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Energy consumption by forward osmosis treatment of landfill leachate for water recovery

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Abstract Forward osmosis (FO) is an alternative approach for treating landfill leachate with potential advantages of reducing leachate volume and recovering high quality water for direct discharge or reuse. However, energy consumption by FO treatment of leachate has not been examined before. Herein, the operational factors such as recirculation rates and draw concentrations were studied for their effects on the quantified energy consumption by an FO system treating actual leachate collected from two different landfills. It was found that the energy consumption increased with a higher recirculation rate and decreased with a higher draw concentration, and higher water recovery tended to reduce energy consumption. The highest energy consumption was 0.276 ± 0.033 kW h m−3 with the recirculation rate of 110 mL min−1 and 1-M draw concentration, while the lowest of 0.005 ± 0.000 kW h m−3 was obtained with 30 mL min−1 recirculation and 3-M draw concentration. The leachate with lower concentrations of the contaminants had a much lower requirement for energy, benefited from its higher water recovery. Osmotic backwashing appeared to be more effective for removing foulants, but precise understanding of membrane fouling and its controlling methods will need a long-term study. The results of this work have implied that FO treatment of leachate could be energy efficient, especially with the use of a suitable draw solute that can be regenerated in an energy efficient way and/or through combination with other treatment technologies that can reduce contaminant concentrations before FO treatment, which warrants further investigation.
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... However, one of the major challenges of nutrients and energy recovery from wastewater is the low-strength nature of wastewater, which not only impacts the recovery efficiency but also increases the construction cost for building reactors with large volumes [4]. Therefore, it is critical to find an effective approach to increase the concentration of matters such as chemical oxygen demand (COD) and nutrients (nitrogen and phosphorus) [4,7]. Membrane-based technology including microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) have been studied and applied for various sources of wastewater treatment, including landfilling leachate [8,9] and textile wastewater [10,11]. ...
... It should be mentioned that when designing the FO system for wastewater treatment, all factors elaborated above should be considered comprehensively, since these factors are interactive, and some potential trade-offs exist. For example, previous studies indicated that the energy consumption of the FO process could be reduced by system optimisation [3,7,28,37,55]. Iskander et al. [7] reported a study focusing on the energy perspective of the FO system for landfill leachate treatment. Their result indicated that the application of the osmotic backwashing process or chemical cleaning could effectively mitigate the membrane fouling and slow down the reduction of water flux. ...
... For example, previous studies indicated that the energy consumption of the FO process could be reduced by system optimisation [3,7,28,37,55]. Iskander et al. [7] reported a study focusing on the energy perspective of the FO system for landfill leachate treatment. Their result indicated that the application of the osmotic backwashing process or chemical cleaning could effectively mitigate the membrane fouling and slow down the reduction of water flux. ...
Article
Full-text available
The application of membrane technologies for wastewater treatment to recover water and nutrients from different types of wastewater can be an effective strategy to mitigate the water shortage and provide resource recovery for sustainable development of industrialisation and urbanisation. Forward osmosis (FO), driven by the osmotic pressure difference between solutions divided by a semi-permeable membrane, has been recognised as a potential energy-efficient filtration process with a low tendency for fouling and a strong ability to filtrate highly polluted wastewater. The application of FO for wastewater treatment has received significant attention in research and attracted technological effort in recent years. In this review, we review the state-of-the-art application of FO technology for sewage concentration and wastewater treatment both as an independent treatment process and in combination with other treatment processes. We also provide an outlook of the future prospects and recommendations for the improvement of membrane performance, fouling control and system optimisation from the perspectives of membrane materials, operating condition optimisation, draw solution selection, and multiple technologies combination.
... There have been several systematic studies focused on the stand-alone FO membrane [7][8][9]. However, the significant problems caused by fouling when employing wastewater as a feed solution have inhibited the large-scale implementation of the FO process [10][11][12], especially for treatment of high strength wastewater [13][14][15]. Fouling not only causes a decrease in water flux and product quality but the associated cleaning damages the membrane. Herein lies the critical drawback which is intense fouling; this is mainly induced by a fraction of effluent organic matter (EfOM) such as polysaccharides, proteins, humic substances, and fulvic acids, organic acids and lipids [16]. ...
... The relative specific energy consumption (SEC-kWh/m 3 ) was calculated so as to evaluate the comparative performance during the long-term tests. Calculation is standard and accords with previous works [13,40,41]. Fouling-induced flux decline and increment of channel pressure drop leads to a variation in energy consumption for different operating conditions [42]. ...
... The present work suggests that 21 LMH is a sound guideline but to minimize membrane costs 25 LMH should be explored because elsewhere this value has been reported to be the critical flux, albeit at a higher value of CFV. However, increase of CFV will cause an increase in energy consumption [13,41]. Therefore in further work, critical flux behavior under different CFVs should be investigated so as to achieve an appropriate balancing of fouling mitigation and energy consumption. ...
Article
A strategy of using critical fluxes to control organic fouling of polyamide thin film composite (PA-TFC) forward osmosis (FO) membranes during wastewater reclamation was developed for FO mode. This work was a comprehensive investigation with various organic foulants covering complex mixtures as well as single foulants. The foulants were alginate (ALG), Humic acid (HA), and Bovine Serum Albumin (BSA) and the study covered different concentration (40; 80; 120; 160 mg/L). Our results indicated that there was a single value of critical flux, 35 LMH for 160 mg/L and single foulant. However the presence of mixed foulants i.e., ALG+BSA, ALG+HA, HA+BSA, at an overall foulant concentration of 160 mg/L gave rise to foulant-foulant-membrane interactions that caused a significant decrease in critical flux values to 25-30 LMH. Using these results as a guide, long-term tests in which there was no fouling or negligible fouling were successfully implemented. Operating below critical flux maintains a sustainable operation with the characteristic of full reversibility, which is vital if chemical cleaning is to be minimized. Characterization of fouling around critical values was made through physico-chemical analyses including SEM, EEM, aggregate size, zeta potential, and FTIR. It was found that FO fouling became irreversible when operated at a flux ≥ 35 LMH for single foulants and fluxes of 25 LMH and 30 LMH for ALG+BSA and HA+BSA foulants respectively, being a foulant concentration of 160 mg/L; such conditions are favorable for the formation of the cohesive and compact cake layer. Economic assessments based on specific energy consumption facilitated the production of guidelines for practical design and operation.
... From an economic point of view, the forward osmosis (FO) process is superior to NF or the RO treatments owing to its numerous advantages, which include the high rejection for organic and inorganic pollutants, no requirement for externally aided hydraulic pressure, and a lower extent of membrane fouling with good reversibility (Iskander et al., 2017;Lee et al., 2010). The FO process is based on the principle of the water permeation across a semi-permeable membrane driven by the difference in the osmotic potential gradient between feed water and draw solution (Cath et al., 2006). ...
... The FO process is based on the principle of the water permeation across a semi-permeable membrane driven by the difference in the osmotic potential gradient between feed water and draw solution (Cath et al., 2006). Recently, FO has been successfully applied in the direct concentration of the complex and high strength wastewater streams, such as textile wastewater (Han et al., 2016), drilling mud from oil refining (Hickenbottom et al., 2013), landfill leachate (Iskander et al., 2017;Qin et al., 2016), and domestic wastewater (Aftab et al., 2017(Aftab et al., , 2015. FO has also proved its excellent applicability in treating landfill leachate for the recovery of inorganics, the removal of aromatic hydrocarbons, and the water recovery from high saline and biologically treated leachates (Dong et al., 2014;Iskander et al., 2017;Li et al., 2017;Qin et al., 2016;Wu et al., 2018). ...
... Recently, FO has been successfully applied in the direct concentration of the complex and high strength wastewater streams, such as textile wastewater (Han et al., 2016), drilling mud from oil refining (Hickenbottom et al., 2013), landfill leachate (Iskander et al., 2017;Qin et al., 2016), and domestic wastewater (Aftab et al., 2017(Aftab et al., , 2015. FO has also proved its excellent applicability in treating landfill leachate for the recovery of inorganics, the removal of aromatic hydrocarbons, and the water recovery from high saline and biologically treated leachates (Dong et al., 2014;Iskander et al., 2017;Li et al., 2017;Qin et al., 2016;Wu et al., 2018). However, despite a number of such practical applications, no attention has been paid to the organic fouling potential of landfill leachate in FO, which serves as a critical factor to determine the operational cost and water recovery. ...
Article
Forward osmosis (FO) has been adopted to treat complex wastewater such as landfill leachate due to its high rejection of organics. In this study, the in-line adsorptive process using biochar (BC) or powdered activated carbon (PAC) was applied to a cross flow FO system to enhance the mitigation of the FO membrane fouling from landfill leachate. The changes in the leachate composition along the treatments were tracked by excitation emission matrix-parallel factor analysis (EEM-PARAFAC) to identify tryptophan-like (C1), fulvic-like (C2), and humic-like (C3) components. After a single operation of FO, the C1 was found to be the main constituent responsible for membrane fouling irrespective of varying operation conditions regarding draw solute concentrations and flow rates. Both sorbents (i.e., BC and PAC) exhibited the preferential removal behavior towards C1 > C2 > C3, which was well supported by their individual adsorption isotherm model parameters. The addition of in-line adsorption treatment to FO resulted in substantial improvements in the filtered volume (>57%) and the flux recovery (>80%) compared to the single FO operation. Without chemical cleaning of membrane, the flux was fully recovered at a dose of 10 g/L BC or 0.3 g/L of PAC. A significant and negative correlation was found between the flux recovery and the C1 of the feed leachate or the corresponding spectral peak intensity (p < 0.05) for the integrated FO system, suggesting the potential of using on-line fluorescence monitoring for the performance of the integrated system in terms of fouling mitigation. This study provided a new insight into the effectiveness of BC or PAC adsorption as the in-line integration with an FO system for the targeted removal of FO membrane foulants in landfill leachate.
... Zhao et al. even reached fluxes at 45-50 LMH by using modified TFC membranes. Landfill leachate is also a source of minerals such as ammonium and phosphate, but also potassium, sodium, magnesium and calcium ions can be recovered (Iskander et al., 2017;Wu et al., 2018). Wu et al. (Wu et al., 2018) treated landfill leachate with high concentrations of magnesium, calcium and ammonium with FO to reach a VCF of 1.6. ...
... Also the recovered nutrient might have low solubility in the feed solution (i.e. the solubility of struvite in water at 25 • C is ~170 ppm), thus precipitation can be achieved at low overall solution concentration. The ability of FO to concentrate the solutions to saturation levels has been well documented in various studies (Iskander et al., 2017;S. Wu et al., 2018;Z. ...
... This is in accordance with the study of Aydiner et al. (Aydiner et al., 2014), finding higher capital expenses for FO-RO treatment of whey due to FO membrane cost but shorter payback time explained by high water recovery and low energy consumption. In another study describing water recovery from landfill leachate (Iskander et al., 2017), the maximum energy consumption was in the range of 0.276 ± 0.033 kW h m − 3 , however, the energy consumption for draw solution recovery was not been included into the analysis. For an ammonia-carbon dioxide FO desalination system, where the draw solution was concentrated through distillation, the specific electric energy consumption has been calculated to be 0.24 kWh/m 3 (McGinnis and Elimelech, 2007). ...
Article
Socioeconomic development and new technological advancements have greatly increased the demand for metals, minerals and nutrients. Thus, substantial interest in developing technologies to recover these commodities from seawater, various brines and wastewater streams (industrial and domestic) has emerged. Less explored and innovative membrane processes including membrane crystallization (MCr), forward osmosis (FO) and membrane capacitive deionization (MCDI) are gaining interest in this regard. The current study provides a critical review of the current trends in applying MCr, FO and MCDI for recovery of metals, minerals and nutrients from various streams. The processes are compared in terms of types of fouling, energy consumption, overall composition of suitable feed solutions, feasible concentration ranges and potential to recover the targeted metal from a multi-component solution. The ultimate objective is to establish future research directions for further improvement of each process and to identify which of the processes is more suitable under a given scenario.
... In general, physical treatments have exhibited removals of 23e97% (average 77%) UV absorbance and 34e98% (average 65.8%) UVQS in terms of TOC (Fig. 3). Membrane separation that works on the size exclusion principle includes reverse osmosis (RO), forward osmosis (FO), nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF) (Amaral et al., 2015b;Huo et al., 2009;Iskander et al., 2017c;Zhao et al., 2013a;Zolfaghari et al., 2017). Huo et al. (2009) reported that an RO process was able to remove 100% HA, 99.7% FA, and 98.4% HPI from a biologically treated leachate. ...
... Huo et al. (2009) reported that an RO process was able to remove 100% HA, 99.7% FA, and 98.4% HPI from a biologically treated leachate. FO could remove~98% UVQS (in terms of TOC) from landfill leachate during water recovery (Iskander et al., 2017c). A removal efficiency of 43% for TOC by combined lime precipitation (8 g L À1 lime) and MF was reported for humic substances from landfill leachate, while NF increased the removal to 86% (Amaral et al., 2015b). ...
Article
Landfill leachate contains extremely diverse mixtures of pollutants and thus requires appropriate treatment before discharge. Co-treatment of landfill leachate with sewage in wastewater treatment plants is a common approach because of low cost and convenience. However, some recalcitrant organic compounds in leachate can escape biological treatment processes, lower the UV transmittance of waste streams due to their UV-quenching properties, and interfere with the associated disinfection efficacy. Thus, the leachate UV quenching substances (UVQS) must be removed or reduced to a level that UV disinfection is not strongly affected. UVQS consist of three major fractions, humic acids, fulvic acids and hydrophilics, each of which has distinct characteristics and behaviors during treatment. The purpose of this review is to provide a synthesis of the state of the science regarding UVQS and possible treatment approaches. In general, chemical, electrochemical, and physical treatments are more effective than biological treatments, but also costlier. Integration of multiple treatment methods to target the removal of different fractions of UVQS can aid in optimizing treatment. The importance of UVQS effects on wastewater treatment should be better recognized and understood with implemented regulations and improved research and treatment practice.
... Therefore, many treatment methods such as biological, chemical, physical, wetland and advanced oxidation processes have been applied to treat the LL [2]. In order to treat the LL, lots of methods have been examined in the published literature, including physical [3][4][5][6][7][8][9][10][11][12], chemical [13][14][15][16][17][18][19][20][21][22] and biological [23][24][25][26][27][28][29][30][31][32] approaches. In addition to the classical treatment methods mentioned above, in recent years, electrochemical methods (electrocoagulation, electro-Fenton, electro-dialysis, etc.) have been used as a pre-treatment stage in the LL treatment process. ...
... This can be explained theoretically in the absence of any pollutants for pure water under standard conditions: with Al electrodes in acidic medium, monomeric hydroxometallic cations Al(OH) 3 are formed (Eqs. (4) and (11)). For neutral media, both polymeric hydroxometallic cations and metal hydroxide precipitates coexist at higher pH. ...
... Researchers have developed reuse water from wastewater in WWTPs that can effectively use as a multipurpose candidate, could reverse the overexploitation of existing reserves and make better channels with them (Leverenz et al., 2011). Most of the type wastewaters, especially secondary treated municipal wastewater, leachate wastewater and low strength wastewater can help make reuse water for various purposes (Iskander et al., 2017). Treatment methods such as OMBR-RO, OMBR-RO coupled with MF that can treat wastewater effectively. ...
... A wastewater rich in carbohydrate, with low ammonium nitrogen concentration may significantly higher the production of power density which in turn lower the recovery of nutrients (Gude, 2016). Moreover, the high energy recovery in BESs and water recovery in membrane technologies were linked with swine wastewater and landfill leachate respectively (Ichihashi and Hirooka, 2012;Iskander et al., 2017). Ironically, BESs turn low-strength wastewaters into energy products such as hydrogen and electricity with only small volumes. ...
... For a discussion of the later, see [22]. Whilst several studies have focused on the stand-alone FO for reclaiming primary/secondary wastewater effluent [5][6][7], even for high strength wastewater [8,9], the FO membrane can be integrated with other processes (RO, UF, MD) as a means of osmotic dilution to attain simultaneous water reclamation and desalination [10][11][12][13]. ...
... Whilst their findings indicated CPs became more serious as DS concentration increased, these effects may be mitigated to a certain extent with increasing cross-flow velocity (CFV) i.e., from 5.56 to 11.11 cm/s [27], from 2.11 to 36.40 cm/s [28]. It has been found that fouling diminished by elevating CFV i.e., from 10.7 cm/s (Re = 615) to 32.1 cm/s (Re = 1936) [11] or from 6 to 24 cm/s [29]; however, this option will cause an increase in energy consumption [8,30]. Although the effect of CPs has been analyzed for the FO membrane process, e.g. ...
Article
The long-term performance of forward osmosis during simulated wastewater reclamation was investigated for 120 h operation with a focus upon the influence of flux on flux decline and the synergistic effect of fouling on concentration polarization. Our comprehensive investigation focused on different fluxes (25; 30; 34 LMH) for simulated wastewater containing either a high protein or a low protein fraction. Compared to an initial flux of 25 LMH, operation at an initial 34 LMH favored the formation of a thicker and more compact cake layer which resulted in significant increase in both cake structural parameter (four-fold) and cake layer enhanced concentration polarization (ten-fold). After 40 h operation without physical cleaning the additional effect of cake layer enhanced concentration polarization and fouling resistance consumed 25% of the total driving force; the significant internal concentration polarization still had the greatest impact. In contrast operation at the lower flux of 25 LMH generated less fouling with a lower cake structural parameter (119 μm). The resultant flux decline was only 3% in contrast to the 15–18% found for the higher flux of 34 LMH. For operation above an initial 30 LMH it was found that FO fouling became irreversible if the wastewater contained a high protein fraction. Overall for a thin film composite membrane and a wastewater with a foulant concentration of 160 mg/L an initial flux of 25 LMH is the recommended threshold; this is 25% less that the critical value determined in earlier short-term studies.
... Old leachate usually contains high total ammonium nitrogen (TAN) concentrations and low BOD/COD ratio (< 0.3), as a result of organic matter stabilization under anaerobic conditions [4] [13]. The leachate treatment processes more used include, physicochemical treatment (e.g., coagulation, flocculation, granular activated carbon treatment, etc.), biological treatment (e.g., activated sludge, aerated lagoon, etc.), and electrochemical treatment [15][16] [17]. Membrane technologies including microfiltration, ultrafiltration, nanofiltration, and reverse osmosis (RO) have been studied and applied for leachate treatment [15][17] [18], and among them RO can recover high quality water from leachate [19] allowing the permeate direct discharge on the environment. ...
... The leachate treatment processes more used include, physicochemical treatment (e.g., coagulation, flocculation, granular activated carbon treatment, etc.), biological treatment (e.g., activated sludge, aerated lagoon, etc.), and electrochemical treatment [15][16] [17]. Membrane technologies including microfiltration, ultrafiltration, nanofiltration, and reverse osmosis (RO) have been studied and applied for leachate treatment [15][17] [18], and among them RO can recover high quality water from leachate [19] allowing the permeate direct discharge on the environment. Recent studies indicate that the treatment of pre-filtered leachate by a pilot scale RO unit obtained 93.4% recovery with 79.2% COD and 69.8% of ammonia rejection [19] [20]. ...
Chapter
The sustainable urban waste management is one of the biggest challenges that societies have been facing. The deposition of urban waste in landfill is a very common solution, but requires the implementation of leachate treatment systems, that guarantee the protection of natural resources, namely of surface waters and groundwater. This study was performed at Sotavento Landfill and aimed to test a new leachate treatment system, that allow to reduce the ammonia level in the produced permeate. To improve the nitrification/denitrification, was implemented an experimental flotation treatment, between the stabilization lagoon and the reverse osmosis system (RO), which consists of a 100 m³ reactor, where the air is injected through a Venturi system, with the purpose of degrade organic molecules into more simple ones. Between April and July of 2016, were monitored Ammonia, BOD5, COD, Conductivity, pH and Total Nitrogen, in four points throughout the treatment system, storm lagoon, stabilization lagoon, after the flotation system and permeate.
... Water treatment can make use of a variety of membrane separation processes [118,119]. Nanofiltration, ultrafiltration, microfiltration, RO, membrane bioreactors, forward osmosis, electrodialysis, membrane distillation, diafiltration, CDI, and continuous electrodeionization are all involved in these processes (Fig. 5a) [120][121][122][123][124][125][126]. It is evident that all of these technologies represent excellent advancements in water treatment. ...
Article
Wastewater is contaminated water that must be treated before it may be transferred into other rivers and lakes in order to prevent further groundwater pollution. Over the last decade, research has been conducted on a wide variety of contaminants, but the emerging contaminants are those caused primarily by micropollutants, endocrine disruptors (EDs), pesticides, pharmaceuticals, hormones, and toxins, as well as industrially-related synthetic dyes and dye-containing hazardous pollutants. Most emerging pollutants did not have established guidelines, but even at low concentrations they could have harmful effects on humans and aquatic organisms. In order to combat the above ecological threats, huge efforts have been done with a view to boosting the effectiveness of remediation procedures or developing new techniques for the detection, quantification and efficiency of the samples. The increase of interest in biotechnology and environmental engineering gives an opportunity for the development of more innovative ways to water treatment remediation. The purpose of this article is to provide an overview of emerging sources of contaminants, detection technologies, and treatment strategies. The goal of this review is to evaluate adsorption as a method for treating emerging pollutants, as well as sophisticated and cost-effective approaches for treating emerging contaminants.
... FO process as such is a low energy process; Iskander et al. mentioned numbers as low as 0.005 and up to 0.276 kWh.m − 3 as the highest energy consumption in the context of FO for treatment of LL [14]. However, most FO studies do not include the regeneration of the DS as part of the concentration process, which must be considered since it represents an important part of the energy costs. ...
Article
A forward osmosis (FO) – electrodialysis (ED) pilot was built and tested for landfill leachate (LL) concentration and draw and water recovery. 70% water extraction from high salinity (35mS.cm⁻¹) LL was achieved through FO in batch operation; no fouling or clogging were observed during the operation of the pilot. Operating with constant high salinity draw solution (>100 mS.cm⁻¹) was required to reach 70% water extraction especially for the final step of LL concentration. FO allowed for high rejection (>90%) of most LL compounds and their effective concentration in the concentrated LL except for ammonium which was partially lost through the membrane or by stripping. Lowering the pH of the LL (from 8.3 down to 6.5) allowed to reduce losses by stripping but led to higher overall losses due to longer filtration time required (higher salinity of the feed solution following hydrochloric acid addition for neutralization). Ultimately, tests in continuous mode (one pass through the FO module) demonstrated that ammonium losses can be reduced significantly (below 15%), thus allowing for efficient operation in counter current mode, resulting also in a better usage of the osmotic pressure. Regeneration of the draw solution and production of a dilute water stream within the discharge requirements (<6 ms.cm⁻¹) was achieved by ED. Energy consumption of the FO-ED system remain below 8 kWh.m⁻³ allowing the process to be energetically competitive in comparison with other LL concentration technologies and other FO hybrid systems.
... [23] Different membrane separation processes can be used for water treatment. [109,[151][152][153] These processes include nanofiltration, [154][155][156] ultrafiltration, [157,158] microfiltration, [159,160] RO, [161][162][163] membrane bioreactors, [168][169][170] forward osmosis, [164,166,167] electrodialysis, [168][169][170][171] membrane distillation, [172,173] diafiltration, [174] CDI, [175] and continuous electrodeionization. [176] All these processes show great achievement in advanced water treatment. However, membrane process is affected by membrane biofouling [3,22,23,109,165,[177][178][179][180][181] and energy consumption [178] ; the latter leads to decreased membrane performance and increased maintenance cost [109,177] and affects flux and quality of produced water. ...
Article
Nanotechnology is currently a fast-rising socioeconomic and political knowledge-based technology owing to the unique characteristics of its engineered nanomaterials. This branch of technology is useful for water and wastewater remediation. Many scientists and researchers have been conducting different studies and experiments on the applications of engineered nanomaterials at the local to international level. This review mainly aims to provide a current overview of existing knowledge on engineered nanomaterials and their applications in water and wastewater remediation. Furthermore, the present risks and challenges of nanotechnology are examined.
... 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
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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.
... The FO process is applied for the osmotic dilution or the pre-treatment of seawater for hybrid FO-RO and multi-effect desalination plants [16,17]. Apart from desalination, currently, FO is utilized for the treatment of secondary or tertiary sewage effluent [18], landfill leachate water [19,20], and wastewater [21,22]. As mentioned above, since the energy consumption is low, zero liquid discharge systems make FO a sustainable technology for reclaiming wastewater treatment [16,23]. ...
Article
Organic fouling in the forward osmosis process is complex and influenced by different parameters in the forward osmosis such as type of feed and draw solution, operating conditions, and type of membrane. In this article, we reviewed organic fouling in the forward osmosis by focusing on wastewater treatment applications. Model organic foulants used in the forward osmosis literature were highlighted, which were followed by the characteristics of organic foulants when real wastewater was used as feed solution. The various physical and chemical cleaning protocols for the organic fouled membrane are also discussed. The study also highlighted the effective pre-treatment strategies that are effective in reducing the impact of organic fouling on the forward osmosis (FO) membrane. The efficiency of cleaning methods for the removal of organic fouling in the FO process was investigated, including recommendations on future cleaning technologies such as Ultraviolet and Ultrasound. Generally, a combination of physical and chemical cleaning is the best for restoring the water flux in the FO process.
... Iskander et al. [93] estimated the energy consumption of the FO system for purifying landfill leachate. Several operating parameters, such as the draw solution concentration and flow rate, were optimized. ...
... In addition, forward osmosis (FO) [9][10][11] could be a successful process to treat leachate via the combination of additional treatment technologies especially for high contaminant concentrations of hazardous wastewater. ...
Article
Full-text available
In order to optimize conditions for the treatment of leachates by electrocoagulation process by using aluminum (Al) electrodes, the experimental design methodology was applied. Indeed, all factors considered have an important effect to treat leachates which likely contaminate groundwater, rivers and grounds. The investigated variables were initial pH (U1), reaction time (U2) and applied current density “J” (U3). The response surface methodology was applied by using the Doehlert Matrix. The statistical analysis was performed by using NemrodW software (LPRAI, version 2000). Suitability of the model and the success of Doehlert Matrix design for the optimization of the electrocoagulation process indicates that the predicted and experimental values were in fair agreement. In addition, the postulated model is valid and predictive. According to the response surface methodology, the optimal conditions for 98% of COD and 97% of color intensity removal responses were found at the current density 14.4 mA cm−2; the reaction time 72.5 min and the initial pH 6.2.
... However, with the innovation of DS regeneration technologies, DS may become less energy-intensive. Previous studies showed that using commercial fertilizer as DS in the FO system can reduce energy cost because of no need for regeneration [42,43], which inspired us using commercial fertilizer instead of NaCl in the future to further reduce energy consumption. When FO membrane is used as the separation membrane instead of MF or UF membrane in the anaerobic bioreactors, AnOMBRs would achieve relatively higher D-CH 4 collection than other anaerobic bioreactors with lower energy consumption, which has significance for energy recovery and mitigation of greenhouse gas emission. ...
Article
Dissolved CH4 (D-CH4) rejection by forward osmosis (FO) membranes requires systematically investigate to mitigate anaerobic effluents pollution and energy loss. In this study, effects of membrane materials, orientations and alginate fouling on dissolved CH4, H2 and CO2 rejections were evaluated. FO was further connected with UASB effluent (FO-UASB) to recover D-CH4 for the first time. Results showed that D-CH4 rejections by CTA-ES and CTA-NW membranes were above 99.99% in the active layer facing feed solution (AL-FS) and active layer facing draw solution (AL-DS) orientations. Dissolved H2 rejections (87.5%-92.3%) achieved higher than dissolved CO2 rejections (52.5%-73.8%) in AL-FS orientation which was attributed to dissolved gas permeability through FO. Alginate fouling layer improved dissolved H2 rejection while concentrative internal concentration polarization aggravated dissolved CO2 rejection by fouled CTA-ES membrane in AL-DS orientation. D-CH4 was successfully collected by FO-UASB in the synergy effect of FO rejection and liquid-to-gas mass transfer. The maximum total CH4 collection rate was 599.0 mg COD/(L·d) and 603.4 mg COD/(L·d) at 35 °C and 25 °C in the FO-UASB.
... Typically, 50-80% of the NF/RO feed is recovered as water. The maximization of high-quality water recovery during the LFL treatment through membrane processes can reduce the concentrate volume and guarantee high reclaimed water production (Iskander et al., 2017b). As mentioned earlier, several patented technologies to improve feed water recovery based on MLD and ZLD strategies are available. ...
Article
Membrane filtration processes have been used to treat landfill leachate. On the other hand, closing the leachate treatment loop and finding a final destination for landfill leachate membrane concentrate (LLMC)-residual stream of membrane systems-is challenging for landfill operators. The re-introduction of LLMC into the landfill is typical; however, this approach is critical as concentrate pollutants may accumulate in the leachate treatment facility. From that, leachate concentrate management based on resource recovery rather than conventional treatment and disposal is recommended. This work comprehensively reviews the state-of-the-art of current research on LLMC management from leachate treatment plants towards a resource recovery approach. A general recovery train based on the main LLMC characteristics for implementing the best recovery scheme is presented in this context. LLMCs could be handled by producing clean water and add-value materials. This paper offers critical insights into LLMC management and highlights future research trends.
... Forward osmosis (FO), an osmotically driven membrane process, has been proposed as a low fouling alternative for the treatment of challenging waste streams, such as raw sewage [16,17], leachate [18,19], and digested centrate [20][21][22]. During FO operation, clean water transports from a feed solution, through a semipermeable membrane, into a draw solution with osmotic pressure deviation between these two solutions as the driving force. ...
Article
We compared the performance of conventional and aquaporin thin-film composite forward osmosis (FO) membranes (denoted as HTI and AQP membrane, respectively) for concentration of digested manure centrate. Results show that the two FO membranes were capable to concentrate digested centrate for resource recovery. During concentration of digested manure centrate, a cohesive fouling layer formed on the HTI membrane surface, resulting in more dramatic flux decline and less fouling reversibility in comparison to the AQP membrane. The two FO membranes exhibited effective and comparable rejection of bulk organic matter, total phosphorus, and heavy metals, leading to their notable enrichment in digested manure centrate. By contrast, ammonium nitrogen (NH4⁺-N) was only retained by approximately 40% using the two FO membranes with a slightly higher retention by the HTI membrane, since it was less negatively charged. As a result, total nitrogen was ineffectively rejected by the two FO membranes. It is noteworthy that the HTI membrane also contributed to higher rejection of most antibiotics than the AQP membrane, possibly due to enhanced retention by the fouling layer and retarded forward diffusion. Results from this study evidence the outperformance of the AQP membrane as a new generation FO membrane over its conventional counterpart with respect to antifouling property, while further improvement in membrane selectivity, particularly of monovalent cations (e.g. NH4⁺-N), is needed to advance FO applications in resource recovery from challenging waste streams.
... Traditional membrane separation technologies such as UF, NF, and RO are driven by external pressure. In contrast, forward osmosis (FO), an osmosis-driven membrane process, has been proposed as a low-stain alternative for treating challenging waste streams [18][19][20]. FO membranes have high selectivity, low fouling tendency, high fouling reversibility, and consume little energy when properly treating wastewater [21]. Therefore, the technology of FO membrane has a good application prospect in the field of biogas slurry concentration. ...
Article
Biogas slurry poses a severe challenge to the sustainable management of livestock farms. The technology of the forward osmosis (FO) membrane has a good application prospect in the field of biogas slurry concentration. Further research is needed to verify the effects of different draw solutions on FO membranes in biogas slurry treatment and the related membrane fouling characteristics. In this study, three different draw solutions were selected to evaluate the performance of FO membranes for biogas slurry concentration. Membrane fouling was investigated by characterization after FO membrane treatment to identify fouling contaminants. The result showed that FO membrane treatment can realize the concentration of biogas slurry and MgCl2 as the draw solution has the best effect on the concentration of biogas slurry. The different draw solutions all contributed to the efficient retention of most organics and TP while each treatment was ineffective at retaining nitrogen. The cake layer that appeared after the biogas slurry was concentrated covered the surface of the FO membrane. Some functional groups were detected on the surface after membrane fouling, such as C-O and C=C. Moreover, the C element accounts for 57% of the main components of the cake layer after the membrane fouling. Membrane fouling is caused by both organic fouling and inorganic fouling, of which organic fouling is the main reason. This study provides a technical reference for the high-value utilization of biogas slurry.
... Moreover, an electricity recovery of 5.1 A m À2 and COD removal of 82% were also achieved, confirming MDC's high potential for multiple concurrent applications including value-added products recovery (Liu et al., 2014b). Simultaneous removal and recovery of NH 4 eN was achieved in an integrated FO and MDC system, where 64% of the NH 4 eN was removed from the cathode chamber using the FO cell leachate (Iskander et al., 2017). Moreover, some other studies have applied modified MDCs to treat PRW and spent engine oil with boron recovery and significant electricity production in lab-scale prototypes (Ping et al., 2015;Sabina et al., 2014;. ...
Article
Shortage of potable water is the driving force behind desalination practices mainly performed by conventional thermal and membrane-based technologies. However, conventional desalination technologies are unsustainable due to their high energy requirements. This highlights the necessity of developing more sustainable and eco-friendly alternatives. As an emerging technology, microbial desalination cell (MDC) has attracted a great deal of attention due to its ability to desalinate seawater, treat wastewater, and recover electricity and value-added products in a single reactor. The technology produces electricity through the biodegradation of organics present in wastewater. The recovered electricity derives the migration of ions, and is subsequently collected as value-added product. The present review summarizes the prospects of MDC as (i) a sustainable green desalination technology, (ii) a cost-effective approach for simultaneous wastewater treatment and recovery of value-added products (i.e., HCl, NaOH, H2O2, H2, humic and fulvic acid), and (iii) an electrochemical process for + removal of targeted pollutants (i.e., NH4⁺-N, Cu, Cr, Pb, Ni, As). Despite the favorable environmental and economic attributes of MDCs, large-scale application of those technology is limited due to a number of engineering and operational challenges. Therefore, this review carefully summarizes all the challenges associated with engineering parameters (i.e., reactor design, internal resistance, cost-effectiveness of electrodes and membranes, membrane fouling), and operating factors (i.e., pH imbalance due to ion migration, low ion transport rate, growth and adhesion of electroactive biofilms, and biofilm inhibition). The interrelationships between the engineering/operational challenges and MDC performances are also concisely explained. Finally, research needs to scale up MDCs for simultaneous desalination, wastewater treatment, and energy-resource recovery are proposed.
... deionized water (DI water), and then dried in the fume hood for further analysis. For physical cleaning and fouling control, the FO membrane was flushed with DI water for 30 min with a recirculation rate of 200 mL min −1 (16.98 cm s −1 ) after each batch test based on previous studies[20,21]. ...
... MDCs eliminate the need for using water pressurisation and drawing solutions, which consume 0.98 kPa (Cheng et al., 2014) and 0.276 kWh m −3 (Iskander et al., 2017), respectively. Although a direct applied voltage between anodes and cathodes is unnecessary in a conventional MDC system, a considerable amount of energy input is required for pumping the influent into anodes, cathodes, desalination chambers or RED cells. ...
Article
Microbial desalination cells (MDCs) have been experimentally proven as a versatile bioelectrochemical system (BES). They have the potential to alleviate environmental pollution, reduce water scarcity and save energy and operational costs. However, MDCs alone are inadequate to realise a complete wastewater and desalination treatment at a high-efficiency performance. The assembly of identical MDC units that hydraulically and electrically connected can improve the performance better than standalone MDCs. In the same manner, the coupling of MDCs with other BES or conventional water reclamation technology has also exhibits a promising performance. However, the scaling-up effort has been slowly progressing, leading to a lack of knowledge for guiding MDC technology into practicality. Many challenges remain unsolved and should be mitigated before MDCs can be fully implemented in real applications. Here, we aim to provide a comprehensive chronological-based review that covers technological limitations and mitigation strategies, which have been developed for standalone MDCs. We extend our discussion on how assembled, coupled and scaled-up MDCs have improved in comparison with standalone and lab-scale MDC systems. This review also outlines the prevailing challenges and potential mitigation strategies for scaling-up based on large-scale specifications and evaluates the prospects of selected MDC systems to be integrated with conventional anaerobic digestion (AD) and reverse osmosis (RO). This review offers several recommendations to promote up-scaling studies guided by the pilot scale BES and existing water reclamation technologies.
... I would also like to thank Dr. Ching-Chieh Lin, Dr. Jerry Lin and Dr. Helen Lou. Moisture coming from the degraded wastes mixes with percolated rainwater and form landfill leachate (Iskander et al. 2017). 51.9% of the landfilled wastes were consists of food, wood, yard trimmings, paper and cardboard (US EPA 2014). ...
Thesis
Full-text available
Municipal solid waste landfills generate leachate which is a mixture of the percolated rainwater and moisture from the solid wastes. Leachate needs to be treated as they can leach through the soil subsurface and contaminate soil and groundwater. Cotreatment with sewage in publicly owned treatment works (POTWs) is the most preferred disposal method for leachate. However, bio-refractory materials like humic substances interfere with biological treatment process in POTWs and quench the UV254 radiation, hence, impeding the UV disinfection process. The characterization of humic substances in landfill leachates are important to understand the UV254 quenching properties of leachates. Organic content of the leachates from the elevated temperature landfills are above typical range. Therefore, treatment of leachates from elevated temperature landfills (ETLFs) are more difficult. A method has been developed in this study to isolate humic substances from landfill leachates and applied on the leachates from elevated temperature landfills (ETLFs). Leachates have been biologically treated and humic substances have also been isolated from the treated leachates to understand the biodegradability of the humic substances. Leachates in methanogenesis phase and humic acids in all the leachates showed the most potential for UV absorbance.
... Iskander et at. [274] estimated the FO process's energy consumption using 1-3 M NaCl as DS to draw water from feed solution (leachate). They observed the process's energy consumption as 0.276 ± 0.033 kW h/m 3 at 110 mL/min flow rate with 1 M DS and reported the lower energy consumption as 0.005 kW h/m 3 for 30 mL/min flow rate with 3 M DS. ...
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.
... With the growing amount of municipal solid waste being disposed into landfills, the production of undesirable landfill leachate containing a range of persistent contaminants has also got more serious (Jovanov et al., 2018). It has been reported that the FO membrane process could be employed to concentrate the landfill leachate though the process suffered from membrane fouling issues (Iskander et al., 2017). In a study conducted by Aftab et al. (2019b), activated carbon (AC) and biochar (BC) have been integrated with FO process as pretreatment to alleviate the membrane fouling issues. ...
Article
Study of forward osmosis (FO) has been increasing steadily over recent years with applications mainly focusing on desalination and wastewater treatment processes. The working mechanism of FO lies in the natural movement of water between two streams with different osmotic pressure, which makes it useful in concentrating or diluting solutions. FO has rarely been operated as a stand-alone process. Instead, FO processes often appear in a hybrid or integrated form where FO is combined with other treatment technologies to achieve better overall process performance and cost savings. This article aims to provide a comprehensive review on the need for hybridization/integration for FO membrane processes, with emphasis given to process enhancement, draw solution regeneration, and pretreatment for FO fouling mitigation. In general, integrated/hybrid FO processes can reduce the membrane fouling propensity; prepare the solution suitable for subsequent value-added uses and production of renewable energy; lower the costs associated with energy consumption; enhance the quality of treated water; and enable the continuous operation of FO through the regeneration of draw solution. The future potential of FO lies in the success of how it can be hybridized or integrated with other technologies to minimize its own shortcomings, while enhancing the overall performance.
... To minimize human health risk and avoid ingestion of xenobiotics, reverse osmosis (RO) as a more advanced and robust technology has been implemented for water purification at the expense of high energy investment (>1.5 kWh m À3 for seawater desalination) (Yangali-Quintanilla et al., 2011). In recent years, osmotically driven membrane process (ODMP), especially forward osmosis (FO) or FO-based systems, have emerged as a potentially energy-efficient alternative for versatile applications, such as seawater desalination , wastewater treatment (Holloway et al., 2007;Iskander et al., 2017;Zou et al., 2017), brine concentration (McGinnis et al., 2013;Tang and Ng, 2008), food processing (Garcia-Castello et al., 2009;Sant'Anna et al., 2012), bioenergy production (Ge et al., 2013b;Qin and He, 2017), and power generation (Logan and Elimelech, 2012;Yip et al., 2011). FO harnesses osmotic pressure gradient across a semi-permeable membrane to reclaim highquality water, offering major merits include reduced operating pressure, high rejection of undesired compounds (comparable to RO), reversible membrane fouling, and less energy demand if energy-intensive draw regeneration can be properly addressed or avoided (Liu et al., 2011;McGinnis and Elimelech, 2007). ...
Article
Forward osmosis (FO) has emerged as a potentially energy-efficient membrane treatment technology to yield high-quality reusable water from various wastewater/saline water sources. A key challenge remained to be solved for FO is reverse solute flux (RSF), which can cause issues like reduced concentration gradient and loss of draw solutes. Yet no universal parameters have been developed to compare RSF control performance among various studies, making it difficult to position us in this “battle” against RSF. In this paper, we have conducted a concise review of existing RSF reduction approaches, including operational strategies (e.g., pressure-, electrolysis-, and ultrasound-assisted osmosis) and advanced membrane development (e.g., new membrane fabrication and existing membrane modification). We have also analyzed the literature data to reveal the current status of RSF reduction. A new parameter, mitigation ratio (MR), was proposed and used together with specific RSF (SRSF) to evaluate RSF reduction performance. Potential research directions have been discussed to help with future RSF control. This review intends to shed more light on how to effectively tackle solute leakage towards a more cost-effective and environmental-friendly FO treatment process.
... Water treatment can make use of a variety of membrane separation processes [118,119]. Nanofiltration, ultrafiltration, microfiltration, RO, membrane bioreactors, forward osmosis, electrodialysis, membrane distillation, diafiltration, CDI, and continuous electrodeionization are all involved in these processes (Fig. 5a) [120][121][122][123][124][125][126]. It is evident that all of these technologies represent excellent advancements in water treatment. ...
Article
Significant aspects of the world's water scenario, primarily associated with global population growth and climate change, necessitate new technology implementation to ensure a supply of drinking water and prevent global water contamination. In light of this, the incorporation of state-of-the-art nanotechnology in conventional process engineering opens new paths for improved wastewater treatment technologies. Nano-based materials techniques, such as disinfection, desalination, sensing and monitoring, photocatalysis, membrane process, adsorption, biological treatment, coagulation/precipitation, and oxidation are discussed in this overview of current breakthroughs in nanotechnologies for removal of pollutants from wastewater. The benefits of these nano-based materials for wastewater treatment approaches, as well as the technical challenges are discussed in this review. The current state of commercialization, as well as future research opportunities in nano-based materials and technologies are highlighted. Additionally, the anticipated scientific breakthroughs, the constraints of nanotechnology for desalination processes, such as rules and regulations, and potential health risks are addressed. The regulation of nanoengineered materials and technologies used in wastewater treatment is being addressed in both Europe and United States of America.
... However, the product of FO is not potable water but a diluted draw solution that requires a regenerating step to extract clean water [22]. It is worth quoting that FO, alone or in combination with other processes [17,19,[24][25][26][27], has been proposed as an appropriate technology for wastewater treatment [19,28,29] with a high energy efficiency [20,30]. A suitable membrane for FO process must exhibit among others a high hydrophilic character, a high water permeance, a highly selective thin layer with a support having a low tortuosity factor and a high porosity [31]. ...
Article
An alternative use of end-of-life reverse osmosis (RO) membranes is proposed for forward osmosis (FO) application as recycled FO (RFO) membranes and transformed recycled FO (TRFO) membranes. Different passive cleaning protocols in pilot plant and laboratory scale were followed using sodium hypochlorite (NaClO) at different concentrations and exposure time. The RFO with the best performance was selected for its transformation by interfacial polymerization (IP) technique to improve further the FO performance. Both the morphological structure and transport properties of the RFO and TRFO membranes were studied by means of different characterization techniques. Although the RFO membranes are suitable for FO, the TRFO membranes are more competitive. The highest FO water permeate fluxes (12.21 kg/m²·h and 15.12 kg/m²·h) were obtained for the membrane recycled applying the highest NaClO exposure dose applied in pilot plant (10⁶ ppm·h) followed by IP of a thin polyamide layer. These permeate fluxes were better or at least comparable to commercial membranes used under the same FO conditions. The results indicated that it is possible to use discarded RO membranes in FO technology for wastewater treatment after adequate treatment procedures extending their lifetime and contributing to a circular economy and sustainability in membrane science and related materials.
... Responsive draw agent Functional magnetic nanoparticle [72,73], thermo/electric-responsive hydrogel [74,75], pH/thermo-responsive polyelectrolyte [76,77] Magnetic/pH/thermo/electric stimulation Hydroacid complexes Citric acid-Fe complex [78], oxalic acid-Cr-tetramethylammonium salt [30], oxalic acid-Cr complex [79] NF, MD leachate could be energy efficient, especially with suitable draw solution that can be recovered without energyintensive process required [90]. For example, Iskander et al. reported that, a low energy consumption of 0.005AE0.000 ...
Article
Full-text available
During the last decades, the utilization of osmotic pressure-driven forward osmosis technology for wastewater treatment has drawn great interest, due to its high separation efficiency, low membrane fouling propensity, high water recovery and relatively low energy consumption. This review paper summarizes the implementation of forward osmosis technology for various wastewater treatment including municipal sewage, landfill leachate, oil/gas exploitation wastewater, textile waste-water, mine wastewater, and radioactive wastewater. However, membrane fouling is still a critical issue, which affects water flux stability, membrane life and operating cost. Different membrane fouling types and corresponding fouling mechanisms, including organic fouling, inorganic fouling, biofouling and combined fouling are therefore further discussed. The fouling control strategies including feed pre-treatment, operation condition optimization, membrane selection and modification, membrane cleaning and tailoring the chemistry of draw solution are also reviewed comprehensively. At the end of paper, some recommendations are proposed.
... Several treatment methods have been used to treat the landfill leachate, such as biological processes (Li et al. 2017;Zhang et al. 2016;Robinson. 2017), membrane processes (Ahn et al. 2002), coagulation and flocculation methods (Wang et al. 2015;Liu et al. 2012), flotation methods (Adlan et al. 2011), adsorption and chemical precipitation (Hur and Kim 2000;Erabee et al. 2017), osmosis (Iskander et al. 2017), chemical oxidation (Derco et al. 2010), Fenton and electrochemical (Vallejo et al. 2012), advanced oxidation techniques Hu et al. 2011;Zhang et al. 2012;Chys et al. 2015) and electro-Fenton (Zhang et al. 2014). However, these methods are found to have certain shortages such as operating cost, transfer of one phase to another, lower pollutant removal efficiency and decreasing the process performance. ...
Article
Full-text available
Treatment of landfill leachate wastewater by electrocoagulation process using an aluminium electrode was investigated in a batch electrochemical cell reactor. Response surface methodology based on central composite design was used to optimize the operating parameters for the removal of % color and % total organic carbon (TOC) together with power consumption from landfill leachate. Effects of three important independent parameters such as current density (X1), inter-electrode distance (X2) and solution pH (X3) of the landfill leachate sample on the % color and % TOC removal with power consumption were investigated. A quadratic model was used to predict the % color and % TOC removal with power consumption in different experimental conditions. The significance of each independent variable was calculated by analysis of variance. In order to achieve the maximum % color and % TOC removal with minimum of power consumption, the optimum conditions were about current density (X1)—5.25 A/dm², inter-electrode distance (X2)—1 cm and initial solution of effluent pH (X3)—7.83, with the yield of color removal of 74.57%, and TOC removal of 51.75% with the power consumption of 14.80 kWh/m³. Electrocoagulation process could be applied to remove pollutants from industrial effluents and wastewater.
... It should be noted that in FO processes, the permeated water needs to be separated from the draw solution if the reclaimed water is considered as a product, meanwhile the draw solutes are re-concentrated. Indeed, additional energy-demanding separation processes are required, which could consume N70% of the total energy (Iskander et al., 2017;Zou et al., 2016). While, if the reclaimed water is combined with a draw solution (e.g., fertilizer) as a product, the most complex and energy-intensive draw solution separation process is not necessary (Awad et al., 2019). ...
Article
Direct membrane filtration has shown great potential in wastewater treatment and resource recovery in terms of its superior treated water quality, efficient nutrient recovery, and sustainable operation, especially under some scenarios where biological treatment is not feasible. This paper aims to give a comprehensive review of the state-of-the-art of direct membrane filtration processes (including pressure-driven, osmotic-driven, thermal-driven, and electrical-driven) in treating different types of wastewater for water reclamation and resource recovery. The factors influencing membrane performance and treatment efficiency in these direct membrane filtration processes are well illustrated, in which membrane fouling was identified as the main challenge. The strategies for improving direct membrane filtration performance, such as physical and chemical cleaning techniques and pretreatment of feed water, are highlighted. Towards scaling-up and long-term operation of direct membrane filtration for effective wastewater reclamation and resource recovery, the challenges are emphasized and the prospects are discussed.
Article
Sewage can become a valuable source if its treatment is re-oriented. Forward osmosis (FO) is an effective pre-treatment for concentrating solutions. A laboratory-scale anaerobic digestion (AD) bioreactor was setup for the treatment of concentrated real sewage by FO membrane to investigate the removal of chemical oxygen demand (COD) and biogas production. Inhibitory batch tests were carried out for the impact of NaCl and NH4⁺-N. Results showed that the concentrated sewage could be purified with 80% COD removal, and energy recovery could be achieved. But the process was inhibited. The results of inhibitory batch test showed that (i) when the NH4⁺-N concentration was lower (<200 mg/L), the biogas production was promoted, when it went high, the inhibition appeared; (ii) single existence of NaCl had negative influence on methane production; (iii) the inhibition was more severe with co-existence of NaCl and NH4⁺-N. The AD performance could be recovered via sludge acclimation.
Article
In this work, a microbial desalination cell (MDC) was employed to desalinate the FO treated leachate for reduction of both salinity and chemical oxygen demand (COD). The FO recovered 51.5% water from a raw leachate and the recovery increased to 83.5% from the concentrated leachate after desalination in the MDC fed with either acetate or another leachate as an electron source and at a different hydraulic retention time (HRT). Easily-degraded substrate like acetate and a long HRT resulted in a low conductivity desalinated effluent. Ammonia was also recovered in the MDC cathode with a recovery efficiency varying from 11 to 64%, affected by current generation and HRT. Significant COD reduction, as high as 65.4%, was observed in the desalination chamber and attributed to the decrease of both organic and inorganic compounds via diffusion and electricity-driven movement.
Article
This study aimed to concentrate and recover resources from municipal wastewater with a novel forward osmosis (FO) system. The FO system used synthetic seawater as the draw solution (DS) to extract water from the feed solution (FS) (synthetic raw municipal wastewater). Because ammonium passed through the FO membrane from the FS to the DS, we cultivated an algal strain (Chlorella vulgaris) in the DS to remove and recover ammonium. For three consecutive FO cycles, the algal FO system removed 35.4% of the ammonium from the DS, increased the concentrations of COD and PO 4 3 - - P in the FS by 43.0%, and achieved a water flux of 11.59 ± 0.49 L m-2 hr-1 . Throughout the FO cycles, the algal biomass concentration of the DS stayed at 606 ± 29 mg COD/L due to simultaneous algal growth and DS dilution. This FO process may be feasible to implement for full-scale applications to concentrate wastewater and recover resources. PRACTITIONER POINTS: A novel forward osmosis (FO) system with an algal draw solution (DS) concentrated municipal wastewater and recovered resources (ammonium). Ammonium but not organic matter or phosphate diffused across the FO membrane from the feed solution (FS) to the DS. The algal FO system increased COD/phosphate concentration in the FS by 43.0% and removed 35.4% of ammonium from the DS. The water fluxes in the algal FO system and the control were 11.59 and 12.02 L m-2 hr-1 , respectively. The novel algal FO process has the potential to improve full-scale efficiency by concentrating municipal wastewater and recovering nutrients.
Chapter
Landfilling is the most widely used method for solid waste disposal, with a heavy burden of generating high-strength wastewater known as leachate. Leachate consists of various mixtures of organic and inorganic pollutants, heavy metal contaminants, dissolved and suspended materials. Therefore, landfill leachate should be collected and adequately treated to prevent its unfortunate fate associated with groundwater and surface water contaminations. Biological and physical/chemical are two major treatment technologies for leachate. Conventional treatment techniques have been widely used in landfill leachate treatment. Even though these techniques might have failed to remove all pollutants effectively, they can be good pretreatment techniques, while new and evolving processes are promising technologies for the effective treatment of leachate. The first part of the chapter sums up the landfill leachate treatability with physicochemical processes. Conventional physicochemical techniques, including coagulation-flocculation, chemical precipitation, and new technologies such as ion exchange, adsorption by activated carbon, membrane filtration, chemical oxidation, electrochemical processes are illustrated and their application to landfill leachate treatment discussed. The second part of this chapter highlights various aerobic and anaerobic biological treatment technologies that employ microorganisms and fungi that are operated either alone or in combination with the physicochemical treatment methods.
Article
In this study, the potential of osmotic backwashing was explored for the alleviation of the forward osmosis (FO) membrane fouling induced by landfill leachate. The normal osmotic backwashing employing NaCl as a draw solute resulted in an improved membrane flux (~ 4 LMH) and a reduction (45%) of the membrane resistance. We proposed an alternative way of osmotic backwashing based on the inherent osmotic potential of landfill leachate itself for the FO system. For the effort, intermittent osmotic relaxation (IOR) was newly introduced to the FO system to enhance the performance. This operation showed a comparable performance with fouling mitigation to the previous normal osmotic backwashing using NaCl as a draw solute. Under an optimized condition (4 h of filtration intervals and 20 min of backwashing time), the integration of the IOR with the FO system led to a 30% reduction in membrane resistance, a complete flux recovery, and 26% increment in the filtered volume. The IOR process does not require additional energy and/or chemical dosage. Therefore, it can be suggested as an innovative, practical, and energy-efficient osmotic backwashing strategy for a stable and the long-term operation of FO systems treating saline wastewater.
Article
Anaerobically digested sludge filtrate after thermal hydrolysis pretreatment (THP-AD) requires large plant and operational costs for post-treatment and re-utilization. This paper reports the innovative forward osmosis (FO) membrane process to enrich organic matter from such a digested sludge filtrate. The proposed membrane separation process can reduce the operational load and environmental dependence of waste sewage treatment plants and may provide a new way for the treatment of THP-AD sludge filtrate. In this study, a cost-effective draw NaCl solution was selected for the FO process. The sensitivity of membrane operational conditions including membrane orientation, system temperature, system flow rate and concentrations of draw solution was investigated and correlated with the FO processing performance. FO mode is a clever choice to reduce the deposition of pollutants on the membrane’s surface, and improve the recovery performance of the membrane. The permeation flux of the THP-AD sludge digestion system decreased more rapidly due to the membrane pollution as well as to the decreasing of driving force caused by the dilution of the draw solution and the concentration of the feed solution. The concentration factor of digested sludge filtrate after FO process was more than five, and the rejection rates of organic and inorganic matter were above 92.5%. The membrane permeability recovery after the offline washing reached up to 98.4% and showed high efficiency at removing membrane fouling substances and at reactivating the membrane. The proposed FO process has potential as an alternative and practical method for treating and utilizing intractable sludge filtrates, conducive to the development of sustainable wastewater plants.
Chapter
Various natural resources including freshwater reserve are depleting as a consequence of rapid increase in population. A sustainable wastewater system should aim at recovering energy and resource materials from waste discharge. Accordingly, this book chapter begins with a short introduction explaining the rationale behind the subject matter followed by a discussion on recent trends in the identification of resource materials from various types of wastewater. The major goal of the chapter, however, is to provide a comprehensive review summarizing recent advancement in various resource recovery technologies (bioelectrochemical systems, zero liquid discharge technologies, and adsorption-based recovery) commonly applied to sewage and effluent from biotechnology and allied industries. Finally, the chapter ends with a recommendation on development of economically feasible and environmentally benign resource recovery schemes for various types of wastewater.
Article
There has been increasing attention in osmotically driven membrane processes (ODMPs), which include forward osmosis (FO) and pressure retarded osmosis (PRO). They provide a sustainable solution against water and energy scarcity issues by utilizing the osmotic pressure difference between two water bodies, feed (low salinity) and draw solution (high salinity), across a semipermeable membrane. Indeed, their main applications, water treatment (e.g., desalination and wastewater treatment) and power generation, facilitate resource recovery from wastewaters. This review updates the recent development of FO and PRO by providing a comprehensive review on their fundamentals, membrane properties, potential applications as well as advanced techniques. In addition, economic analysis and environmental impacts are critically reviewed to highlight their feasibility and sustainability. Resource recovery from wastewaters (e.g., water, nutrient and energy) using FO and PRO is also discussed followed by their commercialization and future trends in order to push forward laboratory research to full-scale commercialization.
Article
The forward osmosis (FO) membrane process is a good option for treating complex wastewater, such as landfill leachate, owing to its high rejection. However, organic membrane fouling and the generation of high-strength concentrate hamper efficient and environmentally friendly operation. To overcome these limitations, an integrated FO system combined with UV/H2O2 oxidation is proposed in this paper. Changes in the heterogeneous organic composition of the leachate were tracked along the treatment processes via size exclusion chromatography and excitation emission matrix combined with parallel factor analysis, which allowed us to pinpoint the organic fractions responsible for FO membrane fouling and evaluate their removal efficiency. Three fluorescent components, including tryptophan-like (C1), fulvic-like (C2), and humic-like (C3) components, were identified in the landfill leachate. A separate UV/H2O2 oxidation system led to selective removal of the organic leachate fractions, causing membrane fouling by ∼80% along with the overall removal of bulk leachate by ∼45%. Compared to traditional FO, the integrated system resulted in improved filtered volume (by 40%), decreased overall membrane resistance (by 30%), complete flux recovery after physical cleaning, and 50% reduction of organic carbon in the membrane concentrate. Moreover, the concentrate from the integrated FO system was characterized by a much lower abundance of large molecules, which is beneficial for the reclamation of concentrate due to its high biodegradability. This study demonstrated the effectiveness of UV/H2O2 oxidation as an integrated option for an FO system used for extended filtration, membrane fouling mitigation, and the production of low-strength landfill leachate concentrate.
Article
Biofilm electrodes wire microbial metabolism to electric current for inter alia energy harvest. Kees et al. show that during formation of biofilm electrodes, not the fittest but the fastest microorganisms persist, preventing healthy competition within the community. This persistence of first settlers has implications for electrode engineering and scaling.
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The escalating loads of municipal solid waste (MSW) end up in open dumps and landfills, producing continuous flows of landfill leachate. The risk of incorporating highly toxic landfill leachate into environment is important to be evaluated and measured in order to facilitate decision making for landfill leachate management and treatment. Leachate pollution index (LPI) provides quantitative measures of the potential environmental pollution by landfill leachate and information about the environmental quality adjacent to a particular landfill. According to LPI values, most developing countries show high pollution potentials from leachate, mainly due to high organic waste composition and low level of waste management techniques. A special focus on leachate characterization studies with LPI and its integration to treatment, which has not been focused in previous reviews on landfill leachate, was given here. Further, the current review provides a summary related to leachate generation, composition, characterization, risk assessment and treatment together with challenges and perspectives in the sector with its focus to developing nations. Potential commercial and industrial applications of landfill leachate is discussed in the study to provide insights into its sustainable management which is original for the study.
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Landfill leachate is a highly polluted and toxic waste stream harmful to the environment and human health, its biological treatment, even if challenging, offers the opportunity of recovering valuable resources. In this study, we propose the application of an extractive membrane bioreactor equipped with a polymeric tubing, made of Hytrel, as an innovative device able to remove specific organic toxic compounds of the leachate and, at the same time, to produce an effluent rich in valuable chemicals suitable for recovery. The leachate treatment consists in a two-step process: the extraction of specific toxic compounds through the polymeric tubing based on the affinity with the polymer, and their subsequent biodegradation in controlled conditions in the bulk phase of the extractive membrane bioreactor, thus avoiding the direct contact of the microbial consortium with the toxic leachate. Three synthetic streams simulating leachates produced by landfills of typical industrial/hazardous waste, mixed municipal and industrial solid waste, and oil shale industry waste, whose toxic fraction is mainly constituted by phenolic compounds, have been tested. Successful performance was achieved in all the tested conditions, with high removal (≥98%) and biodegradation efficiencies (89–95%) of the toxic compounds. No mass transfer limitations across the tubing occurred during the operation and a marginal accumulation (in the range of 4–7%) into the polymer has been observed. Furthermore, volatile fatty acids and inorganic compounds contained in the leachates were fully recovered in the treated effluent. Feasibility study confirmed the applicability of the proposed bioreactor as a powerful technology able to achieve high toxic removal efficiency in leachate treatment and facilitate resource recovery.
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Human urine can be used as a fertilizer, however, due to the high water content (97%), concentration is required to make transportation economically feasible. Reverse osmosis (RO) has been identified as an energy efficient concentration method. Furthermore, to maximize nitrogen recovery from source-separated urine it should be stabilized with an acid or base to prevent urea hydrolysis. However, the method of stabilization will have an impact on the downstream RO process. Calcium hydroxide is often used as a base stabilization method for human urine but would require pre-treatment to remove excess calcium and subsequent membrane scaling. Three pre-treatment methods such as air bubbling, NaHCO3 addition, and NH4HCO3 addition, were investigated in this study. Each method successfully reduced the scaling potential and air bubbling was determined to be the most effective method as it resulted in the highest nutrient recovery during concentration and did not require the addition of any chemicals.Base stabilization with air bubbling pre-treatment was then compared to urine stabilized with citric acid. Acid stabilized urine had a higher nitrogen recovery (7.6% higher). However, solids formed in the real acidified urine and during concentration a brown organic compound formed on the membrane surface. The crystals were identified as uric acid dihydrate and the brown organic fouling resulted in a significant decrease in permeate flux as compared to the base stabilized urine with air bubbling pre-treatment. At a 60% water recovery, 85.5% of the urea and 99.2% of the potassium was recovered in the brine stream and more than 99.9% of the phosphorus was recovered as a separate solid calcium phosphate fertilizer. Whilst nutrient recovery was higher with acid stabilization, the membrane fouling that occurred with this stabilization method meant that base stabilization with air bubbling pre-treatment was the preferred treatment option. It is recommended that acid stabilized urine be concentrated using evaporation processes instead.
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Metal (loids) and Rare Earth Elements (REE) (‘metals’) are used in a wide range of products, and therefore, the improvement of expectations for everyday comforts with demand continues to grow. Metal-bearing wastes are a secondary source of raw material that can meet this demand by providing a previously unconsidered low impact supply source. Total annual leachate production is 1,056,716 m³. Therefore, landfill leachate emerges as a significant potential resource as it contains high concentrations of metals. However, realising a profitable return on investment for leachate processing is a challenge due to relatively low recovery rates of approximately 0.02% of total heavy metals in a landfill being leached out in 30 years. Variation within the multi-element value and the effect of other chemicals in these complex mixtures. There is a need to better understand the mechanisms and potential applicability of extraction methods for optimising metals recovery from leachate. This paper addresses this need by providing a systematic review of the critical factors and environmental conditions that influence the behaviour of metals within the landfilled waste. The paper provides a synthesis of how the factors and conditions may affect leachate recirculation efficiency for recovery in the context of a range of opportunities and challenges facing circular economy practitioners. To approach feasibility metal recovery economically from landfill leachate without energy-intensive and environmentally destructive, future research actions need to be initiated in lab-based and later on semi-pilot to pilot studies, which the review can help achieve the challenges.
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Wastewater discharge of traditional Chinese medicine production is a serious threat to the environment in China. This study investigated the effectiveness of the UF-FO-MD hybrid system for resources recycle from the TCM wastewater. Real TCM wastewater was treated with the self-assemble UF-FO-MD hybrid system. Moreover, the natural surfactant rejection and the FO fouling impact were evaluated by separate FO operation with synthetic TCM wastewater, and MD wetting was also assessed. Results show that the UF-FO-MD hybrid system successfully isolated the macromolecular substances, bioactive compounds and water in the TCM wastewater for recovering useful resources. Natural surfactants in the TCM wastewater could be effectively rejected by FO, avoiding the subsequent MD wetting problem which has occurred in our previous study on the resource recovering with the UF-MD hybrid system. However, FO membrane fouling might be an issue affecting the recovery efficiency of bioactive compounds from TCM wastewater. The bioactive compounds could not be completely concentrated due to potential adsorption on the fouling layer.
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Microbial fuel cells were designed and operated to treat landfill leachate while simultaneously producing electricity. Two designs were tested in batch cycles using landfill leachate as a substrate without inoculation (908 to 3,200 mg/L chemical oxygen demand (COD)): Circle (934 mL) and large-scale microbial fuel cells (MFC) (18.3 L). A total of seven cycles were completed for the Circle MFC and two cycles for the larger-scale MFC. Maximum power densities of 24 to 31 mW/m(2) (653 to 824 mW/m(3)) were achieved using the Circle MFC, and a maximum voltage of 635 mV was produced using the larger-scale MFC. In the Circle MFC, COD, biological oxygen demand (BOD), total organic carbon (TOC), and ammonia were removed at an average of 16%, 62%, 23%, and 20%, respectively. The larger-scale MFC achieved an average of 74% BOD removal, 27% TOC removal, and 25% ammonia reduction while operating over 52 days. Analysis of the microbial characteristics of the leachate indicates that there might be both supportive and inhibiting bacteria in landfill leachate for operation of an MFC. Issues related to scale-up and heterogeneity of a mixed substrate remain.
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The major potential environmental impacts related to landfill leachate are pollution of groundwater and surface waters. Landfill leachate contains pollutants that can be categorized into four groups (dissolved organic matter, inorganic macrocomponents, heavy metals, and xenobiotic organic compounds). Existing data show high leachate concentrations of all components in the early acid phase due to strong decomposition and leaching. In the long methanogenic phase a more stable leachate, with lower concentrations and a low BOD/COD-ratio, is observed. Generally, very low concentrations of heavy metals are observed. In contrast, the concentration of ammonia does not decrease, and often constitutes a major long-term pollutant in leachate. A broad range of xenobiotic organic compounds is observed in landfill leachate. The long-term behavior of landfills with respect to changes in oxidation-reduction status is discussed based on theory and model simulations. It seems that the somewhere postulated enhanced release of accumulated heavy metals would not take place within the time frames of thousands of years. This is supported by a few laboratory investigations. The existing data and model evaluations indicate that the xenobiotic organic compounds in most cases do not constitute a major long-term problem. This may suggest that ammonia will be of most concern in the long run.
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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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In this paper a process for the treatment of landfill leachate involving evaporation and reverse osmosis was proposed. Experimental tests were performed on an industrial landfill leachate. The leachate was subjected to evaporation so as to obtain a distillate containing a small amount of organic material and a substantial amount of inorganic substances (consisting primarily of metals and ammonium salts). The distillate of the evaporation treatment was then subjected to reverse osmosis. The reverie osmosis tests were performed using two different membranes: the AD membrane (thin two-ply film of polyamide) and the SC membrane (thin three-ply film of polyamide). Tests carried out at different values of pH showed a reduction of organic content of about 88% when AD membranes were used and about 80% with SC membranes independently of pH. As regards ammonium, comparable reductions of over 97% were registered for both types of membrane in the optimal conditions of pH = 6.4 (97.1% for AD membranes and 97.7% for SC).
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In most countries, sanitary landfilling is nowadays the most common way to eliminate municipal solid wastes (MSW). In spite of many advantages, generation of heavily polluted leachates, presenting significant variations in both volumetric flow and chemical composition, constitutes a major drawback. Year after year, the recognition of landfill leachate impact on environment has forced authorities to fix more and more stringent requirements for pollution control. This paper is a review of landfill leachate treatments. After the state of art, a discussion put in light an opportunity and some results of the treatment process performances are given. Advantages and drawbacks of the various treatments are discussed under the items: (a) leachate transfer, (b) biodegradation, (c) chemical and physical methods and (d) membrane processes. Several tables permit to review and summarize each treatment efficiency depending on operating conditions. Finally, considering the hardening of the standards of rejection, conventional landfill leachate treatment plants appear under-dimensioned or do not allow to reach the specifications required by the legislator. So that, new technologies or conventional ones improvements have been developed and tried to be financially attractive. Today, the use of membrane technologies, more especially reverse osmosis (RO), either as a main step in a landfill leachate treatment chain or as single post-treatment step has shown to be an indispensable means of achieving purification.
Article
Landfill leachate (LL) is harmful to aquatic environment because it contains high concentrations of dissolved organic matter, inorganic components, heavy metals, and other xenobiotics. Thus, the remediation of LL is crucial for environmental conservation. Here, a potential application of the forward osmosis (FO) filtration process with ammonium bicarbonate (NH4HCO3) as a draw solution (DS) was investigated to remediate membrane bioreactor-treated LL (M-LL). After the leachate treatment, the toxicity and removal efficiencies of polycyclic aromatic hydrocarbons (PAHs) were evaluated using zebrafish and cultured human cells. The water recovery rate was improved using the current protocol up to 86.6% and 91.6% by both the pressure retarded osmosis (PRO) mode and the forward osmosis (FO) mode. Water flux increased with the increasing DS concentrations, but solution velocities decreased with the operation time. Toxicity tests revealed that the M-LL treated by NH4HCO3 had no toxic effect on zebrafish and human cells. Moreover, green fluorescent protein (GFP) expression in the transgenic zebrafish Tg(cyp1a:gfp) induced by PAHs was very weak compared to the effects induced by untreated M-LL. Since the diluted DS met local safety requirements of liquid fertilizer, it could be directly applied as the liquid fertilizer for fertigation. In conclusion, this novel FO system using NH4HCO3 as the DS provides a cheap and efficient protocol to effectively remove PAHs and other pollutants in LL, and the diluted DS can be directly applied to crops as a liquid fertilizer, indicating that this technique is effective and eco-friendly for the treatment of different types of LL.
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The industrial processes require large quantities of water. The presence of discharges results not only in significant environmental impact but implies wastage of water resources. This problem could be solved treating and reusing the produced wastewaters and applying the new zero liquid discharge approach. This paper discusses the design and the performances of reverse osmosis membranes for the upgrading of full scale platform for industrial liquid wastes. The final effluent from the ultrafiltration unit of the full scale plant was monitored to design the reverse osmosis unit. Previous modelling phase was used to evaluate the specific ordinary and maintenance costs and the final effluent quality (2.7 €/m3). The system was designed in triple stages at different operative pressures. The economic feasibility and the payback period of the technology at different percentages of produced permeate were determined. The recovery of 90% was identified as profitable for the reverse osmosis application. One experimental pilot plant applying the reverse osmosis was used to test the final effluent. Moreover, the same flow was treated with second pilot system based on the forward osmosis process. The final efficiencies were compared. Removals higher than 95% using the reverse system were obtained for the main macropollutants and ions. No sustainable applicability of the forward osmosis was determined.
Article
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.
Article
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.
Article
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.
Article
This review focuses on the present status of forward osmosis (FO) niches in two main areas: seawater desalination and wastewater reuse. Specific applications for desalination and impaired-quality water treatment and reuse are described, as well as the benefits, advantages, challenges, costs and knowledge gaps on FO hybrid systems are discussed. FO can play a role as a bridge to integrate upstream and downstream water treatment pro-cesses, to reduce the energy consumption of the entire desalination or water recovery and reuse processes, thus achieving a sustainable solution for the water-energy nexus. FO hybrid membrane systems showed to have advantages over traditional membrane process like high pressure reverse osmosis and nanofiltration for desalination and wastewater treatment: (i) chemical storage and feed water systems may be reduced for capital, oper-ational and maintenance cost, (ii) water quality is improved, (iii) reduced process piping costs, (iv) more flexible treatment units, and (v) higher overall sustainability of the desa-lination and wastewater treatment process. Nevertheless, major challenges make FO systems not yet a commercially viable technology, the most critical being the development of a high flux membrane, capable of maintaining an elevated salt rejection and a reduced internal concentration polarization effect, and the availability of appropriate draw solu-tions (cost effective and non-toxic), which can be recirculated via an efficient recovery process. This review article highlights the features of hybrid FO systems and specifically provides the state-of-the-art applications in the water industry in a novel classification and based on the latest developments toward scaling up these systems.
Article
Filtration behaviors, membrane fouling and cleaning were investigated in a forward osmosis (F0) membrane system used to post-treat the effluent of a membrane bioreactor (MBR) fed with landfill leachate ([FL). In short-term tests, it was observed that the water flux with the membrane active layer facing the draw solution (AL-DS mode) was lower than that with the membrane active layer facing the feed solution (AL-FS mode) for [FL treatment. Mathematical models could well simulate the flux evolution of AL-FS mode while the flux of AL-DS deviated from the modeling curve, suggesting that fouling could be rapidly developed within 1 h filtration for AL-DS mode. During long-term filtration, about 98.6% of COD, 96.6% of TR and 76.9% of ammonium were rejected by the FO system. A decrease of water flux was also observed with an increase in operation time. Confocal laser scanning microscopy and Fourier transform infrared spectroscopy confirmed the existence of polysaccharides and proteins in the fouling layer. Inorganic fouling was mainly caused by Ca, Na, Mg, K, Si, Fe and Al. It was also found that the effect of cake enhanced concentration polarization played an important role during long-term operation. About 88.9% of the permeate flux was recovered after hydraulic cleaning while it reached 98.9% of the initial flux after chemical cleaning, indicating that chemical cleaning was needed to eliminate irreversible fouling and to recover membrane permeability during long-term operation.
Article
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
Water resources are becoming increasingly scarce in many areas of the world due to development and increased demand. In consequence, the market for reverse osmosis (RO) is expanding to meet the increasing requirement by use of seawater and wastewater resources. Membrane filtration has gradually gained acceptance as the preferred pre-treatment to RO. However, although perceived as desirable, UF/MF is also thought to be an expensive option, and consideration of UF/MF is sometimes restricted to applications which are thought to be especially problematic. In wastewater treatment applications, UF/MF is the pretreatment technology of choice due to the highly fouling nature of the feed. This paper provides examples of the energy cost for various water sources, comparing waste-water reuse with surface water, brackish water and seawater desalination. In the wastewater case, conventional activated sludge followed by UF/MF-RO is compared with MBR-RO. The comparison shows that wastewater reuse is a very attractive energy option, and that schemes should be considered where possible using UF/MF-RO after conventional sewage treatment, or MBR for smaller schemes, or where space is at a premium. Conventional surface water sources have an energy cost of 0.1–0.3 kW h/m 3 , with brackish water sources normally falling in the range 0.8–1.7 kW h/m 3 . The energy cost of wastewater reuse from conventional treatment is in the range 0.8–1.2 kW h/m 3 , whilst MBR-RO is in the range 1.2–1.5 kW h/m 3 . Seawater has the most expensive energy cost, with a medium salinity feed needing an energy of 2.3–4.0 kW h/m 3 . Although the non-conventional sources all use higher energy than surface or groundwater sources, the cost of transfer and distribution should also be considered. A typical power cost for distribution is 0.6 kW h/m 3 , so proximity of the source and demand may be a key factor. The data can be used to provide guidance for resource development.
Article
Forward (direct) osmosis (FO) using semi-permeable polymeric membranes may be a viable alternative to reverse osmosis as a lower cost and more environmentally friendly desalination technology. The driving force in the described FO process is provided by a draw solution comprising highly soluble gases—ammonia and carbon dioxide. Using a commercially available FO membrane, experiments conducted in a crossflow, flat-sheet membrane filtration cell yielded water fluxes ranging from 1 to 10 m/s (2.1 to 21.2 gal ft −2 d −1 or 3.6 to 36.0 l m −2 h −1) for a wide range of draw and feed solution concentrations. It was found, however, that the experimental water fluxes were far lower than those anticipated based on available bulk osmotic pressure difference and membrane pure water permeability data. Internal concentration polarization was determined to be the major cause for the lower than expected water flux by analysis of the available water flux data and SEM images of the membrane displaying a porous support layer. Draw solution concentration was found to play a key role in this phenomenon. Sodium chloride rejection was determined to be 95–99% for most tests, with higher rejections occurring under higher water flux conditions. Desalination of very high sodium chloride feed solutions (simulating 75% recovery of seawater) was also deemed possible, leading to the possibility of brine discharge minimization.
Article
Treatment of landfill leachate has gained increasing attention during recent years, and several commercial RO leachate treatment plants have been installed in, e.g., Germany, the Netherlands and Switzerland. In this investigation the influence on membrane performance when treating new types of landfill leachate was studied. Three different types of landfill leachate were included in this study: leachate from a conventional landfill and two leachates from a new type of landfill. At the new landfill the waste is divided into different categories and deposed in waste cells with separate leachate collecting systems. Leachate from a cell with biodegradable waste and from a cell with special waste, containing mainly ashes, were included in this study. A linear correlation between flux and conductivity was found for leachate both from the conventional landfill and from the biodegradable waste cell. The flux varied, depending on the conductivity of the leachate, between 48 and 3 l/m2/h. The reduction of pollutants was high. The reduction of the chemical oxygen demand and NH4N was more than 98% for leachate from both the conventional landfill and the biodegradable waste, for example. The salt concentration, and thus the osmotic pressure, was very high in the leachate from the cell containing special waste. The flux was therefore too low for RO to be a suitable treatment process for this leachate.
Article
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.
Article
Advanced oxidation processes (AOPs) such as Fenton, electro-Fenton and photo-Fenton have been applied effectively to remove refractory organics from landfill leachate. The Fenton reaction is based on the addition of hydrogen peroxide to the wastewater or leachate in the presence of ferrous salt as a catalyst. The use of this technique has proved to be one of the best compromises for landfill leachate treatment because of its environmental and economical advantages. Fenton process has been used successfully to mineralize wide range of organic constituents present in landfill leachate particularly those recalcitrant to biological degradation. The present study reviews the use of Fenton and related processes in terms of their increased application to landfill leachate. The effects of various operating parameters and their optimum ranges for maximum COD and color removal are reviewed with the conclusion that the Fenton and related processes are effective and competitive with other technologies for degradation of both raw and pre-treated landfill leachate.
Article
Osmotically driven membrane processes are an emerging set of technologies that show promise in water and wastewater treatment, desalination, and power generation. The effective operation of these systems requires that the reverse flux of draw solute from the draw solution into the feed solution be minimized. A model was developed that describes the reverse permeation of draw solution across an asymmetric membrane in forward osmosis operation. Experiments were carried out to validate the model predictions with a highly soluble salt (NaCl) as a draw solution and a cellulose acetate membrane designed for forward osmosis. Using independently determined membrane transport coefficients, strong agreement between the model predictions and experimental results was observed. Further analysis shows that the reverse flux selectivity, the ratio of the forward water flux to the reverse solute flux, is a key parameter in the design of osmotically driven membrane processes. The model predictions and experiments demonstrate that this parameter is independent of the draw solution concentration and the structure of the membrane support layer. The value of the reverse flux selectivity is determined solely by the selectivity of the membrane active layer.
Article
Ammonium is an important source of nitrogen for plants. It is taken up by plant cells via ammonium transporters in the plasma membrane and distributed to intracellular compartments such as chloroplasts, mitochondria and vacuoles probably via different transporters in each case. Ammonium is generally not used for long-distance transport of nitrogen within the plant. Instead, most of the ammonium transported into plant cells is assimilated locally via glutamine synthetases in the cytoplasm and plastids. Ammonium is also produced by plant cells during normal metabolism, and ammonium transporters enable it to be moved from intracellular sites of production to sites of consumption. Ammonium can be generated de novo from molecular nitrogen (N(2)) by nitrogen-fixing bacteria in some plant cells, such as rhizobia in legume root nodule cells, and at least one ammonium transporter is implicated in the transfer of ammonium from the bacteria to the plant cytoplasm. Plant physiologists have described many of these ammonium transport processes over the last few decades. However, the genes and proteins that underlie these processes have been isolated and studied only recently. In this review, we consider in detail the molecular structure, function and regulation of plant ammonium transporters. We also attempt to reconcile recent discoveries at the molecular level with our knowledge of ammonium transport at the whole plant level.
Article
This paper aims at providing an overview of electrochemical oxidation processes used for treatment of landfill leachate. The typical characteristics of landfill leachate are briefly reviewed, and the reactor designs used for electro-oxidation of leachate are summarized. Electrochemical oxidation can significantly reduce concentrations of organic contaminants, ammonia, and color in leachate. Pretreatment methods, anode materials, pH, current density, chloride concentration, and other additional electrolytes can considerably influence performance. Although high energy consumption and potential chlorinated organics formation may limit its application, electrochemical oxidation is a promising and powerful technology for treatment of landfill leachate.
Forward Osmosis Systems: Landfill Leachate
  • Hti
HTI, 2010. Forward Osmosis Systems: Landfill Leachate. <http://www. htiwater.com/divisions/industrial_waste/forward_osmosis_systems/case-study_landfill-leachate.html>.