Removal of Trace Organic Chemicals and Performance of a Novel Hybrid Ultrafiltration-Osmotic Membrane Bioreactor

Abstract

A hybrid ultrafiltration-osmotic membrane bioreactor (UFO-MBR) was investigated for over 35 days for nutrient and trace organic chemical (TOrC) removal from municipal wastewater. The UFO-MBR system uses both ultrafiltration (UF) and forward osmosis (FO) membranes in parallel to simultaneously extract clean water from an activated sludge reactor for nonpotable (or environmental discharge) and potable reuse, respectively. In the FO stream, water is drawn by osmosis from activated sludge through an FO membrane into a draw solution (DS), which becomes diluted during the process. A reverse osmosis (RO) system is then used to reconcentrate the diluted DS and produce clean water suitable for direct potable reuse. The UF membrane extracts water, dissolved salts, and some nutrients from the system to prevent their accumulation in the activated sludge of the osmotic MBR. The UF permeate can be used for nonpotable reuse purposes (e.g., irrigation and toilet flushing). Results from UFO-MBR investigation illustrated that the chemical oxygen demand, total nitrogen, and total phosphorus removals were greater than 99%, 82%, and 99%, respectively. Twenty TOrCs were detected in the municipal wastewater that was used as feed to the UFO-MBR system. Among these 20 TOrCs, 15 were removed by the hybrid UFO-MBR system to below the detection limit. High FO membrane rejection was observed for all ionic and nonionic hydrophilic TOrCs and lower rejection was observed for nonionic hydrophobic TOrCs. With the exceptions of bisphenol A and DEET, all TOrCs that were detected in the DS were well rejected by the RO membrane. Overall, the UFO-MBR can operate sustainably and has the potential to be utilized for direct potable reuse applications.

Biodegradation of cellulose triacetate and polyamide forward osmosis membranes in an activated sludge bioreactor: Observations and implications

“…OMBR can significantly enhance the treatment of various trace organic contaminants (TrOCs) [6][7][8][9].…”

Performance of a Novel Fertilizer-Drawn Forward Osmosis Aerobic Membrane Bioreactor (FDFO-MBR): Mitigating Salinity Build-Up by Integrating Microfiltration

“…In fact, compared to conventional MBR, the OMBR process has a lower fouling tendency due to the osmotic driving force instead of hydraulic pressure [8][9][10]. Besides, MBR effluent still contains a number of viruses, ions, and trace organic compounds (TOrCs) which can potentially result in risks to human beings and the environment [11,12]. The high rejection of FO membrane can therefore provide a better rejection of contaminants and retain a significant portion of suspended solids; which is another advantage of this OMBR system compared to the conventional ones.…”

The role of forward osmosis and microfiltration in an integrated osmotic-microfiltration membrane bioreactor system

“…The FO membrane can effectively retain small organic contaminants in the bioreactor, thereby facilitating their subsequent biodegradation (Alturki et al, 2013;Coday et al, 2014). Indeed, recent studies have shown the excellent performance of OMBR for TrOC removal, particularly the compounds featured with a negative charge (Alturki et al, 2012;Lay et al, 2012;Holloway et al, 2014). Thus, OMBR can potentially produce high quality reclaimed water for potable reuse, irrigation, or direct discharge in environmentally sensitive areas.…”

“…The short SRT could also adversely affect the biological performance (Grelier et al, 2006). Several studies have recently proposed the integration of an microfiltration (MF) or ultrafiltration (UF) process with OMBR to bleed out inorganic salts from the bioreactor (Holloway et al, 2014(Holloway et al, , 2015Wang et al, 2014b). By applying the approach, Holloway et al (2014Holloway et al ( , 2015 showed a stable operation of a pilot UFO-MBR treating raw domestic wastewater over a period of four months.…”

“…Several studies have recently proposed the integration of an microfiltration (MF) or ultrafiltration (UF) process with OMBR to bleed out inorganic salts from the bioreactor (Holloway et al, 2014(Holloway et al, , 2015Wang et al, 2014b). By applying the approach, Holloway et al (2014Holloway et al ( , 2015 showed a stable operation of a pilot UFO-MBR treating raw domestic wastewater over a period of four months. Removal to below the detection limit was reported for 15 out of 20 TrOCs investigated in their study using a pilot reverse osmosis process for draw solution and clean water recoveries (Holloway et al, 2014).…”