Understanding the organic micropollutants transport mechanisms in the fertilizer-drawn forward osmosis process

© 2019 Elsevier Ltd We systematically investigated the transport mechanisms of organic micropollutants (OMPs) in a fertilizer-drawn forward osmosis (FDFO) membrane process. Four representative OMPs, i.e., atenolol, atrazine, primidone, and caffeine, were chosen for their different molecular weights and structural characteristics. All the FDFO experiments were conducted with the membrane active layer on the feed solution (FS) side using three different fertilizer draw solutions (DS): potassium chloride (KCl), monoammonium phosphate (MAP), and diammonium phosphate (DAP) due to their different properties (i.e., osmotic pressure, diffusivity, viscosity and solution pH). Using KCl as the DS resulted in both the highest water flux and the highest reverse solute flux (RSF), while MAP and DAP resulted in similar water fluxes with varying RSF. The pH of the FS increased with DAP as the DS due to the reverse diffusion of NH4+ ions from the DS toward the FS, while for MAP and DAP DS, the pH of the FS was not impacted. The OMPs transport behavior (OMPs flux) was evaluated and compared with a simulated OMPs flux obtained via the pore-hindrance transport model to identify the effects of the OMPs structural properties. When MAP was used as DS, the OMPs flux was dominantly influenced by the physicochemical properties (i.e., hydrophobicity and surface charge). Those OMPs with positive charge and more hydrophobic, exhibited higher forward OMP fluxes. With DAP as the DS, the more hydrated FO membrane (caused by increased pH) as well as the enhanced RSF hindered OMPs transport through the FO membrane. With KCl as DS, the structural properties of the OMPs were dominant factors in the OMPs flux, however the higher RSF of the KCl draw solute may likely hamper the OMPs transport through the membrane especially those with higher MW (e.g., atenolol). The pore-hindrance model can be instrumental in understanding the effects of the hydrodynamic properties and the surface properties on the OMPs transport behaviors

Investigation of pilot-scale 8040 FO membrane module under different operating conditions for brackish water desalination 2 3

Abstract 8 Two spiral wound forward osmosis (SWFO) membrane modules with different spacer design (CS; 9 corrugated spacer and MS; medium spacer) were investigated for the fertilizer drawn forward osmosis 10 desalination of brackish groundwater (BGW) at a pilot-scale level. This study mainly focused on 11 examining the influence of various operating conditions such as feed flow rate, total dissolved solids 12 (TDS) concentration of the BGW feed, and draw solution (DS) concentrations using ammonium 13 sulphate ((NH 4 ) 2 SO 4 , SOA) on the performance of two membrane modules. The feed flow rate played 14 a positive role in the average water flux of the pilot-scale FO membrane module due to enhanced 15 mass transfer coefficient across the membrane surface. Feed TDS and DS concentrations also played a 16 significant role in both FO membrane modules because they are directly related to the osmotic driving 17 force and membrane fouling tendency. CS module performed slightly better than MS module during 18 all experiments due to probably enhanced mass transfer and lower fouling propensity associated with 19 the corrugated spacer. Besides, CS spacer provides larger channel space that can accommodate larger 20 volume of DS and hence could maintain higher DS concentration. However, the extent of dilution for 21 the CS module is slightly lower. 22 2

Urine Treatment on the International Space Station: Current Practice and Novel Approaches

A reliable, robust, and resilient water recovery system is of paramount importance on board the International Space Station (ISS). Such a system must be able to treat all sources of water, thereby reducing resupply costs and allowing for longer-term space missions. As such, technologies able to dewater urine in microgravity have been investigated by different space agencies. However, despite over 50 years of research and advancements on water extraction from human urine, the Urine Processing Assembly (UPA) and the Water Processor Assembly (WPA) now operating on the ISS still achieve suboptimal water recovery rates and require periodic consumables resupply. Additionally, urine brine from the treatment is collected for disposal and not yet reused. These factors, combined with the need for a life support system capable of tolerating even dormant periods of up to one year, make the research in this field ever more critical. As such, in the last decade, extensive research was conducted on the adaptation of existing or emerging technologies for the ISS context. In virtue of having a strong chemical resistance, small footprint, tuneable selectivity and versatility, novel membrane-based processes have been in focus for treating human urine. Their hybridisation with thermal and biological processes as well as the combination with new nanomaterials have been particularly investigated. This article critically reviews the UPA and WPA processes currently in operation on the ISS, summarising the research directions and needs, highlighted by major space agencies, necessary for allowing life support for missions outside the Low Earth Orbit (LEO). Additionally, it reviews the technologies recently proposed to improve the performance of the system as well as new concepts to allow for the valorisation of the nutrients in urine or the brine after urine dewatering

Boron transport through polyamide-based thin film composite forward osmosis membranes

The boron transport in forward osmosis (FO) process using thin film composite (TFC) membranes has been investigated. Two common fertilizers were used as draw solutes and a model seawater as the feed. The influence of several physical and chemical operating conditions on boron solute flux and boron rejection rates was investigated. The examined factors include draw solution types, membrane orientation, feed and draw solution concentrations, boron feed concentration, crossflow rate, and feed solution pH. The key mechanisms that govern boron transports are reverse draw solute flux and internal concentration polarization experienced by the membrane during the FO process. Results show that the use of draw solute with small hydrated radius could improve boron rejection hindered by the higher reverse diffusion of draw solutes. The osmotic process operated in the pressure retarded osmosis (PRO) mode results in lower boron rejection. However, the most effective boron removal was achieved by operating the feed solution at high pH (pH = 11) because boron in the solution contains larger-size borate species, and thus increases boron rejection rate up to 94% by electrostatic repulsion. This study mainly focused on the performance of TFC membrane in boron removal. (C) 2014 Elsevier B.V. All rights reservedclose3

Critical flux on a submerged membrane bioreactor for nitrification of source separated urine

Membrane fouling is the biggest challenge in membrane based technology operation. Studies on critical flux mainly focused on membrane bioreactor for municipal wastewater and/or greywater treatment, which can significantly differ from the ultrafiltration membrane bioreactor (UF-MBRs) to treat source separated urine. In this work, the inhibitory factors on nitrifying bacteria activity were investigated for fast acclimation of nitrifying bacteria with high ammonium concentration and optimization of a high-rate partial nitrification MBR. The maximum nitrification rate of 447 +/- 50 mgN L-1 d(-1) was achieved when concentration of ammonia in feed urine is approximately 4006.3 +/- 225.8 mg N L-1 by maintaining desired pH around 6.2 and FA concentrations below 0.5 mgL(-1). Furthermore, for the first time, the impact of different operational and filtration conditions (i.e. aeration intensity, filtration method, imposed flux, intermittent relaxation, biomass concentration) on the reversibility of membrane fouling was carried out for enhancement of membrane flux and fouling mitigation. Fouling mechanisms for minor irreversible fouling observed under sub-critical condition were pore blocking and polarization. To mitigate membrane fouling, the UF module with effective membrane surface area of 0.02 m(2) is recommended to be operated at the aeration intensity of 0.4 m 3 h(-1), intermittent relaxation of 15 min, biomass concentration of 3.5 g L-1. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Simultaneous phosphorous and nitrogen recovery from source-separated urine: A novel application for fertiliser drawn forward osmosis

Re-thinking our approach to dealing with waste is one of the major challenges in achieving a more sustainable society. However, it could also generate numerous opportunities. Specifically, in the context of wastewater, nutrients, energy and water could be mined from it. Because of its exceptionally high nitrogen (N) and phosphorous (P) concentration, human urine is particularly suitable to be processed for fertiliser production. In the present study, forward osmosis (FO) was employed to mine the P and N from human urine. Two Mg2+-fertilisers, i.e. MgSO4 and Mg(NO3)(2) were selected as draw solution (DS) to dewater synthetic non-hydrolysed urine. In this process, the Mg2+ reverse salt flux (RSF) were used to recover P as struvite. Simultaneously, the urea was recovered in the DS as it is poorly rejected by the FO membrane. The results showed that, after concentrating the urine by 60%, about 40% of the P and 50% of the N were recovered. XRD and SEM EDX analysis confirmed that P was precipitated as mineral struvite. If successfully tested on real urine, this process could be applied to treat the urine collected in urban areas e.g., high-rise building. After the filtration, the solid struvite could be sold for inland applications whereas the diluted fertiliser used for direct fertigation of green walls, parks or for urban farming. Finally, reduction in the load of N, P to the downstream wastewater treatment plant would also ensure a more sustainable urban water cycle

Submerged module of outer selective hollow fiber membrane for effective fouling mitigation in osmotic membrane bioreactor for desalination

This paper investigated the membrane fouling mitigation efficacy and performance of a home-made submerged module containing outer selective hollow fiber thin film composite forward osmosis (OSHF TFC FO) membrane in osmosis membrane bioreactor (OMBR) system treating municipal wastewater for desalination. Initial tests, optimization of draw solution flowrate and pumping mode for the submerged module were carried out before it was applied into the OMBR system. Overall, the OMBR system exhibited an initial water flux of approximately 6.3 LMH using 35 g/L NaCl as draw solution, and high removal efficiencies of bulk organic matter and nutrients. Moreover, membrane fouling was effectively mitigated with slow rate of flux decline during 33-day operation of the OMBR system. These results indicated that the submerged membrane module of OSHF TFC FO membrane has stable and reliable performances making it suitable for OMBR supplication without the need of air scouring to prevent membrane fouling.- Qatar National Research Fund (QNRF) - grant #NPRP 9-052-2-020. - Australian Research Council (ARC) - grant #IH170100009. - Bhutan Trust Fund for Environmental Conservation (BTFEC) - grant #MB0167Y16

Removal of organic micro-pollutants by conventional membrane bioreactors and high-retention membrane bioreactors

The ubiquitous presence of organic micropollutants (OMPs) in the environment as a result of continuous discharge from wastewater treatment plants (WWTPs) into water matrices—even at trace concentrations (ng/L)—is of great concern, both in the public and environmental health domains. This fact essentially warrants developing and implementing energy-efficient, economical, sustainable and easy to handle technologies to meet stringent legislative requirements. Membrane-based processes—both stand-alone or integration of membrane processes—are an attractive option for the removal of OMPs because of their high reliability compared with conventional process, least chemical consumption and smaller footprint. This review summarizes recent research (mainly 2015–present) on the application of conventional aerobic and anaerobic membrane bioreactors used for the removal of organic micropollutants (OMP) from wastewater. Integration and hybridization of membrane processes with other physicochemical processes are becoming promising options for OMP removal. Recent studies on high retention membrane bioreactors (HRMBRs) such as osmotic membrane bioreactor (OMBRs) and membrane distillation bioreactors (MDBRs) are discussed. Future prospects of membrane bioreactors (MBRs) and HRMBRs for improving OMP removal from wastewater are also proposed

Techno-economic feasibility of recovering phosphorus, nitrogen and water from dilute human urine via forward osmosis

Due to high phosphorus (P) and nitrogen (N) content, human urine has often proven to suitable raw material for fertiliser production. However, most of the urine diverting toilets or male urinals dilute the urine 2 to 10 times. This decreases the efficiency in the precipitation of P and stripping of N. In this work, a commercial fertiliser blend was used as forward osmosis (FO) draw solution (DS) to concentrate real diluted urine. During the concentration, the urea in the urine is recovered as it diffuses to the fertiliser. Additionally, the combination of concentrate PO4 3-, reverse Mg2+ flux from the DS and the Mg2+ presents in the flushing water, was able to recover the PO4 3- as struvite. With 50% concentrated urine, 93% P recovery was achieved without the addition of an external Mg2+. Concurrently, 50% of the N was recovered in the diluted fertiliser DS. An economic analysis was performed to understand the feasibility of this process. It was found that the revenue from the produced fertilisers could potentially offset the operational and capital costs of the system. Additionally, if the reduction in the downstream nutrients load is accounted for, the total revenue of the process would be over 5.3 times of the associated costs