Hypersaline brines are of growing environmental concern. While high-salinity desalination and zero liquid discharge (ZLD) are increasingly attractive treatment options, the high salt and scalant ...contents pose considerable technical difficulties to existing desalination techniques. In this review, we introduce sources of hypersaline brines, examine factors driving high-salinity desalination, and present the thermodynamic minimum energy of hypersaline desalination and ZLD, highlighting effects of mineral precipitation and imperfect salt rejection. We then critically examine prospects and challenges of 10 alternative technologies for hypersaline desalination: electrodialysis, osmotically-mediated reverse osmosis, forward osmosis, membrane distillation, humidification-dehumidification, solvent extraction desalination, supercritical water desalination, freeze desalination, clathrate hydrate desalination, and solar thermal desalination. Although electrodialysis and osmotically-mediated reverse osmosis show promise of having competitive energy efficiencies, these membrane-based techniques are still constrained by concentrate salinity limits. Recovery and reuse of heat will be vital for competitiveness of thermally-driven approaches. Technologies that intrinsically precipitate salts in bulk solution, namely solvent extraction desalination, supercritical water desalination, and humidification-dehumidification, can advantageously avoid mineral scaling. Due to the highly heterogeneous nature of hypersaline streams and the wide array of end-use goals, the high-salinity desalination market will ultimately be best served by a range of different technologies with distinctive capabilities.
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•Ten emerging technologies for high-salinity desalination are critically reviewed.•ED and OMRO show most promise in achieving high energy efficiencies.•SED, HDH, FO, MD, and STD can be driven by low-grade heat.•SED, SCWD, and HDH can potentially sidestep scaling issues.•High-salinity brines are diverse and will require different desalination approaches.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Oilfield PW sources, characteristics, and discharge regulations are reviewed.•Oilfield PW management including the state-of-the-art approaches are discussed.•Single treatment methods cannot meet all ...reuse and disposal requirements.•Design of an efficient hybrid system needs a structured and a risk-based approach.
Various stages of oil production and processing in petroleum industry produce an enormous amount of oilfield produced water (PW). Discharge of this huge amount of PW has an adverse impact on the surrounding environment as it contains different types of toxic and complex organic and inorganic compounds. For a long time, conventional treatment methods have been used to purify PW; however, these techniques could not meet the environmental regulations especially when the purpose is to reuse water. Therefore, more research efforts are required to select an effective technology that can mitigate the challenges through the best management strategy. In this study, the oilfield PW sources and characteristics, discharge regulations, treatment management, and recent advancements, challenges, and future needs in physical, chemical, thermal, biological, membrane, and hybrid treatment techniques are reviewed. Since the wastewater includes different recalcitrant pollutants, single technologies to date have not been successful enough in rendering it to a reusable form or meeting disposal requirements. Therefore, combined technologies might offer a promising process not only to meet the regulatory criteria but also to provide opportunities to use PW as a non-conventional water source. Furthermore, PW management needs a structured framework and a risk-based approach considering environmental, technical, and economic aspects to choose and design the most efficient strategy(ies).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Zero liquid discharge (ZLD)a wastewater management strategy that eliminates liquid waste and maximizes water usage efficiency has attracted renewed interest worldwide in recent years. Although ...implementation of ZLD reduces water pollution and augments water supply, the technology is constrained by high cost and intensive energy consumption. In this critical review, we discuss the drivers, incentives, technologies, and environmental impacts of ZLD. Within this framework, the global applications of ZLD in the United States and emerging economies such as China and India are examined. We highlight the evolution of ZLD from thermal- to membrane-based processes, and analyze the advantages and limitations of existing and emerging ZLD technologies. The potential environmental impacts of ZLD, notably greenhouse gas emission and generation of solid waste, are discussed and the prospects of ZLD technologies and research needs are highlighted.
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IJS, KILJ, NUK, PNG, UL, UM
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•Correlations of water reuse to local water resource and GDP levels were analysed.•Centralized water reuse framework and utilization patterns were identified.•Characteristics and ...applications of centralized water reuse systems were discussed.•A case study on the multiple-application water reuse model is conducted.•The importance of water reuse for urban sustainable management was highlighted.
In the context of rapid urbanization and water shortage, many cities of the world, especially megacities in rapidly developing zones, have urgent needs in improving their sustainable water management without compromising the local socioeconomic development. Water reuse has been increasingly recognized as a sustainable water management strategy. The results of this paper have shown that the development of water reuse in China is found to have positive correlations to local water resource availability and GDP levels, and the water reuse rate in some megacities has already reached 35–60%. Centralized water reuse systems have widely gained favor. Thus, a centralized water reuse framework with three utilization patterns is proposed. Particularly, a multiple-utilization model that applies a hierarchical use structure is found to be viable for meeting multiple water quality requirements. Other patterns address environmental and cascading ways in maximizing the value of reclaimed water use. A case study in a Chinese megacity, Tianjin, is demonstrated where a large-scale centralized water reuse project with a multiple barrier treatment approach and a hierarchical distribution and use structure has contributed to water reuse development in a safe, reliable and economical manner. This paper can be beneficial to water authorities and practitioners for long-term urban water management in other rapidly developing cities and regions that have encountered similar water-related problems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
To meet surging water demands, water reuse is being sought as an alternative to traditional water resources. However, contamination of water resources by trace organic compounds (TOrCs), including ...pharmaceuticals, personal care products, disinfection byproducts, and industrial chemicals is of increasing concern. These compounds are not readily removed by conventional water treatment processes and require new treatment technologies to enable potable water reuse. Forward osmosis (FO) has been recognized in recent years as a robust process suitable for the treatment of highly impaired streams and a good barrier to TOrCs. To date, at least 14 studies have been published that investigated the rejection of various TOrCs by FO membranes under a variety of experimental conditions. In this paper, TOrC rejection by FO has been critically reviewed, evaluating the effects of membrane characteristics and orientation, experimental scale and duration, membrane fouling, feed solution chemistry, draw solution composition and concentration, and transmembrane temperature on process performance. Although it is important to continue to investigate the removal of diverse TOrCs by FO, and especially with new FO membranes, it is critically important to adhere to standard testing conditions to enable comparison of results between studies. Likewise, feed concentration of TOrCs during FO testing must be environmentally relevant (most commonly 10–100 ng/L range for most wastewaters) and not excessively high, and in addition to testing TOrC rejection in clean feedwater, the effects of real water matrix and membrane fouling on TOrC rejection must be evaluated.
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•SWAT was modified for the multi-source water irrigation system with paddy rice.•A method was proposed to calculate return flow and its reuse amount based on the modified SWAT.•Two indicators were ...employed to analyze the spatial scale effect of reuse of return flow.•With the increase of spatial scale, the reuse rate of return flow increased and tended to stabilize.
Return flows in irrigation systems are often reused contributing to overall efficiency. To investigate the fate of return flows and the scale effects of reuses, the SWAT (Soil and Water Assessment Tool) model was modified to better represent the characteristics of paddy rice irrigation systems, which includes a simulation module for automatic multi-source irrigation (AMSIM). The modified SWAT model was used to simulate the hydrological processes in the Yangshudang (YSD) watershed of the Zhanghe Irrigation System (ZIS) in China. Furthermore, we proposed a method to calculate the amounts of return flows and the reused amount based on the output of the model. The sub-basins nesting method was used to divide the study area into six scales. We calculated the rainfall & irrigation water reuse rates (ηI+P) and the irrigation water reuse rates (ηI) at different scales and analyzed the changes of these two indicators over different scales. The results revealed that the modified SWAT model succeeded in simulating hydrological processes in a paddy rice irrigation system. ηI+P and ηI increased with the increase of scale. ηI+P was higher in the wet years and lower in the dry years, while ηI was higher in the dry years and lower in the wet years. The reason for increase of ηI+P and ηI as the scales increases were due to the fact that the return flows was repeatedly intercepted by downstream paddy fields, farm ponds, and drainage channels at larger scales, This reuse rates however reach the upper limit at a scale of 3500 ha, after which ηI+P and ηI no longer increase.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The separation properties of polyamide reverse osmosis and nanofiltration membranes, widely applied for desalination and water reuse, are constrained by the permeability-selectivity upper bound. ...Although thin-film nanocomposite (TFN) membranes incorporating nanomaterials exhibit enhanced water permeance, their rejection is only moderately improved or even impaired due to agglomeration of nanomaterials and formation of defects. A novel type of TFN membranes featuring an interlayer of nanomaterials (TFNi) has emerged in recent years. These novel TFNi membranes show extraordinary improvement in water flux (e.g., up to an order of magnitude enhancement) along with better selectivity. Such enhancements can be achieved by a wide selection of nanomaterials, ranging from nanoparticles, one-/two-dimensional materials, to interfacial coatings. The use of nanostructured interlayers not only improves the formation of polyamide rejection layers but also provides an optimized water transport path, which enables TFNi membranes to potentially overcome the longstanding trade-off between membrane permeability and selectivity. Furthermore, TFNi membranes can potentially enhance the removal of heavy metals and micropollutants, which is critical for many environmental applications. This review critically examines the recent developments of TFNi membranes and discusses the underlying mechanisms and design criteria. Their potential environmental applications are also highlighted.
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The use of enzymes in industrial processes requires the improvement of their features in many instances. Enzyme immobilization, a requirement to facilitate the recovery and reuse of these ...water-soluble catalysts, is one of the tools that researchers may utilize to improve many of their properties. This review is focused on how enzyme immobilization may improve enzyme stability. Starting from the stabilization effects that an enzyme may experience by the mere fact of being inside a solid particle, we detail other possibilities to stabilize enzymes: generation of favorable enzyme environments, prevention of enzyme subunit dissociation in multimeric enzymes, generation of more stable enzyme conformations, or enzyme rigidification via multipoint covalent attachment. In this last point, we will discuss the features of an “ideal” immobilization protocol to maximize the intensity of the enzyme-support interactions. The most interesting active groups in the support (glutaraldehyde, epoxide, glyoxyl and vinyl sulfone) will be also presented, discussing their main properties and uses. Some instances in which the number of enzyme-support bonds is not directly related to a higher stabilization will be also presented. Finally, the possibility of coupling site-directed mutagenesis or chemical modification to get a more intense multipoint covalent immobilization will be discussed.
•Enzyme immobilization in a porous structure may protect the enzyme from some inactivating causes•Enzyme immobilization may freeze some stable enzyme conformation•Multi-subunit enzyme immobilization may prevent enzyme subunit dissociation•Enzyme immobilization may enhance enzyme stability by generating special environments•Enzyme multipoint covalent attachment should increase enzyme rigidity
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Microalgae-based wastewater treatment conforms the new trends of wastewater treatment in future.•Most wastewater with inappropriate C/N and N/P ratios for microalgae cultivation.•Factors affecting ...nutrients recovery by microalgae are strongly related to the wastewater characteristics.•More research is needed on the design and operation of microalgae-based wastewater treatment process to be more economical.
The water resource crisis and concerns with environmental pollution are pushing for upgrading of conventional wastewater treatment process. Microalgae-based wastewater treatment process has shown many advantages that can meet the new demand for improved wastewater treatment. However, considering the issues related to the complexity of wastewater characteristics and adaptability of microalgae species, and the challenges to the design and optimization of treatment processes in order to achieve higher removal efficiencies with lower costs, further exploration and research are still needed. This review provides an overview of microalgae strains commonly used for wastewater treatment, physical and chemical properties of various wastewaters and their suitability for algae cultivation, factors affecting algae growth, nutrient assimilation/removal and biomass productivity. The design and operation of microalgae-based wastewater treatment processes are also discussed. Moreover, the issues and limitations of microalgae-based wastewater treatment are also discussed and suggestions are proposed for the further research and development.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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