Large Volumes Of Freshwater Research Articles

Optimal resource reallocation can achieve water conservation, emissions reduction, and improve irrigated agricultural systems

CONTEXTCrop production consumes large volumes of fresh water and is a key contributor to anthropogenic greenhouse gas (GHG) emissions. Increasing crop output to ensure adequate food supplies under water and land scarcity relies excessively on intensive agricultural inputs (e.g., fertilizers, pesticides, and agricultural films), leading to irreparable environmental consequences (water scarcity and degradation and GHG emissions). Therefore, research on a nexus approach and resource optimization model were carried out. OBJECTIVETo fill the gap of objectives priority and optimal allocation of water resources at irrigation area scale, this study constructed a model to achieve optimal water conservation, GHG emissions reduction, and economic benefit improvement, covering the cumulative environmental burden of agricultural inputs, production processes, trade and consumption related to agricultural activities. METHODSBased on a resource-environmental-economic framework, we took the blue water footprint (WFblue) as a decision variable and developed an integrated water resource optimization model, which was solved by the non-dominated Sorting Genetic Algorithm-II in Matlab. Minimizing crop water footprint (WFcrop), minimizing crop carbon emissions (CEcrop) and maximizing crop economic benefits (EBcrop) were the objectives of the model, and blue water resource, food security, electric energy consumption and land security were the constraint conditions. In addition, three scenarios were tested based on the priority of the objective functions. RESULTS AND CONCLUSIONSAnnually, WFcrop was 1234.29 × 106 m3 and CEcrop was 522.45 Gg CO2 eq for food production in Lianshui Irrigation District from 2005 to 2019. Grain crops exhibited a greater WFcrop and contributed significantly more to CEcrop than oilseed crops. Virtual water and carbon flows increased with food transfer. By adjusting the WFblue of crops compared to the baseline scenario (BS), the average WFcrop decreased by 10.0 %, CEcrop decreased by 4.0 %, and EBcrop increased by 6.4 % under Scenario 2 (minimizing WFcrop and maximizing EBcrop), respectively. Similarly, there were average reductions of 9.2 % in WFcrop, 6.2 % in CEcrop, and EBcrop increased by 5.6 % under Scenario 3 (minimizing CEcrop and maximizing EBcrop) compared to the BS. Therefore, the integrated model achieved the optimization objectives. SIGNIFICANCEThis research not only broadens the scope of traditional environmental impact assessments in agricultural production, but also underscores the positive impact of scientifically and rationally redistributing resources for water conservation, GHG emissions reduction, and economic benefit improvement.

Wastewater Treatment Using Shear Enhanced Flotation Separation Technology: A Pilot Plant Study for Winery Wastewater Processing

The agricultural sector is one that requires and consumes enormous amounts of fresh water globally. Commercial wine production in particular uses large volumes of fresh water and, through various processes, generates significant quantities of wastewater. The wastewater produced by wineries typically exhibits elevated levels of chemical oxygen demand (COD), total suspended solids (TSS), an acidic pH, and varying salinity and nutrient contents. The overall characteristics of winery wastewater indicate that it is a potential environmental hazard if not processed and disposed of appropriately. Due to significant variations in wastewater contaminant levels among wineries, the implementation of a universally applicable, environmentally friendly, and sustainable waste management system seems practically unattainable. This study investigated the design, fabrication, and modification of a shear enhanced flotation separation (SEFS) pilot plant to be used as a primary treatment stage during winery wastewater processing. This technology combines the synergistic advantages of hydrodynamic shear, coagulation, flocculation, and dissolved air flotation. To date, there have been only limited publications on the feasibility and application of hydrodynamic shear and its potential to assist with coagulation/flocculation and flotation efficiencies specifically for winery wastewater treatment. The results obtained indicate that the SEFS pilot plant may well be able to process winery wastewater to a quality level where reuse of the water for irrigation of crops may be considered.

Understanding the Susceptibility of the Tropical Proglacial Environment in Peru Using Optical Imagery and Radon Measurements

The tropical glaciers of the Cordillera Blanca have played host to some of the most significant mass movements ever recorded in the world and Peru; many proglacial lakes formed in this mountain range have natural dikes made of moraine material, which, if they collapse, would present a risk for the cities located downstream of a proglacial lake, where the proglacial lake Palcacocha has a remarkable background regarding floods. The Sentinel-2 MSI (Multi-Spectral Instrument, Level-2A) has a specific band for snow probability mapping that indicates glaciers and snow cover; this is effective for recognizing proglacial lakes by calculating the NDWIice. It is also helpful for lithology with SWIR for granite moraine deposits and slate moraines in the proglacial environment Palcacocha; these deposits surround the proglacial lake, with NDWIice determining the perimeter where sediment interacts with the rocks and meltwater. In addition, there are high radon concentrations made by ice avalanche impacts on the proglacial lake. Unstable glacier blocks cause ice avalanches into this proglacial lake, and the radon responds to flow variations from these high-impact avalanches. We used the device RadonEye PLus2, which allows real-time detection of radon flux changes in the proglacial environment. Our results indicated that ice avalanches making a high impact in the proglacial lake cause turbulent flow and generate radon concentration marks with a rising magnitude, while the absence of ice avalanches in the lake will cause the values to go down. The relationships of radon concentrations in the atmosphere for a tropical proglacial environment are radon and temperature (R2 = 0.364), radon and humidity (R2 = 0.469). In a passive proglacial environment with prolonged rainfall, radon concentrations tend to decrease, with an inversely proportional relationship between humidity and radon in the tropical proglacial environment. Proglacial lakes in the tropical zone often have large volumes of freshwater with high slopes from tropical glaciers, and climate change effects are an imminent danger for nearby cities.

A numerical study on the responses of coastal water quality to river runoff after heavy rainfall in the case of a complex coastline with two artificial islands

Heavy rainfall causes large volumes of freshwater and nutrient salts to flow from rivers into the sea. This leads to major changes in the ecological environment of estuarine waters in a short period of time. The responses of the estuarine hydro-environment become more complex with the concentrated construction of artificial structures, which is a major cause of marine ecological disasters. This paper considers the Tang Estuary in Qinhuangdao, where artificial structures (e.g., ports, artificial islands, and bridges) are concentrated, as a prototype with the weak tidal dynamic environment. A nested prototype of hydrodynamics and water quality was established using a Delft3D model, with coupled waves and flows. The model was used to simulate the spatial and ephemeral characteristics of the short-term responses of ecological environmental factors, such as dissolved inorganic nitrogen (DIN), nitrate-nitrogen (i.e., NO3-N), ammonium-nitrogen (NH4-N), and orthophosphate (i.e., PO4-P), to an episode of heavy rainfall in August 2022. The results showed that concentrations of DIN and NO3-N in the source areas remain high after the flooding process. The concentration recovered to normal values approximately 5.5 days after the flooding process. In contrast, NH4-N and PO4-P showed a response with ephemeral correspondence with the flooding process, and concentration recovery took only approximately 1 day. This paper proposes two short-term response modes of pollutant diffusion, which provide help in exploring the role of hydro-environmental changes in offshore algal hazards and the effect of permeable buildings on pollutant dispersion. This additionally provides possibilities with the forecasting of red tide and green tide, and for their prevention in the future.

Policy and Kidney Community Engagement to Advance toward Greener Kidney Care.

Policy and Kidney Community Engagement to Advance toward Greener Kidney Care.

Changes in the oxygen isotope composition of the Bering Sea contribution to the Arctic Ocean are an independent measure of increasing freshwater fluxes through the Bering Strait.

A large volume of freshwater is incorporated in the relatively fresh (salinity ~32–33) Pacific Ocean waters that are transported north through the Bering Strait relative to deep Atlantic salinity in the Arctic Ocean (salinity ~34.8). These freshened waters help maintain the halocline that separates cold Arctic surface waters from warmer Arctic Ocean waters at depth. The stable oxygen isotope composition of the Bering Sea contribution to the upper Arctic Ocean halocline was established as early as the late 1980’s as having a δ18OV-SMOW value of approximately -1.1‰. More recent data indicates a shift to an isotopic composition that is more depleted in 18O (mean δ18O value ~-1.5‰). This shift is supported by a data synthesis of >1400 water samples (salinity from 32.5 to 33.5) from the northern Bering and Chukchi seas, from the years 1987–2020, which show significant year-to-year, seasonal and regional variability. This change in the oxygen isotope composition of water in the upper halocline is consistent with observations of added freshwater in the Canada Basin, and mooring-based estimates of increased freshwater inflows through Bering Strait. Here, we use this isotopic time-series as an independent means of estimating freshwater flux changes through the Bering Strait. We employed a simple end-member mixing model that requires that the volume of freshwater (including runoff and other meteoric water, but not sea ice melt) flowing through Bering Strait has increased by ~40% over the past two decades to account for a change in the isotopic composition of the 33.1 salinity water from a δ18O value of approximately -1.1‰ to a mean of -1.5‰. This freshwater flux change is comparable with independent published measurements made from mooring arrays in the Bering Strait (freshwater fluxes rising from 2000–2500 km3 in 2001 to 3000–3500 km3 in 2011).

Optical and electrochemical microfluidic sensors for water contaminants: A short review

During the past few years, a large volume of freshwater has been transformed into contaminated water due to anthropogenic activities. For monitoring and tackling the issue of contamination in water, various effective and reasonable methods are available such as titrimetric analysis and chromatography analysis, etc. However, these techniques require a longer time and large sample volumes for the analysis. Therefore, to deal with such problems, a new technology, microfluidic sensing is emerging. Microfluidic sensing is an advanced and cost-effective technique and can perform real-time analysis using a very small quantity of analytes. In this review, different microfluidic technique-based electrochemical and optofluidic sensors have been discussed. Additionally, critical analysis for the implementation of such sensors has been carried out. Among different sensing approaches, the advantages of electrochemical microfluidic devices outweigh that of optical microfluidic sensors.

Green processes for phospholipid recovery and fractionation

Conventional phospholipid (PL) recovery and purification techniques use large volumes of fresh water, organic solvent, and alcohols. Due to diminishing fresh water resources and concerns about the use of organic solvents, the development of more environmentally benign processing techniques is vital to the sustainability of PL production.This article considers three greener alternatives to conventional processing technologies.

Focused Flows to Maintain Natural Nursery Habitats

Regulatory standards for environmental flows to estuaries are not common, but they are required in Texas. This has led to adoption of complex freshwater inflow regimes that reflect seasonal and yearly fluctuations that vary geographically throughout the state. The flow regimes are based on dilution of saline water with fresh water in whole systems. Because the estuaries are large lagoons, large volumes of fresh water are required to meet standards. However, this volume of water is not available during dry periods. We present a new concept, focused flows, for lower flow volumes that would maintain the ecological health of the upper reaches of estuaries during droughts. The concept is based on maintaining ecological integrity of nursery habitats, which is an important ecological function of estuaries. These focused flows would protect nursery habitats during droughts and allow estuaries to recover more quickly when the hydrology returns to average or higher flow periods. This approach could be applied globally where increasing water infrastructure and deficits are a concern or increasing aridity due to climate change is reducing river flows to coasts.

Chemical, Physical and Biological Carwash Wastewater Treatments for Water Recycling: Critical and Comparative Analyses

The carwash industry uses large volumes of freshwater and release wastewater containing harmful chemicals into the environment. The type and quantity of cleaning chemicals and finish products used and the amount of dirt present on the vehicle affect the physical, chemical and biological characteristics of the carwash wastewater. The growing public concerns for water conservation and the environmental health of water waterways has led to several environmental regulations to encourage wastewater reclamation and reduction of pollution loads. The environmentally friendly carwash operation requires a good washing technology with compatible washing chemicals and advanced water treatment methods with proper water recycling system. The desire of professional carwash operators to conserve water and/or reduce discharges dictate the choice of approach and reclaim equipment to be installed. This study describes the treatment options for carwash wastewaters for recycling in order to achieve pollution reduction, water conservation and economic benefits for carwash operators. These treatments include chemical coagulation-flocculation, electrocoagulation, electrooxidation, granular filtration, microfiltration, ultrafiltration, nanofiltration, reverse osmosis, biofilters, bioreactors, wetlands and adsorption. The advantages and disadvantages of each method were determined. Each method was evaluated and compared with other methods using a standard set of criteria that included: cost, maintenance and control, efficiency, suitability, value added product, environmental and health impact and size and land requirement. These criteria were developed based of the advantages and disadvantages of the treatment methods. Each criterion was assigned a score based on its relative importance. A comparative analysis was performed on the 12 methods of carwash wastewater treatments using the eight criteria. The results indicated that granular filter treatment had the highest score (87) followed by reverse osmosis (84). It is therefore recommended that a combination of granular filter and reverse osmosis be used to treat carwash wastewater. The granular filter is used as a pre-treatment option to remove suspended solids, heavy metals and pathogenic microorganisms and the reverse osmosis unit is used as a final treatment for polishing the granular filter effluent and remove all remining organic molecules, cysts, bacteria, virus and all minerals including dissolved individual ions. The final product is a spotfree rinse water resulting in glass, chrome, and all painted surfaces to dry spot-free. Granular filter is easy to set up using locally available material, is economical and has a low capital and operating cost and a short residence time and can achieve reductions of up to 100% of COD, TSS and turbidity. Reverse osmosis results in complete removal of pathogens and virus and up to 99 % removal of dissolved solids.

Use of the gray water footprint as an indicator of contamination caused by artisanal mining in Colombia

The production chain in the gold mining sector in Colombia is one of the most controversial as it requires large volumes of fresh water, and in some cases generates discharges without adequate prior treatment, which results in a high degree of contamination for ecosystems. In the municipality of Suarez there is a large territory dedicated to artisanal mining therefore, in order to provide relevant information for the mitigation of pollution caused by mining, a regional study is completed. In this study, the gray water footprint (GWF) was determined in 6 beds dedicated to artisanal gold mining, in the municipality of Suarez, Cauca, Colombia associated with high contents of TSS (Total suspended solids) and Hg (Mercury). The results showed indicated that the greatest problem in the high levels of GWF by artisanal gold mining activities is related to the dumping of total suspended solids and to a lesser extent the dumping of mercury, however the volume of water necessary to assimilate the pollutant load of mercury still high, so the implementation of clean technologies and the non-use of Hg is recommended.Therefore, it is recommended to build treatment systems to reduce the pollutant load discharge for minimize the environmental impact generated by them.

The energy-water nexus of China’s interprovincial and seasonal electric power transmission

Modern energy systems use large amounts of water for electric power production. This has important impacts on future water management and energy system planning decisions. In this study, we quantify the physical water use of power production and virtual water transfer via power transmission between Chinese provinces using the information on 5408 electricity-generating units and interprovincial power transmission. We show that China’s power production withdrew 62.7 billion m3 of freshwater in 2017, of which 13 billion m3 was consumed (i.e. not returned to the original water basin but lost via evaporation, etc.). A large volume of freshwater was virtually traded through the transmission system. Overall, 6.2 billion m3 of freshwater withdrawal and 2.1 billion m3 of water consumption was traded. Nationally, power transmission reduced freshwater withdrawal but increased consumption in China because, compared to the east, the west generally has a larger water consumption factor but a lower withdrawal factor. Water stress was more equally distributed across provinces through power transmission. We find large seasonal variations in inter-regional virtual water consumption transfer, with an August peak. While the Yangtze River basin and downstream of the Yellow River basin have abundant water relative to other basins, the many power plants located along the two rivers aggravate local water stress. These dynamics will become increasingly important for policymakers and energy planners as China undergoes climatic changes and a rapid energy transition.

Treatment of Produced Water in the Permian Basin for Hydraulic Fracturing: Comparison of Different Coagulation Processes and Innovative Filter Media

Produced water is the largest volume of waste product generated during oil and natural gas exploration and production. The traditional method to dispose of produced water involves deep well injection, but this option is becoming more challenging due to high operational cost, limited disposal capacity, and more stringent regulations. Meanwhile, large volumes of freshwater are used for hydraulic fracturing. The goal of this study is to develop cost-effective technologies, and optimize system design and operation to treat highly saline produced water (120–140 g/L total dissolved solids) for hydraulic fracturing. Produced water was collected from a salt water disposal facility in the Permian Basin, New Mexico. Chemical coagulation (CC) using ferric chloride and aluminum sulfate as coagulants was compared with electrocoagulation (EC) with aluminum electrodes for removal of suspended contaminants. The effects of coagulant dose, current density, and hydraulic retention time during EC on turbidity removal were investigated. Experimental results showed that aluminum sulfate was more efficient and cost-effective than ferric chloride for removing turbidity from produced water. The optimal aluminum dose was achieved at operating current density of 6.60 mA/cm2 and 12 min contact time during EC treatment, which resulted in 74% removal of suspended solids and 53–78% removal of total organic carbon (TOC). The energy requirement of EC was calculated 0.36 kWh/m3 of water treated. The total operating cost of EC was estimated $0.44/m3 of treated water, which is 1.7 or 1.2 times higher than CC using alum or ferric chloride as the coagulant, respectively. The EC operating cost was primarily associated with the consumption of aluminum electrode materials due to faradaic reactions and electrodes corrosions. EC has the advantage of shorter retention time, in situ production of coagulants, less sludge generation, and high mobility for onsite produced water treatment. The fine particles and other contaminants after coagulation were further treated in continuous-flow columns packed with different filter media, including agricultural waste products (pecan shell, walnut shell, and biochar), and new and spent granular activated carbon (GAC). Turbidity, TOC, metals, and electrical conductivity were monitored to evaluate the performance of the treatment system and the adsorption capacities of different media. Biochar and GAC showed the greatest removal of turbidity and TOC in produced water. These treatment technologies were demonstrated to be effective for the removal of suspended constituents and iron, and to produce a clean brine for onsite reuse, such as hydraulic fracturing.

Corrigendum to: Watching the tide roll away – contested interpretations of the nature of the Lower Lakes of the Murray Darling Basin

The Murray Darling Basin Plan (Murray Darling Basin Authority 2012) represents the largest investment by government in an Australian environmental management challenge and remains highly conflicted owing to the contested allocation of diminishing water resources. Central to the decision to reallocate consumptive water to environmental purposes in this Plan was the case made to maintain the freshwater character of two lakes at the terminus of the Murray Darling Basin, in South Australia. This freshwater state was identified as the natural condition on the basis of selected anecdotal evidence and was enshrined in the site's listing under the Ramsar Convention. The commitment to the freshwater state was challenged under drought when sea water was seen as a means of averting acidification when low river flows risked the exposure of sulfidic sediments. Independent evidence from water quality indicators (diatoms) preserved in lake sediment records, however, attested to an estuarine, albeit variable, condition before the commissioning of near-mouth barrages in 1940. This interpretation for a naturally estuarine history, published after peer review, was overlooked in a report to the South Australian government, which argued, without the provision of new evidence from the lakes, that they were fresh for their entire history. This revised interpretation is widely cited in the scientific literature, government reports and online discussion and underpins a watering strategy aimed at a freshwater future for the Lower Lakes. The allocation of large volumes of fresh water to achieve this condition presents significant difficulties owing to the highly contested nature of water use across the Basin.

Watching the tide roll away – contested interpretations of the nature of the Lower Lakes of the Murray Darling Basin

The Murray Darling Basin Plan (Murray Darling Basin Authority 2012) represents the largest investment by government in an Australian environmental management challenge and remains highly conflicted owing to the contested allocation of diminishing water resources. Central to the decision to reallocate consumptive water to environmental purposes in this Plan was the case made to maintain the freshwater character of two lakes at the terminus of the Murray Darling Basin, in South Australia. This freshwater state was identified as the natural condition on the basis of selected anecdotal evidence and was enshrined in the site’s listing under the Ramsar Convention. The commitment to the freshwater state was challenged under drought when sea water was seen as a means of averting acidification when low river flows risked the exposure of sulfidic sediments. Independent evidence from water quality indicators (diatoms) preserved in lake sediment records, however, attested to an estuarine, albeit variable, condition before the commissioning of near-mouth barrages in 1940. This interpretation for a naturally estuarine history, published after peer review, was overlooked in a report to the South Australian government, which argued, without the provision of new evidence from the lakes, that they were fresh for their entire history. This revised interpretation is widely cited in the scientific literature, government reports and online discussion and underpins a watering strategy aimed at a freshwater future for the Lower Lakes. The allocation of large volumes of fresh water to achieve this condition presents significant difficulties owing to the highly contested nature of water use across the Basin.

Design and Application of High-Temperature Raw-Seawater-Based Fracturing Fluids

Summary Typically, water-based fracturing treatments consume a large volume of fresh water. Providing consistent freshwater sources is difficult and sometimes not feasible, especially in remote areas and offshore operations. Therefore, several seawater-based fracturing fluids have been developed in an effort to preserve freshwater resources. However, none of these fluids minimizes fracture-face skin and proppant-conductivity impairment, which can be critical for unconventional well treatments. Several experiments and design iterations were conducted to tailor raw-seawater-based fracturing fluids. These fluids were designed to have rheological properties that can transport proppant under dynamic and static conditions. The optimized seawater-based fracturing-fluid formulas were developed such that no scale forms when additives are mixed in or when the fracturing-fluid filtrate is mixed with different formation brines. The tests were conducted using a high-pressure/high-temperature (HP/HT) rheometer, coreflood, and by aging cells at 250 to 300°F. The developed seawater-based fracturing fluids were optimized with an apparent viscosity greater than 100 cp at a shear rate of 100 seconds–1 and a temperature of 300°F for more than 1 hour. The use of polymeric- and phosphonate-based scale inhibitors (SIs) prevented the formation of severe calcium sulfate (CaSO4) scale in mixtures of seawater and formation brines at 300°F. Controlling the pH of fracturing fluids prevented magnesium and calcium hydroxide precipitation that occurs at a pH value of greater than 9.5. Most importantly, SIs had a negative effect on the viscosity of seawater fracturing fluid during testing because of their negative interaction with metallic crosslinkers. The developed seawater-based fracturing fluids were applied for the first time in an unconventional and a conventional carbonate well and showed very promising results; details of field treatments are discussed in this paper.

Water Footprint and Water Pinch Analysis in Ethanol Industrial Production for Water Management

Fuel ethanol is considered to be a clean alternative fuel to meet increasing energy demands and mitigate environmental pollution. Faced with challenges in terms of energy security and environmental pollution, China is vigorously developing fuel ethanol. However, ethanol-manufacturing is a water-intensive industry; it consumes large volumes of fresh water and generates a corresponding amount of waste water. Expansion of this industry can reduce water quality and cause water stress. This study aims to combine the water footprint (WF) with a water pinch analysis technique to manage water consumption and sewage discharge systematically in an ethanol plant. A well-operated cassava ethanol plant in China was chosen as a case study. The WF of industrial ethanol production was evaluated. The total WF was 17.08 L/L ethanol, comprised of a 7.69 L blue water footprint (BWF), and a 9.39 L gray water footprint (GWF). The direct WF was 16.38 L/L ethanol, and the indirect WF was 0.70 L/L ethanol. Thereafter, a water pinch analysis was conducted, and the optimal direct water reuse scheme was studied. After the water network was optimized, the BWF was reduced by 0.98 L/L ethanol, while the GWF was reduced by 1.47 L/L ethanol. These results indicate that the combined use of WF and pinch analysis can provide the starch-based ethanol industry with an effective tool to improve its water management.

Geochemical data for produced waters from conventional and unconventional oil and gas wells: Results from Colorado, USA

Geochemical data for more than 120,000 oil and natural gas wells from the major sedimentary basins in the USA are listed in the USGS National Produced Waters Geochemical Database [1]. In this summary, we report and discuss the geochemical data on produced waters obtained from published literature and the Colorado Oil and Gas Conservation Commission (COGCC) from close to 4,000 new oil and gas wells in Colorado. We emphasize geochemical data of produced waters from shale and tight reservoirs that have increased dramatically in Colorado since 2011, due to deep horizontal drilling, downhole telemetry and massive multi-stage hydraulic fracturing. These operations require large volumes of fresh water, but contamination of groundwater is the major environmental concern. Also, induced seismicity caused by water injection has been reported from several areas in Colorado, including Trinidad, Raton basin, and Greely, Denver basin. Produced water salinities in Colorado obtained from unconventional oil and gas wells are relatively low, generally less than 30,000 mg/L TDS. Produced water salinities from conventional oil and gas wells overlap those from unconventional wells, but many wells have higher salinities (up to 90,000 mg/L TDS) and different chemical compositions.

A review on the removal of conditioning chemicals from cooling tower water in constructed wetlands

Large volumes of freshwater are used globally for cooling towers. The reuse of discharged cooling tower water in cooling towers itself could mitigate freshwater scarcity problems. Prior to its reuse, the cooling tower blowdown has to be desalinated. However, physicochemical desalination techniques are hampered by conditioning chemicals (CC) that are added to the cooling tower water circuit to prevent corrosion, mineral scaling, and biofouling and can damage physicochemical desalination equipment. The potential of constructed wetlands (CWs) for the cost-effective removal of these CC prior to desalination is discussed in this review. The characteristics of CWs that determine their suitability for the removal of CC from cooling tower blowdown are elucidated, such as multiple removal pathways working simultaneously. In addition, specific challenges for the design of a constructed wetland for cooling tower blowdown treatment are reviewed, such as configuration options, the toxicity of CC, and the formation and removal of harmful byproducts.

Study on Fluid-Rock Interaction and Reuse of Flowback Fluid for Gel Fracturing in Desert Area

Hydraulic fracturing requires a large volume of fresh water, which is difficult and expensive to obtain in the desert area such as Tarim Basin. Currently, flowback fluid is typically transported to the sewage treatment plant and then discharged after reaching environmental requirements; however, this is not only costly, but also a waste of water resource. Therefore, it is imperative to understand the potential interactions between fracturing fluid and reservoir rock, and then find solutions to reuse the flowback water for subsequent fracturing. In this study, once flowback fluid was directly collected from the field, its chemical compositions were analyzed; then, filtering, decoloring, and chelating methods were chosen to effectively remove or shield the unfavorable reintroduced components. Moreover, pH value was further tuned during different stages of the recycling process to ensure good gelation and cross-linking properties of guar. Cross-linked guar synthesized with the flowback fluid was evaluated in the lab through shear resistance tests and coreflood tests under the reservoir conditions; results indicated the recycled gel behaved similarly as the original gel, or even better. From this work, a cheap and effective treatment process was proposed to reuse the flowback fluid in the desert area.