A closed-loop forward osmosis-nanofiltration hybrid system: Understanding process implications through full-scale simulation

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>

Community Forestry in Bhutan

Sonam Phuntsho 한국농촌경제연구원 2014 한국농촌경제연구원 연구자료 Vol.- No.-

A comprehensive review of hybrid forward osmosis systems: Performance, applications and future prospects

Chekli, L.,Phuntsho, S.,Kim, J.E.,Kim, J.,Choi, J.Y.,Choi, J.S.,Kim, S.,Kim, J.H.,Hong, S.,Sohn, J.,Shon, H.K. Elsevier Scientific Pub. Co 2016 Journal of membrane science Vol.497 No.-

Forward osmosis (FO) has been increasingly studied in the past decade for its potential as an emerging low-energy water and wastewater treatment process. However, the term ''low-energy'' may only be suitable for those applications in where no further treatment of the draw solution (DS) is required either in the form of pretreatment or post-treatment to the FO process (e.g. where the diluted DS is the targeted final product which can be used directly or simply discarded). In most applications, FO has to be coupled with another separation process in a so-called hybrid FO system to either separate the DS from the final product water or to be used as an advanced pre-treatment process to conventional desalination technologies. The additional process increases the capital cost as well as the energy demand of the overall system which is one of the several challenges that hybrid FO systems need to overcome to compete with other separation technologies. Yet, there are some applications where hybrid FO systems can outperform conventional processes and this study aims to provide a comprehensive review on the current state of hybrid FO systems. The recent development and performance of hybrid FO systems in different applications have been reported. This review also highlights the future research directions for the current hybrid FO systems to achieve successful implementation.

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.

Graphene oxide incorporated polysulfone substrate for the fabrication of flat-sheet thin-film composite forward osmosis membranes

Park, M.J.,Phuntsho, S.,He, T.,Nisola, G.M.,Tijing, L.D.,Li, X.M.,Chen, G.,Chung, W.J.,Shon, H.K. Elsevier Scientific Pub. Co 2015 Journal of membrane science Vol.493 No.-

The preparation and performances of the newly synthesized thin film composite (TFC) forward osmosis (FO) membranes with graphene oxide (GO)-modified support layer are presented in this study. GO nanosheets were incorporated in the polysulfone (PSf) to obtain PSf/GO composite membrane support layer. Polyamide (PA) active layer was subsequently formed on the PSf/GO by interfacial polymerization to obtain the TFC-FO membranes. Results reveal that at an optimal amount of GO addition (0.25wt%), a PSf/GO composite support layer with favorable structural property measured in terms of thickness, porosity and pore size can be achieved. The optimum incorporation of GO in the PSF support layer not only significantly improved water permeability but also allowed effective PA layer formation, in comparison to that of pure PSf support layer which had much lower water permeability. Thus, a TFC-FO membrane with high water flux (19.77Lm<SUP>-2</SUP>h<SUP>-1</SUP> against 6.08Lm<SUP>-2</SUP>h<SUP>-1</SUP> for pure PSf) and reverse flux selectivity (5.75Lg<SUP>-1</SUP> against 3.36Lg<SUP>-1</SUP> for pure PSf) was obtained under the active layer facing the feed solution or AL-FS membrane orientation. Besides the improved structural properties (reduced structural parameter, S) of the support layer, enhanced support hydrophilicity also contributed to the improved water permeability of the membrane. Beyond a certain point of GO addition (≥0.5wt%), the poor dispersion of GO in dope solution and significant structure change resulted in lower water permeation and weaker mechanical properties in support as well as FO flux/selectivity of consequent TFC membrane. Overall, this study suggests that GO modification of membrane supports could be a promising technique to improve the performances of TFC-FO membranes.

Environmental and economic impacts of fertilizer drawn forward osmosis and nanofiltration hybrid 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>

Sulfur-containing air pollutants as draw solution for fertilizer drawn forward osmosis desalination process for irrigation use

Tran, V.H.,Phuntsho, S.,Park, H.,Han, D.S.,Shon, H.K. Elsevier 2017 Desalination Vol.424 No.-

This study investigated suitability and performance of the sulfur-based seed solution (SBSS) as a draw solution (DS), a byproduct taken from the photoelectrochemical (PEC) process where the SBSS is used as an electrolyte for H<SUB>2</SUB> production. This SBSS DS is composed of a mixture of ammonium sulfate ((NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB>) and ammonium sulfite ((NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>3</SUB>), and it can be utilized as fertilizer for fertilizer drawn forward osmosis (FDFO) desalination of saline water. The FDFO process employed with thin-film composite (TFC) membrane and showed that the process performance (i.e. water flux and reverse salt flux) is better than that with cellulose triacetate (CTA) membrane. In addition, it produced high water flux of 19LMH using SBSS as DS at equivalent concentration at 1M and 5g/L NaCl of feed solution (model saline water). Experimental results showed that the reverse salt flux of SBSS increased with the increase in pH of the DS and that lowering the concentration of ammonium sulfite in the SBSS led to the higher water flux of feed solution. The result also demonstrated that this SBSS is practically suitable for the FDFO process toward development of water-energy-food nexus technology using sulfur chemicals-containing air pollutant.

Nanofiltration for water and wastewater treatment - a mini review

Shon, H. K.,Phuntsho, S.,Chaudhary, D. S.,Vigneswaran, S.,Cho, J. Copernicus GmbH 2013 Drinking water engineering and science Vol.6 No.1

<P><p><strong>Abstract.</strong> The application of membrane technology in water and wastewater treatment is increasing due to stringent water quality standards. Nanofiltration (NF) is one of the widely used membrane processes for water and wastewater treatment in addition to other applications such as desalination. NF has replaced reverse osmosis (RO) membranes in many applications due to lower energy consumption and higher flux rates. This paper briefly reviews the application of NF for water and wastewater treatment including fundamentals, mechanisms, fouling challenges and their controls.</p> </P>

Development of thin-film composite membranes modified by nanomaterials for forward osmosis

Myoung Jun Park,Sherub Phuntsho,Ho Kyong Shon 대한환경공학회 2015 대한환경공학회 학술발표논문집 Vol.2015 No.10

Environmental and economic assessment of hybrid FO-RO/NF system with selected inorganic draw solutes for the treatment of mine impaired water

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>