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This paper presents studies on the interactions and effects of biomacromolecules compounds on forward osmosis (FO) membrane performance. Individual components and a combination of various organic substances such as bovine serum albumin (BSA), dextran, sodium alginate and xanthan gum were used as model feeds and tested for their influences on FO performance with the active layer of the FO hollow fiber membrane facing the feed solution (AL-FS). The interactions between foulants were examined by using fluorescence spectroscopy, rotational rheometry and laser doppler micro-electrophoresis techniques. For a system containing combined organic foulants, it was found that viscosity was not the dominant factor governing FO membrane fouling as the decrease in viscosity did not always result in less fouling. The effect of divalent cations on the FO fouling behavior was also studied by adding CaCl 2 . The presence of calcium ions has exacerbated the flux decline, this occurred particularly for any combined organic foulants containing alginate, due to intermolecular bridging among alginate molecules. It is interesting to note that combined BSA + alginate caused moderate flux decline, while BSA and alginate alone did not cause any observable water flux loss. The (BSA + alginate) fouling became more severe with the presence of calcium ions. [ABSTRACT FROM AUTHOR]

Produced water management is one of the key challenges faced by the oil and gas industry globally. Specifically, the gas industry in Qatar is challenged to minimize the produced/process water (PPW) volumes injected into disposal wells to ensure long term sustainability of the reservoirs. This research evaluated a novel application of forward osmosis (FO) to reduce the volumes of PPW disposed of by deep well injection using brine from thermal desalination plants or seawater as draw solutions. In the case of brines, this process also provides some environmentally beneficial dilution before discharge. In order to verify the PPW volume reduction concept, bench-scale FO experiments were carried out using commercial flat sheet membranes. FO performance was evaluated using PPW with and without pretreatment and results confirm that pretreatment is key to the successful implementation of FO for the treatment of PPW. Experimental results indicate that FO is effective in achieving 50% volume reduction of pretreated PPW with stable flux of 12 LMH. Lab analyses show that the TOC in the diluted draw solution was below the detection limit indicating that the TOC from the feed did not appear in the draw solution and hence would not be discharged to the environment. [ABSTRACT FROM AUTHOR]

In this paper, the viability of using micellar draw solutions (DS) for Forward Osmosis (FO) is presented for the first time. Above the critical micelle concentration (CMC) and the Krafft temperature (Tk), the monomers in a surfactant solution aggregate to form micelles, resulting in a relatively constant osmotic pressure above the CMC. These properties can be useful for a FO system in order to maintain a constant water flux and to enable draw solution regeneration at low energy. Three cationic and two anionic surfactants were studied at different concentrations as potential draw solutions for FO applications. Both flat sheet and hollow fiber FO membranes were used in the study. The study revealed that the micellar solutions generated more stable flux compared to other inorganic DS; the hypothesis of a constant flux above the CMC was valid only for concentrations slightly above the CMC, and micellar solutions behaved similar to inorganic solutes at concentrations significantly higher than the CMC. It was shown that external concentration polarization (ECP) does not have a significant effect in micellar solutions just above the CMC. Furthermore, all surfactants demonstrated between 3 and 300 times less reverse transport compared to NaCl at similar concentrations. Finally, the surfactant solute could be regenerated with recoveries as high as between 95% and 99%. It was thus verified that micellar solutions are an attractive DS for application to Forward Osmosis and potentially in the forward osmosis membrane bioreactor (FO-MBR). [ABSTRACT FROM AUTHOR]

Abstract: Great efforts from the membrane community have been devoted in developing suitable membranes for forward osmosis (FO) applications in recent years. In the current study, the layer-by-layer (LBL) polyelectrolyte assembly technique has been successfully applied onto a microporous polyethersulfone (PES) hollow fiber substrate to make novel LBL hollow fiber membranes suitable for FO process for the first time. The FO performance of the LBL hollow fibers with different numbers of deposited layers has been evaluated using deionized (DI) water as the feed and MgCl2 solution of various concentrations as the draw solution in both orientations. With 6 layers deposited and in the active layer facing draw solution (AL-facing-DS) orientation, the membrane showed high water fluxes of 14.6, 25.9 and 40.5L/m2 h with corresponding salt to water flux, J s /J v, ratio of 0.034, 0.066 and 0.201g/L using 0.05, 0.1 and 0.5M draw solution, respectively. These promising results demonstrate the potential application of the LBL hollow fibers in FO process using low concentration draw solutions, which can substantially reduce the draw solution replenishment, and the energy consumption for draw solution regeneration and separation. [Copyright &y& Elsevier]