Liquid Discharge Research Articles

Plugging Experiments on Different Packing Schemes during Hydrate Exploitation by Depressurization

Marine natural gas hydrate (NGH) can mainly be found in argillaceous fine-silt reservoirs, and is characterized by weak consolidation and low permeability. Sand production is likely to occur during the NGH production process, and fine-silt particles can easily plug the sand-control media. In view of this, experiments were conducted to assess the influence of the formation sand on the sand retention media in gravel-packed layers under gas–water mixed flow, and the plugging process was analyzed. The results show that following conclusions. (1) The quartz-sand- and ceramic-particle-packed layers show the same plugging trend, and an identical plugging law. The process can be divided into three stages: the beginning, intensified, and balanced stages of plugging. (2) The liquid discharge is a key factor influencing the plugging of gravel-packed layers during NGH exploitation by depressurization. As the discharge increases, plugging occurs in all quartz-sand packing schemes, while the ceramic-particle packing scheme still yields a high gas-flow rate. Therefore, quartz sand is not recommended as the packing medium during NGH exploitation, and the grain-size range of ceramic particles should be further optimized. (3) Due to the high mud content of NGH reservoirs, a mud cake is likely to form on the surface of the packing media, which intensifies the bridge plugging of the packed layer. These experiment results provide an important reference for the formulation and selection of sand-control schemes.

Antiscalant and its deactivation in zero/minimized liquid discharge (ZLD/MLD) application in the mining sector – Opportunities, challenges and prospective

Mining wastewater is inherently challenging to achieve zero or minimal liquid discharge (ZLD/ MLD) due to the high scale of the wastewater and the physical site constraints. This article highlights contextualized challenges for mining applications and also proposes a novel perspective on coupling antiscalants (AS) and downstream antiscalant deactivation technology (ASDT). ASDT is a relatively new concept that overcomes the limitation of water recoveries at the maximal TDS of 70 g/L by treating and desalting brines. The coupling of AS and ASDT can hence result in lower treatment costs by enhancing crystallization performance and enhancing water recovery with higher RO recoveries. Mining-specific scales, unique wastewater combinations, and physical constraints of mining sites are bottlenecks, and their potential mitigation methods are further explored in this article. Overall, this article provides an overview of the AS and ASDT applications and provides insightful future perspectives to address current challenges in mining wastewater applications.

Securing Zero Liquid Discharge (ZLD) in Molasses-Based Distilleries Located in Ganga Basin by Charter Action Plan

Securing Zero Liquid Discharge (ZLD) in Molasses-Based Distilleries Located in Ganga Basin by Charter Action Plan

Implementing a one-dimensional quick model for dynamic simulation and economic analysis of a forced circulation crystallizer

Forced circulation crystallizer is one of the main contributors in Zero Liquid Discharge wastewater treatment processes. This technology enables the extraction of pure water from wastewater and separates impurities in the form of crystals. In the present study, a fast one-dimensional (nodal) model with high accuracy is introduced to predict the dynamic performance of the crystallization process in an FC crystallizer. Besides, to design and optimize a crystallizer, the parameters affecting the system performance should be evaluated from thermodynamic and economic perspectives. For this purpose, the developed model is used to investigate the crystallizer thermo-economic performance. Results show that the performance of the crystallizer system has the most significant sensitivity to varying the inlet feed concentration, suspension concentration, and rotational speed of the circulation pump. Increasing the suspension concentration reduces the mean diameter of output crystals. Also, increasing the pump rotational speed by about two times decreases the mean size of output crystals by approximately 41.39 %. From an economic point of view, increasing the heat input has a significant effect on the reduction of the dynamic payback period. Also, increasing the inlet feed concentration by 36 % leads to a 7.84 % increase in the internal rate of return.

Evaluating dye recovery and reusability potential from dyebath effluent using forward osmosis membranes for minimum liquid discharge

This study focuses on the evaluation of dye recovery and reuse potential from denim and polyester effluents using forward osmosis (FO). A cationic surfactant, tetraethylammonium bromide (TEAB), was used as the draw solution (DS). After optimizing the DS and feed solution (FS) concentrations and temperatures in batch experiments, a DS concentration of 0.75 M was selected at a 60 °C temperature for the semi-continuous mode. It generated a high flux of 18 L/m2/h and a low reverse solute flux (RSF) of 0.4 g/m2/h with 100% dye rejection. Dye reconcentration of 82–98% was achieved in the dyebath effluents. The unique property of surfactants to combine hundreds of monomers into micelle resulted in negligible RSF. Reversible fouling was observed on the membrane active layer, and NaOH and citric acid cleaning achieved about 95% of flux recovery. The functional groups on the membrane's active layer remained undisturbed due to foulant interactions showing its chemical stability against reactive dyes. Recovered dye characterization using 1D proton nuclear magnetic resonance (1HNMR) analysis depicted a 100% structural resemblance to the original dye. Hence, it can be reused for dyeing the next batch. Diluted TEAB solution can be used as fabric detergent and softener within the same textile industry in the finishing process. A minimum liquid and persistent pollutant (dyes) discharge is achieved by adopting the methodology proposed in this work with a strong potential of translating it to an industrial scale.

Submerged Discharges in Liquids for Nanoobject Synthesis: Expectations and Capabilities

Submerged Discharges in Liquids for Nanoobject Synthesis: Expectations and Capabilities

A dye-based desalinating evaporator independent on solar absorber of excellent optical properties for efficient desalination

Different from traditional organic photothermal composites, dye is a type of nonconducting organic substance that commonly employed to endow fabric cloth with diverse color. Especially, its characterizations of strong adhesion and low-cost remind us the potential application prospect to establish a sustainable desalination system by it. Whereas, through previous investigation, the low absorbance hampered it from efficient utilizing solar energy. Referring to the 3D-cup structure that reported before, herein, an evaporative structure, which even can be assembled by diverse colors of cloth other than black cloth, available to turn diverse colors in to black body cavity was demonstrated in this work. Even after long period of 120 h for desalinating brine with salinity of 10 wt%, the evaporator with EAI index of 7.4 is fabricated to attain a superior broadband absorbance of 98 % and a high steam output of 4.072 kg m−2 h−1, in the function of the mechanism that main working place is transferring from bottom to the wall interface. Besides, the salt deposition forming on the wall of the evaporator can be facilely removed and collected, with the Zero liquid discharge (ZLD) concept being successfully realized by facile regeneration of device. This work demonstrates one other advantage of the 3D-cup shaped structure that enable to transfer multi-color spectrum into full-wavelength solar utilization. This discovery has never been reported before, making it possible to fabricate a solar-vapour evaporator independent on solar absorber of excellent optical properties for efficient desalination.

Electrohydraulic Yutkin effect and electrospark discharges in liquids

Electrospark discharges in liquids are the subject of numerous studies, as they are a source of powerful wave pulses that can be used in various technological processes. One of the first researchers of this phenomenon was L.O. Yutkin, who substantiated and investigated the electrohydraulic effect (EHE). This effect allows to transform electrical energy into mechanical energy of powerful shock waves, which opens up great opportunities for increasing the efficiency of various technologies. The purpose of the study is to analyze the history of the study of electric spark discharges in liquids, the contribution of L.O. Yutkin to the development of the theory and practical application of the EHE, and to highlight the advantages of wave treatments based on this effect. In the course of the study, scientific papers and experimental data obtained in the study of electrospark discharges in liquids and the electrohydraulic effect were analyzed. The theoretical foundations of these phenomena were considered, as well as practical applications of EHE in various industries. The electrohydraulic effect (EHE), discovered by L.O. Yutkin, is a unique phenomenon that allows converting electrical energy into mechanical energy of powerful shock waves. This is achieved by generating an electric discharge in a liquid, which leads to the formation of a plasma channel and the subsequent occurrence of a shock wave. The main advantage of wave treatments based on EHE is the ability to introduce large amounts of energy into the medium, which allows to increase the efficiency of numerous technological processes. The electrohydraulic Yutkin effect remains an inexhaustible source for the creation of advanced technologies that are already widely used in many industries

A hydrate-based zero liquid discharge method for high-concentration organic wastewater: resource recovery and water reclamation

High-concentration organic wastewater has become a great challenge for wastewater treatment due to its toxicity and non-biodegradability. Traditional water treatment methods focus on removing or destroying organic pollutants rather than considering the high-concentration organic wastewater as a resource. As an ambitious sustainability goal, resource recovery from wastewater to achieve zero liquid discharge (ZLD) has attracted widespread attention. Here, a hydrate-based method is proposed to treat textile wastewater to facilitate the reuse of dyes and enhance water reclamation. The mechanism of interaction between hydrate and organic pollutants was invested. The results show that organic pollutants are rejected from the growing hydrate lattice and concentrated in the residual solution. This method can achieve a max removal efficiency of 93.6% and a water production rate of 80%. In the range of 0–2000 mg/L, the concentration of organic pollutants does not affect the removal effect and water production rate. The concentrated dye can be reused again. The proposed method exhibits potential for recovering resource and clean water from wastewater while achieving ZLD.

Mixing gold and iron in nanoparticles by electrical discharges in liquid: A new approach

The possibility to create homogeneous nanoparticles containing iron and gold by nanosecond-pulsed discharges in liquids, without any laser assistance, is demonstrated. Thanks to a new kind of electrode where elements are coated by PVD on a silicon plate, AuFe nanoparticles, ranging from 10 to 50 nm, are synthesized. Depending on their residence time in the discharge, the structure of the homogeneous nanoparticles evolves to become a core–shell structure, either nested or not. Larger submicrometric particles (from 100 to 500 nm) are specifically formed with the present process by the ejection of liquid droplets from the molten pool created by the discharge on electrode surfaces. These larger particles are produced by solidification of a AuFe shell on a silicon core. This new mechanism can be used to create core–shell particles with a shell containing several, possibly immiscible, elements. Thermal post-treatment performed in situ in a TEM microscope shows the AuFe shell, where Au and Fe separate, turning either into a Janus structure or into a SiFe core facetted by gold pyramids.

Polyoxometalates‐Modulated Hydrophilic‐Hydrophobic Composite Interfacial Material for Efficient Solar Water Evaporation and Salt Harvesting in High‐Salinity Brine

Solar vapor generation (SVG) represents a promising technique for seawater desalination to alleviate the global water crisis and energy shortage. One of its main bottleneck problems is that the evaporation efficiency and stability are limited by salt crystallization under high‐salinity brines. Herein, we demonstrate that the 3D porous melamine‐foam (MF) wrapped by a type of self‐assembling composite materials based on reduced polyoxometalates (i.e. heteropoly blue, HPB), oleic acid (OA), and polypyrrole (PPy) (labeled with MF@HPB‐PPyn‐OA) can serve as efficient and stable SVG material at high salinity. Structural characterizations of MF@HPB‐PPyn‐OA indicate that both hydrophilic region of HPBs and hydrophobic region of OA co‐exist on the surface of composite materials, optimizing the hydrophilic and hydrophobic interfaces of the SVG materials, and fully exerting its functionality for ultrahigh water‐evaporation and anti‐salt fouling. The optimal MF@HPB‐PPy10‐OA operates continuously and stably for over 100 h in 10 wt% brine. Furthermore, MF@HPB‐PPy10‐OA accomplishes complete salt‐water separation of 10 wt% brine with 3.3 kg m−2 h−1 under 1‐sun irradiation, yielding salt harvesting efficiency of 96.5%, which belongs to the record high of high‐salinity systems reported so far and is close to achieving zero liquid discharge. Moreover, the low cost of MF@HPB‐PPy10‐OA (2.56 $ m−2) suggests its potential application in the practical SVG technique.

Membrane distillation with electrospun omniphobic membrane for treatment of hypersaline chemical industry wastewater

Hypersaline chemical industry wastewater comprises various species with complex characteristics, challenging the proposal treatment of such wastewater. Membrane distillation (MD) is a promising technology to realize the zero liquid discharge treatment of wastewater, due to its high salt rejection and insensitivity to the feed concentration. However, the practical application of the MD process is hindered by membrane wetting and fouling issues. Herein, we developed an innovative strategy to fabricate a robust omniphobic membrane via bio-inspired silicification and fluorosilanization on an electrospun poly(vinylidene fluoride-co-hexafluoropropylene) nanofiber mat. The polydopamine/polyethylenimine (PDA/PEI) deposition time was optimized based on the results of membrane morphology, wettability, and pore structure measurements. The MD process achieved a stable flux using the omniphobic membrane even when treating feed solution containing sodium dodecyl sulfate (SDS). In addition, the omniphobic membrane significantly outperformed the pristine membrane in treating hypersaline chemical industry wastewater. This work provides a novel method for fabricating robust electrospun omniphobic membranes for high-performance treatment of hypersaline chemical industry wastewater via the MD process.

Thermodynamic and kinetic analyses of Janus membrane scaling in membrane distillation for zero liquid discharge engineering

Scaling phenomena are the principal obstacle to the factual application of membrane distillation (MD). In this study, we fabricated a Janus membrane composed of a commercial polytetrafluoroethylene substrate, a superhydrophobic surface layer, and a hydrophilic reverse side coated by MXene nanosheets via a simple spraying method. The virgin and modified membranes were carried out and compared in zero liquid discharge (ZLD) MD experiments. MD flux analysis showed that all the membranes experienced severe flux decline during the ZLD process. Saturation index, Gibbs free energy and nucleation energy barrier were calculated to explain the observed difference in scaling behavior. Screenage assessment of the homogeneous nucleation and heterogeneous nucleation showed that the severe scaling developed from some small clusters of the new phase, wherein the thermodynamic energy barrier played a critical role in determining the anti-scaling behavior for these unsmooth surfaces. Model analysis and data fitting were used to conclude the kinetic behavior of the virgin and modified membranes in the ZLD engineering. Finally, we evaluated the reversible and irreversible scaling after twice washing. Therefore, this study may provide instructive insights to design novel anti-fouling membranes and promote practical applications such as industrial brine treatment and ZLD engineering.

Feasibility study of common effluent treatment plant for management of industrial wastewater: Case study of Bangladeshi textile industries

AbstractTextile industries play a vital role in the economy of Bangladesh contributing significantly to its gross domestic product. However, they are associated with high environmental pollution, especially water pollution. Since small‐scale textile industries cannot afford the treatment cost of discharged wastewater, they tend to contaminate water sources—both groundwater and surface water. To intervene in response to this situation, the existing treatment system was assessed in the present study. The effluents from industries under this research were analyzed for color, pH, TSS, TDS, chlorides, sulfates, COD, BOD, and total hardness. A Common Effluent Treatment Plant (CETP) with zero liquid discharge was suggested as a solution. It was observed that the water recovery in the proposed scheme by reverse osmosis and salt recovery using nanofiltration were 90%–95% and 80%–90%, respectively. Cost analysis also indicated that the cost of treating water can also be decreased by 18.7% which can show that water recovery is even more affordable for small‐scale industries. Finally, a linear programming model was developed to assist the industries with decision‐making in the selection of treatment schemes. This research revealed that a CETP using zero liquid discharge technology is a potential solution to the environmental crisis due to industrial wastewater discharge. This could ensure reduced water pollution, increased drinking water availability, improved public health, and thus could be a potential driver for environmental sustainability.

Electrodialytic crystallization to enable zero liquid discharge

The management of hypersaline brines (that is, wastewater of high salinity) is a technical challenge that has received increasing attention due to their growing volume, environmental impacts and increasingly stringent regulations. Here we present electrodialytic crystallization (EDC) as a new process to achieve brine crystallization without evaporation. In an EDC process, the brine stream recirculating between an electrodialysis cell and a crystallizer remains oversaturated via continuous electromigration of ions from the feed stream across the ion exchange membranes. We first used Na2SO4 as the model salt to demonstrate the feasibility of EDC and to perform a systematic investigation of how crystallization kinetics and crystal size distribution depend on current density and crystallization mode. We then elucidated the criterion of crystallizability and showed how it depends on salt species, membrane properties and operating conditions. Lastly, we analysed the energy consumption of an EDC-reverse osmosis treatment train for achieving zero liquid discharge of a Na2SO4 brine. Overall, this study provides a proof of concept for EDC as an electric-field driven and non-evaporative crystallization process, and lays the foundation for its future technical development and optimization. Achieving zero liquid discharge is an essential step towards the sustainability of hypersaline brine treatment. A potential method to achieve zero liquid discharge on the basis of electrodialysis crystallization is now demonstrated.

Study on the water resources and the opportunities for sustainable desalination & minimal/zero liquid discharge (MLD/ZLD) practices in Greece (Eastern Mediterranean)

Study on the water resources and the opportunities for sustainable desalination & minimal/zero liquid discharge (MLD/ZLD) practices in Greece (Eastern Mediterranean)

Pulsed gas–liquid discharge plasma catalytic degradation of bisphenol A over graphene/CdS: process parameters optimization and O3 activation mechanism analysis

In the present work, pulsed gas–liquid hybrid discharge plasma coupled with graphene/CdS catalyst was evaluated to eliminate bisphenol A (BPA) in wastewater. The optimization of a series of process parameters was performed in terms of BPA degradation performance. The experimental results demonstrated that nearly 90% of BPA (20 mg l−1) in the synthetic wastewater (pH = 7.5, σ = 10 μS m−1) was degraded by the plasma catalytic system over 0.2 g l−1 graphene/CdS at 19 kV with a 4 l min−1 air flow rate and 10 mm electrode gap within 60 min. The BPA removal rate increased with increasing the discharge voltage and decreasing the initial BPA concentration or solution conductivity. Nevertheless, either too high or too low an air flow rate, electrode gap, catalyst dosage or initial solution pH would lead to a decrease in BPA degradation. Moreover, optical emission spectroscopy was used to gain information on short-lived reactive species formed from the pulsed gas–liquid hybrid discharge plasma system. The results indicated the existence of several highly oxidative free radicals such as ·O and ·OH. Finally, the activation pathway of O3 on the catalyst surface was analyzed by density functional theory.

3D Numerical Simulation of Metal Bipolar Plate Proton Exchange Membrane Fuel Cell Considering Wavy Interlaced Flow Field

A metal bipolar plate fuel cell (FC) composed of gas distribution zones (GDZ) with ordered distribution of “dot matrix” structures, a complex waveform staggered fluid region, and the effect of cooling flow field (FF) is proposed in this investigation. The 3D multiphase model is applied to simulate the two‐phase flow in the FC. First, the cathode catalyst layer (CCL) has a higher electrochemical reaction rate (ERR) when gas diffusion layer (GDL) is anisotropic, and the ERR under channels is much higher than ribs. Increasing the thickness of GDL is not conducive to gas mass transfer, and the maximum current density reduction rate is 2.94%. Increasing the porosity of GDL is beneficial to improve the mass transport efficiency, and the liquid discharge is promoted. Second, the increase of GDL contact angle affects the cathode microporous layer and liquid saturation in CCL, and the current density is the highest when the contact angle is 120°. Finally, the volume‐of‐fluid model is utilized to analyze the drainage process in the GDZ and cathode small‐size FF. It is indicated in the results that water tends to concentrate at the outlet corner of GDZ in liquid form.

Wastewater Assessment and Biochemical Oxygen Demand Value Prediction from Mining Operations: A Case Study

Wastewater is a byproduct of industrial or household waste processes, and its contamination level must be determined before treatment. Discharges of liquid effluents generated by mining operations, one of the most prevalent forms of industrial waste water, pose a risk to human health and the environment. This study evaluates the physicochemical quality of industrial liquid effluent discharges from the Boukhadra mine (Algeria). Samples were collected from the washing water to identify the level of contamination of these liquid discharges and to measure physicochemical parameters such as temperature (T), hydrogen potential (pH), Electrical Conductivity (EC), Suspended Solids (SS), Chemical Oxygen Demand (COD), Biological Oxygen Demand for 5 days (BOD5), Oils and Greases (O&G), iron (Fe+2) and Kjeldahl Nitrogen (NTK). It was found that the concentration values of those effluents exceeded the maximum contamination limits specified by international industrial waste standards. A simple and reliable prediction model was developed to estimate DBO5, based on MES, COD, and O&G, by using classical regression analysis and fitting Design of Experiments (DOE) methodology. When comparing the analytical results, it was found that the quadratic model provided a better estimation, with a high correlation coefficient (R2) of 0.9976. The parameters determined in this study will enable engineers to quickly estimate the degree of wastewater contamination and choose adequate treatment strategies.

A demonstration project for desulfurization wastewater evaporation technology: Field test and performance analysis

Desulfurization wastewater evaporation technology is an effective approach to achieve zero liquid discharge. However, limited information is available on the practical engineering performance and related risks of the technology. In this study, we conducted a field test of desulfurization wastewater evaporation technology in a demonstration project. The results indicated the technology was highly feasible and applicable to three operating conditions with varying desulfurization wastewater flow rates. The migration characteristics of Cl were investigated, revealing that less than 3 % of Cl was released into gaseous HCl. The concentrations of other typical pollutants, such as NOx and SO2, remained unchanged after treatment, indicating that the wastewater evaporation technology did not significantly affect the distribution of gaseous pollutants or the comprehensive fly ash utilization. Moreover, the study found that the evaporation process promoted the agglomeration of particulate matter, as confirmed by larger particle sizes and XRD analysis. The total operating cost of wastewater evaporation ranged from 25 to 30 yuan per ton of wastewater, primarily consisting of coal consumption for extracting flue gas. The data obtained in this work complements and verifies existing research on wastewater evaporation technology.