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Phuntsho, Sherub,Kim, Jung Eun,Hong, Seungkwan,Ghaffour, Noreddine,Leiknes, TorOve,Choi, Joon Yong,Shon, Ho Kyong Elsevier Scientific Pub. Co 2017 Desalination Vol. No.
<P><B>Abstract</B></P> <P>This study presents simulation of a closed-loop forward osmosis (FO)-nanofiltration (NF) hybrid system using fertiliser draw solution (DS) based on thermodynamic mass balance in a full-scale system neglecting the non-idealities such as finite membrane area that may exist in a real process. The simulation shows that the DS input parameters such as initial concentrations and its flow rates cannot be arbitrarily selected for a plant with defined volume output. For a fixed FO-NF plant capacity and feed concentration, the required initial DS flow rate varies inversely with the initial DS concentration or vice-versa. The net DS mass flow rate, a parameter constant for a fixed plant capacity but that increases linearly with the plant capacity and feed concentration, is the most important operational parameter of a closed-loop system. Increasing either of them or both increases the mass flow rate to the system directly affecting the final concentration of the diluted DS with direct energy implications to the NF process. Besides, the initial DS concentration and flow rates are also limited by the optimum recovery rates at which NF process can be operated which otherwise also have direct implications to the NF energy. This simulation also presents quantitative analysis of the reverse diffusion of fertiliser nutrients towards feed brine and the gradual accumulation of feed solutes within the closed system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Initial DS flow rate and concentration cannot be set at any arbitrary values. </LI> <LI> Initial DS flow rate and concentration vary inversely for a fixed plant capacity. </LI> <LI> Net DS mass flow rate <I>m</I> <SUB>D</SUB> is the most important parameter for a closed system. </LI> <LI> <I>m</I> <SUB>D</SUB> is constant for a fixed plant capacity but increases with capacity and feed TDS. </LI> <LI> FO and NF rejection rates influence feed solute accumulation in the closed system. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Dynamic perfomance of cellulose triacetate forward osmosis membrane system
심왕근,김상채,( Sherub Phuntsho ),( Ho Kyong Shon ) 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0
Water and energy scarcity are becoming worldwide issues. At present membrane based processes have been considered as promising approaches for solving these special problems. On the other hand, fertilizer driven forward osmosis (FDFO) process has recently received great interest in the agricultural area due to its feasible application for irrigation and relatively lower energy requirement for managing the process. In this work we comparatively examined the desalination characteristics of two spiral wound cellulose tri acetate (CTA) FO membranes using brackish groundwater. In particular the performance relationships between water flux and different operating conditions such as flow rate, concentration and osmotic pressure were investigated. In order to theoretically examine the FDFO desalination process, two-dimensional dynamic model was developed and used to evaluate the effect of operating process parameters on the system.
Kim, Jung Eun,Phuntsho, Sherub,Chekli, Laura,Hong, Seungkwan,Ghaffour, Noreddine,Leiknes, TorOve,Choi, Joon Yong,Shon, Ho Kyong Elsevier 2017 Desalination Vol.416 No.-
<P><B>Abstract</B></P> <P>Environmental and economic impacts of the fertilizer drawn forward osmosis (FDFO) and nanofiltration (NF) hybrid system were conducted and compared with conventional reverse osmosis (RO) hybrid scenarios using microfiltration (MF) or ultrafiltration (UF) as a pre-treatment process. The results showed that the FDFO-NF hybrid system using thin film composite forward osmosis (TFC) FO membrane has less environmental impact than conventional RO hybrid systems due to lower consumption of energy and cleaning chemicals. The energy requirement for the treatment of mine impaired water by the FDFO-NF hybrid system was 1.08kWh/m<SUP>3</SUP>, which is 13.6% less energy than an MF-RO and 21% less than UF-RO under similar initial feed solution. In a closed-loop system, the FDFO-NF hybrid system using a TFC FO membrane with an optimum NF recovery rate of 84% had the lowest unit operating expenditure of AUD $0.41/m<SUP>3</SUP>. Besides, given the current relatively high price and low flux performance of the cellulose triacetate and TFC FO membranes, the FDFO-NF hybrid system still holds opportunities to reduce operating expenditure further. Optimizing NF recovery rates and improving the water flux of the membrane would decrease the unit OPEX costs, although the TFC FO membrane would be less sensitive to this effect.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Environmental impacts of the FDFO-NF(TFC) hybrid system can be lower than RO hybrid systems. </LI> <LI> The FDFO-NF hybrid system consumes 21% less energy than the UF-RO hybrid system. </LI> <LI> The unit OPEX cost of FDFO-NF (TFC) system is 14% lower than UF-RO hybrid system. </LI> <LI> Improving flux and lowering the cost of the CTA FO membrane can make the FDFO-NF cost effective. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kim, Jung Eun,Phuntsho, Sherub,Ali, Syed Muztuza,Choi, Joon Young,Shon, Ho Kyong Pergamon Press 2018 Water research Vol.128 No.-
<P><B>Abstract</B></P> <P>This study evaluates various options for full-scale modular configuration of forward osmosis (FO) process for osmotic dilution of seawater using wastewater for simultaneous desalination and water reuse through FO-reverse osmosis (RO) hybrid system. Empirical relationship obtained from one FO membrane element operation was used to simulate the operational performances of different FO module configurations. The main limiting criteria for module operation is to always maintain the feed pressure higher than the draw pressure throughout the housing module for safe operation without affecting membrane integrity. Experimental studies under the conditions tested in this study show that a single membrane housing cannot accommodate more than four elements as the draw pressure exceeds the feed pressure. This then indicates that a single stage housing with eight elements is not likely to be practical for safe FO operation. Hence, six different FO modular configurations were proposed and simulated. A two-stage FO configuration with multiple housings (in parallel) in the second stage using same or larger spacer thickness reduces draw pressure build-up as the draw flow rates are reduced to half in the second stage thereby allowing more than four elements in the second stage housing. The loss of feed pressure (pressure drop) and osmotic driving force in the second stage are compensated by operating under the pressure assisted osmosis (PAO) mode, which helps enhance permeate flux and maintains positive pressure differences between the feed and draw chamber. The PAO energy penalty is compensated by enhanced permeate throughput, reduced membrane area, and plant footprint. The contribution of FO/PAO to total energy consumption was not significant compared to post RO desalination (90%) indicating that the proposed two-stage FO modular configuration is one way of making the FO full-scale operation practical for FO-RO hybrid system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Initial DS flow rate and pressure drop are important parameters for FO modulation. </LI> <LI> Single housing cannot accommodate above 4 FO elements due to DS pressure build-up. </LI> <LI> Multiple housing in the 2nd stage with thicker DS spacer reduces DS pressure build-up. </LI> <LI> The 2nd stage PAO enhances driving force and water flux and, reduces plant footprint. </LI> <LI> The 2-stage FO offers the best configuration with lower membrane area and energy use. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kim, Jung Eun,Phuntsho, Sherub,Chekli, Laura,Choi, Joon Yong,Shon, Ho Kyong Elsevier Scientific Pub. Co 2018 Desalination Vol. No.
<P><B>Abstract</B></P> <P>A hybrid forward osmosis (FO) and reverse osmosis (RO)/nanofiltration (NF) system in a closed-loop operation with selected draw solutes was evaluated to treat coal mine impaired water. This study provides an insight of selecting the most suitable draw solution (DS) by conducting environmental and economic life cycle assessment (LCA). Baseline environmental LCA showed that the dominant components to energy use and global warming are the DS recovery processes (i.e. RO or NF processes) and FO membrane materials, respectively. When considering the DS replenishment in FO, the contribution of chemical use to the overall global warming impact was significant for all hybrid systems. Furthermore, from an environmental perspective, the FO-NF hybrid system with Na<SUB>2</SUB>SO<SUB>4</SUB> shows the lowest energy consumption and global warming with additional considerations of final product water quality and FO brine disposal. From an economic perspective, the FO-NF with Na<SUB>2</SUB>SO<SUB>4</SUB> showed the lowest total operating cost due to its lower DS loss and relatively low solute cost. In a closed-loop system, FO-NF with NaCl and Na<SUB>2</SUB>SO<SUB>4</SUB> had the lowest total water cost at optimum NF recovery rates of 90 and 95%, respectively. FO-NF with Na<SUB>2</SUB>SO<SUB>4</SUB> had the lowest environmental and economic impacts. Overall, draw solute performances and cost in FO and recovery rate in RO/NF play a crucial role in determining the total water cost and environmental impact of FO hybrid systems in a closed-loop operation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The feasibility of FO hybrid systems for mine impaired water treatment was evaluated. </LI> <LI> SRSF and draw solute replenishment cost play a crucial role in reducing life cycle impacts of the FO hybrid systems. </LI> <LI> RO/NF permeate quality influences the total DS replenishment costs in a closed system. </LI> <LI> FO-NF with Na<SUB>2</SUB>SO<SUB>4</SUB> showed the lowest environmental and economic impacts. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>