High-Performance Forward Osmosis Membranes Used for Treating High-Salinity Oil-Bearing Wastewater

Simultaneous Wastewater Treatment and Resources Recovery by Forward Osmosis Coupled with Microbial Fuel Cell: A Review

Osmotic microbial fuel cells (OsMFCs) with the abilities to simultaneously treat wastewater, produce clean water, and electricity provided a novel approach for the application of microbial fuel cell (MFC) and forward osmosis (FO). This synergistic merging of functions significantly improved the performances of OsMFCs. Nonetheless, despite their promising potential, OsMFCs currently receive inadequate attention in wastewater treatment, water reclamation, and energy recovery. In this review, we delved into the cooperation mechanisms between the MFC and the FO. MFC facilitates the FO process by promoting water flux, reducing reverse solute flux (RSF), and degrading contaminants in the feed solution (FS). Moreover, the water flux based on the FO principle contributed to MFC's electricity generation capability. Furthermore, we summarized the potential roles of OsMFCs in resource recovery, including nutrient, energy, and water recovery, and identified the key factors, such as configurations, FO membranes, and draw solutions (DS). We prospected the practical applications of OsMFCs in the future, including their capabilities to remove emerging pollutants. Finally, we also highlighted the existing challenges in membrane fouling, system expansion, and RSF. We hope this review serves as a useful guide for the practical implementation of OsMFCs.

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.

Seawater-driven forward osmosis for pre-concentrating nutrients in digested sludge centrate

Seawater-driven forward osmosis to enrich nutrients from sludge centrate and reduce membrane fouling is demonstrated. Due to enrichment and pH increase in the feed solution, without appropriate control measure, nutrient precipitation can occur directly on the membrane surface causing severe membrane fouling and reducing nutrient enrichment efficiency. Indeed without agitating the feed, there was less precipitation on the membrane surface, compared to with agitation. In addition, increase in the membrane area over permeate volume ratio significantly reduced the filtration time and nutrient precipitation. A novel technique to maintain the draw solution (DS) at an acidic condition was developed to improve nutrient enrichment and reduce membrane fouling. By using this technique and a high membrane surface to permeate volume ratio, nutrient enrichment similar to the theoretical efficiency was successfully demonstrated. Our technique reduced the filtration time to achieve 70% water recovery by over 90% (compared to unbuffered seawater as the DS, small membrane area, and feed agitation), as a result of significantly less membrane fouling. The amount of phosphorus precipitate on the membrane surface decreased by more than 10 times. The enrichment of ammonia and phosphorus as a function of water recovery was similar to the theoretical calculation, indicating negligible nutrient loss due to precipitation.