Performance Of Osmotic Membrane Bioreactor Research Articles

Surfactant addition to draw solution on the performance of osmotic membrane bioreactor

Surfactant addition to draw solution on the performance of osmotic membrane bioreactor

Effects of surfactant addition to draw solution on the performance of osmotic membrane bioreactor

This study investigated the effects of surfactant addition to the draw solution on the performance of osmotic membrane bioreactor (OMBR). Forward osmosis (FO) tests were conducted with the addition of sodium dodecyl benzene sulfonate (SDBS), a representative surfactant, to both inorganic and ionic organic draw solutions, including sodium chloride (NaCl), sodium acetate (NaOAc), and sodium propionate (NaPro), to determine the desirable draw solution for OMBR operation. Results show that SDBS impacts were more notable for inorganic draw solution in comparison to its ionic organic counterparts at the same osmotic pressure (60 bar) in FO operation. In specific, SDBS addition up to 5 mM considerably reduced the reverse diffusion of NaCl draw solute (approximately 69.7%) with insignificant impact on water flux. Thus, salinity build-up in the bioreactor could be effectively mitigated when SDBS was added to the NaCl draw solution in OMBR operation. This mitigation led to stable sludge characteristics and biological treatment to sustain OMBR performance regarding water production (approximately 10 L/m2h) and contaminant removal (e.g. over 90% for pharmaceutically active compounds).

Osmotic Membrane Bioreactor and Its Hybrid Systems for Wastewater Reuse and Resource Recovery: Advances, Challenges, and Future Directions

Osmotic membrane bioreactor (OMBR), which integrates forward osmosis (FO) with biological treatment process, has been recently developed to advance wastewater treatment and reuse. During OMBR operation, driven by osmotic pressure gradient, biologically treated water transports from the mixed liquor, through a semi-permeable FO membrane, into a highly concentrated draw solution. Compared to conventional MBR, OMBR has several advantages, including better product water quality, lower fouling propensity, and higher fouling reversibility. OMBR can be operated in the osmotic dilution mode when the draw solution, such as liquid fertilizers or seawater, can be reused or discharged directly. In most cases, OMBR is integrated with an additional process, commonly including reverse osmosis, membrane distillation, and electrodialysis, to form hybrid systems for sustainably reconcentrating draw solutions and producing clean water for reuse. In addition, several membrane processes, such as microfiltration, ultrafiltration, and electrodialysis, are combined with OMBR to address its inherent issue, salinity build-up in the bioreactor, and achieve resource (e.g., nutrients and energy) recovery. This review aims to provide a comprehensive understanding on the performance of OMBR and its hybrid systems in wastewater reuse and resource recovery. OMBR analogs and their performance are also systematically introduced. Key technical challenges and their potential solutions to the further development of OMBR and its hybrid systems are highlighted. This review sheds light on future research for the further development of OMBR and its hybrid systems.

Osmotic versus conventional membrane bioreactors integrated with reverse osmosis for water reuse: Biological stability, membrane fouling, and contaminant removal

This study systematically compares the performance of osmotic membrane bioreactor – reverse osmosis (OMBR-RO) and conventional membrane bioreactor – reverse osmosis (MBR-RO) for advanced wastewater treatment and water reuse. Both systems achieved effective removal of bulk organic matter and nutrients, and almost complete removal of all 31 trace organic contaminants investigated. They both could produce high quality water suitable for recycling applications. During OMBR-RO operation, salinity build-up in the bioreactor reduced the water flux and negatively impacted the system biological treatment by altering biomass characteristics and microbial community structure. In addition, the elevated salinity also increased soluble microbial products and extracellular polymeric substances in the mixed liquor, which induced fouling of the forward osmosis (FO) membrane. Nevertheless, microbial analysis indicated that salinity stress resulted in the development of halotolerant bacteria, consequently sustaining biodegradation in the OMBR system. By contrast, biological performance was relatively stable throughout conventional MBR-RO operation. Compared to conventional MBR-RO, the FO process effectively prevented foulants from permeating into the draw solution, thereby significantly reducing fouling of the downstream RO membrane in OMBR-RO operation. Accumulation of organic matter, including humic- and protein-like substances, as well as inorganic salts in the MBR effluent resulted in severe RO membrane fouling in conventional MBR-RO operation.