High Salinity Wastewater Research Articles

Insights into sulfamethazine degradation by peroxymonosulfate activation using H2 reduced hematite in high-salinity wastewater: Performances and mechanisms

Sulfamethazine (SMT) is recognized as a persistent, bioaccumulate, and toxic antibiotic pollutant that is difficult to be completely eliminated through traditional wastewater treatment methods. Although advanced oxidation processes (AOPs) utilizing peroxymonosulfate (PMS) have demonstrated potential in degrading SMT, the lack of inexpensive and efficient PMS activators remains a significant obstacle for its practical application. In this study, we present the synthesis of a highly effective PMS activator, the naturally-occurring minerals-based material − H2– reduced hematite (HRH), on an industrial scale using a fluidized bed reactor. Impressively, within the PMS AOPs system, the synthesized HRH catalyst not only achieves 99.3 % degradation of SMT within 20 min, demonstrating a remarkable 10-fold increase in the degradation rate compared to pristine hematite, but also showcases excellent recyclability and durability. Additionally, this HRH/PMS system were proved to effectively remove SMT under high-salinity conditions. More importantly, through systematic characterization and theoretical calculations, an in-depth investigation into the primary activation mechanism and degradation pathway in this reaction process is provided. This work provided a highly feasible strategy for the application of natural mineral-based catalyst for the degradation of pollutants via PMS activation in high-salinity wastewater.

Unveiling significant roles of phytohormone 6-benzylaminopurine in empowering Phaeodactylum tricornutum for high-salinity wastewater treatment and bioresource recovery

High-salinity presents significant challenges in microalgal wastewater treatment and bioresource recovery due to salinity stress. This study explored the use of salt-tolerant microalgae in conjunction with phytohormone regulation. 1 µM 6-benzylaminopurine increased the biomass of Phaeodactylum tricornutum by 38.3 % and enhanced lipid production by 36.8 %. 6-benzylaminopurine significantly improved the removal of inorganic carbon, total nitrogen, and total phosphorus by 85.2 %, 27.4 %, and 31.9 %. Specifically, 6-benzylaminopurine improved K+ transportation by 71.0 %, increased the activity of Ca2+ transport ATPase and Ca2+ sensors by 49.0 %–83.0 %, optimized osmotic balance, and alleviated salt-induced damage. The contents of proline and extracellular polymers increased by 34.8 % and 35.5 %. A 38.4 % reduction in reactive oxygen species indicated that high-salinity stress was mitigated. The analysis of Sustainable Development Goals showed a 56.2 % improvement in Affordable and Clean Energy. Overall, these findings further highlighted the promising application of the phytohormone 6-benzylaminopurine in microalgal high-salinity wastewater treatment and lipid production.

Salvinia natans-Based Hierarchical Structures for Solar Thermal Clean Water Production from High-Salinity Wastewater.

Biomaterial-based solar-driven evaporation has great potential for wastewater treatment and seawater desalination with a high energy conversion and utilization efficiency. However, technology gaps still exist for effectively and directly applying multiscale structures and intrinsic water transport channels of natural materials to enhance high-efficiency photothermal evaporation. In this study, a high-performance biomass-derived photothermal evaporative material was obtained using Salvinia natans, a common aquatic floating plant, together with simple poly(m-phenylenediamine) oxidation modification, building a hybrid biomass evaporator. With advantageous natural features of adequate water transport, microscale-nanoscale hierarchical structures, effective water activation, and antisalt-fouling function, the hybrid biomass evaporator achieves a high evaporation rate of 2.24 kg m-2 h-1 under one sun radiation (1 kW m-2). In addition, modified Salvinia natans also demonstrate certain ability to remove heavy metals during the photothermal evaporation of wastewater. This work offers a new perspective on the synthesis of an environmentally friendly and cost-effective solar-driven evaporator material, which has the advantages of low cost, simple process, and high photothermal conversion efficiency, and can be widely applied to seawater desalination and the treatment of wastewater with high salt concentrations.

Study on the Effect of Complex Organics on the Phase Equilibrium of the Multicomponent Salt Systems in the High Saline Wastewater of Coal Chemical Industry

Study on the Effect of Complex Organics on the Phase Equilibrium of the Multicomponent Salt Systems in the High Saline Wastewater of Coal Chemical Industry

Enhanced selectivity of reactive intermediates by modifying electrodes with layered materials for the green high-salinity wastewater treatment

Improving the selectivity of the reactive intermediates such as ClO− and •OH by modifying nickel foam electrodes with ion exchangeable layered materials would greatly enhance the efficiency of high-salinity wastewater treatment. A universal pattern was verified herein that through functioning as a permeable overlayer regulating the transport of cations/anions, ClO− and •OH could be the predominant intermediates in the anionic/cationic layered material modified electrode. The significance of selectivity enhancement includes improving electrochemical efficiency and reducing the usage of chemical reagents. For instance, it is demonstrated that electrochemically degrading high salinity azo wastewater using decorated electrodes would be as effective as chemical treatment. Furthermore, electrochemical oxidation using cation layered material modified electrode could reduce the pKa of the oxidized cellulose filter paper as effectively as using H2O2.

Great truths are always simple: A millimeter-sized macroscopic lanthanum-calcium dual crosslinked carboxymethyl chitosan aerogel bead as a promising adsorbent for scavenging oxytetracycline from wastewater

Given their increasing environmental and health harms, it is crucial to develop green and sustainable techniques for scavenging antibiotics represented by oxytetracycline (OTC) from wastewater. In the present work, a structurally simple lanthanum-calcium dual crosslinked carboxymethyl chitosan (CMCS-La3+-Ca2+) aerogel was innovatively synthesized for adsorptive removal of OTC. It was found that CMCS and La3+ sites collaboratively participated in OTC elimination, and OTC removal peaked over the wide pH range of 4–7. The process of OTC sorption was better described by the pseudo-second-order kinetic model and Redlich-Peterson model, and the saturated uptake amount toward OTC was up to 580.91 mg/g at 303 K, which was comparable to the bulk of previous records. The as-fabricated composite also exerted exceptional capture capacity toward OTC in consecutive adsorption-desorption runs and high-salinity wastewater. Amazingly, its packed column continuously ran for over 60 h with a dynamic uptake amount of 215.21 mg/g until the adsorption was saturated, illustrating its great potential in scale-up applications. Mechanism studies demonstrated that multifarious spatially-isolated reactive sites of CMCS-La3+-Ca2+ cooperatively involved in OTC capture via multi-mechanisms, such as n-π EDA interaction, H-bonding, La3+-complexation, and cation-π bonding. All the above superiorities endow it as a promising adsorbent for OTC-containing wastewater decontamination.

Aerobic granular sludge inoculant for enhancing high salinity wastewater treatment: Performance and value-added biopolymer recovery

In this study, two lab-scale aerobic granular sludge (AGS) systems, seeded with intertidal wetland sediment (IWS) and activated sludge (AS), were constructed to compare their treatment performances and alginate-like exopolymers (ALE) recovery potential in high salinity wastewater treatment. Both reactors (RIWS and RAS) exhibited excellent total organic carbon (TOC) reduction rates > 95.0 %, while RIWS exhibited an improved total nitrogen (TN) removal than RAS (84.4 % vs 75.7 %). The presence of several inorganic particulates (acted as nucleus) in IWS accelerated the formation of granules in RIWS. The ALE yield of RIWS reached 466.6 ± 52.2 mg/g VSS, which was 1.6 times higher than that of RAS (286.2 ± 5.2 mg/g VSS). Moreover, to illustrate the different ALE recovery potentials, the proposed ALE biosynthesis pathway was also assessed. It was observed that the abundance of function genes encoding ALE biosynthesis of RIWS was significantly higher than that of RAS, revealing its superior ALE recovery potential. This study proposed a novel and effective treatment method for high-salinity wastewater with high potential resource recovery.

Experimental investigation on performance of heat pump air circulation evaporating separation system for saline wastewater treatment

There is a gradual increase in the discharge of saline wastewater which is harmful to the environment and human health. A novel heat pump air circulation evaporating separation (HP-ACES) system for saline wastewater treatment is proposed and experimentally investigated. The results show that the system evaporation efficiency (SEE) initially decreases before increasing with the expansion valve opening at different refrigerant charges. However, the SER increases by 0.67 kg/h at 1.21 kg refrigerant charge while they descend and then rise at 1.53 and 1.86 kg refrigerant charges. Noted that the effects of expansion valve opening on the SER and SEE are lessened with refrigerant charge. Moreover, there exist the optimal values of total air flow and air flow proportion of packing concentration tower at which the SER and SEE peak, and both of the solution concentration and cooling water flow negatively affect the SER and SEE. Besides, compared with similar evaporating separation systems, the HP-ACES system has higher energy efficiency for treating high saline wastewater and the SEE ranges from 0.86 to 1.64 kg/kWh (5–25 % CaCl2 solution). However, the SEE is low, and it is necessary to reveal the cause and propose the optimization schemes in the future.

Treatment of various saline wastewaters by membrane distillation with omniphobic polyvinyl alcohol membrane

An omniphobic membrane was fabricated to address the issues associated with traditional hydrophobic membrane wetting in membrane distillation (MD) and used to treat industrial high-salinity wastewater. An electrospun nanofiber membrane with excellent hydrophobicity (high water contact angle value of 157°) was fabricated by hydrophilic, biodegradable, and inexpensive polyvinyl alcohol (PVA) via electrospinning method modified by glutaraldehyde cross-linking, Al2O3 nanoparticles coating, and impregnated fluorination. Moreover, the resulting membrane presented satisfactory wettability resistance in treating solutions containing 20 % NaCl and sodium dodecylbenzene sulfonate. In comparison to commercial polyvinylidene fluoride membrane, the omniphobic PVA membrane showcased remarkable separation performance when treating coal gasification brine and acid mine drainage. Based on our findings, we conducted a comprehensive evaluation of the anti-wetting and anti-scaling properties of the omniphobic PVA membrane. Furthermore, we delved into an in-depth analysis and discussion of the mechanisms behind the low surface energy and multi-level re-entrant structures that contribute to these properties. The results indicate that the omniphobic PVA membrane holds potential for application in MD processes aimed at water recovery from industrial wastewater containing complex compounds.

Water Lily-Inspired CNT@cotton towel solar evaporator with Marangoni effect and optimal water supply for achieving zero liquid discharge desalination and irrigation

Solar-driven interfacial evaporation is an environmentally friendly technology to address the global water scarcity crisis by efficiently purifying unavailable water resources (seawater, brackish water, high salinity wastewater and various water resources). However, the inevitable contradiction between salt deposition and highly efficient water evaporation during long-term desalination remains a major challenge. In this work, we report a self-floating bionic water lily evaporator with zero liquid discharge, consisting of CNT@cotton towel with the uneven-gap structure as the photothermal material and the square groove insulation foam with controllable water supply as edge-preferred crystallization support. The formed four-building-in ramp structure generates different surface tensions along the whole ramp and brings Marangoni flow. With the combination of Marangoni flow and optimal water supply volume, salt is spatially isolated from the CNT@CT surface, the biomimetic design can achieve continuous water evaporation and salt collection (79 g m-2h−1) for 84 h in 10 wt% NaCl under edge-preferred crystallization. The purified water meets drinking water standards and is applied to growing crops. This distinctive solar evaporator provides new insights for designing a low-cost and zero-liquid-discharge evaporator, advancing its application in high-saline brines, various water resources, and irrigation.

The green resource recovery process of a new type of selective bipolar membrane electrodialysis system for saline wastewater treatment

The selective electrodialysis with bipolar membrane (BMSED) is an advanced electro-membrane process that combines monovalent perm-selective ion exchange membrane and a bipolar membrane, and presented significant potential in high salinity wastewater treatment and reclamation. Herein, we accomplished an in-depth assessment of the external-integration and internal-integration systems for the treatment of high-salinity mining wastewater and seawater desalination concentrate brine. The issues surrounding their cycling performance during batch operation, their anti-fouling potential in the presence of Mg2+/Ca2+ ions, and its specific operational cost were thoroughly investigated. The results suggest that the internal integration system demonstrates suitable stability during long-term operation under batch (cycling) mode. Nevertheless, the membrane exhibited inorganic scaling due to co-ion leakage at high current density. A highly pure NaOH was obtained through an internal integration process at a cost of 0.68 $/kg, outperforming the external integration system (98.96 %, 1.85 $/kg). The findings presented in this study offer valuable insights for the industrial application of BMSED technology in managing high salinity wastewaters.

Study on the effect of volatile organic compounds on the treatment of high-salt wastewater by low-temperature evaporation

ABSTRACT High-salinity wastewater, owing to its intricate composition and challenging treatment requirements, poses a significant hurdle in water environmental governance. In this study, low-temperature evaporation technology is used to tackle wastewater containing the volatile organic compound such as N,N-dimethylacetamide (DMAC). Utilisation of comprehensive approaches involving experimental testing, mathematical modelling, and Aspen Plus software simulations, The influence of DMAC on evaporation efficiency is researched through the following factors which encompassing its effects on boiling point elevation, partial molar activation energy, and the formation of by-products. Additionally, the comparation of the impact of temperature, ionic strength, intermolecular interactions on the evaporation rate and the concentration of the volatile component DMAC in the condensate is also conducted in this study. After conducting a multiple linear regression analysis of evaporation efficiency using the Statistical Product and Service Solutions (SPSS) tool, it was discovered that temperature serves as the primary determinant influencing the evaporation rate. Additionally, ionic strength impacts solution viscosity, intermolecular interactions, and saturated vapour pressure by altering the intermolecular forces, thereby indirectly influencing both the evaporation rate and the quality of condensate water. The comparative analysis of single-effect and double-effect evaporation indicates that the optimal operating condition for double-effect evaporation yields an evaporation rate of 70%, with a remarkable 88% reduction in steam consumption compared to single one. Based on heat and mass balance principles, the mathematical model for double-effect evaporation is established to offer crucial data support for practical industrial applications.

Stability optimization of iron-based catalysts: Application of Cr-enriched alloy steel catalyst in ozonation pharmaceutical wastewater

Catalytic ozonation for advanced treatment of industrial wastewater has proved to be effective, and the stability of the catalyst is crucial for the long-term application of the ozonation process in practical engineering. In this study, the electrochemical characteristics of four iron (Fe) shavings: alloy steels (38CrMoAl and 40Cr) and carbon steels (A3 and 45#) were investigated, and a new citric acid-optimized H2O2 modification method was proposed. The low open circuit potential (OCP) of carbon steels indicated that they were more likely to be oxidized therefore required shorter modification times. The higher the OCP of alloy steels, the higher H2O2 concentration was required to enhance modification efficiency. By adding citric acid, the rapid modification of alloy steel was achieved, and the catalysts exhibited lower passivation current (Ip), indicating a lower rate of substrate loss and a longer lifetime of alloy steel catalysts. Furthermore, chromium (Cr) enrichment occurred in the oxide layer of alloy steel catalysts. The Cr/Fe (atomic ratio) in oxide layer for 38CrMoAl and 40Cr increased from 0.018 to 0.040 and from 0.010 to 0.037, respectively. The presence of CrOOH and Cr2O3 within the oxide layer reinforced the layer’s overall structural integrity and enhanced its protection for the internal substrate, making the catalysts more resistant to adapt to high-salinity wastewater. Through laboratory tests, it was found that among the four catalysts, 38CrMoAl showed the highest stability and good catalytic activity with low Fe loss concentration. Therefore, the pilot-scale application effect of 38CrMoAl catalyst was evaluated. In the advanced treatment of pharmaceutical wastewater, chemical oxygen demand (COD) and total organic carbon (TOC) removals were 56.3% and 32.4%, respectively. These results showed that the stability of catalyst can be improved by optimizing the selection of steel, and the introduction of citric acid achieved Cr enrichment effect and amplified the potential stability advantage of alloy steel. The research provides guidance on raw material selection for catalyst preparation to different industries' wastewater treatment, especially in high-salinity wastewater ozonation treatment, which can realize the long-term stable application of catalyst.

Hydrophobic C60-modified PVDF membrane with micro-nano structures for mitigating CaSO4 scaling in direct contact membrane distillation (DCMD)

Membrane scaling is a non-negligible problem for membrane distillation (MD) in the treatment of high-salinity wastewater (e.g., calcium sulfate and calcium carbonate). In this study, fullerene (C60) was adhered to a polyvinylidene fluoride (PVDF) membrane using a polydimethylsiloxane (PDMS) solution to create a micro-nano structure, fabricating the C60/PDMS-PVDF membrane. This membrane was then re-immersed in a PDMS solution to further reinforce the C60 nanoparticles on the surface, forming the PDMS/C60/PDMS-PVDF membrane. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the membrane surface morphology. Fourier transform infrared (FT-IR) was used to explore the membrane chemical composition. Liquid entry pressure (LEP) and water contact angle (WCA) measurements were employed to assess the membrane wettability. The results showed that C60-modification created the micro-nano structure on the membrane surface. The WCA of the PVDF membrane was 112.7 ± 2.4°, with a sliding angle far greater than 90°, whereas the PDMS/C60/PDMS-PVDF membrane exhibited a WCA of 147.9 ± 3.2° and a sliding angle of 6.3°. Compared to the virgin PVDF membrane, the LEP value of the PDMS/C60/PDMS-PVDF membrane increased from 68.4 ± 2.7 kPa to 87.2 ± 3.3 kPa. In direct contact membrane distillation (DCMD), a CaSO4 solution (2 g/L) was used to test the membrane performance. After 48 hours of operation, the flux of the PDMS/C60/PDMS-PVDF membrane remained at approximately 3.57 kg/(m2·h), and the salt rejection rate was over 99.96 %. This could be attributed to the C60 modification forming a micro-nano structure on the membrane surface, which trapped an air layer. This air layer could reduce the contact area between the crystal and the membrane, decrease nucleation probability, and shorten the residence time of liquid on the membrane surface. Additionally, the PDMS/C60/PDMS-PVDF membrane exhibited superior stability during the ultrasonic destruction experiment due to the encapsulation of PDMS. In summary, a novel hydrophobic membrane with a micro-nano structure was fabricated through C60 modification, offering superior anti-scaling properties and stability in treating high-salinity wastewater.

Construction of a novel poly(amide-ester) thin film composite hollow fiber nanofiltration membrane with high water permeance

Highly permeable hollow fiber (HF) nanofiltration (NF) membrane is strongly desired since it could achieve efficient desalination with much less energy consumption. In this study, we used 4,4′,4′′-trihydroxytriphenylmethane (TP) as an aqueous co-monomer with piperazine (PIP) to react with trimesoyl chloride (TMC) to prepare a new internally pressurized poly(amide-ester) HF NF membrane. With the incorporation of TP molecules, the synthesized poly(amide-ester) separation layer achieved larger pore size and better hydrophilicity, giving the HF NF membrane excellent water permeance. Under optimum conditions, the HF NF membrane has a water permeance of 151 L m−2 h−1 MPa−1, which is 50 % higher than that of the control HF NF membrane, while maintaining a Na2SO4 rejection of 97.5 %. Moreover, it displays excellent desalination performance towards heavy metal salt solutions and high salinity solutions. It also maintains excellent desalination performance during a long-time filtration experiment, which indicates its good durability performance. In summary, this new poly(amide-ester) HF NF membrane shows good promise for the treatment of heavy metal and high-salinity wastewaters.

Impacts of high salinity on antifouling performance of hydrophilic polymer-modified reverse osmosis (RO) membrane

Reverse osmosis (RO) is a crucial process for treating waters across various salinity levels, but membrane fouling persists as an inherent challenge. While surface modification with hydrophilic polymers such as polyethylene glycol (PEG) and its derivatives is a prevailing strategy to alleviate fouling, its effectiveness has primarily been explored in low-salinity conditions, leaving a critical knowledge gap regarding the performance of such membranes in high-salinity environments and their susceptibility to feed salinity variations. We here investigated the antifouling characteristics of PEG-modified RO membranes for high-salinity wastewater and seawater treatment. Remarkably, our findings indicated a substantial decrease in fouling resistance under high-salinity conditions compared to low-salinity wastewaters used as control. The reduction in Lewis acid-base interactions, induced by decreased water structuring, was found to be a critical factor for the diminished fouling resistance based on the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) analysis. Complementary experimental and theoretical studies unveiled the disruptive role of high-concentration NaCl on PEG-water hydrogen bonds, causing PEG dehydration and configurational compression, which thus compromised the enthalpic barrier and entropic repulsion against fouling. Our study emphasizes the pivotal role of feed salinity in determining the fouling resistance of membranes modified with hydrophilic polymers, a factor often neglected in prior research.

Enhanced separation of monovalent and divalent ions in high salinity wastewater by selective electrodialysis: Experimental investigation and performance prediction

To fulfill the industrial requirements of salt fractionation and recovery from saline wastewater, a two-chamber selective electrodialysis (SED) stack incorporating commercial monovalent selective anion exchange membranes was employed and investigated in this study. Three different initial concentration ratios of NaCl/Na2SO4, namely 1:1 (10 g/L:10 g/L), 3:1 (30 g/L:10 g/L), and 5:1 (50 g/L:10 g/L) were examined to simulate various scenarios of saline wastewater. The influence of applied current density on membrane selectivity and overall system efficiency was further evaluated. The results indicated that an increase in the NaCl fraction within the feed solution directly correlates with enhanced concentration and purity of Na2SO4 in the product, achieving purities exceeding 92 %. A lower current density contributed to improved concentration and purity of Na2SO4, whereas higher current densities were conducive to augmenting the concentration and purity of NaCl. Additionally, a linear correlation was observed between the volumetric water transport and NaCl migration. Through numerical simulations, the concentrations of Na2SO4 and NaCl in the effluent were predicted, facilitating a comparative analysis with the salt fractionation efficiency of commercial nanofiltration membranes. Subsequent assessments of energy consumption and current efficiency revealed that the SED system ensured high product concentration and purity at reasonably low energy consumption (0.22–0.28 kWh per kg NaCl) alongside a high current efficiency (83–89 %). These findings offer critical insights into the optimization of salt fractionation process and highlight its economic and technical feasibility for the sustainable management of industrial saline wastewater.

Fouling behavior of nanofiltration membrane during the refining treatment of morphlines-dominant reverse osmosis concentrate

Nanofiltration (NF) has been proven to be with great potential for the separation of morpholines with molecular weight less than 200 Da in refining reverse osmosis concentrate (ROC), but its application is significantly restricted by the membrane fouling, which can reduce the rejection and service time. To enable the long-term operation stability of nanofiltration, this work focuses on the fouling behavior of each substance in the hydrosaline organic solution on nanofiltration membrane, aiming to give insight into the fouling mechanism. To this end, in this work, the effects of salts (i.e NaCl and Na2SO4), organic substances (including N-(2-hydroxypropyl)morpholine(NMH) and 4-morpholineacetate(MHA)) and representative divalent ions (Ca2+ and Mg2+) on the performance and physicochemical properties of DK membrane were systematically investigated. The results show that both salts and organics can induce DK membrane swelling, leading to an increase of the mean effective pore size. After the filtration of Na2SO4–NaCl–H2O, the mean pore size increased by 0.002 nm, resulting in the decrease of the removal ratio of NMH and MHA for 3.82% and 13.10%, respectively. With static adsorption of NMH and MHA, the mean pore size of DK membrane increased by 0.005 and 0.003 nm. The swelling slowed the entrance of more organic molecules into membrane pores. Among them, MHA led to the terrible irreversible pore blocking. As the concentration of Ca2+ increased, gypsum scaling was formed on the membrane surface. During this process, NMH and MHA played different roles, i.e. NMH accelerated the CaSO4 crystallization while MHA inhibited. As a conclusion, the fouling behavior of substances in the high saline organic wastewater on DK membrane were systematically revealed with the fouling mechanisms proposed, which could provide an insightful guidance for membrane fouling control and cleaning in the treatment of high salinity and organic wastewater.

Multifunctional MoS2 membrane for integrated solar-driven water evaporation and water purification

Solar-driven interfacial water evaporation shows great potential to address the global water crisis, but its efficient implementation in the presence of organic wastewater remains challenging. Here, we achieved integrated water evaporation and organic compound degradation by designing a multifunctional MoS2 membrane. Under 1.0 sun irradiation, the membrane exhibits an evaporation rate of 2.07 kg m−2 h−1 and 82% degradation efficiency of organic pollutants, with negligible organic pollutant residues in the condensate. The high performance is attributed to the thermal energy generated by the evaporation process of MoS2 membrane. This promotes an increase in the rate constant of interfacial electron transfer during the photocatalytic reaction, accelerating the generation of free radicals and facilitating the removal of organic pollutants. The study demonstrated that fresh water can be collected from high-salinity wastewater at a rate of 1.56 kg m−2 h−1. The MoS2 membrane provides a sustainable approach to addressing the water crisis.

Research Progress on High Salinity and High COD Industrial Wastewater Treatment Technology

In the production process of chemical products such as ethylene and epichlorohydrin, a large amount of industrial wastewater is generated, which has high salt content (over 3.5%), high COD value (over 10000mg·L-1), and characteristics such as biological inhibition and toxicity. At present, it is difficult for sewage treatment plants to effectively treat this type of wastewater. Therefore, the treatment of this type of industrial wastewater has become one of the main obstacles to the green development of the chemical industry. This article reviews the research progress on the generation and treatment technology of high salinity and high COD industrial wastewater, including physicochemical, biological, and physicochemical biological coupling methods. The next steps in the treatment of such industrial wastewater are proposed.