Forward Osmosis Membrane Technology Research Articles

Effects of Critical Operation and Cleaning Parameters on Performances and Economic Benefits of Biogas Slurry Concentration by Forward Osmosis Membrane

Forward osmosis membrane technology (FO) shows potential application prospects in biogas slurry concentration, which is conducive to promoting the sustainable development of biogas projects. However, at present, the key influencing factors of membrane concentration using FO are not well understood. Therefore, this study analyzed the influence of draw solution concentration, pH, temperature and cross-flow velocity on the concentration efficiency of FO membrane, and optimized the operation parameters of FO membrane. The results showed that the concentration effect of the NaCl draw solution at pH 5 or 9 was better than that at pH 7. The order of factor influencing the water flux was as follows: draw liquid concentration > cross-flow velocity > operating temperature. The optimal combination obtained by orthogonal analysis was under 45 °C, with a cross-flow velocity of 1 L/min and the use of 1.5 mol/L NaCl as draw solution. The results of the membrane cleaning implied that the recovery rate of the fouled membrane after acid-base cleaning is significantly higher (88%) than other cleaning solutions. This research offers a scientific reference for applying positive osmosis technology to re-utilize biogas slurry resources.

Life cycle assessment of concentrated apple juice production in China: Mitigation options to reduce the environmental burden

Though many studies concern the agro-food sector and its environmental impacts in some countries worldwide, literature is quite rare in works regarding life cycle assessment (LCA) application on concentrated apple juice (CAJ) in China. However, China is a global leader in CAJ production and export, so the sustainability of which is of great consequence to apple farmers and stakeholders in its value chain. With its feasibility to assess and quantify all environmental inputs and outputs that occur at all phases of production, LCA is receiving increasing attention as a tool to support global sustainability initiatives. This paper represents one of the first studies on CAJ using the LCA method to present the environmental impacts and suggest feasible strategies to improve environmental performance. We find that the apple production phase is the main cause of environmental impacts, with a contribution up to 86.68%, while the juice production phase only accounts for 13.32%. For the apple production phase, fertilizers and pesticides represent more than 88.87% in all the categories considered. For the juice production phase, bio-pellets contribute more than 74.73% in eight of the eleven impact categories. Thus, fertilizers, pesticides, and bio-pellets were recognized to be the main hotspots. The scenario analysis indicates that the environmental impacts have a significant reduction (by 21.39–98.39%) in each category via reducing the number of fertilizers by 33, 38, and 35% for N, P2O5, and K2O, and 99% for pesticides, and 33.31% for bio-pellets, respectively. Urgently, the mitigation option should pay attention to the replacement of currently used fertilizers and pesticides, and bio-pellets used to traditional thermal concentration by the standards of organically produced in the apple production phase and forward osmosis membrane technology in the juice production phase simultaneously, which is most significant for the sustainable development of CAJ.

Advancement of forward osmosis (FO) membrane for fruit juice concentration

Simultaneous fruit juice concentration and preservation of the heat-sensitive sensorial and nutritional components is a challenging topic in food processing. Forward-osmosis (FO) membrane is one of the promising alternatives to concentrate juice at low temperature and pressure. There are a number of negative propensities in FO operation, inter alia, internal and external concentration polarization, organic fouling, and product contamination due to back salt diffusion from the draw solution. To address these issues, preparation methods have been developed to obtain highly hydrophilic membrane with low fouling tendency, concentration polarization, and solute diffusion. The desired membrane has been obtained by modifying active and support layers of the membrane. Draw solutions are also optimized recently with desirable characteristics such as low reverse salt permeation, easy to re-concentrate, favorable price, stable and minimal toxicity. This paper reviews mechanism and principle of FO membrane technology, recent advancement of the membrane (including membrane preparation and modification, and important parameters), as well as challenges and strategies for the future development of FO membranes in fruit juice concentration.

Research on Forward Osmosis Membrane Technology Still Needs Improvement in Water Recovery and Wastewater Treatment

Forward osmosis (FO) has become an evolving membrane separation technology to recover water due to its strong retention capacity, sustainable membrane fouling, etc. Although a good deal of research has been extensively investigated in the past decades, major challenges still remain as follows: (1) the novel FO membrane material properties, which significantly influence the fouling of the FO membranes, the intolerance reverse solute flux (RSF), the high concentration polarization (CP), and the low permeate flux; (2) novel draw solution preparation and utilization; (3) salinity build-up in the FO system; (4) the successful implementation of the FO process. This work critically reviews the last five years’ literature in development of the novel FO membrane material, structure in modification, and preparation, including comparison and analysis on the traditional and novel draw solutes coupled with their effects on FO performance; application in wastewater treatment, especially hybrid system and integrated FO system; fouling mechanism; and cleaning strategy as discussed in the literature. The current barriers of the research results in each hotspot and the areas that can be improved are also analyzed in detail. The research hotspots in the research and development of the novel membrane materials in various countries and regions have been compared in recent years, and the work of variation in pop research hotspots in the past 10 years has been analyzed and the ideas that fill the blank gaps also have been proposed.

Fabrication of high performance and durable forward osmosis membranes using mussel-inspired polydopamine-modified polyethylene supports

A thin film composite (TFC) forward osmosis (FO) membrane with high performance and superb durability was fabricated on a polydopamine (PDA)-modified polyethylene (DPE) support via an unconventional aromatic solvent-based interfacial polymerization (IP) method. The PDA coating uniformly hydrophilized the hydrophobic pristine polyethylene (PE) support, which enabled the long-term operation stability. The thin (∼8 μm) and highly porous support structure with interconnected pores was preserved after the PDA modification, leading to a remarkably low structural parameter (∼168 μm) of the support. In addition, the use of the toluene-based IP process allowed for the formation of a highly permselective polyamide selective layer on the hydrophilic DPE support, which was challenging with the conventional aliphatic solvent-based IP process. Hence, the prepared DPE-supported TFC (DPE-TFC) membrane exhibited unprecedented high FO performance, i.e., ∼4.5 times higher FO water flux and ∼63% lower specific salt flux (in FO mode) compared to the commercial HTI-CTA membrane. Furthermore, the DPE-TFC membrane possessed superior mechanical robustness, which guarantee durable operability and potential application even in mechanically harsh environments. Hence, the PE-supported FO membrane presents a new paradigm in FO membrane technology.

Berghof Membranes and Aquaporin announce joint development agreement

Berghof Membrane Technology GmbH and Danish water technology company Aquaporin A/S have signed a joint development agreement (JDA) as the companies take steps to commercialize tubular forward osmosis membrane technology.

Application of forward osmosis membrane technology for oil sands process-affected water desalination.

The extraction process used to obtain bitumen from the oil sands produces large volumes of oil sands process-affected water (OSPW). As a newly emerging desalination technology, forward osmosis (FO) has shown great promise in saving electrical power requirements, increasing water recovery, and minimizing brine discharge. With the support of this funding, a FO system was constructed using a cellulose triacetate FO membrane to test the feasibility of OSPW desalination and contaminant removal. The FO systems were optimized using different types and concentrations of draw solution. The FO system using 4 M NH4HCO3 as a draw solution achieved 85% water recovery from OSPW, and 80 to 100% contaminant rejection for most metals and ions. A water backwash cleaning method was applied to clean the fouled membrane, and the cleaned membrane achieved 77% water recovery, a performance comparable to that of new FO membranes. This suggests that the membrane fouling was reversible. The FO system developed in this project provides a novel and energy efficient strategy to remediate the tailings waters generated by oil sands bitumen extraction and processing.

Performance evaluation of sucrose concentration using forward osmosis

Concentrating sugar solutions is a common process used in the production of many food products for either dewatering a high value product or concentrating waste streams prior to disposal. Thermal and pressure-driven dewatering methods are widely used, but they are prohibitively energy intensive and hence, expensive. Osmotically driven membrane processes, like forward osmosis, may be a viable and sustainable alternative to these current technologies. Using NaCl as a surrogate draw solution, this investigation shows that forward osmosis processes can lead to sucrose concentration factors that far exceed current pressure-driven membrane technologies, such as reverse osmosis. For instance, a concentration factor of 5.7 was achieved by forward osmosis with a starting sucrose concentration of 0.29 M, compared to reported concentration factors of up to 2.5 with reverse osmosis. Water fluxes were found to be lower than those commonly obtained in reverse osmosis, which is a consequence of the significantly higher concentration factors in conjunction with internal concentration polarization. The latter is a common problem in forward osmosis processes that utilize current generation anisotropic polymeric membranes. Further advances in forward osmosis membrane technology would yield higher water fluxes and concentration factors.