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Enhancing wastewater reuse by forward osmosis with self-diluted commercial fertilizers as draw solutes

Article

Enhancing wastewater reuse by forward osmosis with self-diluted commercial fertilizers as draw solutes

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Using fertilizers as draw solutes in forward osmosis (FO) can accomplish wastewater reuse with elimination of recycling draw solute. In this study, three commercial fast-release all-purpose solid fertilizers (F1, F2 and F3) were examined as draw solutes in a submerged FO system for water extraction from either deionized (DI) water or the treated wastewater. Systematic optimizations were conducted to enhance water extraction performance, including operation modes, initial draw concentrations and in-situ chemical fouling control. In the mode of the active layer facing the feed (AL-F or FO), a maximum of 324 mL water was harvested using 1-M F1, which provided 41% of the water need for fertilizer dilution for irrigation. Among the three fertilizers, F1 containing a lower urea content was the most favored because of a higher water extraction and a lower reverse solute flux (RSF) of major nutrients. Using the treated wastewater as a feed solution resulted in a comparable water extraction performance (317 mL) to that of DI water in 72 h and a maximum water flux of 4.2 LMH. Phosphorus accumulation on the feed side was mainly due to the FO membrane solute rejection while total nitrogen and potassium accumulation was mainly due to RSF from the draw solute. Reducing recirculation intensity from 100 to 10 mL min−1 did not obviously decrease water flux but significantly reduced the energy consumption from 1.86 to 0.02 kWh m−3. These results have demonstrated the feasibility of using commercial solid fertilizers as draw solutes for extracting reusable water from wastewater, and challenges such as reverse solute flux will need to be further addressed.
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... Some recent works have even used commercial fertilizers as DS (Chekli et al., 2017a;J.E. Kim et al., 2019;Xie et al., 2015;Zou and He, 2016). Besides, it should be noted that in most of the previous FDFO studies, authors highlight the need for further dilution because final concentration of nutrients in DS were above the threshold tolerated by the plants. ...
... The observed ions J s were different when using individual fertilizers or blended (MIX 1). In MIX 1, reverse fluxes followed the trend NO 3 >NH 4 >K > P (Table 4), which is inversely correlated to their hydrated radii at the same charge type (0.34, 0.25, 0.33, and 0.49 nm for NO 3 − , NH 4 + , K + , and PO 4 3− respectively) (Xie et al., 2015), and in accordance to other studies (Gulied et al., 2019;Zou and He, 2016). When using blended fertilizers (MIX 1), J s were found to be lower for K + and NO 3 − , but higher for NH 4 + (Table 4). ...
... For example, the standard Hoagland solution (Hoagland and Arnon, 1950), which is commonly used in hydroponic experiments, has been applied at half strength in some studies (Adrover et al., 2013;Garland et al., 2004;Wiser and Blom, 2016). In contrast to our results, the final DS concentrations obtained in previous studies (Chekli et al., 2017b;Majeed et al., 2015;Xie et al., 2015;Zou and He, 2016) ware way higher than those required for plant growth, so they pointed out the need for substantial dilution prior to application. Other studies showed the potential of FDFO systems to achieve an adequate DS dilution for direct application for plants, but assuming an unlimited FS volume (Phuntsho et al., 2011), which implies not considering the salinity buildup in the FS; or by applying extra pressure in order to increase the nutrient dilution in DS (Chekli et al., 2017a;Jamil et al., 2016;Sahebi et al., 2015). ...
Article
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There is a need for water reuse technologies and applications to minimize the imminent water crisis, caused by the world population growth, the reduction of freshwater resources and the increasing water pollution. Fertilizer-drawn forward osmosis (FDFO) is a promising process capable of simultaneously extracting fresh water from low-quality sources as feed water (e.g., wastewater or greywater), while diluting fertilizer solutions for direct fertigation, avoiding the demand for freshwater for irrigation. Achieving an adequate level of dilution for direct fertigation is a key element to be evaluated for the implementation of FDFO. This study assessed the performance of the forward osmosis process to dilute fertilizer solutions to be applied directly in hydroponic systems. Experiments were carried out under conditions close to osmotic equilibrium to evaluate the process performance up to the maximum dilution point. Tests were carried out with individual and blended fertilizers (i.e., (NH4)2HPO4 or DAP, and KNO3) used as draw solution (DS) and with deionized water or individual salts (NaCl, MgCl2, Na2SO4, MgSO4) in the feed solution (FS). Water fluxes and reverse salt fluxes indicated that both fertilizer DS composition and concentrations play a fundamental role in the process. Suitable nutrient concentrations to be directly applied without further dilution for N, P and K (119, 40, 264 mg.L⁻¹ respectively) were obtained with deionized water as FS and blended DAP (0.025 M) and KNO3 (0.15 M) as DS. However, important fertilizer losses from DS to FS were observed, being the highest for NO3⁻ (33–70% losses from DS to FS). The presence of salts in FS decreased the water fluxes and the DS dilution due to the osmotic equilibrium caused by a greater loss of nutrients from DS to FS (up to 100%), compared with tests using just deionized water as FS. This study points out the potential limitations of the FDFO process, due to the high solute fluxes and low water fluxes in conditions close to osmotic equilibrium.
... Forward osmosis (FO) also called as direct osmosis is a new membrane-separation process in which water moves spontaneously across a semi-permeable membrane from the feed solution (lower osmotic pressure) side to the draw solution (higher osmotic pressure) side [157,187]. Different from the pressure-driven membranes, FO is an osmotically driven technology operated at very low or even non-hydraulic pressure during wastewater treatment [188]. Compared to NF/RO, FO membranes have a lower membrane fouling potential due to loose formation and less compaction of cake foulants in the absence of hydraulic pressure [189]. ...
... Although FO is developing fast recently, there are not many related reports and cases on the application of municipal wastewater treatment and reuse. One of the key challenges to accomplish sustainable water recovery in FO is the separation and recovery of draw solutes, which accounts for most of the energy consumption [188]. In future research, the regeneration of draw solutes should be accomplished without using energy-intensive processes like RO. ...
Article
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Wastewater reuse as a sustainable, reliable and energy recovery concept is a promising approach to alleviate worldwide water scarcity. However, the water reuse market needs to be developed with long-term efforts because only less than 4% of the total wastewater worldwide has been treated for water reuse at present. In addition, the reclaimed water should fulfill the criteria of health safety, appearance, environmental acceptance and economic feasibility based on their local water reuse guidelines. Moreover, municipal wastewater as an alternative water resource for non-potable or potable reuse, has been widely treated by various membrane-based treatment processes for reuse applications. By collecting lab-scale and pilot-scale reuse cases as much as possible, this review aims to provide a comprehensive summary of the membrane-based treatment processes, mainly focused on the hydraulic filtration performance, contaminants removal capacity, reuse purpose, fouling resistance potential, resource recovery and energy consumption. The advances and limitations of different membrane-based processes alone or coupled with other possible processes such as disinfection processes and advanced oxidation processes, are also highlighted. Challenges still facing membrane-based technologies for water reuse applications, including institutional barriers, financial allocation and public perception, are stated as areas in need of further research and development.
... 7 Many factors, such as fertilizer type, nutrient loss, and membrane orientation, need to be considered for the application of product of FDFO for irrigation. 6,8,9 Regarding the fertilizer type, soluble chemicals containing macronutrient elements (i.e., N, P, and K), such as commercially available fertilizers, 10,11 liquid fertilizer, 11,12 and single or blended fertilizers, 7 have been evaluated as the DS of the FO membrane. The nutrient loss from the DS due to reverse diffusion is a critical challenge in FDFO; optimizing operational conditions, developing advanced membranes, and selecting the appropriate fertilizer DS can reduce reverse solute flux (RSF). ...
... To date, the performance of FDFO has been assessed in many fields, such as raw sewage, 12 treated (municipal) wastewater, 10,22 urine, 23 mine impaired groundwater, 24 brackish water, 25 seawater, 7 and coal seam gas (CSG) reverse osmosis brine. 26 Rather than a waste, the shale gas FPW should be considered a mixture of valuable components and water resources for agricultural irrigation, 27 but the application of FDFO for treating this specific wastewater has not yet been evaluated. ...
Article
Fertilizer drawn forward osmosis (FDFO) was proposed to extract fresh water from flowback and produced water (FPW) from shale gas extraction for irrigation, with fertilizer types and membrane orientations assessed. Draw solution (DS) with NH4H2PO4 displayed the best performance, while DS with (NH4)2HPO4 resulted in the most severe membrane fouling. DS with KCl and KNO3 led to substantial reverse solute fluxes. FDFO operation where the active layer of the membrane was facing the feed solution outperformed that when the active layer was facing the DS. Diluted DS and diluted FPW samples were used for irrigation of Cherry radish and Chinese cabbage. Compared to deionized water, irrigation with diluted DS (total dissolved solid (TDS) = 350 mg·L-1) promoted plant growth. In contrast, inhibited plant growth was observed when FPW with high salinity (TDS = 5000 mg·L-1) and low salinity (TDS = 1000 mg·L-1) was used for irrigation of long-term (8-week) plant cultures. Finally, upregulated genes were identified to illustrate the difference in plant growing. The results of this study provide a guide for efficient and safe use of FPW after FDFO treatment for agricultural application.
... Fig. 5b shows that humic acid containing FS is highly suitable for treating using a FO process. [44] also concluded that the higher cross-flow rate increases the SEC significantly, whereas the J w value increases marginally in FO runs. On a leveled dry membrane surface, a water droplet was dripped, and the images of the water drop on the membrane surface were taken by an optical device to measure the water contact angle (SF-5(ii)) at 23 ± 1 o C. Every sample was checked at least 6 times to record an average outcome. ...
... Their study used fertilizer as DS to recover water from synthetic brackish water as FS using CTA membrane. A similar trend of water flux was reported in the study of Zou & He[44]. ...
Article
Wastewater treatment via suitable routes is necessary to protect the environment and fill the shortage of freshwater. An osmotic pressure-driven membrane separation process of forward Osmosis (FO) has gained attention as an alternative water treatment process over the conventional approaches. FO process needs a draw solution (DS). A commonly used fertilizer such as urea in water can be used as a DS, and after the FO run, diluted DS may use as fertilizer. Thus, it can simultaneously generate freshwater for agricultural purposes from industrial wastewater. FO process using thin-film composite flat sheet membrane has been investigated for various lab-made solutions and pulp & paper industrial effluent as feed solutions (FSs) under varying DSs of 0.25, 0.5, 1, and 2 M urea solutions. Limited FO studies examined the long-term and repetitive runs using the same membrane to access the fouling, water, and solute flux behavior with real industrial wastewater as feed solutions (FS). The long-term experimental results prove the strong influences of DS concentration on specific energy consumption (SEC), fouling behavior, and water flux. Increasing the cross-flow rate from 0.33 to 1 L/min has a minor effect on water flux, but SEC increases significantly from 0.17 ± 0.01 kWh/m3 to 0.50 ± 0.03 kWh/m3. FO runs show that the overall water flux enhances due to higher osmotic pressure difference and lesser membrane fouling at higher DS concentration using pulp & paper industrial secondary effluent as FS. This study demonstrates that a low-energy FO process can recover water from industrial wastewater while simultaneously produces a diluted fertilizer for fertigation.
... After several years, single and blended inorganic salts like NH4 + , K + and PO4 3were used as the draw solutes Phuntsho et al. 2011) and it was recorded that those draw solutes can create an osmotic pressure higher than the seawater. Moreover, commercial solid and liquid fertilizers (Zou andHe 2016, Xie et al. 2015) were also inquired as draw solutes. All these researches approved that application of concentrated fertilizers are appropriate as the draw solutions for FO processes. ...
Article
Full-text available
An experiment was conducted at the Department of Crop Botany, Faculty of Agriculture, Bangladesh Agricultural University, Mymensingh during the period from January, 2020 to June, 2020 to evaluate the morpho-physiological response of groundnut genotypes under salinity stress at early seedling stage. The four groundnut genotypes were, namely, V1= BARI Chinabadam-8, V2= Maijchar badam (Dhaka-1), V3= Binachinabadam-6 and V4= Binachinabadam-8. Two salinity levels were, namely, S1= 0 dS/m NaCl and S2= 12 dS/m NaCl used for hydroponic experiment. The treatments were designed in a Completely Randomized Design (CRD) with four replications in a factorial arrangement. The parameters of the experiment measured were root length, shoot length, number of leaves, number of leaflets, leaf area, Soil Plant Analysis Development (SPAD) value, root fresh weight, leaf fresh weight, shoot fresh weight, root dry weight, leaf dry weight, and shoot dry weight. The result indicated that there were significant differences between the genotypes and salinity stress in all of the studied parameters. Maximum root length (33.20 cm), number of leaves (7.25), number of leaflet (24.50), leaf area (128.07 cm2), SPAD value (41.67), leaf fresh weight (3.43 g) and shoot dry weight (0.11 g) were recorded in the genotype Binachinabadam-6 in a combination of control condition. On the contrary the minimum shoot length (12.17 cm), root length (16.72 cm), number of leaves (2.75), number of leaflet (15.50), leaf area (21.90 cm2), SPAD value (31.42), leaf fresh weight (0.72 g), shoot fresh weight (0.92 g), leaf dry weight (0.11 g) and shoot dry weight (0.09 g) were recorded from the genotype Binachinabadam-8 in stress condition. So, the higher susceptible genotype Binachinabadam-8 to saline conditions and the lower was Binachinabadam-6. Therefore, it may be concluded that the variety Binachinabadam-6 will be more suitable for the saline prone areas of Bangladesh.
... Nontoxic gluconate salts have also been reported as novel FO draw solutes with good FO performance for the reconcentration of various fruit juices [29]. Similarly, sodium lignin sulfonate and commercial fertilizers reported as FO draw solutes can also be directly applied in crop irrigation after dilution via FO [30,31]. ...
... Photocatalytic disinfection by GOV-Pt(1%) nanocomposites is likely due to the generation of reactive species like OH -, H2O2, O2 -, eand h + [28]. Basic pH deters and acidic pH accelerates the inactivation process, indicating that pH can be identified as a competent variable [29]. Thus, it can be concluded that the maximum efficiency of the process is at pH 3 (acidic). ...
Article
Microbial water pollution has gained increased attention due to its detrimental effects on humans and to the planet. Photocatalytic disinfection is reported as an efficient method for the treatment of microbial polluted waters. The current study evaluates the photocatalytic disinfection properties of graphene oxide/V2O5/Pt (GOV-Pt(1%)) nanocomposite (alongside its anti-cancer activity) using Salmonella typhimurium as a model system. GOV-Pt(1%) nanocomposite prepared in the study was confirmed by various characterization studies. Scanning electron micrograph confirmed the successful drafting of V2O5 onto graphene oxide sheet and Pt metal without any agglomeration. The optimum conditions for maximum disinfection were catalyst dosage of 100 mg/L, pH 3 and initial inoculum dosage of 6 Log10 CFU/mL. Total organic carbon analysis confirmed the deterioration of bacterial cell wall leading to disinfection. In real effluents, a major decrease (98%) in the total coliform colony forming units (CFU) was observed after disinfection. Sodium-oxalate was found to hinder the disinfection process to the maximum extent followed by Cr(VI), ethylene-diamine tetra acetic acid, isopropanol and H2O2. The results of MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) assay, cell staining assay, and apoptosis assay confirmed that the composite has anti-cancer activity but no cytotoxic activity.
... RSF is defined as the back diffusion of the draw solution solutes across the FO membrane to the feed solution. Reverse solute flux (J s ) is calculated using the following equation [33]. h. ...
Article
In this study, a hybrid ultrafiltration–forward osmosis system was compared with a dual stage ultrafiltration process for the harvesting of marine microalgae. To the best of the authors knowledge none of the previous studies compared the performance of a dual stage ultrafiltration process with a hybrid UF-FO process for the harvesting of marine microalgae. The application of the hybrid process is expected to reduce the energy consumption for harvesting the microalgae without affecting the concentration factor and final product quality. In forward osmosis, the impact of the feed and draw solutions flowrate and the membrane orientation was investigated. The feed solutions were unfiltered microalgae solution and ultrafiltered concentrated microalgae while the draw solution was brine collected from a thermal desalination plant. A maximum total algal harvesting concentration factor of 37.3 was obtained using the hybrid ultrafiltration-forward osmosis system and the dual stage ultrafiltration process. The flowrate used in the forward osmosis process was 2.5 LPM for the feed solution and 0.8 LPM for the draw solution and the active layer was facing the feed solution (i.e. FO mode). The energy consumption in the hybrid ultrafiltration-forward osmosis system was 24% less than the dual-stage ultrafiltration system.
... The development of the energy-efficient hybrid system has become an urgent problem. When the flow rate of the draw solution was reduced from 100 to 10 mL min −1 , the energy consumption was lowered from 1.86 to 0.02 kW h m −3 [125] as the pumps generate higher than 40% of the overall energy prices [126]. It must be however mentioned that this flow rate of the draw solution can increase the energy demand in the FO process and has not been well studied in the literature for different FO applications. ...
... Agricultural irrigation is exhibited as a waterintensive procedure and consumes 72% of the global freshwater extraction. Discovering alternative water resources for irrigation through reclaiming wastewater will be of great importance [1]. Water shortages have called for a significant number of researchers to pay more attention to water sustainability; Therefore, researchers have been considering highly efficient and low-energy desalination techniques [2,3]. ...
Article
Full-text available
This paper deals with various fertilizer influences to draw solutions to the neat CTA/CA, MA/CTA/CA, and the Al2O3/MA/CTA/CA nanocomposite (NC) modified membrane. Also, the applicability of the neat CTA/CA, MA/CTA/CA, and The Al2O3/MA/CTA/CA nanocomposite (NC) modified membrane display high water flux when it used to desalinate brine water sample collected from the brine mid-stream from Mersa Matruh area, NorthWestern Coast of Egypt. The salinity of the collected sample is 12760 mg/L and PH (8.5) and used as FS, and 1M from different fertilizer draw solutes (DFDS) include KCl, NH4Cl, (NH4)2SO4, and K2HPO4 used as DS. The results reveal that the flux was KCl and NH4Cl (17.8 L/m 2 .h) and followed by (NH4)2SO4 (17.1 L/m 2 .h) and K2HPO4 (16.6 L/m 2 .h) using the natural saline water as FS using Al2O3/MA/CTA/CA NC modified membrane. The reusability test of the synthesised Al2O3/MA/CTA/CA NC modified membrane showed good sustainability during the 1260 min continuous test. The FO application displayed a great potential to be interested in brine wastewater desalination and enhanced water source sustainability to use in agriculture fertigation.
... Finally, the same DS was used successfully to concentrate the fruit juices using the FO process. In other studies, no DS regeneration step was required as concentrated fertilizer solutions were used as DS in the FO process [185,238,239]. The diluted DS was utilized directly for the fertigation process, as shown in Fig. 10. ...
Article
Forward osmosis (FO) is a membrane separation technique used to recover water from feed solution (FS) across a semi-permeable membrane, using a concentrated draw solution (DS). The feed solution could be sea/brackish water, wastewater, or other contaminated water. The DS and membrane play important roles in its overall performance. Permeate in FO is not pure water but a diluted DS. So, FO requires an additional step to regenerate DS and to recover freshwater as a product. This additional regeneration process might increase the total capital investment and energy requirement for the FO process. Selecting a proper DS and designing an energy-efficient DS regeneration system are the main challenges to make the FO process energetically viable. The FO process has significant advantages as it operates with very low hydrodynamic pressure, due to which it shows lower membrane fouling propensity. Hence, it helps for saving energy and reducing membrane replacement costs. It has some limitations, such as reverse solute flux, internal and external surface concentration polarization, that need to address before making it commercially more viable. This review focuses on the FO process's recent significant advancements in FO membranes, draw solutions, regeneration processes of draw solutions, overall energy efficiency, membrane fouling and overall performance during the long-term run, and future research directions.
... After several years, single and blended inorganic salts like NH4 + , K + and PO4 3were used as the draw solutes Phuntsho et al. 2011) and it was recorded that those draw solutes can create an osmotic pressure higher than the seawater. Moreover, commercial solid and liquid fertilizers (Zou andHe 2016, Xie et al. 2015) were also inquired as draw solutes. All these researches approved that application of concentrated fertilizers are appropriate as the draw solutions for FO processes. ...
Article
Full-text available
An experiment was conducted at the Department of Crop Botany, Faculty of Agriculture, Bangladesh Agricultural University, Mymensingh during the period from January, 2020 to June, 2020 to evaluate the morpho-physiological response of groundnut genotypes under salinity stress at early seedling stage. The four groundnut genotypes were, namely, V1= BARI Chinabadam-8, V2= Maijchar badam (Dhaka-1), V3= Binachinabadam-6 and V4= Binachinabadam-8. Two salinity levels were, namely, S1= 0 dS/m NaCl and S2= 12 dS/m NaCl used for hydroponic experiment. The treatments were designed in a Completely Randomized Design (CRD) with four replications in a factorial arrangement. The parameters of the experiment measured were root length, shoot length, number of leaves, number of leaflets, leaf area, Soil Plant Analysis Development (SPAD) value, root fresh weight, leaf fresh weight, shoot fresh weight, root dry weight, leaf dry weight, and shoot dry weight. The result indicated that there were significant differences between the genotypes and salinity stress in all of the studied parameters. Maximum root length (33.20 cm), number of leaves (7.25), number of leaflet (24.50), leaf area (128.07 cm 2), SPAD value (41.67), leaf fresh weight (3.43 g) and shoot dry weight (0.11 g) were recorded in the genotype Binachinabadam-6 in a combination of control condition. On the contrary the minimum shoot length (12.17 cm), root length (16.72 cm), number of leaves (2.75), number of leaflet (15.50), leaf area (21.90 cm 2), SPAD value (31.42), leaf fresh weight (0.72 g), shoot fresh weight (0.92 g), leaf dry weight (0.11 g) and shoot dry weight (0.09 g) were recorded from the genotype Binachinabadam-8 in stress condition. So, the higher susceptible genotype Binachinabadam-8 to saline conditions and the lower was Binachinabadam-6. Therefore, it may be concluded that the variety Binachinabadam-6 will be more suitable for the saline prone areas of Bangladesh.
... All chemicals were used directly without any further treatment except for KCl-f. KCl-f solution was centrifuged at 5000 rpm for 10 min [15] and then filtered through filter paper to remove undissolved particles/precipitants. The characteristics of the An-POME and details of the chemicals used are summarized in Tables 2 and 3. ...
Article
Full-text available
Fertilizer-drawn forward osmosis (FDFO) is a potential alternative to recover and reuse water and nutrients from agricultural wastewater, such as palm oil mill effluent that consists of 95% water and is rich in nutrients. This study investigated the potential of commercial fertilizers as draw solution (DS) in FDFO to treat anaerobic palm oil mill effluent (An-POME). The process parameters affecting FO were studied and optimized, which were then applied to fertilizer selection based on FO performance and fouling propensity. Six commonly used fertilizers were screened and assessed in terms of pure water flux (Jw) and reverse salt flux (JS). Ammonium sulfate ((NH4)2SO4), mono-ammonium phosphate (MAP), and potassium chloride (KCl) were further evaluated with An-POME. MAP showed the best performance against An-POME, with a high average water flux, low flux decline, the highest performance ratio (PR), and highest water recovery of 5.9% for a 4-h operation. In a 24-h fouling run, the average flux decline and water recovered were 84% and 15%, respectively. Both hydraulic flushing and osmotic backwashing cleaning were able to effectively restore the water flux. The results demonstrated that FDFO using commercial fertilizers has the potential for the treatment of An-POME for water recovery. Nevertheless, further investigation is needed to address challenges such as JS and the dilution factor of DS for direct use of fertigation.
... A fertigation distribution network is then used to apply the diluted fertilizer solution to crops. According to Zou and He (2016), 1 kg of fertilizer may extract 2459 L of freshwater from high salinity synthesized brackish water. ...
Article
Full-text available
Fertilizer-drawn forward osmosis (FDFO) has received a lot of attention for its potential for producing fertigated water for agriculture purposes. To minimize the use of chemical-based fertilizers and support sustainable organic agriculture, this work investigated the separation performance of FO membrane for different feed concentrations (FS) of brackish water using microalgae Spirulina platensis as an organic fertilizer draw solution (DS). Different feed solution concentrations were investigated ranging 3–20 g/L NaCl, with various draw solutions of spirulina ranging 280–440 g/L. The performance was measured by water flux and recovery. The results showed that using spirulina as a draw solution is a promising solution for fertigation purposes. The results showed that Na⁺ in feed solution is concentrated by 41%, Cl⁻ by 36%, and spirulina is diluted by 20% for feed salinity 5000 mg/L. The highest flux obtained with different feed solution 3000/5000/10,000/20,000 mg/L were 9/6/4.5/7 for draw solution concentration of 360/360/400/420 g/L. The calculated specific reverse solute flux (SRSF) JS/JW varies from 0.1 and 0.8 for different explored FS/DS concentrations. Flux decline and the down-time was investigated for the highest flux observed, showing 290 min of operation before cleaning action is required.
... As urea (CO(NH 2 ) 2 ) widely exists in industrial effluents and domestic sewage, urea-rich wastewater has become the main source of water pollution in recent years due to eutrophication, leading to the damage of ecological environment. Specifically, it could be transformed into nitrate and toxic ammonia, posing a threat to the human's health [1,2]. For this reason, the electrooxidation treatment of urea in wastewater that can convert the urea into harmless N 2 and CO 2 has received great attention from the research community [3,4]. ...
Article
Full-text available
Electrocatalytic urea oxidation reaction (UOR) is regarded as an effective yet challenging approach for the degradation of urea in wastewater into harmless N2 and CO2. To overcome the sluggish kinetics, catalytically active sites should be rationally designed to manuever the multiple key steps of intermediate adsorption and desorption. Herein, we demonstrate that metal-organic frameworks (MOFs) can provide an ideal platform for tailoring binary active sites to facilitate the ratedetermining steps, achieving remarkable electrocatalytic activity toward UOR. Specifically, the MOF (namely, NiMn0.14-BDC) based on Ni/Mn sites and terephthalic acid (BDC) ligands exhibits a low voltage of 1.317 V to deliver a current density of 10 mA cm-2. As a result, a high turnover frequency (TOF) of 0.15 s-1 is achieved at a voltage of 1.4 V, which enables a urea degradation rate of 81.87% in 0.33 M urea solution. The combination of experimental characterization with theoretical calculation reveals that the Ni and Mn sites play synergistic roles in maneuvering the evolution of urea molecules and key reaction intermediates during the UOR, while the binary Ni/Mn Research Manuscript Page 2 of 19 sites in MOF offer the tunability for electronic structure and d-band center impacting on the intermediate evolution. This work provides important insights into active site design by leveraging MOF platform, and represents a solid step toward highly efficient UOR with MOF-based electrocatalysts.
... High-saline water NH 3 /CO 2 as DS and polyamide FO thin film composite membrane 64% water recovery with 300 mg/L TDS [43] Reverse osmosis brine NaCl as DS and flat-sheet cellulose triacetate membrane 90% water recovery [44] NaCl-based synthetic brine Among the several brine treatment methods, being an energy-efficient methodology, FO has numerous advantages compared to RO, such as cost effectiveness, low energy consumption, reduced membrane fouling, high water flux, and remarkable rejection rates, and it can be applied to high-saline brine (<200 g/L). Generally, FO technology utilizes low energy (energy cost can be low as 0.02 kWh/m 3 ) compared to other approaches such as RO [52][53][54]; further cost reduction can be achieved by using a more concentrated draw solution as suggested by Gulied et al. [55]. Therefore, FO is considered as the most suitable brine resource recovery method at present [45]. ...
Article
Full-text available
Desalination brine is extremely concentrated saline water; it contains various salts, nutrients, heavy metals, organic contaminants, and microbial contaminants. Conventional disposal of desalination brine has negative impacts on natural and marine ecosystems that increase the levels of toxicity and salinity. These issues demand the development of brine management technologies that can lead to zero liquid discharge. Brine management can be productive by adopting economically feasible methodologies, which enables the recovery of valuable resources like freshwater, minerals, and energy. This review focuses on the recent advances in brine management using various membrane/thermal-based technologies and their applicability in water, mineral, and energy recoveries, considering their pros and cons. This review also exemplifies the hybrid processes for metal recovery and zero liquid discharge that may be adopted, so far, as an appropriate futuristic strategy. The data analyzed and outlook presented in this review could definitely contribute to the development of economically achievable future strategies for sustainable brine management.
... Forward osmosis (FO) also called as direct osmosis is a new membrane-separation process in which water moves spontaneously across a semi-permeable membrane from the feed solution (lower osmotic pressure) side to the draw solution (higher osmotic pressure) side [176,177]. Compared to NF/RO, FO is an osmotically driven technology operated at very low or even non-hydraulic pressure during wastewater treatment [178], and FO membranes have a lower membrane fouling potential due to loose formation and less compaction of cake foulants in the absence of hydraulic pressure [179]. Moreover, FO membranes present high contaminant rejection rates, high flux recovery after cleaning and high water recovery using low-grade energy resources [180,181]. ...
Thesis
Water reuse is a sustainable development strategy that benefits society and future generations. In this study, a semi-industrial ultrafiltration (UF) pilot plant established at the outlet of a wastewater treatment plant was studied to assess its feasibility and sustainability for non-potable water reuse. The optimization of operating conditions made it possible to support reliable and sustainable filtration performance, the operating conditions were optimized through comparative analysis in terms of water quality, permeability variation, irreversible fouling management, and water recovery rate. The best conditions were J80t40BW1/3 (flux of 80 L·h−1·m−2, filtration cycle time of 40 min, 1 air backwash followed by 3 classical backwashes), J60t60BW1/4 and J60t60BW1/3.The long-term study on condition J60t60BW1/3 provides sustainable and adaptable filtration performance regardless of the temperature and feed water quality variation. In addition, the air backwashes enabled excellent reversibility of membrane fouling, which was approximately 1.25 to 2 times higher than of classic backwashes in average. The quality of the UF permeate was goodenough to be reused in non-potable purposes as it met reuse guidelines of the World Health Organization, reuse standards of France, and the most recent EU regulation for agricultural irrigation. A specific study of membrane cleaning has shown that the addition of NaClO in backwash water can greatly increase cleaning efficiency of air backwashes. Finally, the calculation of the capital expenditure (CAPEX) and operational expenditure (OPEX) of the UF system under optimized conditions gives a profitable net unit price for water production. Through this thesis, UF is confirmed to be a reliable tertiary treatment for water reuse and the results give operational indications for the industrial scale and provides proposals for the management of membrane fouling by air backwash with chemical assistance.Keywords:Ultrafiltration, water reuse, fouling control, air backwash, reuse standard
Article
Water scarcity is one of the major issues that has put economic growth, societal stability, and ecosystem balance unstable. Wastewater reuse has been recognised as a viable method for securing potable water supply. Due to its inherent advantages over pressure-driven and energy-intensive reverse osmosis (RO), forward osmosis (FO) is one of the most researched technologies for wastewater reuse applications. However, the draw solution (DS) regeneration stage is one of the key bottlenecks of the process. Membrane distillation (MD), on the other hand, is an emerging technology that could provide a cost-effective thermally-driven purification process, especially when combined with waste heat or solar thermal. Nevertheless, the MD process also has several drawbacks, such as membrane pore wetting. The MD process can effectively regenerate the FO draw solution and produce high-quality water when integrated with the FO process. Within the hybrid process, the FO membrane removes the contaminants from the feed solution and the MD process is only used to regenerate the DS with no significant membrane wetting. It is, therefore, important to study the integrated FO-MD process to overcome the limitations of individual membrane processes. Integrated FO-MD economics, process design, and modelling of different applications are thoroughly reviewed in this contribution. Future research directions and prospects for scale-up are suggested.
Article
The Gulf Cooperation Council (GCC) countries are located in one of the most arid regions in the world with very less freshwater resources, and hence depending on desalination plants to tackle the water scarcity and satisfy the increasing water demand. However, several adverse effects are associated with the desalination process and thus many technologies are being implemented to reduce their environmental effects. In this paper, the GCC desalination plants, their capacities, socio-economic costs, the nature of the brine discharged, the energy demand and water production costs have been discussed. The review also features the different desalination policies in the GCC countries, their potential environmental impact, the emerging techniques, which reduces the negative impact of the desalination plants on the environment. Also, the different mitigation strategies to lower the environmental impacts of different conventional desalination techniques are analysed. This study has confirmed that the environmental impact assessment should be carried out before building a new desalination plant or prolonging the capacity of the prevailing one for limiting the adverse impact of the facility. The use of renewable energy in the desalination sector is recommended as an impressive idea to reduce the environmental impacts and huge energy costs associated.
Article
The discharge of reject brine from seawater desalination processes is a threat to marine ecosystems. This study investigated the feasibility of forward osmosis (FO) for the treatment of reject brine from multi‐effect distillation (MED) systems. The performances of two commercial FO membranes (ie, cellulose triacetate (CTA) and polyamide thin film composite (TFC) membranes) were compared. The effects of operating conditions, such as draw solution concentration, cross‐flow velocity, and temperature, on concentration polarization and consequently on the water flux, were quantitatively analyzed using a mathematical model. Results showed that the batch FO process could effectively reduce the volume of MED brine to 54.9% using 3 mol/L NaCl. As the draw solution concentration increased from 1 mol/L‐5 mol/L, a significant increase in the initial water flux from 3.23 L·m⁻²·h⁻¹‐17.88 L·m⁻²·h⁻¹ and from 3.55 L·m⁻²·h⁻¹‐24.04 L·m⁻²·h⁻¹ was observed for the CTA and TFC membranes, respectively. However, the proportions of the effective osmotic pressure differences decreased from 20.7% to 11.9% and from 23.5% to 6.2% for the CTA and TFC membranes, respectively, indicating the concentration polarization (CP) was severe for high‐salinity brine treatment. The positive effects of increasing cross‐flow velocity on CP were limited. Moreover, the high temperature of the MED brine effectively mitigated the internal concentration polarization (ICP), thereby enhancing the water flux. Overall, this study provides valuable guidance for the application and optimization of FO in MED brine treatment. This article is protected by copyright. All rights reserved.
Article
In the present study, the osmotic properties of blended amino-acids–metal-salts fertilizer draw solutions, and their forward osmosis (FO) performances were investigated. Considering the different types of amino-acids–metal-salts, the blending of arginine with ZnCl2 solution in the molar ratio of 1 : 6 could lead up to 3.0 and 8.3 times higher osmotic pressure and water flux (i.e., 93.89 bar and 29.57 LMH), respectively, compared to the sum of their individual values. Furthermore, a very little reverse solute flux was noticed using ZnCl2–amino-acids draw solutions. As an effect of solute–solvent interaction, the formation of the novel structure of amino acids with metal salts could enhance the osmotic pressure, providing high water flux and low inverse diffusion of the solute. The desalination of Caspian Sea water was also successfully tested using arginine–ZnCl2 fertilizer draw solution. Therefore, the fertilizer-based draw solutions can present great potential in different applications of the FO process, due to their relatively high water flux and no need for recovery.
Article
Different PPSU nanofiltration (NF) fibers were used for the first time as a potential fiber for saline water desalination by forward osmosis (FO). The characteristics of fibers, such as their surface structure, cross-sectional structure, and thickness were measured using a SEM and an AFM, with fiber porosity also measured. The ef- fects of the PPSU amount and operating conditions on the performance of water transport were investigated. The structural parameter (S = 467–601) displayed small values for three PPSU fibers due to their high porosity and because the fiber was less thick, which corresponded well to their performance. The prepared PPSU fiber tested under the FO process displayed high water fluxes utilizing 3.0 M NaCl as the draw solution. High salt rejection for all PPSU FO fibers was obtained, and the salt reverse fluxes were preserved below 7.30, 6.58, and 3.89 gMH for PSU 25, 29, and 30 wt.%, respectively. Increasing the PPSU amounts led to decreasing the specific reverse salt flux. The PPSU NF hollow fibers prepared in this work are eligible FO membranes for water desalination.
Article
The unavailability of a suitable draw solute constrains the advancement of forward osmosis (FO) technology. Here from a custom-built ionic liquid betainium bis(trifluoromethylsulfonyl)imide ([Hbet][Tf2N]), a multinuclear zinc complex of [Zn4(bet)10(H2O)2][Tf2N]8 (Zn-Bet-Tf2N) has been synthesized via a one-pot complexation reaction for electroplating wastewater treatment via FO processes. Possessing a large number of hydrophilic groups and an expanded structure, Zn-Bet-Tf2N generates a sufficient osmotic pressure to drive the FO process and minimizes reverse solute diffusion. Zn-Bet-Tf2N produces a water flux of 15.0 LMH even at a dilute concentration (0.2 mol/L) with negligible solute leakage during the FO process. The water permeation rates induced by Zn-Bet-Tf2N increase by up to 50 % compared to those of the conventional NaCl, MgCl2 and NH4HCO3 draw solutes in zinc-containing wastewater reclamation. Zn-Bet-Tf2N is readily separated from water after FO through solvent extraction. With no energy input or by-products, the recycling of Zn-Bet-Tf2N is more practical than that of other draw solutes ever reported. Reproducible results are obtained when the recycled Zn-Bet-Tf2N is reused to FO processes. These findings suggest that the Zn-Bet-Tf2N facilitated FO system can achieve high water recovery efficiency, high selectivity and sustainability in zinc-containing wastewater treatment.
Article
Freshwater scarcity is one of the most important issues facing the world today. To address this issue, processes have been developed to purify and desalinate water at an industrial scale, especially based on membrane reverse osmosis RO. However, because of the drawbacks of conventional RO – including the inability to handle high salinity and susceptibility to fouling – forward osmosis (FO) has been introduced as a complementary technology. FO can be coupled with other desalination techniques like membrane distillation and RO to remedy these issues. We aim here to review recent advances in FO and the challenges facing this technology. Important parameters in FO operation include transmembrane water flux and output, energy consumption, fouling, draw solution type and regeneration, and membrane type. Several methods to increase the water flux are discussed, including changes in system temperature, development and alterations in draw solution (DS) properties, modelling and development of new membranes, and techniques to reduce concentration polarization. These developments help to increase water flux and water recovery and to mitigate membrane fouling and concentration polarization. We also discuss the various applications of these novel techniques in different areas, and how they can improve the efficiencies of hybrid systems. Finally, we make recommendations for future developments, to allow the use of FO at a large scale in water purification systems.
Article
The rejection of disinfection byproducts (DBPs) is an important consideration for the application of forward osmosis (FO) in wastewater recycling. However, the transport of organic compounds in FO is not well predicted by existing models, partially because these models have not incorporated the effect of reverse salt flux, a phenomenon previously shown to influence the transport of pharmaceutical compounds. In this study, we investigated the effects of reverse salt flux on DBP transport in FO and the corresponding mechanisms. We used a commercial Aquaporin membrane and tested sixteen DBPs relevant to wastewater recycling. Using draw solutions constituted by NaCl, MgSO4, or glucose in a bench-scale FO system, we first confirmed that higher reverse salt flux resulted in lower DBP permeance. By integrating results from the bench-scale FO system and those from diffusion cell tests, we showed that two mechanisms contributed to the hindered DBP transport: the steric hindrance in the active layer caused by the presence of the draw solute and the retarded diffusion of DBPs in the support layer via a “salting-out” effect. Lastly, we developed a modified solution-diffusion model incorporating these two mechanisms by accounting for the free volume occupied by draw solute molecules in the active layer and by introducing the Setschenow constant, respectively. The modified model significantly improved the prediction of permeance for halogenated DBPs, and revealed the relative importance of steric hindrance (dominant for large DBPs) and retarded diffusion (dominant for hydrophobic DBPs). The modified model did not accurately predict the permeance of nitrosamines, attributable to their extremely high hydrophilicity or large size.
Article
ABSTRCTThis study aimed to investigate pollutant concentration and nitrogen interception characteristics of a forward osmosis (FO) process for concentrating black odorous water. The membrane cell was operated in active layer facing feed solution (AL-FS) mode with aquaporin (AQP) as the membrane material and NaCl solution as the draw solution (DS). The organic pollutants (COD), TP, NH+ 4-N, NO- 3-N, TN, Fe and Mn in black odorous water were concentrated non-intermittently for 24 hours, and their interception characteristics were investigated. The results showed that the average interception rates of COD, TP, NO- 3-N, TN, Fe and Mn were 97.2%, 98.0%, 58.7%, 54.3%, 61.8% and 60.0%, respectively, while the average interception rate of NH+ 4-N was only 1.27%-3.47%. To explore the characteristics of nitrogen interception, a comparison was conducted between AQP membrane and thin film composite (TFC) membrane. Because the surface electronegativity of AQP membrane was stronger than that of TFC, the effect of cation exchange on ammonia nitrogen interception was more serious with AQP membrane. With NaCl solution as DS, the reverse osmosis flux of Na+ was (0.53 ± 0.02 mol·m-2·h-1), which was significantly higher than that of Cl- (0.29 ± 0.03 mol·m-2·h-1) (P < 0.05). The interception effect of AQP membrane on TN was related to the proportion of NH+ 4-N in TN. The pretreatment of black odorous water by aeration could transform part of NH+ 4-N into NO- 3-N, and reduce the negative effect of cation exchange effect on nitrogen interception. The TN interception rate increased from 54.3% to 66.1%.
Article
Forward osmosis membrane bioreactor (FOMBR) is an integrated physical-biological treatment process that has received increased awareness in treating municipal wastewater for its potential to produce high effluent quality coupled with its low propensity for fouling formation. However, reverse salt diffusion (RSD) is a major issue and so far limited studies have reported long-term FOMBR operation under the elevated salinity conditions induced by RSD. This study investigated the performance of a FOMBR in treating municipal wastewater under a controlled saline environment (6 – 8 g L⁻¹ NaCl) using two separate sodium chloride draw solution (NaCl DS) concentrations (35 and 70 g L⁻¹) over 243 days. At 35 g L⁻¹ NaCl DS, the water flux performance dropped from 6.75 L m⁻² h⁻¹ (LMH) to 2.07 LMH after 72 days of operation in the first experimental stage, when no cleaning procedure was implemented. In the subsequent stage, the DS concentration was increased to 70 g L⁻¹ and a weekly physical cleaning regime introduced. Under stable operation, the water flux performance recovery was 67 % after 21 cycles of physical cleaning. For the first time in FOMBR studies, a shortcut nitrogen removal via the nitrite pathway was also achieved under the elevated salinity conditions. At the end of operation (day 243), the ammonia-oxidising bacteria (Nitrosomonas sp.) was the only nitrifier species in the system and no nitrite oxidising bacteria was detected. The above study proves that a FOMBR system is a feasible process for treating municipal wastewater.
Article
This study aimed to investigate pollutant concentration and membrane fouling characteristics of a forward osmosis (FO) process using aquaporin biomimetic membrane (ABM) for concentrating black odorous water. The membrane cells were operated in active layer facing feed solution (ALFS) mode with 2 M NaCl solution as the draw solution. The system was continuously performed for 64 batch cycles, and each cycle duration was 24 h. At the end of each cycle, physical cleaning with deionized water was employed as the membrane recovery strategy. The results showed that the rejection ratios of chemical oxygen demand (COD), total phosphorus (TP) and nitrate (NO3⁻-N) could reached 97.2%, 98.0%, and 85.0%, respectively, while most NH4⁺-N penetrated into the draw solution due to cation exchange. The total nitrogen (TN) rejection ratio was largely dependent upon the NH4⁺-N/TN ratio. At high NH4⁺-N/TN ratio, the successions of ammonia oxidizing bacteria (AOB) communities enriched in the biofouling layer in different experimental stages would affect the transformation degree of NH4⁺-N, and thus lead to much fluctuations of TN rejection. The average initial water flux reached 9.84 L/(m²·h), and the average water flux of each cycle kept stable especially in the later stage of the experiment. In the biofouling layer, polysaccharides enhanced while proteins decreased in the later period. P, Mn, Fe and Na also accumulated on the surface. Norank_f__Reyranellaceae, Erythrobacter, SM1A02, Pirellula, and Hydrogenophaga were the predominant genera enriched in the fouling layer, which would lead to complex pollutants transformations, especially nitrogen transformation, during the FO process.
Article
Forward osmosis (FO) has great potential for low energy consumption wastewater reuse provided there is no requirement for draw solutes (DS) regeneration. Reverse solute flux (RSF) can lead to DS build-up in the feed solution. This remains a key challenge because it can cause significant water flux reduction and lead to additional water quality problems. Herein, an osmotic photobioreactor (OsPBR) system was developed to employ fast-growing microalgae to consume the RSF nutrients. Diammonium phosphate (DAP) was used as a fertilizer DS, and algal biomass was a byproduct. The addition of microalgae into the OsPBR proved to maintain water flux while reducing the concentrations of NH4⁺-N, PO4³⁻-P and chemical oxygen demand (COD) in the OsPBR feed solution by 44.4%, 85.6%, and 77.5%. Due to the forward cation flux and precipitation, intermittent supplements of K⁺, Mg²⁺, Ca²⁺, and SO4²⁻ salts further stimulated algal growth and culture densities by 58.7%. With an optimal hydraulic retention time (HRT) of 3.33 d, the OsPBR overcame NH4⁺-N overloading and stabilized key nutrients NH4⁺-N at ∼ 2.0 mg L⁻¹, PO4³⁻-P < 0.6 mg L⁻¹, and COD < 30 mg L⁻¹. A moderate nitrogen reduction stress resulted in a high carbohydrate content (51.3 ± 0.1%) among microalgal cells. A solids retention time (SRT) of 17.82 d was found to increase high-density microalgae by 3-fold with a high yield of both lipids (9.07 g m⁻³ d⁻¹) and carbohydrates (16.66 g m⁻³ d⁻¹). This study encourages further exploration of the OsPBR technology for simultaneous recovery of high-quality water and production of algal biomass for value-added products.
Article
The potential for concentrated fertilizer to drive water treatment, nutrient recovery, and/or power generation has received increased attention. Recently the concept of fertilizer-driven pressure retarded osmosis (or “Green PRO”) was introduced to the literature and experimentally validated. The limits of power from fertilizer osmosis however have not yet been established, and therefore the potential for this energy source to supply meaningful farm loads is uncertain. In this paper, a combination of analytical, numerical, and experimental methods are used to establish the thermodynamic and process limits of fertilizer energy conversion via PRO. The results indicate that up to 125 Wh/kg of energy is released from fertilizer when it is diluted in water. PRO process dynamics including operation at constant applied pressure, and the need to maintain high power levels throughout the batch process, limit the conversion to work to up to 14.9 Wh/kg. Further, experimentally-calibrated simulation results suggest that only up to 6.8 Wh/kg can be anticipated when considering non-ideal transport dynamics such as reverse solute flux and concentration polarization. The effect of feed source concentration and recovery ratio on batch process dynamics are investigated, and it is found that using wastewater as feed may be comparable to scenarios where high recovery of clean irrigation feed is used. The potential of common hydroponic plant crops is evaluated, and results indicate that advances in membrane technology may allow energy recovery to approach 5% of typical greenhouse electricity consumption.
Article
Antimicrobial nanomaterials provide numerous opportunities for the synthesis of next-generation sustainable water disinfectants. Using the keywords graphene and water disinfection and graphene antibacterial activity, a detailed search of the Scopus database yielded 198 and 1433 studies on using graphene for water disinfection applications and graphene antibacterial activity in the last ten years, respectively. Graphene family nanomaterials (GFNs) have emerged as effective antibacterial agents. The current innovations in graphene-, graphene oxide (GO)-, reduced graphene oxide (rGO)-, and graphene quantum dot (GQD)-based nanocomposites for water disinfection, including their functionalization with semiconductor photocatalysts and metal and metal oxide nanoparticles, have been thoroughly discussed in this review. Furthermore, their novel application in the fabrication of 3D porous hydrogels, thin films, and membranes has been emphasized. The physicochemical and structural properties affecting their antibacterial efficiency, such as sheet size, layer number, shape, edges, smoothness/roughness, arrangement mode, aggregation, dispersibility, and surface functionalization have been highlighted. The various mechanisms involved in GFN antibacterial action have been reviewed, including the mechanisms of membrane stress, ROS-dependent and -independent oxidative stress, cell wrapping/trapping, charge transfer, and interaction with cellular components. For safe applications, the potential biosafety and biocompatibility of GFNs in aquatic environments are emphasized. Finally, the current limitations and future perspectives are discussed. This review may provide ideas for developing efficient and practical solutions using graphene-, GO-, rGO-, and GQD-based nanocomposites in water disinfection by rationally employing their unique properties.
Article
The current study focused on the performance of a lab scale side stream anaerobic fertilizer drawn forward osmosis (An-FDFO) setup and optimization of nutrient rich solution to achieve sustainable water reuse from high strength synthetic textile wastewater. Three fertilizer draw solutes including Mono Ammonium Phosphate (MAP), Ammonium Sulphate (SOA) and Mono Potassium Phosphate (MKP) were blended in six different ratios with total molar concentration not exceeding 1 M. Among six blended draw solutions (DS), combination with high concentration of SOA have shown highest flux and combination with high concentration of MKP have shown highest reverse solute flux, while those with high concentration of MAP remain moderate both in flux and RSF. During long term runs, SOA: MKP (0.75: 0.25 M) showed longest filtration duration of 217 h in Run 1, with highest initial flux of 8.29 LMH and minimum dilution factor to achieve final nutrients concentration fit for direct fertigation, followed by Run 3 MAP: SOA: MKP (0.2: 0.6: 0.2 M) and then Run 2 MAP: MKP (0.75: 0.25). Moreover, deterioration of mixed liquor characteristics occurs in membrane tank due to high RSF. Similarly, the same inhibitory effect of reverse salt on biogas production was also assessed through Bio-Methane Potential experiments. However, Anaerobic Continuous Stirring Tank Reactor exhibited high performance efficacy, highlighting the importance of side stream submerged configuration in forward osmosis (FO) process.
Article
The electrochemical urea oxidation (UOR) involves the generation of gases bubbles, which often cause the blockage of the electrode surface leading to decline activity. Herein, we report the growth of Ni5P4 nanosheets on nickel foam as bifunctional electrode (CA-Ni5P4@NiOx/NF) for urea electrolysis. The results indicated that a thin layer of amorphous NiOx formed on the surface of Ni5P4 nanosheets to yield a unique [email protected] core–shell structure, which can be maintained during long time urea electrolysis. The outstanding UOR performance of CA-Ni5P4@NiOx/NF was attributed to the unique structure, which not only combine the good conductivity and abundant active sites, but also rendered the CA-Ni5P4@NiOx/NF superhydrophilic and aerophobic that significantly facilities the release of gases bubbles formed during UOR to avoid the blockage of the active sites. As a result, the CA-Ni5P4@NiOx/NF electrode exhibited excellent performance for UOR, which only needs 1.45 V (vs. RHE) to deliver a current of 100 mA/cm². When used as anode for direct urea fuel cell (DUFC), it could reach a maximal power density as high as 3.4 mW/cm² with an OCV of 0.76 V. The CA-Ni5P4@NiOx/NF also exhibited excellent activity for hydrogen evolution reaction (HER), with -0.089 V (vs. RHE) to deliver a current of 10 mA/cm². The electrolyzer constructed with CA-Ni5P4@NiOx as both anode and cathode could run for more than 10 h at a high current load about 100 mA/cm² without appreciable potential change, indicating the superb stability of the CA-Ni5P4@NiOx electrode. Our work provides new insights for understanding as well as the development of advanced electrode for DUFC and urea electrolysis.
Article
Regeneration and reuse of draw solute (DS) is a key challenge in the application of forward osmosis (FO) technology. Herein, EDTA-Na2 was studied as a recoverable DS for water extraction by taking advantages of its pH-responsive property. The FO system using EDTA DS achieved a higher water flux of 2.22 ± 0.06 L m⁻² h⁻¹ and a significantly lower reverse salt flux (RSF) of 0.06 ± 0.01 g m⁻² h⁻¹, compared to that with NaCl DS having either the same DS concentration or the same Na⁺ concentration. The suitable pH range for the application of EDTA DS was between 4.0 and 10.5. A simple recovery method via combined pH adjustment and microfiltration was employed to recover EDTA DS and could achieve the recovery efficiency (at pH 2) of 96.26 ± 0.48%, 97.13 ± 1.03% and 98.56 ± 1.40% by using H2SO4, H3PO4 and HCl, respectively. The lowest acid cost for DS recovery was estimated from 0.0012 ± 0.0001 to 0.0162 ± 0.0003 $ g⁻¹ by using H2SO4. The recovered EDTA DS could be reused in the subsequent FO operation and the overall recovery efficiency was 94.4% for four reuse cycles. These results have demonstrated the feasible of EDTA-Na2 DS and a potentially cost-effective recovery approach, and encouraged further exploration of using EDTA-based compounds as a draw solute for FO applications.
Article
The potential for concentrated fertilizer to drive water recovery via forward osmosis has received increased attention in recent years. Questions remain however about the quantities of water that can be recovered from batch processes, and how significant recovery volumes are relative to the overall water balance of crops. In this study, we establish the thermodynamic and practical limits of recovering water from a fertilizer osmosis batch process, and thereby provide insights into the future prospects of this concept. It is shown that common fertilizers can recover between 112 and 138 l/kg via fertilizer osmosis from a municipal wastewater feed source while maintaining practical flux of at least 5 l m⁻² h⁻¹. The effects of membrane type, feedwater concentration, and permeate to feed recovery ratio are analyzed with a combination of analytical, numerical, and experimental methods. Water recovery limits are compared against the irrigation requirements of hydroponic crops. Between 32 and 99% of a plant's irrigation water can be supplied by fertilizer osmosis at competitive flux levels, provided that low concentration feed such as municipal or hydroponic wastewater is available. Such recovery volumes represent a significant portion of the plant water balance, and should justify future research in the area of fertilizer osmosis.
Article
Wastewater contains a significant amount of recoverable nitrogen. Hence, the recovery of nitrogen from wastewater can provide an option for generating some revenue by applying the captured nitrogen to producing bio-products, in order to minimize dangerous or environmental pollution consequences. The circular bio-economy can achieve greater environmental and economic sustainability through game-changing technological developments that will improve municipal wastewater management, where simultaneous nitrogen and energy recovery are required. Over the last decade, substantial efforts were undertaken concerning the recovery of nitrogen from wastewater. For example, bio-membrane integrated system (BMIS) which integrates biological process and membrane technology, has attracted considerable attention for recovering nitrogen from wastewater. In this review, current research on nitrogen recovery using the BMIS are compiled whilst the technologies are compared regarding their energy requirement, efficiencies, advantages and disadvantages. Moreover, the bio-products achieved in the nitrogen recovery system processes are summarized in this paper, and the directions for future research are suggested. Future research should consider the quality of recovered nitrogenous products, long-term performance of BMIS and economic feasibility of large-scale reactors. Nitrogen recovery should be addressed under the framework of a circular bio-economy.
Article
Reverse solute flux (RSF) is a key issue for operating forward osmosis (FO) systems and can cause the loss of draw solute (DS) and salt accumulation in the feed. Herein, an electrolysis-assisted FO (e-FO) system was developed for simultaneous RSF reduction and recovery of the reverse-fluxed DS. Applying a voltage of 1.5 V led to RSF of 3.34 ± 0.01 mmol m⁻² h⁻¹ (0.47 g m⁻² h⁻¹) in the e-FO system, 67.5 ± 0.5% lower than that of the control system; in addition, the e-FO system recovered ~0.32 g L⁻¹ of the reverse-fluxed DS and this could not be realized in the control. When the e-FO system was examined with three types of the mimicked fertilizer, RSF reduction and DS recovery were largely affected by the individual components of a fertilizer DS. The energy consumption of the e-FO system was reduced by ~90%, from 0.38 ± 0.01 to 0.04 ± 0.01 kWh m⁻³ when the recirculation rate decreased from 60 to 15 mL min⁻¹. Those results have demonstrated the technical feasibility of an e-FO system that is capable of reducing RSF and recovering the lost DS and will encourage further investigation by addressing several identified challenges.
Article
Fertilizer driven forward osmosis (FDFO) process would be feasible due to the possible prevention of the drainage of dewatered and concentrated pesticide effluent from agricultural pesticide industries to the environment. Instead, it would be possible to return the concentrated pesticide solution to the processing cycle, and on the other hand, employ directly the obtained diluted fertilizer draw solution for irrigation. This study investigated the performance of zinc-nitrate/amino-acids blends as fertilizer type draw solution, and distilled water, saline water (seawater), and synthetic wastewater containing pesticides as feed. The results indicated that the synergetic effect of blended type fertilizer presented significantly higher osmotic pressure and water flux than the sum of their individual ones, especially when the amount of amino acid increased. Conversely, an ignorable reverse flux of blended fertilizer draw solute was observed. The fertilizer blend with a molar ratio of 1:6 zinc-nitrate/amino-acid achieved the higher average fluxes of 34.7 and 23.92 L/m2h from distilled and saline waters compared to common draw solutions such as metal salts. Furthermore, the FDFO exhibited a high rejection (over 99%) of bentazon and imidacloprid in feed solutions compared to other agricultural pesticides due to their larger molecular weight and molecular size. The applied FDFO represented a significant reduction in specific energy consumption (from 0.17 to 0.049 kWh/m3) in a bench-scale setup as compared to the RO process almost at the same water permeation flux and the rejection of bentazon.
Conference Paper
Pretreatment method is essential for obtaining crude cellulose for synthesis of carboxymethyl cellulose (CMC) from biomass. Previously, alkaline pretreatment followed by bleaching with sodium chlorite or acid were commonly used for synthesis of CMC. In this study, [BMIM][Cl] ionic liquid (IL) and NaOH treatments were conducted on oil palm empty fruit bunch (EFB) followed by bleaching with hydrogen peroxide (H2O2) to compare the properties of synthesized CMC. The crude EFB cellulose from pretreatment is bleached and used for synthesis of CMC by adding 1.2 g/g of sodium monochloroacetic acid (SMCA) and 30% of NaOH concentration at 55C for 3 h. The CMC obtained was characterized by using SEM-EDX, FTIR, and XRD. Based on the results, CMC can be synthesized using both ionic liquid and alkaline pretreatment methods followed by H2O2 bleaching and have obtained high degree of substitution (DS) of 0.82 and 0.83, respectively, while CMC synthesis from bleached EFB cellulose without pretreatment has obtained low DS. Based on the characterization of CMC, different morphologies and structures of CMC have been presented due to the effects of different pretreatment process. Carboxymethyl cellulose synthesis from EFB with NaOH-H2O2 treatment has low crystallinity as compared to CMC from EFB with IL-H2O2. Related functional group and chemical bonding show small differences between all synthesized CMC. The EDX analysis shows that elements presented were reflected in the CMC structure. Therefore, the synthesis of CMC from NaOH-H2O2 and IL-H2O2 treatment shows similar chemical properties but with different morphology and structure.
Conference Paper
Full-text available
The water recovery system (WRS) within the Environmental Control and Life Support System (ECLSS) for the International Space Station (ISS) recovers and recycles up to 90% water from human waste. However, the WRS has lifetime/durability limitations requiring the supply of hazardous chemicals and filter units to treat the system components to maintain their targeted performance. Therefore, next-generation systems are required to reduce waste, enhance water recoverability, and improve process efficiency. Accordingly, Faraday Technology and the University of Puerto Rico (UPR) are developing a bio-electrochemical system to efficiently treat urine waste streams to improve the water recovery system's efficiency/durability by eliminating the hard-to-remove urea (~2%) component from the wastewater. Within the bio-electrochemical system, a bioreactor will convert urea from the wastewater to ammonia by hydrolysis: NH2(CO)NH2 + H2O → 2NH3 + CO2. Next, the bioreactor effluent will travel through an ammonia electrolyzer reactor: 2NH3 → N2 + 3H2, thus, generating urea/ammonia-free wastewater effluent. Within this activity, we have (1) leveraged existing knowledge to design and test the bio-electrochemical reactor; (2) explored the efficacy of (P. Vulgaris) bacteria for bioreactor, (3) evaluated electrocatalyst for ammonia reactor, (4) optimized the efficiency and wastewater treatment rate with urine simulants. By doing so, we have demonstrated the potential to achieve nearly 100% ammonia removal during optimized operation. Herein, we will discuss the optimization and scaling of ammonia electrolyzer reactor where a sister paper within the ICES 2021 symposium (ICES-2021-402, ICES300 session) will focus on the bioreactor for this activity. Specifically, we will discuss the results from a bench-scale system that provided the information required to design and build a demonstration-scale electrolyzer capable of removing ammonia from 6L of urine per day (NASA-STD-3001 Vol 2). The next step for this activity will be a zero-gravity flight test scheduled for May 2021 such that the technology can be validated in microgravity. Establishing the potential to enable compatibility with the existing ECLSS infrastructure and become an integral part of the closed-loop living systems required for long-term life support on National Aeronautics and Space Administration (NASA)'s manned space missions.
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Forward osmosis (FO) membrane process is expected to realize energy-saving seawater desalination. To this end, energy-saving water recovery from a draw solution (DS) and effective DS regeneration are essential. Recently, thermo-responsive DSs have been developed to realize energy-saving water recovery and DS regeneration. We previously reported that high-temperature reverse osmosis (RO) treatment was effective in recovering water from a thermo-responsive ionic liquid (IL)-based DS. In this study, to confirm the advantages of the high-temperature RO operation, thermo-sensitive IL-based DS was treated by an RO membrane at temperatures higher than the lower critical solution temperature (LCST) of the DS. Tetrabutylammonium 2,4,6-trimethylbenznenesulfonate ([N4444][TMBS]) with an LCST of 58 °C was used as the DS. The high-temperature RO treatment was conducted at 60 °C above the LCST using the [N4444][TMBS]-based DS-lean phase after phase separation. Because the [N4444][TMBS]-based DS has a significantly temperature-dependent osmotic pressure, the DS-lean phase can be concentrated to an osmotic pressure higher than that of seawater at room temperature (20 °C). In addition, water can be effectively recovered from the DS-lean phase until the DS concentration increased to 40 wt%, and the final DS concentration reached 70 wt%. From the results, the advantages of RO treatment of the thermo-responsive DS at temperatures higher than the LCST were confirmed.
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Forward osmosis (FO) has attracted growing attention in the field of membrane-based separation technology over the last two decades. Despite recent advancements in various osmosis-assisted processes, few studies have succeeded in commercialization. This paper reviews the state-of-the-art developments of FO membrane, limitation analysis, and commercial proper applications. First, the development of FO technology in terms of FO membranes, FO draw solution (DS), and FO systems is reviewed. Based on a literature database survey spanning 1965-2020, current limitations of FO, particularly in terms of DS regeneration, energy consumption, and scale-up implementation, are identified to overcome the obstacles to commercialization. The key applications of the FO membrane process in commercial sectors are further classified into three configurations (i.e., osmotic dilution, osmotic concentration, and simultaneous osmotic dilution and concentration), and their successful applications are discussed. Since industrial demonstrations of simultaneous osmotic dilution and concentration are in progress, we believe that FO technology with no need for DS regeneration will be commercialized soon in the future.
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This study investigates the performance of an integrated osmotic and microfiltration membrane bioreactor (O/MF-MBR) system for wastewater treatment and reclamation. The O/MF-MBR system simultaneously used microfiltration (MF) and forward osmosis (FO) membranes to extract water from the mixed liquor of an aerobic bioreactor. The MF membrane facilitated the bleeding of dissolved inorganic salts and thus prevented the build-up of salinity in the bioreactor. As a result, sludge production and microbial activity were relatively stable over 60days of operation. Compared to MF, the FO process produced a better permeate quality in terms of nutrients, total organic carbon, as well as hydrophilic and biologically persistent trace organic chemicals (TrOCs). The high rejection by the FO membrane also led to accumulation of hydrophilic and biologically persistent TrOCs in the bioreactor, consequently increasing their concentration in the MF permeate. On the other hand, hydrophobic and readily biodegradable TrOCs were minimally detected in both MF and FO permeates, with no clear difference in the removal efficiencies between two processes. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.
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In the past four decades, membrane development has occurred based on the demand in pressure driven processes. However, in the last decade, the interest in osmotically driven processes, such as forward osmosis (FO) and pressure retarded osmosis (PRO), has increased. The preparation of customized membranes is essential for the development of these technologies. Recently, several very promising membrane preparation methods for FO/PRO applications have emerged. Preparation of thin film composite (TFC) membranes with a customized polysulfone (PSf) support, electorspun support, TFC membranes on hydrophilic support and hollow fiber membranes have been reported for FO/PRO applications. These novel methods allow the use of other materials than the traditional asymmetric cellulose acetate (CA) membranes and TFC polyamide/polysulfone membranes. This review provides an outline of the membrane requirements for FO/PRO and the new methods and materials in membrane preparation.
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With the world’s population growing rapidly, pressure is increasing on the limited fresh water resources. Membrane technology could play a vital role in solving the water scarcity issues through alternative sources such as saline water sources and wastewater reclamation. The current generation of membrane technologies, particularly reverse osmosis (RO), has significantly improved in performance. However, RO desalination is still energy intensive and any effort to improve energy efficiency increases total cost of the product water. Since energy, environment and climate change issues are all inter-related, desalination for large-scale irrigation requires new novel technologies that address the energy issues. Forward osmosis (FO) is an emerging membrane technology. However, FO desalination for potable water is still a challenge because, recovery and regeneration of draw solutes require additional processes and energy. This article focuses on the application of FO desalination for non-potable irrigation where maximum water is required. In this concept of fertiliser drawn FO (FDFO) desalination, fertilisers are used as draw solutions (DS). The diluted draw solution after desalination can be directly applied for fertigation without the need for recovery and regeneration of DS. FDFO desalination can make irrigation water available at comparatively lower energy than the current desalination technologies. As a low energy technology, FDFO can be easily powered by renewable energy sources and therefore suitable for inland and remote applications. This article outlines the concept of FDFO desalination and critically evaluates the scope and limitations of this technology for fertigation, including suggestions on options to overcome some of these limitations.
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Forward osmosis (FO) is a novel and emerging low energy technology for desalination. It will be particularly more attractive, if the draw solution separation and recovery are not necessary after FO process. The application of this new concept is briefly described here in this paper for the desalination of saline water for irrigation, using fertilizer as a draw agent. Instead of separating the draw solution from desalinated water, the diluted fertilizer draw solution can be directly applied for fertigation. We report the results on the commonly used chemical fertilizers as FO draw solution. Based on the currently available FO technology, about nine different commonly used fertilizers were finally screened from a comprehensive list of fertilizers and, their performances were assessed in terms of pure water flux and reverse draw solute flux. These results indicate that, most soluble fertilizers can generate osmotic potential much higher than the sea water. The draw solutions of KCl, NaNO3 and KNO3 performed best in terms of water flux while NH4H2PO4, (NH4)2HPO4, Ca(NO3)2 and (NH4)2SO4 had the lowest reverse solute flux. Initial estimation indicates that, 1kg of fertilizer can extract water ranging from 11 to 29L from sea water.
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One of the most pervasive problems afflicting people throughout the world is inadequate access to clean water and sanitation. Problems with water are expected to grow worse in the coming decades, with water scarcity occurring globally, even in regions currently considered water-rich. Addressing these problems calls out for a tremendous amount of research to be conducted to identify robust new methods of purifying water at lower cost and with less energy, while at the same time minimizing the use of chemicals and impact on the environment. Here we highlight some of the science and technology being developed to improve the disinfection and decontamination of water, as well as efforts to increase water supplies through the safe re-use of wastewater and efficient desalination of sea and brackish water.
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Objective. To describe TB/HIV clinic outcomes in a rural, Ministry of Health hospital. Design. Retrospective, secondary analyses. Descriptive statistics and logistic regression analyses evaluated baseline characteristics and outcomes. Results. Of 1,911 patients, 89.8% were adults aged 32.0 (±12.6) years with baseline CD4 = 243.3 (±271.0), 18.2% < 50 cells/mm3. Pulmonary (84.8%, (32.2% smear positive)) exceeded extrapulmonary TB (15.2%). Over 5 years, treatment success rose from 40.0% to 74.6%, lost to follow-up dropped from 36.0% to 12.5%, and deaths fell from 20.0% to 5.4%. For patients starting ART after TB treatment, those with CD4 ≥ 50 cells/mm3 were twice as likely to achieve treatment success (OR = 2.0, 95% CI = 1.3–3.1) compared to those with CD4 < 50 cells/mm3. Patients initiating ART at/after 2 months were twice as likely to achieve treatment success (OR = 2.0, 95% CI = 1.3–3.3). Yearly, odds of treatment success improved by 20% (OR = 1.2, 95% CI = 1.0–1.5). Conclusions. An integrated TB/HIV clinic with acceptable outcomes is a feasible goal in resource-limited settings.
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In recent years, numerous large-scale seawater desalination plants have been built in water-stressed countries to augment available water resources, and construction of new desalination plants is expected to increase in the near future. Despite major advancements in desalination technologies, seawater desalination is still more energy intensive compared to conventional technologies for the treatment of fresh water. There are also concerns about the potential environmental impacts of large-scale seawater desalination plants. Here, we review the possible reductions in energy demand by state-of-the-art seawater desalination technologies, the potential role of advanced materials and innovative technologies in improving performance, and the sustainability of desalination as a technological solution to global water shortages.
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Osmotic membrane bioreactor (OMBR) is an emerging technology that integrating a forward osmosis (FO) process into a membrane bioreactor (MBR). This technology has been gaining increasing popularity in wastewater treatment and reclamation due to its excellent product water quality, low fouling tendency and high fouling reversibility over conventional MBRs. In past decade especially the last 3 years, novel insights and significant advancements have been achieved in many aspects of OMBR accompanied with greatly increased number of published papers. This paper attempts to critically review the recent developments in OMBRs and to present a clear outline for further studies. Firstly, OMBR fundamentals including its configuration and FO process are presented. Subsequently, performance of OMBRs is summarized and compared to conventional MBRs. Additionally, mechanisms, impacts and mitigations of salt accumulation and membrane fouling related to the core challenge of low water flux in OMBRs are addressed. Finally, future research prospects are discussed in order to further improve OMBR technology and drive it from laboratory research to real practical applications.
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Reverse flux of ammonium draw solute is a serious problem for applying forward osmosis (FO) in water/wastewater treatment. In this study, anaerobic ammonium oxidization (anammox) was synergistically linked to FO for removal of reverse-fluxed ammonium, thereby creating an osmotic anammox system. The feasibility of this system was demonstrated through both batch and continuous operation, and the anammox process was developed in two stages: sole anammox and nitritation-anammox. With addition of nitrite, the sole anammox process achieved an effluent ammonium concentration of 9.9±9.5mgNL-1. The nitritation-anammox maintained an ammonium concentration of 3.1±4.2mgNL-1, and increased the water flux to 2.46±0.24LMH (Lm-2h-1) compared with the sole anammox (1.90±0.14LMH). The nitritation-anammox process exhibited advantages over anammox process in assisting the FO with respect to water flux improvement and chemical savings. The osmotic anammox system can be linked to previously developed microbial electrolysis cells that recover ammonium from high-strength wastes as a draw solute for FO operation. The results encourage further investigation of this system for effects of organic residues, decreasing nitrate accumulation, understanding biofilm on the FO membrane, and long-term performance with actual waste.
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Osmotic membrane bioreactor (OMBR) is an emerging technology using water osmosis to accomplish separation of biomass from the treated effluent; however, accumulation of salts in the wastewater due to water flux and loss of draw solute due to reverse salt flux seriously hinders OMBR development. In this study, a hybrid OMBR-Electrodialysis (ED) system was proposed and investigated to alleviate the salinity buildup. The use of an ED (3 V applied) could maintain a relatively low conductivity of 8 mS cm-1 in the feed solution, which allowed the OMBR to operate for 24 days, about 6 times longer than a conventional OMBR without a functional ED. It was found that the higher voltage applied to the ED, the smaller area of ion exchange membrane was needed for salt separation. The recovered salts by the ED were successfully reused as a draw solute in the OMBR. At energy consumption of 1.88-4.01 kWh m-3, the hybrid OMBR-ED system could achieve a stable water flux of about 6.23 LMH and an efficient waste salt recovery of 1.26 kg m-3. The hybrid OMBR-ED system could be potentially more advantageous in terms of less waste saline water discharge and salt recovery, compared with an OMBR+RO system. It also offers potential advantages over the conventional OMBR+post ED treatment in higher water flux and less wastewater discharge.
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The performance of recently developed polyamide thin film composite hollow fibre forward osmosis (HFFO) membrane module was assessed for the desalination of brackish groundwater for fertigation. Four different fertilisers were used as draw solution (DS) with real BGW from the Murray–Darling Basin in Australia. Membrane charge and its electrostatic interactions with ions played a significant role in the performance of the HFFO module using fertiliser as DS. Negatively charged polyamide layer promotes sorption of multivalent cations such as Ca2 + enhancing ion flux and membrane scaling. Inorganic scaling occurred both on active layer and inside the support layer depending on the types of fertiliser DS used resulting in severe flux decline and this study therefore underscores the importance of selecting suitable fertilisers for the fertiliser drawn forward osmosis (FDFO) process. Water flux under active layer DS membrane orientation was about twice as high as the other orientation indicating the need to further optimise the membrane support structure formation. Water flux slightly improved at higher crossflow rates due to enhanced mass transfer on the fibre lumen side. At 45% packing density, HFFO could have three times more membrane area and four times more volumetric flux output for an equivalent 8040 cellulose triacetate flat-sheet FO membrane module.
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On-site treatment and reuse is an increasingly preferred option for produced water management in unconventional oil and gas extraction. This paper analyzes and compares the energetics of several desalination technologies at the high salinities and diverse compositions commonly encountered in produced water from shale formations to guide technology selection and to inform further system development. Produced water properties are modeled using Pitzer's equations, and emphasis is placed on how these properties drive differences in system thermodynamics at salinities significantly above the oceanic range. Models of mechanical vapor compression, multi-effect distillation, forward osmosis, humidification–dehumidification, membrane distillation, and a hypothetical high pressure reverse osmosis system show that for a fixed brine salinity, evaporative system energetics tend to be less sensitive to changes in feed salinity. Consequently, second law efficiencies of evaporative systems tend to be higher when treating typical produced waters to near-saturation than when treating seawater. In addition, if realized for high-salinity produced waters, reverse osmosis has the potential to achieve very high efficiencies. The results suggest a different energetic paradigm in comparing membrane and evaporative systems for high salinity wastewater treatment than has been commonly accepted for lower salinity water.
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Adequate dilution of fertiliser draw solution (DS) during fertiliser drawn forward osmosis (FDFO) desalination is important to meet nutrient concentration level for direct fertigation. The maximum DS dilution, however, occurs until the point of osmotic equilibrium between DS and feed solution (FS) thereby limiting the extent of DS dilution. Post-treatment such as nanofiltration (NF) process is required to reduce the fertiliser concentration. In this study however, pressure assisted fertiliser drawn osmosis (PAFDO) process was investigated to enhance DS dilution beyond the point of osmotic equilibrium and potentially eliminate NF post-treatment. The hydraulic pressure applied enhanced water flux significantly depending on the pressure. The applied pressure was found more effective at lower DS concentrations than at higher DS concentrations. For example, when a pressure of 10 bar was applied to 10 g/L NaCl FS with 0.1 M (NH4)2SO4 DS, the water flux increased by 1928% against 38% with 3.0 M (NH4)2SO4 DS. This additional water flux could dilute the fertiliser DS beyond the osmotic equilibrium concentrations thereby meeting the fertigation standard. PAFDO could potentially eliminate NF post-treatment significantly helping reduce the footprint and capital cost. However, the effective gain in water flux due to applied pressure at osmotic equilibrium decreased with the increase in the FS concentrations.
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This study has presented a proof-of-concept system for the self-sustained supply of ammonium-based draw solute for wastewater treatment through coupling a microbial electrolysis cell (MEC) and forward osmosis (FO). The MEC produced an ammonium bicarbonate draw solute via recovering ammonia from a synthetic organic solution, which was then applied in the FO for extracting water from the MEC anode effluent. The recovered ammonium could reach a concentration of 0.86 mol L–1, and with this draw solution, the FO extracted 50.1 ± 1.7% of the MEC anode effluent. The lost ammonium during heat regeneration could be supplemented with additional recovered ammonium in the MEC. The MEC achieved continuing treatment of both organic and ammonium in the returned feed solution mixed with fresh anolyte, although at lower efficiency compared to that with completely fresh anolyte. These results encourage further investigation to optimize the coordination between MEC and FO with improved performance.
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Fertiliser-drawn forward osmosis (FDFO) desalination has been recently studied as one feasible application of forward osmosis (FO) for irrigation. In this study, the potential of membrane scaling in the FDFO process has been investigated during the desalination of brackish groundwater (BGW). While most fertilisers containing monovalent ions did not result in any scaling when used as an FO draw solution (DS), diammonium phosphate (DAP or (NH4)2HPO4) resulted in significant scaling, which contributed to severe flux decline. Membrane autopsy using scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD) analysis indicated that the reverse diffusion of DAP from the DS to the feed solution was primarily responsible for scale formation during the FDFO process. Physical cleaning of the membrane with deionised water at varying crossflow velocities was employed to evaluate the reversibility of membrane scaling and the extent of flux recovery. For the membrane scaled using DAP as DS, 80-90% of the original flux was recovered when the crossflow velocity for physical cleaning was the same as the crossflow velocity during FDFO desalination. However, when a higher crossflow velocity or Reynolds number was used, the flux was recovered almost completely, irrespective of the DS concentration used. This study underscores the importance of selecting a suitable fertiliser for FDFO desalination of brackish groundwater to avoid membrane scaling and severe flux decline.
Article
Fertilizer-drawn forward osmosis is a low-energy desalination concept particularly developed for the irrigation use of desalinated water. It has an advantage of not requiring regeneration of the draw solution (DS), thus, it can be used directly for the purpose of irrigation without any additional treatment. The current study was aimed to evaluate the real application of forward osmosis (FO) targeting irrigation of tomato crops based from their fertilizer requirements. Fertilizer-DSs were prepared to drive seawater desalination using commercially available fertilizers such as NH4NO3, NH4Cl, KNO3, KCl, NH4H2PO4, and urea. DSs were prepared to represent varying nitrogen:phosphorous:potassium (N:P:K) ratios used in assorted tomato growth stages. The FO performance evaluated in terms of the flux and reverse solute flux (RSF) showed significant variations in outcome. The resultant flux for different DSs was influenced by the particular fertilizer present in DS mixture and its concentration. This flux varied from 2.50 to 12.49 LMH. Comparatively, DS carrying high osmotic pressure components showed high-flux outcome. The fraction Jw/∆π of these fertilizer-DSs varied from 0.062 to 0.19 LMH/bar, which indicates a changing flux outcome against the same osmotic pressure. To select the best performing fertilizer-DS, nitrogen source fertilizers like urea, NH4NO3, and NH4Cl were further evaluated for 10-0-10 NPK value. It was found that NH4Cl-based DS mixtures performed better than urea- and NH4NO3-based DS. The RSF results indicated that all nitrogen- and potassium-based DS exhibited higher N- and K-RSF. However, the DS using NH4H2PO4 delivered extremely low P-RSF of 12.35 g/m2/h. Long-term run tests with seawater quality feed solution resulted in FO producing a final DS enriched in nutrients greater than the tomato plant’s requirement. This implies that the use of dilution or any other technique to reduce excessive nutrients is essential before using the final DS for tomato irrigation.
Article
The concept of fertiliser drawn forward osmosis (FDFO) desalination lies in the premise that fertilisers that serve as draw solutions (DS) add value to the FDFO product water for fertigation. However, because FDFO desalination is concentration based, the process cannot continue beyond the concentration equilibrium, one of the major limitations of the forward osmosis (FO) process. This results in final FDFO product water that, unless subjected to substantial dilution with fresh water, exceeds the acceptable nutrient concentrations for direct fertigation. In this study, nanofiltration (NF) has been assessed as an integrated process to FDFO desalination, either as a pre-treatment or post-treatment, to reduce the nutrient concentrations in the final product water and thereby allow direct use of the product water for fertigation without further dilution. NF as pre-treatment or post-treatment was found effective in reducing the nutrient concentrations using brackish groundwater (BGW) sources with relatively low total dissolved solid (TDS). However, when using higher TDS BGW sources, the product water still required further dilution or post-treatment before fertigation. NF as post-treatment was found to be more advantageous both in terms of reduced nutrient concentrations in the final product water and energy consumption.
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Seawater desalination for agricultural irrigation will be an important contributor to satisfying growing water demands in water scarce regions. Irrigated agriculture for food production drives global water demands, which are expected to increase while available supplies are further diminished. Implementation of reverse osmosis, the current leading technology for seawater desalination, has been limited in part because of high costs and energy consumption. Because of stringent boron and chloride standards for agricultural irrigation water, desalination for agriculture is more energy intensive than desalination for potable use, and additional post-treatment, such as a second pass reverse osmosis process, is required. In this perspective, we introduce the concept of an integrated forward osmosis and reverse osmosis process for seawater desalination. Process modeling results indicate that the integrated process can achieve boron and chloride water quality requirements for agricultural irrigation while consuming less energy than a conventional two-pass reverse osmosis process. The challenges to further development of an integrated forward and reverse osmosis desalination process and its potential benefits beyond energy savings are discussed.
Article
Osmotically driven membrane processes (ODMPs) such as forward osmosis (FO) and pressure retarded osmosis (PRO) are extensively investigated for utilization in a broad range of applications. In ODMPs, the operating conditions and membrane properties play more critical roles in mass transport and process performance than in pressure-driven membrane processes. Search of the literature reveals that ODMP membranes, especially newly developed ones, are tested under different temperatures, draw solution compositions and concentrations, flow rates, and pressures. In order to compare different membranes, it is important to develop standard protocols for testing of membranes for ODMPs. In this article we present a standard methodology for testing of ODMP membranes based on experience gained and operating conditions used in FO and PRO studies in recent years. A round-robin testing of two commercial membranes in seven independent laboratories revealed that water flux and membrane permeability coefficients were similar when participants performed the experiments and calculations using the same protocols. The thin film composite polyamide membrane exhibited higher water and salt permeability than the asymmetric cellulose-based membrane, but results with the high permeability thin-film composite membrane were more scattered. While salt rejection results in RO mode were relatively similar, salt permeability coefficients for both membranes in FO mode were more varied. Results suggest that high permeability ODMP membranes should be tested at lower hydraulic pressure in RO mode and that RO testing be conducted with the same membrane sample used for testing in FO mode.
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It isn't just membrane fouling that is seen as an important issue in Membrane Bioreactor (MBR) operation. Research undertaken in Australia and US highlights other areas of concern for users and operators…
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In this investigation, a protocol for the selection of optimal draw solutions for forward osmosis (FO) applications was developed and the protocol was used to determine the most appropriate draw solutions for specific FO applications using a currently available FO membrane. The protocol includes a desktop screening process and laboratory and modeling analyses. The desktop screening process resulted in 14 draw solutions suitable for FO applications. The 14 draw solutions were then tested in the laboratory to evaluate water flux and reverse salt diffusion through the FO membrane. Internal concentration polarization was found to lower both water flux and reverse salt diffusion by reducing the draw solution concentration at the interface between the support and dense layers of the membrane. Draw solution reconcentration was evaluated using reverse osmosis (RO) system design software. Analysis of experimental data and model results, combined with consideration of the costs associated with the FO and RO processes showed that a small group of seven draw solutions appeared to be the most suitable. The different characteristics of these draw solutions highlighted the importance of considering the specific FO application and membrane types being used prior to selecting the most appropriate draw solution.
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Water productivity is generally defined as crop yield per cubic metre of water consumption, including 'green' water (effective rainfall) for rain-fed areas and both 'green' water and 'blue' water (diverted water from water systems) for irrigated areas. Water productivity defined as above varies from region to region and from field to field, depending on many factors, such as crop patterns and climate patterns (if rainfall fits crop growth), irrigation technology and field water management, land and infrastructure, and input, including labour, fertilizer and machinery. In this chapter, we analyse water productivity at the global and regional levels through a holistic modelling framework, IMPACT-WATER, an integrated water and food model developed at the International Food Policy Research Institute (IFPRI). Scenario analysis is undertaken to explore the impact of technology and management improvement and invest- ment on water productivity and to search for potentials in improving food security through enhancing water productivity. It is found that the water productivity of rice ranged from 0.15 to 0.60 kg m3, while that of other cereals ranged from 0.2 to 2.4 kg m3 in 1995. From 1995 to 2025, water productivity will increase. The global average water productivity of rice and other cereals will increase from 0.39 kg m3 to 0.52 kg m3 and from 0.67 kg m3 to 1.01 kg m3, respectively. Both the increase in crop yield and improvement in basin efficiency contribute to the increase in water productivity, but the major contribu- tion comes from increase in the crop yield. Moreover, water productivity of irrigated crops, although higher than that of rain-fed crops in developing countries, is lower in developed countries.
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The empirical correction to Stokes' law proposed by Robinson and Stokes has been extended for small ions to provide a concordant set of radii for the hydrated ions. Ions with a crystal ionic radius of about 2 Å. exhibit a minimum hydrated radius of 3.3 Å. corresponding to the maximum in the equivalent conductance. The internal consistency of the set of radii is demonstrated by correlation with the temperature coefficient of equivalent conductance, the viscosity B-coefficient and the partial molar ionic entropy. Except for the small monatomic ions with the minimum hydrated radius, the hydrated ionic radius at 25° is demonstrated to be a linear function of the viscosity B-coefficient. The significance of this relation is discussed in terms of the structural modification rendered by the ions to water.
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A novel forward (direct) osmosis (FO) desalination process is presented. The process uses an ammonium bicarbonate draw solution to extract water from a saline feed water across a semi-permeable polymeric membrane. Very large osmotic pressures generated by the highly soluble ammonium bicarbonate draw solution yield high water fluxes and can result in very high feed water recoveries. Upon moderate heating, ammonium bicarbonate decomposes into ammonia and carbon dioxide gases that can be separated and recycled as draw solutes, leaving the fresh product water. Experiments with a laboratory-scale FO unit utilizing a flat sheet cellulose tri-acetate membrane demonstrated high product water flux and relatively high salt rejection. The results further revealed that reverse osmosis (RO) membranes are not suitable for the FO process because of relatively low product water fluxes attributed to severe internal concentration polarization in the porous support and fabric layers of the RO membrane.
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This investigation evaluates the use of organic ionic salt solutions as draw solutions for specific use in osmotic membrane bioreactors. Also, this investigation presents a simple method for determining the diffusion coefficient of ionic salt solutions using only a characterized membrane. A selection of organic ionic draw solutions underwent a desktop screening process before being tested in the laboratory and evaluated for performance using specific salt flux (reverse salt flux per unit water flux), biodegradation potential, and replenishment cost. Two of the salts were found to have specific salt fluxes three to six times lower than two commonly used inorganic draw solutions, NaCl and MgCl(2). All of the salts tested have organic anions with the potential to degrade in the bioreactor as a carbon source and aid in nutrient removal. Results demonstrate the potential benefits of organic ionic salt draw solutions over currently implemented inorganics in osmotic membrane bioreactor systems.
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A novel osmotic membrane bioreactor (OsMBR) is presented. The system utilizes a submerged forward osmosis (FO) membrane module inside a bioreactor. Through osmosis, water is transported from the mixed liquor across a semi-permeable membrane, and into a draw solution (DS) with a higher osmotic pressure. To produce potable water, the diluted DS is treated in a reverse osmosis (RO) unit; the by-product is a reconcentrated DS for reuse in the FO process. Preliminary results from experiments conducted with a flat-sheet cellulose triacetate FO membrane demonstrated high sustainable flux and relatively low reverse transport of solutes from the DS into the mixed liquor. Membrane fouling was controlled with osmotic backwashing. The FO membrane was found to reject 98% of organic carbon and 90% of ammonium-nitrogen; the OsMBR process (bioreactor and FO membrane) was found to remove greater than 99% of organic carbon and 98% of ammonium-nitrogen, respectively; suggesting a better compatibility of the OsMBR with downstream RO systems than conventional membrane bioreactors.
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Osmosis is a physical phenomenon that has been extensively studied by scientists in various disciplines of science and engineering. Early researchers studied the mechanism of osmosis through natural materials, and from the 1960s, special attention has been given to osmosis through synthetic materials. Following the progress in membrane science in the last few decades, especially for reverse osmosis applications, the interests in engineered applications of osmosis has been spurred. Osmosis, or as it is currently referred to as forward osmosis, has new applications in separation processes for wastewater treatment, food processing, and seawater/brackish water desalination. Other unique areas of forward osmosis research include pressure-retarded osmosis for generation of electricity from saline and fresh water and implantable osmotic pumps for controlled drug release. This paper provides the state-of-the-art of the physical principles and applications of forward osmosis as well as their strengths and limitations.
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The energy requirements of ammonia–carbon dioxide forward osmosis (FO) desalination are predicted by the use of chemical process modeling software (HYSYS). The FO process is modeled using single or multiple distillation columns to separate draw solution solutes from the product water for solute recycling within the FO system. Thermal and electrical energy requirements of the process are calculated, as well as a combined term for equivalent electrical work. The results of the simulations are compared to the energy requirements of current desalination technologies. Energy savings of FO compared to current technologies, on an equivalent work basis, are projected to range from 72% to 85%. Forward osmosis desalination is in an early stage of its development, and several areas of future work promise opportunities to improve its energy utilization and cost.
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