membranes have recently drawn tremendous attentions among membrane scientists due to their excellent chemical, mechanical stability and antifouling properties against oil deposition/adsorption.