Large Volumes Of Water Research Articles

Determining hydraulic diffusivity from ambient noise in subsurface flow rate and temperature data

SUMMARY Determining the properties that control fluid flow and pressure migration through rocks is essential for understanding groundwater, energy reservoirs and fault zones. However, direct measurements of these properties underground generally require expensive and invasive processes such as pumping large volumes of water in or out of the ground. These conventional methods may change the structure that they are trying to measure and do not resolve variations in space without complex, multiple experiments. Here, we capitalize on the existing, natural fluctuations of pore pressure, flow and temperature that are always present underground, likely driven by tides, seismic waves and other noise in the Earth. We develop the theoretical framework to utilize these noises to determine hydrogeologic structure. We begin with prior work demonstrating a connection between cross-correlation and Green's functions for diffusive processes and illustrate how the existing theory could be used specifically for the case of inferring hydraulic diffusivity from closely spaced observations of pore pressure. We extend the current theory to include a capability for inferring Green's functions from closely spaced flow rate measurements, rather than pore pressure data. We then note that closely spaced temperature measurements are much more practical as an observational system, however, diffusive transport is likely not the dominant cause of high-frequency fluctuations of temperature in the Earth. Advective transport is a more plausible controlling factor and thus we need to incorporate advection into the theory and model the corresponding response functions. We therefore develop a semi-analytical method that includes advection and numerically compute the corresponding response function. We use these synthetics to illustrate how cross-correlation of ambient noise in subsurface temperature measurements carries information about hydraulic structure and show that it is possible to constrain hydraulic diffusivity values from cross-correlation of closely spaced continuous temperature measurements. This new method opens up the possibility of passive determination of reservoir properties with high spatial resolution from closely spaced, continuous temperature data, which is a realistic deployment strategy that could be used in a wide variety of settings.

Aquifer recharge capacity assessment of an anthropogenically impacted wetland by the DC resistivity geophysical method

Population growth and social and economic development demand increasing volumes of water for public supply, especially in scenarios where surface sources such as rivers may not meet the basic demands for the population. In southeastern Brazil, with emphasis on the Piracicaba region, there is a conflict over water use regarding agricultural and industrial activities, where the sugar-alcohol sector is widely highlighted. The region has thousands of hectares of sugarcane cultivated, which requires intensive use of fertilizers and pesticides, in addition to the need for large volumes of water in the production of sugar and ethanol, where the main effluent produced is represented by vinasse, used as fertilizer complement and soil hydration in sugarcane fields. This work presents the results of a geophysical diagnosis in a closed wetland, located in a sugarcane field region, to evaluate the hydrogeological function of this environment in aquifer recharge and the risks that land use can cause in the quality and availability of surface and underground water resources. The geophysical survey consisted of nine lines of electrical resistivity tomography in Schlumberger arrangement, submitted to 2D processing and inversion followed by interpolation and generation of 3D visualization models. The results indicate a direct connection between water accumulated in the wetland and the aquifer underneath, separated by an aquitard interface about 44 m thickness. The study points out to the high vulnerability to the input of pesticides and vinasse effluent from the surrounding sugarcane fields to the interior of the wetland, given the absence of riparian forest or buffer zone, in addition to the risk of contamination of surface and groundwater. Understanding the local hydrological dynamics should subsidize the sustainable use of the soil providing preservation of water resources, with emphasis on aquifers, a source of increasing importance in the face of the imminent scarcity of surface resources.

Evaluating fundamental biochar properties in relation to water holding capacity

Biochar products that hold and release water within a stable carbonised porous structure provide many opportunities for climate mitigation and a range of applications such as for soil amendments. Biochar that are produced from various organic feedstocks by pyrolysis can provide multiple co-benefits to soil including improving soil health and productivity, pH buffering, contaminant control, nutrient storage, and release, however, there are also risks for biochar application in soils. This study evaluated fundamental biochar properties that influence Water Holding Capacity (WHC) of biochar products and provides recommendations for testing and optimising biochar products prior to soil applications. A total of 21 biochar samples (locally sourced, commercially available, and standard biochars) were characterised for particle properties, salinity, pH and ash content, porosity, and surface area (with N2 as adsorbate), surface SEM imaging, and several water testing methods. Biochar products with mixed particle size, irregular shapes, and hydrophilic properties were able to rapidly store relatively large volumes of water (up to 400% wt.). In contrast, relatively less water (as low as 78% wt.) was taken up by small-sized biochar products with smooth surfaces, along with hydrophobic biochars that were identified by the water drop penetration test (rather than contact angle test). Water was stored mostly in interpore spaces (between biochar particles) although intra-pore spaces (meso-pore and micropore scale) were also significant for some biochars. The type of organic feedstock did not appear to directly affect water holding, although further work is needed to evaluate mesopore scale processes and pyrolytic conditions that could influence the biochemical and hydrological behaviour of biochar. Biochars with high salinity, and carbon structures that are not alkaline pose potential risks when used as soil amendments.

Validation of a nutria (Myocastor coypus) environmental DNA assay highlights considerations for sampling methodology

AbstractNutria (Myocastor coypus) is a semiaquatic rodent species that is invasive across multiple regions within the United States. Here, we evaluated a qPCR assay previously described for use in Japan for application across invasive populations in the United States. We also compared two environmental DNA sampling methodologies for this assay: field filtration of large volumes of water passed through filters versus direct sampling of small volumes of water. We validated assay specificity, generality, and sensitivity, compared assay performance between two independent laboratories, and successfully tested the assay in situ on a known wild population. The filtration method required fewer samples for environmental DNA detection than direct sampling, but the choice of methods should be assessed based on specific field conditions and time and budget considerations. Our extensive assay validation and comparison across laboratories suggest that the assay is ready to be applied in environmental DNA monitoring of nutria throughout the United States.

Batik Effluent Treatment and Decolorization—A Review

Batik is a piece of woven cloth decorated with beautiful patterns and designs and has become a signature product of the Malay Archipelago, including Malaysia and Indonesia. Batik industry consumes a large volume of water and produces a large amount of wastewater during the boiling process and dyeing process, both for hand-drawn (batik lukis) and block-printed (batik cap) batik. The release of colored effluents that contain a large number of dyes and chemicals can harm the environment and become a human health concern, particularly in south east Asian countries. Therefore, treatments of batik effluent are very crucial and have caught a lot of attention from researchers. The color removal is a major challenge, especially from this industry, as up until now there is no single and cost-effective treatment that can effectively decolorize as well as treat the dye effluent. Since batik is part of the textile industry, most treatment methods have been adapted from textile effluent treatment. Here, we review a variety of textile wastewater treatment techniques to make a good consideration of selecting the most appropriate method to be applied in batik wastewater. First, we briefly review the batik process, including the potential dyes that are mostly used in batik processing. Secondly, we describe all possible techniques and their performance to reduce dye concentration and decolorization. Finally, we review all advantages and disadvantages of these techniques for domestic and industrial applications.

Online Membrane Sampling for the Mass Spectrometric Analysis of Oil Sands Process Affected Water-Derived Naphthenic Acids in Real-World Samples

Large volumes of oil sands process-affected waters (OSPW) result from heavy oil extraction in Alberta, Canada. Currently, a toxic legacy of ca. 500 Mm3 is stored in tailings ponds under a zero-discharge policy. OSPW is a complex mixture of suspended and dissolved materials including a wide range of inorganic and organic contaminants. Classically defined naphthenic acids (NAs; CnH2n+ZO2) are one of the primary toxic fractions in OSPW and have therefore been the subject of considerable research interest. Most studies employ considerable sample cleanup followed by liquid chromatography and/or high-resolution mass spectrometry (HRMS) for the characterization of these complex mixtures. However, these strategies can be time- and cost-intensive, limiting the scope of research and adoption for regulatory purposes. Condensed phase membrane introduction mass spectrometry (CP-MIMS) is emerging as a “fit-for-purpose” approach for the analysis of NAs. This technique directly interfaces the mass spectrometer with an aqueous sample using a hydrophobic semi-permeable membrane, requiring only pH adjustment to convert NAs to a membrane-permeable form. Here, we examine the perm-selectivity of classical NAs (O2) relative to their more oxidized counterparts (O3–O7) and heteroatomic (N, S) species collectively termed naphthenic acid fraction compounds (NAFCs). The investigation of 14 model compounds revealed that classically defined NAs are greater than 50-fold more membrane permeable than their oxidized/heteroatomic analogs. HRMS analysis of real OSPW extracts with and without membrane clean-up further supported selectivity towards the toxic O2 class of NAs, with >85% of the overall signal intensity attributable to O2 NAs in the membrane permeate despite as little as 34.7 ± 0.6% O2 NAs observed in the directly infused mixture. The information collected with HRMS is leveraged to refine our method for analysis of NAs at unit mass resolution. This new method is applied to 28 archived real-world samples containing NAs/NAFCs from constructed wetlands, OSPW, and environmental monitoring campaigns. Concentrations ranged from 0–25 mg/L O2 NAs and the results measured by CP-MIMS (unit mass) and SPE-HRMS (Orbitrap) showed good agreement (slope = 0.80; R2 = 0.76).

Experimental Work on Salt-Based Cooling Systems

The energy consumption for space cooling is progressively increasing. Integrating renewable energy into space cooling systems is critical for reducing CO2 emissions from the building sector. The salt-based cooling system is an appealing alternative as it can be charged by solar energy. This system is based on the characteristic of endothermic salts, which generate a considerable cooling effect when dissolved in water. A screening test was performed in this work to evaluate the cooling performance of several endothermic salts. Furthermore, a laboratory-scale system was developed to demonstrate the endothermic salt-based thermal storage and cooling generation system. Temperature decreases up to 12.3 °C were observed in the system containing Potassium Chloride salt. The temperature drop was maintained after the system underwent a charging/discharging cycle; however, the cooling period was shortened. The system demonstrated an inherent low efficiency due to the large volume of water required in the discharging phase, demanding a considerable amount of energy to evaporate the water in the charging phase. As a result, the application of this system will be restricted to the usage of low-grade energy during the charging phase.

Removal of highly concentrated methylene blue dye by cellulose nanofiber biocomposites

The contamination of water by dyes in high concentrations is a worldwide concern, and it has prompted the development of efficient, economical, and environmentally friendly materials and technologies for water purification. The hydration and adsorption capacity for methylene blue (MB) in biocomposites (BCs) based on cellulose nanofiber (CNF) (0 to 2 wt%) were studied. BCs were synthesized through a simple and straightforward route and characterized by spectroscopy, microscopic techniques and thermogravimetric analysis, among others. Hydration studies showed that BCs prepared with 2 wt% of CNF can absorb large volumes of water, approximately 2274 % in the case of poly 2-acrylamide-2-methyl-1-propanesulfonic acid (PAMPS)-CNF and 2408 % in poly sodium 4-styrene sulfonate (PSSNa)-CNF. These BCs showed outstanding adsorption capacity for highly concentrated MB solutions (4536 mg g−1 PAMPS-CNF and 11,930 mg g−1 PSSNa-CNF). It was confirmed that the adsorption mechanism is through electrostatic interactions. Finally, BCs showed high MB adsorption efficiency after several sorption-desorption cycles and on a simulated textile effluent. Furthermore, the theoretical results showed a preferential interaction between MB and the semiflexible polymer chains at the lowest energy setting. The development and study of a new adsorbent material with high MB removal performance that is easy to prepare, economical and reusable for potential use in water purification treatments was successfully achieved.

Biodiesel Production by Heterogeneous Catalysis and Eco‐friendly Routes

AbstractBiodiesel is produced on a large scale as an eco‐friendly substitute and additive to fossil fuels. Catalytic homogeneous processes using strong acids, alkalis, and natural oils have been realized in industry. However, these traditional methods have several disadvantages, such as the generation of large volumes of waste, high water and reagent needs, use of hazardous reagents, high operation costs, and utilization of valuable feedstocks and catalysis, respectively. Different solutions have subsequently been investigated, such as cheap alternative feedstocks, co‐solvents and catalysts, sustainable operational conditions, advanced reactor designs and scales, and advantageous pre‐ and post‐reaction treatments. This review explores and analyzes the main aspects of current biodiesel technologies and opportunities. It also describes some advanced improvement strategies.

Sludge-based activated biochar for adsorption treatment of real oil sands process water: Selectivity of naphthenic acids, reusability of spent biochar, leaching potential, and acute toxicity removal

Large volumes of oil sands process water (OSPW) containing naphthenic acids (NAs) and other contaminants are generated by oil sands operations. For the first time, pristine and zinc chloride-activated biochars from sludge from a municipal wastewater treatment plant are studied in the adsorption of NAs in real OSPW. By using activated biochar instead of pristine biochar, the adsorption capacity (qt) for total NAs (classical and oxidized NAs) increased from 2.3 to 26.6 mg/g. The increase in qt for activated biochar was related to the improvement of surface area from 7.9 to 513 m2/g, the abundance of mesopores (89% of pore volume), and the oxygen-containing surface groups. Equilibrium was reached at 2 h of contact time. Considering the thousands of structures of NAs in the OSPW, the activated biochar presented higher affinity for NAs with higher carbon and double bond equivalency numbers, therefore, NAs with more hydrophobic and higher cyclicity characteristics. Pore-filling, hydrogen bonding, and π-π interactions are the adsorption mechanisms. Thermal regeneration of spent activated biochar was studied, and in the fifth cycle of regeneration, the regenerated biochar had qt of 7.1 mg/g, which was 5 times higher than the adsorption capacity of fresh pristine biochar. Adsorption treatment of OSPW using activated biochar decreased the following parameters: metals Mg (7%), Ca (21%), Sr (27%), and Ba (60%), organic matter by means of DOC (63%) and COD (66%), acute toxicity towards V. fischeri (66%) and bioavailability of organics (91%). These findings promote circular economy as it presents an efficient adsorbent for NAs in OSPW developed from sludge, reducing the environmental impact associated with sludge disposal and allowing the efficient reclamation and reuse of OSPW.

Emulsified Silica Gel for Deep Reservoir Water Conformance Control

Large volumes of water are produced with the production of oil, posing challenges of corrosion, scaling, and an increased water–oil ratio. Silica-based gels have previously been used as water sealants; however, reservoirs with high temperature and/or salinity cause early gelation, thereby preventing deep penetration into the reservoir. This work discusses factors affecting gel formation from colloidal silica and mixing methods for the preparation of a thermally stable Pickering emulsion and the effect of various parameters on its rheology. Sensitivities include salinities ranging from 5 to 20 wt % for seven different salts, silica gel concentrations from 20 to 28 wt %, pH values from 4 to 9, and temperatures from 80 to 150 °C. The effect of each parameter on the gelation time and gel strength was studied at a constant shear rate and pressure of 100 s–1 and 1100 psi, respectively. A commercial phyllosilicate (organoclay) has been used with diesel to form an invert emulsion of 28% silica gel, with diesel as a continuous phase and colloidal silica as a dispersed phase. Dynamic gel tests were performed to study the effect of the emulsion mixing method, temperature, and organoclay concentrations on the emulsion stability, strength, and viscosity. A lower concentration of salt has a longer gelation time with a lower gel strength. Increasing pH increases the gel strength but reduces the gelation time. The Pickering emulsion formed is stable to high shear, high temperatures, and high salinities. The bulk mixing method produces a direct emulsion, whereas drop-by-drop mixing results in an invert emulsion. A comparison of the gelation time and viscosity has also been provided with non-emulsified silica gel to highlight the benefit of encapsulation in terms of increased gelation time. This work will help academia and industry in designing a cost-effective system for water conformance control in harsh reservoir conditions.

Plasma-Activated Tap Water Production and Its Application in Atomization Disinfection

Plasma-activated tap water (PATW) is a new technology for obtaining a high concentration of active aqueous plasma substances by discharging underwater. Commonly plasma-activated water (PAW) is realized by activating deionized water or distilled water, which has problems such as high cost, a small discharge area, and insufficient dissolution of active substances. This paper reports the development of a dielectric barrier discharge array to generate a high concentration of active aqueous plasma substances. The device can realize a uniform, stable, and large-area discharge in a large volume of tap water, and it has the advantages of low cost, high integration, and reusability. Using the device to treat 1000 mL of tap water for 1 h can reduce the pH of the tap water from 8.10 to 2.54, and the logarithmic value of killing E. coli is greater than 5.0. We sprayed PATW onto clothes to sterilize the bacteria when people were through the disinfection door and verified that the PATW had a good sterilization effect. The short-lived substances, singlet oxygen, and superoxide anion radicals played a key role in the sterilization process by PATW.

Uncharted pathways of the Southern Ocean’s sink of carbon dioxide

Uncharted pathways of the Southern Ocean’s sink of carbon dioxide The Southern Ocean sequesters vast amounts of carbon and heat from the atmosphere, thereby mitigating climate warming. This exchange occurs mainly during winter when intense mixing brings large volumes of deep water into contact with the atmosphere. SO-CUP investigates the magnitude and drivers of carbon uptake with novel wintertime observations made available recently with the deployment of autonomous profiling floats.

Predictions of the Wettable Parameters of an Axisymmetric Large-Volume Droplet on a Microstructured Surface in Gravity

In this study, a numerical model was developed to predict the wettable parameters of an axisymmetric large-volume droplet on a microstructured surface in gravity. We defined a droplet with the Bond number Bo>0.1 as a large-volume droplet. Bo was calculated by using the equation Bo=ρlgγlv3V4π23 where ρl is the density of liquid, γlv is the liquid-vapor interfacial tension, g is the gravity acceleration and V is the droplet volume. The volume of a large-volume water droplet was larger than 2.7 μL. By using the total energy minimization and the arc differential method of the Bashforth-Adams equation, we got the profile, the apparent contact angle and the contact circle diameter of an axisymmetric large-volume droplet in gravity on a microstructured horizontal plane and the external spherical surface. The predictions of our model have a less than 3% error rate when compared to experiments. Our model is much more accurate than previous ellipsoidal models. In addition, our model calculates much more quickly than previous models because of the use of the arc differential method of the Bashforth-Adams equation. It shows promise for use in the design and fabrication of microfluidic devices.

Human-driven long-term disconnect of nutrient inputs to the Yellow River basin and river export to the Bohai Sea

Combining long-term measurements of nitrogen (N) and phosphorus (P) concentrations in the Yellow River (YR) (1981–2018) and river discharge (1981–2018) to the Bohai Sea (BS) with model-based estimates of nutrient delivery shows a disconnect between nutrient delivery and export fluxes to the BS. Basin-wide nutrient delivery to surface water, primarily from agriculture and sewage, exhibited an increasing trend over the whole period. However the nutrient export fluxes to BS declined from 1981 to 2002, followed by a period of large inter-annual variability. Nutrient export is strongly controlled by water discharge, the Water and Sediment Regulation Scheme (WSRS), and the large volume of water containing nutrients that is extracted for primarily irrigation. Dissolved organic N (average 15% in the period 2001–2018) and dissolved organic P (68%) accounted for an important share of total dissolved N and P, which is due to agricultural inputs and preferential retention of inorganic forms in the YR basin. River nutrient export fluxes alone cannot explain the changes in the frequency and area of red tides in the BS due to impacts of the WSRS, the long water residence time in the BS and climate change. This calls for the application of mechanistic models for describing the impact of combined long-term changes in the BS ecosystem.

Influence of mixing speed, solids concentration and enzyme dosage on dry solids yield and protein recovery during enzymatic hydrolysis of sardine (Sardina pilchardus) processing by-products using Alcalase 2.4L: a multivariable optimisation approach

AbstractYield and protein recovery are important variables for process design, which cannot be achieved using degree of hydrolysis (DH). Even though it is known that mixing speed and solids concentration affect mass and energy transfer in bioprocess reaction, previous research has not provided a clear relationship between these two variables and their effect on yield of dry solids and protein recovery during enzyme hydrolysis. The yield of dry solids and protein recovery from enzyme hydrolysis of sardine processing by-products was compared at different levels of mixing speed (100–300 rpm), solids concentration (26–50%) and enzyme dosage (1.318–4.682%). Results showed that low mixing speed (100 rpm), low solids concentration (26–30.8%) and high enzyme dosage (4.682%) optimised degree of hydrolysis to 25.7%, yield of dry solids to 69.1% and protein recovery to 83.0%. Under these conditions, protein loss to emulsion and sludge were minimised to 5.82% and 11.2%, respectively. Although low solids concentration resulted in high solids yield and high protein recovery due to favourable mass transfer effects, hydrolysing material under these conditions will come at a significant cost of larger equipment designs and energy cost for mixing and downstream processing because of the large volume of water to be handled. There is therefore a need for a holistic approach to enzyme hydrolysis optimisation studies, with downstream processing in mind. The significant findings of this study show the impact of process variables and their interaction, particularly solids concentration, on process performance using multivariable optimisation.

Synergistic arsenic removal using chitosan-based nanocomposite beads and cross-flow ultrafiltration: A significant reduction of membrane fouling

Hybrid adsorption-membrane processes provide a suitable alternative for treating large volumes of arsenic-contaminated water by combining the specificity of adsorption with the membrane process’s flexibility in terms of scale-up. The performance of such processes, with respect to removal efficiency and effluent flow rate, largely depends on the characteristics of the adsorbent used. In the present study, we have evaluated the use of in-situ precipitated iron oxyhydroxide chitosan beads (IICB) in combination with cross-flow Ultrafiltration (UF) for the treatment of arsenic-contaminated water. The performance of the combined adsorption-UF process was assessed at three different TMP (0.2–0.6 MPa). Combined Hermia’s model modified for cross-flow UF was found to be a good fit for permeate flux profiles of contaminated groundwater treated using the IICB-UF process. The effect of adding IICB on membrane fouling was evaluated using the resistance-in-series model and XDLVO theory (through contact angle measurements). For arsenic-spiked groundwater, at a dose of 2 g/L IICB, the combined UF process could bring down arsenic to permissible limits (<10 µg/L) and reduce irreversible fouling by up to 32 ± 2%. The reduction of free energy of adhesion and UV254 absorbance values indicated an overall decrease in fouling potential of contaminated feed. Thus, arsenic adsorption using bionanocomposite beads followed by UF (without separation of adsorbent beads prior to UF step) has operational advantages over either of the standalone treatment processes. A similar hybrid technology by varying suitable adsorbents can be successfully applied to remove other toxic pollutants as well.

A self-floating photothermal evaporator with 3D gradient water channel for highly efficient solar seawater desalination

Solar-driven photothermal interface evaporation is considered one of the most promising strategies for dealing with seawater desalination for the scarcity of freshwater resources. However, it still faces the challenges of achieving superior optical absorption combined with outstanding evaporation performance. So as to improve the utilization of solar energy and reduce the loss of heat transfer. We designed a unique three-dimensional self-floating gradient composite membrane via the method of spray, speed shear, and sinking. In this research, a self-floating Polyvinylidene fluoride/Multi-walled carbon nanotubes@polydopamine‑carbon fiber/Polyphenylene sulfide (PVDF/MWCNTs@PDA-CF/PPS) solar evaporation film composed of a hydrophobic PVDF/MWCNTs layer and a PDA-modified CF/PPS fiber substrate with a hydrophilic three-dimensional gradient structure was investigated. The upper is coated with a hydrophobic solar-absorbing coating to ensure that the heat is concentrated in the photothermal layer. The lower is a unique three-dimensional gradient water delivery structure, which not only has an insulated water channel but also can continuously supply water, which will also limit the large volume of water contacting the photothermal layer, reducing the heat loss. PVDF/MWCNTs@PDA-CF/PPS exhibits high evaporation efficiency (1.24 kg m−2 h−1). This structural design will provide a promising solution to the global shortage of fresh water for desalination.

Hydrochemistry, Sources and Management of Fracturing Flowback Fluid in Tight Sandstone Gasfield in Sulige Gasfield (China)

Hydraulic fracturing technologies have been frequently utilized in the oil and gas industry as exploration and development efforts have progressed, resulting in a significant increase in the extraction of natural gas and petroleum from low-permeability reservoirs. However, hydraulic fracturing requires a large amount of freshwater, and the process results in the production of large volumes of flowback water along with natural gas. In this study, three tight sandstone gas wells were fractured in the Sulige gasfield (China), and a total of 103 flowback fluid samples were collected. The hydrochemical characteristics, water quality and sources of hydrochemical components in the flowback fluid were discussed. The results show that the flowback fluid is characterized by high salinity (Total dissolved solids (TDS) up to 38,268mg/L, Cl- up to 24,000mg/L), high concentrations of metal ions (e.g., Fe, Sr2+, Ba2+) and high chemical oxygen demand (COD). The flowback fluid is a complex mixture of fracturing fluid and formation water, and its composition is impacted by water-rock interactions that occur during hydraulic fracturing. The major contaminants include COD, Fe, Ba2+, Cl-, Mn and pH, which constitute a high risk of environmental pollution. Meanwhile, chemical elements such as K, Ba and Sr are unusually enriched in the flowback fluid, which has an excellent potential for recycle of chemical elements. The Sulige gasfield's flowback fluid recovery methods and treatment scenarios were discussed, taking into consideration the pollution and resource characteristics of the flowback fluid. Options for dealing with the flowback fluid include deep well reinjection, reuse for making up fracturing fluid, recycling of chemical elements and diverse reuse of flowback water. This research offers guidance for managing the fracturing flowback fluid in unconventional oil and gas fields.

Effect of Wettability and Adhesion Property of Solid Margins on Water Drainage

Liquid flows at the solid surface and drains at the margin under gravity are ubiquitous in our daily lives. Previous research mainly focuses on the effect of substantial margin's wettability on liquid pinning and has proved that hydrophobicity inhibits liquids from overflowing margins while hydrophilicity plays the opposite role. However, the effect of solid margins' adhesion properties and their synergy with wettability on the overflowing behavior of water and resultant drainage behaviors are rarely studied, especially for large-volume water accumulation on the solid surface. Here, we report the solid surfaces with high-adhesion hydrophilic margin and hydrophobic margin stably pin the air-water-solid triple contact lines at the solid bottom and solid margin, respectively, and then drain water faster through stable water channels termed water channel-based drainage over a wide range of water flow rates. The hydrophilic margin promotes the overflowing of water from top to bottom. It constructs a stable "top + margin + bottom" water channel, and a high-adhesion hydrophobic margin inhibits the overflowing from margin to bottom and constructs a stable "top + margin" water channel. The constructed water channels essentially decrease marginal capillary resistances, guide top water onto the bottom or margin, and assist in draining water faster, under which gravity readily overcomes the surface tension resistance. Consequently, the water channel-based drainage mode achieves 5-8 times faster drainage behavior than the no-water channel drainage mode. The theoretical force analysis also predicts the experimental drainage volumes for different drainage modes. Overall, this article reveals marginal adhesion and wettability-dependent drainage modes and provides motivations for drainage plane design and relevant dynamic liquid-solid interaction for various applications.