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With the aim of investigating the efficiency of biochar for desalination, experiments with adsorbent treatment at four levels including sesame flour, biochar at temperatures of 400, 500 and 600 ℃ and salt water treatment at four levels including 5, 10, 20 and 35 dS/m were conducted in three replications as a factorial experiment in the form of a completely randomized design in a discontinuous environment. The adsorption of the salinity factor ions was studied in the presence and absence of copper ions. The results showed that the desalination capacity without the presence of copper ions in the best adsorbent (Biochar 600) was obtained at the studied salinities of 411.6 mg/g. While the desalination capacity in the presence of copper ions using the same adsorbent at the studied salinities was 382.2 mg/g, indicating competition between ions and 8.0% decrease in adsorption capacity for salinity 35 dS/m. In both the presence and absence of copper, the highest adsorption was assigned to chlorine and sodium ions and the lowest to potassium ion. In summary, sesame flour biochar, owing to its high active surface area, porous structure, and suitable functional groups on the surface, effectively adsorbs salt ions in the presence of copper ions during the adsorption process.

In the present study, a bioelectrochemical reactor (BEC) was utilized to treat two types of real saline produced water (PW). BEC was designed based on the combination of electrocoagulation (EC) process with halophilic microorganisms, and it was assessed in terms of biodegradation of hydrocarbons. The effects of various operating parameters including the current density, electrical contact time (On/Off), hydraulic retention time (HRT), and total dissolved solids (TDS) at different levels on the chemical oxygen demand (COD) removal efficiency, settleability, and performance of isolated halophilic microorganisms were examined. Additionally, a novel neural network (ANN) approach modelling using adaptive factors was used to predict and optimize the effects and interactions between operating parameters during BEC process by predicting complicated mechanisms and variations associated with microorganisms. In addition, a new algorithm was developed for the sensitivity analysis to achieve the optimum operating conditions and obtain maximum efficiency in COD removal, sludge volume index (SVI), mixed liquor suspended solids (MLSS), and specific electrical energy consumption (SEEC), simultaneously. BEC was found to be significantly more effective at removing most hydrocarbons, particularly pristine and phytane. In addition, the results showed a significant improvement in settling ability of the biological flocs with average SVI of 91.5 mL/g and a size of 178.25 μm using BEC. Based on estimated operating costs and energy consumption, BEC was more cost-effective and efficient than other bioelectrochemical systems. [ABSTRACT FROM AUTHOR]

Bisphenol A, a hazardous endocrine disruptor, poses significant environmental and human health threats, demanding efficient removal approaches. Traditional biological methods struggle to treat BPA wastewater with high chloride (Cl−) levels due to the toxicity of high Cl− to microorganisms. While persulfate-based advanced oxidation processes (PS-AOPs) have shown promise in removing BPA from high Cl− wastewater, their widespread application is always limited by the high energy and chemical usage costs. Here we show that peroxymonosulfate (PMS) degrades BPA in situ under high Cl− concentrations. BPA was completely removed in 30 min with 0.3 mM PMS and 60 mM Cl−. Non-radical reactive species, notably free chlorine species, including dissolved Cl2(l), HClO, and ClO− dominate the removal of BPA at temperatures ranging from 15 to 60 °C. Besides, free radicals, including •OH and Cl2•−, contribute minimally to BPA removal at 60 °C. Based on the elementary kinetic models, the production rate constant of Cl2(l) (32.5 M−1 s−1) is much higher than HClO (6.5 × 10−4 M−1 s−1), and its degradation rate with BPA (2 × 107 M−1 s−1) is also much faster than HClO (18 M−1 s−1). Furthermore, the degradation of BPA by Cl2(l) and HClO were enlarged by 10- and 18-fold at 60 °C compared to room temperature, suggesting waste heat utilization can enhance treatment performance. Overall, this research provides valuable insights into the effectiveness of direct PMS introduction for removing organic micropollutants from high Cl− wastewater. It further underscores the critical kinetics and mechanisms within the PMS/Cl⁻ system, presenting a cost-effective and environmentally sustainable alternative for wastewater treatment.

Recycling salt and water from saline wastewater is crucial for environmental preservation, resource conservation, and social economy sustainability. The heat pump air circulation evaporating separation (HP-ACES) system for saline wastewater treatment is proposed. Nevertheless, it is discovered that the system evaporation efficiency (SEE) is low and solid crystalline salt does not precipitate during the experiment. Therefore, an established and validated mathematical model of the HP-ACES system is provided and the average relative errors of the system evaporation rate (SER) and SEE are 5.3 % and 7 %, respectively. The theoretical analysis of the non-optimized system indicates that the main cause of the low SEE of the HP-ACES system during the test is incorrect cooling water flow. Hence, the system optimization scheme is presented and the comparison of the HP-ACES system's performances before and after optimization is conducted. Results demonstrate that the SEE of the optimized HP-ACES system has been greatly improved (optimized system: 0.62–2.46 kg/kWh, non-optimized system: 0.77–0.91 kg/kWh). Additionally, there is almost no change in the yield and composition of the solid crystalline salt when the inlet air temperature of spray separation tower is above 90 °C.

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.

Electrocatalytic treatment of chemical saline wastewater showed great technical advantages due to its characteristics of simple operation, high catalytic efficiency and little secondary pollution. The review takes the classification and composition of titanium-based anodes as the starting point. Typical studies of wastewater treatment by electrocatalytic technology based on free radicals and non-free radicals were also discussed. Combined with the previous researches about electrocatalytic mechanisms in recent years, the mechanisms of titanium-based anodes were analyzed in terms of ·OH, active chlorine and others. The studies on titanium-based anodes in chemical wastewater containing different salt concentrations, such as dye wastewater, coal chemical wastewater, landfill leachate wastewater, fertilizer and pesticide production wastewater, etc., were thoroughly examined. According to the amount of electricity required for the removal of organic matter per unit, the energy consumption of titanium-based anodes for wastewater treatment by electrochemistry was described. The review would provide theoretical basis and technical support for electrocatalytic treatment of chemical saline wastewater.

This study investigated a feasible model for treating actual shrimp farm wastewater at a pilot scale that could be applied to farms in the Mekong Delta area. The research was carried out using a hybrid constructed wetlands (HCWs) model, which included a floating constructed wetland (FCW, total area of 1,500 m2) and a horizontal sub-surface constructed wetland (HSCW, total area of 400 m2). The HCWs were cultivated with native plants including: Scirpus littoralis Schrab, Cyperus alternifolius, and Paspalum vaginatum. These plants are all adapted to the high salinity levels of shrimp farm wastewater. The system was operated for 30 days to treat shrimp farm effluent. Results indicated that the model effectively removed organic matter and nitrogen compounds from the wastewater. The treated wastewater had low concentrations of COD (10.0-15.4 mg/L), BOD5 (7.1-12.5 mg/L), NH4+-N (0.04-1.11 mg/L), and TN (0.17-1.83 mg/L), which met the reliable conditions for reuse or safety requirements for discharge to aquatic systems. The findings of this study have significant implications for the sustainable management of shrimp farm wastewater in the Mekong Delta area. The HCWs model is a feasible and effective way to treat this type of wastewater, and it could be adapted to other regions facing similar challenges.

In this research, the exit treated wastewater from the gravity filtration unit, mechanical and chemical treatment unit, biological treatment unit and finally UV disinfection treatment unit enters to a solar desalination unit. Wastewater evaporation process is performed in this unit. In this study, in order to increase the UV waves in solar energy, nano-flooring has been used on the floor of the solar pond. The laboratory results show that the average difference between the experimental data and the theoretical results for simple coating, coating made of zinc oxide nanoparticles and coating made of aluminum oxide nanoparticles is equal to 2%, 2.3% and 1.6%, respectively. Laboratory results show that the average temperature difference between theory and laboratory when simple coating, nano zinc oxide coating and nano aluminum oxide coating are used are 0.5%, 2.89% and 0.67%, respectively. The laboratory results show that the minimum and maximum average temperature of different layers of wastewater are related to the months of January and July, respectively. This research shows that the maximum and minimum temperature difference of the first layer and the last layer of wastewater are in April and March, respectively.

Phenolic compounds are commonly found in industrial effluents and can be hazardous to organisms even at low concentrations. Over the years, researchers have demonstrated that bioremediation is a cost-effective and environmentally friendly alternative to physicochemical approaches used to remove phenol. The aim of this study was to investigate the removal of phenol from saline wastewaters by a halotolerant strain of the genus Janibacter. For this purpose, bacterial cells were immobilized on different supports, from which mica and zeolite were ultimately chosen due to their higher removal efficiency. The wet weight of immobilized cells per 1 g of mica and zeolite was 0.51 and 0.48 g, respectively. Free cells consumed 100 mg/L of phenol in 88 h, while immobilized cells used it in 40 h. Immobilized cells revealed a higher thermostability and could operate over a wider pH range and salinity. Unlike free cells, immobilized cells could remove 700 mg/L of phenol and could be reused for at least nine cycles. Interestingly the phenol removal efficiency of zeolite-immobilized cells remained unchanged after 4 months of storage at 4 and − 20 °C, which could be of great advantage for industrial applications. Complete destruction of phenol was observed through the meta pathway comprising phenol hydroxylase and catechol 2,3-dioxygenase enzymes. Key points: • Mica- and zeolite-immobilized cells were able to consume high concentrations of phenol. • Cells immobilized on mica and zeolite had considerable operational and storage stability. • Immobilized cells could be a good candidate for phenol removal in saline environments. [ABSTRACT FROM AUTHOR]

This paper described an experimental study for treating salt containing wastewater with a bench-scale SBBR (sequencing batch biofilm reactor). By gradually increasing salinity of the wastewater, the activated sludge of high salt-tolerance was acclimatized, and the treatment test of simulated salt wastewater was carried out with wastewater samples of five sorts of salinity: 0 g/L, 8 g/L, 16 g/L, 24 g/L and 32 g/L. The experimental results showed that with the increase of salinity gradient, the efficiencies of removing NH4+-N, COD and TP decreased notably: in case where salinity was 32 g/L, and compared with salinity of 0 g/L, NH4+-N declined from 98% to 84%; COD from 98% to 73%; and TP from 97% to 47%. Additionally, the microbial activity, which was characterized by SOUR (specific consumption rate) and DHA (dehydrogenase activity) of biofilm, increased on condition of salinity being below 8 g/L, while decreased when salinity was up to greater than 8 g/L. Salinity made it possible to increase the content of extracellular polymer (EPS) in biofilms from 26.15 mg/g SS to 216.27 mg/g SS, among which polysaccharide (PS) content of TB-EPS grew most, and the increase of EPS could improve the resistance of microorganisms to salinity and the cells' protective effectiveness. It was found that under different salinity conditions there were growing three largest dominant phyla: actinomycetes, proteomycetes and patella bacteria in the biofilms, and the average relative abundance remained between 72% and 83%, among which the relative abundance of actinomycetes increased significantly with the increase of salinity, and the relative abundance of variant phylum decreased with the increase of salinity; the relative abundance of Kineosphaera, Micropruina and TM7a increased rapidly with the increase of salinity, and on the condition of salinity being up to 32 g/L, they became the three biggest dominant genera. To sum up, from the perspective of microbial community characteristics, the effects of increasing salinity on the structure and diversity of microbial communities were explored, the results could provide a theoretical basis for the further study on COD, NH4+-N and TP removal mechanisms of SBBR systems under high salinity stress. [ABSTRACT FROM AUTHOR]

Falling film evaporation technology is widely used in the treatment of salt-containing wastewater in coal chemical industry. However, there is still a lack of research on the inlet method of vertical falling film evaporation tubes. In this paper, the heat and mass transfer processes of saline wastewater under vertical and tangential inlets were investigated using numerical simulations. On this basis, the differences in flow and heat transfer processes between saline wastewater and pure water under tangential inlet were investigated. The results showed that the flow velocity of saline wastewater with a falling film evaporation tube in a tangential inlet mode was larger. Meanwhile, the turbulence in this way was more intense and the fluid temperature in the vertical tube was higher. Saline wastewater has higher temperature and smaller liquid volume fraction than pure water liquid membrane in the range of 193–1,000 mm from the inlet. The use of tangential inlet method to treat salt-containing wastewater has higher evaporation efficiency and is a very effective way to guide the improvement of heat transfer efficiency. HIGHLIGHTS Study on the heat transfer of a falling film evaporator tube with different inlets.; The liquid film velocity at the tangential inlet is faster than that at the vertical inlet.; Salty wastewater is thinner than pure water, which is more conducive to evaporation.;

A seven month, pot study was conducted to evaluate the impact of moderately saline wastewater on the growth potential of six forestry plant species viz., Eucalyptus calmaldulensis, Dendrocalamus strictus, Casurina equisetfolia, Cassia fistula, Melia dubia, and Bambusa arundinacea under different drainage conditions namely, well-drained saline (WDS) condition and poor-drained saline condition (PDS) and the control with well-drained non-saline condition. WDS treatment resulted in no mortality whereas PDS treatment resulted in mortality in the range of 33–66%. The plant height and root dry biomass increased in the range of 145% to 221.6% and 4.3–37.1 g respectively in WDS treatment, however, 23.60% to 173.4% and 4.1–10.1 g in PDS treatment. Among all, Eucalyptus camaldulensis and Dendrocalamus strictus showed high Na+ accumulation in roots (2.16 ± 0.02% and 1.13 ± 0.01%), shoots (1.98 ± 0.01% and 0.74 ± 0.01%) and leaves (1.27 ± 0.02% and 0.86 ± 0.01%) in WDS treatment and in case of PDS treatment root (1.01 ± 0.01% and 0.23 ± 0.01%), shoot (1.12 ± 0.02% and 0.11 ± 0.01%), and leaf (0.07 ± 0.01% and 0.1 ± 0.02). The overall performance of both Eucalyptus camaldulensis and Dendrocalamus strictus was highest in WDS treatment. Therefore, it was concluded, that both plants had better performance than other plant species, a proper drainage system defines the overall productivity and treatment efficiency. Forestry is not only a necessity for increasing tree cover and decreasing pressure on natural forests but also a most desired land use plan especially for reclaiming and rehabilitating the degraded lands. This study concluded that salt-affected and waterlogged areas and moderately saline waters can be utilized satisfactorily in raising forests using suitable plant species. Eucalyptus camaldulensis and Dendrocalamus strictus which showed good performance for salt tolerance and survival can be effectively used to mitigate the problems of waterlogged conditions and soil salinity remediation. Utilizing these species extensively can be a sustainable and suitable approach to promote afforestation and mitigate the problems of waterlogged conditions and for green belt development. [ABSTRACT FROM AUTHOR]

In this research, the efficiency of a solar distillation system as a passive technique in the process of water distillation from wastewater was investigated. The solar distillation process is proposed as a desalination process with zero discharge (ZD), in order to prevent salt water from entering to the sea and using salt water. In this study, three solar ponds with three different floors were used. Laboratory data show that the density of wastewater varies between 1.09 and 1.27 g/cm3 when using simple flooring. The amount of density changes when using floor covering made of nanozinc oxide is between 1.05 and 1.21 g/cm3. Laboratory data show that changes in density when using flooring made of nanoaluminum oxide are between 1 and 1.17 g/cm3. The laboratory results show that heat capacity of the wastewater decreases with increase in the depth of the effluent. Results show that flooring made of nanoaluminum oxide increases the rate of evaporation by about 17% and flooring made of zinc oxide by about 11%. [ABSTRACT FROM AUTHOR]

Abstract This study investigates biological treatment of outlet wastewater from flocculation reactor. This stream has an unpleasant odor. So, a biological treatment unit has been used to separate biological contaminants. Results show that 35 min can be considered as optimum oxygen injection time. Results show that the reduction of nitrate and phosphate is 67% and 60.8% with increasing oxygenation time, respectively. Results show that BOD and COD decrease by about 1.8% and 1% with increasing oxygenation time from 35 to 40 min, respectively. Studies show that organic carbon and petroleum hydrocarbons decrease from 20.1 to 4.8 mg/l and 0.14–0.4 mg/l by increasing oxygen injection time from 5 to 35 min, respectively. Results show that wastewater turbidity decreasing is from 4.3 NTU to 2.1 NTU in biological unit. Results show that range of pH is between 9.9 and 10.4.

Both the flow state of the liquid film and the heat transfer effect all affected the efficiency of falling film evaporation directly. In this study, based on computational fluid dynamics and orthogonal tests, numerical simulations were performed for different inlet velocities, inlet temperatures, and upper and lower tube diameter ratios of evaporation tubes with tangential inlet methods. Results showed that the tangential inlet method makes the liquid film distributed evenly. The increase in the ratio of upper and lower pipe diameters could enhance the heat transfer effect. When it was 1.5:1, the export salt concentration increased to 5.87%. When the inlet velocity increased, the heat transfer effect became better. The inlet temperature had a positive effect on the heat transfer effect. The orthogonal test results showed that when the upper and lower tube diameter ratio was 1.5:1, the inlet flow rates reached 0.4 ​m/s and the inlet temperature was 303 ​K, the flow distance increased by 6.98%.

Solar driven air evaporating separation (AES) technology has extensive application in the field of saline wastewater treatment due to its energy saving and cleanliness. However, these current systems generally utilize solar collectors to heat working fluids (air and wastewater), and then pass these heat carrying fluids into the evaporator to complete the mass transfer evaporation process, so as to realize the separation of the wastewater. This conventional process inevitably leads to the mismatch between heat and mass transfer of two working fluids in evaporator, which limits the efficient utilization of the energy. Accordingly, a novel thermal collector–evaporator integrated unit, in which the collecting process and evaporating process are carried out at the meantime and the collected heat directly supplies the latent heat consumed by this evaporation process, is designed to couple with the solar air evaporating separation system for saline wastewater treatment in this paper. Meanwhile, the system thermodynamic simulation model is established and detailed system performance experimental investigations are carried out. The results show that this system is feasible, and this special design is indeed conducive to improve the system thermal utilization (compared with the traditional system, the average irradiation utilization efficiency ηican be increased by 21.2%). Furthermore, by comparing the experimental and simulation results, the thermodynamic model can effectively predict various system state parameters during operation (errors are all basically within ±10%). More importantly, from the system dynamic characteristic analysis results, the stored wastewater has the phenomenon of heat storage and heat release, which is beneficial to prolong the duration of maintaining high GOR, evaporation efficiency (EE) and system energy utilization efficiency (ηsys). Even under experimental conditions in winter, this system can still sustain high wastewater treatment performance and energy efficiency (When c=10%, three average indicator: GOR = 3.99, EE = 6.97 kg/kWh, ηsys=73.8%).

Concentration followed by electrolysis is one of the most promising ways for saline wastewater treatment, since it could produce H2, Cl2, and an alkaline solution with deacidification potential. However, due to the diversity and difference of wastewater, knowledge on the suitable salt concentration for wastewater electrolysis and the effects of mixed ions are still lacking. In this work, electrolysis experiments of mixed saline water were conducted. The salt concentration for stable dechlorination was explored, with in-depth discussions on the effects of typical ions such as K+, Ca2+, Mg2+, and SO42−. Results showed that K+ had a positive effect on the H2/Cl2 production of saline wastewater through accelerating the mass transfer efficiency in the electrolyte. However, the existence of Ca2+ and Mg2+ had negative effects on the electrolysis performance by forming precipitates, which would adhere to the membrane, reduce the membrane permeability, occupy the active sites on the cathode surface, and also increase the transport resistance of the electrons in the electrolyte. Compared to Mg2+, the damaging effect of Ca2+ on the membrane was even worse. Additionally, the existence of SO42− reduced the current density of the salt solution by affecting the anodic reaction while having less of an effect on the membrane. Overall, Ca2+ ≤ 0.01 mol/L, Mg2+ ≤ 0.1 mol/L and SO42− ≤ 0.01 mol/L were allowable to ensure the continuous and stable dechlorination electrolysis of saline wastewater. [ABSTRACT FROM AUTHOR]

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Purified drinking water is the basic need of human beings. Purification of water assisted by freely available solar energy can be the best alternative compared with other water purification techniques available in the market today which consume nonrenewable energy. Distillation, which is the most ancient method, is being used for water purification. The device in which solar thermal energy converts brackish water into pure drinkable form is known as a solar still. Present article reports an extensive study of numerous designs of solar stills. The article also includes a review of effect of each parameter that influences the water productivity that is, pure water. Considerations of thermodynamics, heat transfer, and mass transfer are also explained in brief. The reviews of various kinds of analysis namely, theoretical, experimental, computational, cost, and water quality have been reported. [ABSTRACT FROM AUTHOR]

It was important to establish the scaling mechanism to slow down scaling, which is one of the important problems faced by saline wastewater treatment with falling film evaporators. In this paper, the phase equilibrium data of ternary system NaCl-CaCl2-H2O at 303.15–373.15 K were measured, and the prediction of the flow characteristics and scaling tendency of salt-containing wastewater in the evaporation tube was investigated by numerical simulation based on the phase equilibrium results. The results showed that the mesostable phase diagram of the ternary system was of simple type, and w(NaCl) and w(CaCl2) showed regular variation with temperature when w(NaCl) in the system was 15–28%. Moreover, the components of the four saline wastewaters (10% NaCl + 9, 10, 11, 12% CaCl2) with less salt content had a faster heating and a faster rate of evaporation of the liquid film in the evaporation tube. Based on the solubility in the experiments and simulations, it was concluded that NaCl crystals were precipitated at tube lengths of 718 mm, 942 mm, 966 mm, and 1,000 mm for four salt concentrations in the evaporation process by comparison, and the reliability of the predicted loci was also demonstrated by a falling film evaporation experimental setup. HIGHLIGHTS Creatively predict scaling site based on phase equilibrium and fluid simulation.; Systematic study of multi-temperature phase equilibrium data for ternary systems.; Fine analysis of the flow characteristics of the brine in the evaporation tube.;

Microwave heating has excellent potential for applications in wastewater treatment. This study proposes a highly efficient continuous liquid-phase microwave heating system to overcome the problems of low treatment capacity, low dynamic range of loads, and insufficient heating uniformity of the existing equipment. First, a quarter-wavelength impedance-matching layer improves heating efficiency, and the heating uniformity has been enhanced by horn antennas. Second, an experimental system is developed. The simulation and experimental results are consistent, with the microwave system achieving over 90% energy utilization for different thicknesses and concentrations of salt water. Finally, simulations are performed to analyze microwave efficiency and heating uniformity at different flow rates, salinities, dielectric properties, and sawtooth structures. The system can efficiently heat loads with a wide range of dielectric properties, including saline water. Generally, when the permittivity varies from 10 to 80, and the loss tangent varies dynamically from 0.15 to 0.6, more than 90% of microwave efficiency and excellent temperature distribution (The coefficient of temperature variation COV < 0.5) can be achieved. The system's modular design enables scaling up to further boost processing capacity. Overall, the system provides high-throughput, high-efficiency, high-uniformity, and large-dynamic-range microwave water treatment, which has promising applications in industrial water treatment. [ABSTRACT FROM AUTHOR]

This study investigates biological treatment of outlet wastewater from flocculation reactor. This stream has an unpleasant odor. So, a biological treatment unit has been used to separate biological contaminants. Results show that 35 min can be considered as optimum oxygen injection time. Results show that the reduction of nitrate and phosphate is 67% and 60.8% with increasing oxygenation time, respectively. Results show that BOD and COD decrease by about 1.8% and 1% with increasing oxygenation time from 35 to 40 min, respectively. Studies show that organic carbon and petroleum hydrocarbons decrease from 20.1 to 4.8 mg/l and 0.14–0.4 mg/l by increasing oxygen injection time from 5 to 35 min, respectively. Results show that wastewater turbidity decreasing is from 4.3 NTU to 2.1 NTU in biological unit. Results show that range of pH is between 9.9 and 10.4. [ABSTRACT FROM AUTHOR]

In this research, the goal was simultaneous elimination of salt (NaCl) and dye (C·I Acid Orange 7 or AO7) through integration of capacitive deionization (CDI) technique with UV-based electrochemical advanced oxidation process (UV-EAOP). To optimize salt adsorption capacity (SAC) of MnO 2 electrode, Taguchi's experimental design methodology was employed to fine-tune synthesis parameters, including bath temperature, current density, and precursor concentrations. BiOCl was synthesized and implemented as an anode to bolster AOP's effectiveness. Several experiments were conducted to analyze the effects of applying the combined AOP and CDI. The findings revealed that parameter optimization improved SAC, and the application of UV irradiation decreased electrode's SAC. Furthermore, it was observed that AO7 could enhance SAC while lowering salt adsorption rate (SAR). More importantly, the combined application of CDI and AOP resulted in superior pollutant removal efficiency and improved SAC, despite reduced SAR. Finally, color was entirely eliminated after 90 min, and the generated species were recognized by GC–MS. Additionally, a possible pathway for AO7 degradation was suggested based on the generated species. [Display omitted] • Simultaneous removal of salt and dye was evaluated by CDI and AOP hybrid system. • Dye completely removed after 90 min. • Optimizing the electrode upgraded SAC by about 51 %. • AO7 presence improved SAC within 5 min, and reduced SAR within 5 min. [ABSTRACT FROM AUTHOR]

[Display omitted] • Original IS had lower denitrification and S cycle genes in IS than those of AS. • Biofilm inoculated by IS enriched more functional genes than by AS in SAD systems. • Biofilm domesticated by IS had more S cycle genes at high stress of S2- and SO 4 2- • Microbes for S cycle more sensitive to the toxicity of S2- than denitrifiers. To develop a reliable sulfide (S2-) autotrophic denitrification (SAD) process under S2- and SO 4 2- salinity stresses, the biofilm performance and microbial mechanisms were comparatively studied using different inocula of activated sludge (AS) and intertidal sediment (IS). Biofilm IS enriched more denitrification genes (0.34 %) and S2- oxidation genes (0.29 %) than those with AS. Higher denitrification performance was obtained under S2- (100 mg/L) and SO 4 2- (5–15 g/L Na 2 SO 4) stresses, but no significantly differences were observed under levels of 0–200 mg/L S2- and 30 g/L Na 2 SO 4. Notably, biofilm samples in SAD systems with IS still had more S2- oxidation genes at high S2- levels of 100–200 mg/L and Na 2 SO 4 level of 30 g/L. The key functional genus Thiobacillus accumulated well at 30 g/L Na 2 SO 4 , but was strongly inhibited at 200 mg/L S2-. The findings were advantage to SAD application under sulfide and salinity stresses. [ABSTRACT FROM AUTHOR]

Efficient removal of refractory organic matter is the focus of research in the treatment of actual wastewater with Peroxymonosulfate-based advanced oxidation processes(PMS-AOPs). However, the high concentration of chloride ions (Cl−) ubiquitously present in wastewater changes the reactive species (RS) present in the process, and the mechanism of this change is still not clear. This study investigated the effects of Cl− on the transformation behavior of RS and treatment performance under microwave (MW) combined with cobalt ions (Co2+)-activated PMS. The results showed that increasing the Cl− concentration can enhance the removal performance of the MW/Co2+/PMS process for ammonia (NH 4 +-N), accompanied by the production of nitrate nitrogen (NO 3 -N), monochloramine (NH 2 Cl) and dichloramine (NHCl 2), which was related to the transformation of existing reactive oxygen species (ROS, •OH and SO 4 •−) into reactive chlorine species (RCS), with hypochlorous acid (HClO) as an important intermediate. Cl− can generate HClO through free radical oxidation (•OH and SO 4 •−) dominance and non-free radical oxidation (PMS and Co3+) promotion, and the heat transferred by MW can further trigger conversion between HClO and PMS, thereby changing the distribution of RS. Increasing the dosage of PMS and the dosage of Co2+ promoted the transformation of Cl− to reactive species in the MW/Co2+/PMS process. At MW power=160 W, [Co2+]=17.5 μM,[PMS]=10 mM, and [Cl−]=17 mM, the maximum cumulative [HClO] reached 1910.97 μM, and the decay rate was 0.1815 min−1.The macromolecular organic matter in aqueous environment competes with ammonia for the RCS. Through regulating [Cl−] in mature leachate, RCS has a certain oxidation effect to organic matter, but its limited oxidation ability leads to a decrease in the mineralization effect. • Free radical oxidation (•OH and SO 4 •−) dominated the formation of HOCl. • A higher [Co2+] could promote the formation of HClO but retard its conversion. • RCS promotes NH 4 + removal and compensate for organics degradation. [ABSTRACT FROM AUTHOR]

• 0.50 V was the optimized voltage in the eGDMBR system with highest stable flux • eGDMBR mitigated the negative effect of salinity on COD removal. • A porous biofilm was engineered in eGDMBR-0.50 with the lowest EPS content • Membrane fouling was mitigated by shifting the bacterial community in eGDMBR Gravity-driven membrane bioreactor (GDMBR) endowed with low maintenance and energy consumption owing to its combinations between biological degradation and membrane rejection, however, has not been reported in treating the saline wastewater due to the potential biological inhibition. This study investigated the effects of salt on GDMBR performance, and introduced a novel low voltage electric field (eGDMBR) with hopes to mediate the biological activity and improve the filtration performance. The influence of different low voltage electric fields (0.25 V, 0.50 V, and 0.75 V) on the flux variations and contaminants removal of eGDMBR were investigated. The results demonstrated that integrating low voltage electric field into GDMBR would not impact the appearance of flux stabilization, but delivered a significant influence on its stabilized flux level, and 0.50 V was the optimized voltage, contributing to a substantial flux improvement of 47.10 % in eGDMBR-0.50. Moreover, with the assistance of low voltage electric fields, eGDMBR process obtained an effective removal of chemical oxygen demand (COD), ammonia nitrogen (NH 4 +-N) and total phosphorus (TP), accounting for average removal efficiency of 54.01 %, 73.08 % and 25.74 %, respectively. Compared to the control, coupling 0.50 V voltage electric field to GDMBR was beneficial to engineer a loose, porous and heterogeneous structure of membrane biofilm and also reduce the accumulation of extracellular polymeric substance (EPS), significantly contributing to alleviating the membrane fouling. Furthermore, with the assistance of low voltage electric fields, the Proteobacteria was enriched by a relative abundance of 58.58 % in the membrane biofilm of eGDMBR-0.50, which was in favor of the degradation of COD and NH 4 +-N. Therefore, these findings indicated that eGDMBR conferred significant superiorities in treating the saline wastewater and mitigating membrane fouling. [ABSTRACT FROM AUTHOR]

The electrochemical treatment of saline wastewater is prone to the formation of inorganic chlorinated byproducts, being a significant challenge for this technology. In this study, we introduce an electrooxidation system utilizing a self-supporting nitrogen-doped carbon-based cathode embedded in carbon cloth (N@C-CC), designed to generate H₂O₂. This system aims to rapidly neutralize free chlorine produced at the anode, a precursor to inorganic chlorinated byproducts, thereby reducing their formation. Our results demonstrate that using the N@C-CC cathode in saline wastewater treatment yielded considerably lower concentrations of ClO₃⁻ and ClO₄⁻ (0.08 mM and 0.024 mM, respectively), which were only 20.5% and 22.7% of the levels produced using a Pt cathode without H₂O₂ generation. Moreover, the presence of cathodically generated H₂O₂ that quenches free chlorine did not significantly impact the degradation performance of phenol. Electron paramagnetic resonance tests and quenching experiments indicated that 1O₂ was primarily responsible for phenol removal. Validation with real wastewater demonstrated reductions of 68.6% and 56.3% in ClO 3 − and ClO 4 − concentrations, respectively, while effectively removing other pollutants. This study thus offers a compelling method for mitigating the formation of inorganic chlorinated byproducts during the electrooxidation of saline wastewater. [Display omitted] • N@C-CC cathode has good H 2 O 2 production performance in a wide pH range. • A novel electrochemical system based on N@C-CC cathode is proposed. • This system can effectively reduce formation of inorganic chlorinated byproducts. • Elimination of free chlorine is crucial in mitigating inorganic chlorinated byproducts. [ABSTRACT FROM AUTHOR]

This first-attempted study displayed the multi-skilling performance of microbial fuel cells (MFCs) for treating saline wastewater in terms of soluble organics biodegradation, bioelectricity conversion, redox-mediators obtainment and salinity reuse. Results indicated that a bioelectricity conversion efficiency of ca. 0.865–0.960 kWh/kg COD Mn with over 90% organics removal in 10.0–20.0 g NaCl/L conditions could be realized. Meanwhile, the redox mediators-like substances could be enriched from saline wastewater via MFCs treatment, which exhibited relatively high redox properties as electron shuttles. Moreover, the dominant members of Bacteroides , Azospirillum , Dyella , Sphingomonas , Ignavibacteriales and Clostridium cooperated together for completing bioelectrogenesis effectively with high capabilities of salinity tolerance. Higher salinity (ca. 30.0–40.0 g NaCl/L) impaired key hydrolase activities, reduce microbial metabolic functions and weaken anodic microbial diversity, which negatively reduce MFCs' running properties. Finally, the harvested salinity from saline wastewater through MFCs could be used effectively as a promising way of achieving waste sludge solubilization. This study could help to re-shape the thinking about future saline wastewater and excess sludge treatment/management toward resource recovery and cost minimization. [Display omitted] [ABSTRACT FROM AUTHOR]

A considerable effort has been made to exploring the oxidation of clofibric acid (CA) in advanced oxidation processes (AOPs). However, few studies are available on degradation mechanism and toxicity assessment of CA in saline pharmaceutical wastewater. Here the effect of chlorine on the degradation kinetics of CA by Fe 2+ / persulfate (PS) process were studied. Oxidation efficiency, mineralisation, intermediate by-products, reactive oxygen species (ROS) and toxicity assessment were examined. Notably, a high removal efficiency (70.91%) but low mineralisation (20.99%) of CA were observed at pH 3.0 during the Fe 2+ /PS system. Furthermore, we found Cl - exerted a beneficial impact on CA degradation. However, the degree of CA mineralisation was relatively minor. Under high salinity (100 mM) condition, the primary reactive species within the Fe 2+ /PS system were SO 4 ⋅ - , OH · , Cl 2 /HClO, and Fe(IV). Several undesirable chlorinated by-products were formed. A reasonable degradation pathway was proposed. According to the ecological structure-activity relationship (ECOSAR) programme, some transformation products exhibited higher toxicity levels than CA itself in both acute and chronic toxicity assessment, especially in high-salinity environments. These findings elucidate an increased challenges and ecological risk for CA oxidation by Fe 2+ /PS treatment in saline pharmaceutical wastewater.

Wastewater treatment technologies have been recently improved to a great extent in order to get higher contaminant removal efficiency and to meet the stringent effluent regulations. In this context, a moving bed biological reactor (MBBR) provides large contact surface for growth of microorganisms and low volume resulting in higher performance of treatment plants. This study aims at determining the effectiveness of an in-house designed and built-up MBBR reactor in increasing COD removal efficiency in a Mahshahr Petrochemical Zone Wastewater Treatment Plant located in southwest of Iran. After 187 days of operating the reactor continuously, COD removal efficiency improvement achieved for salinity of 0.5%, 1%, 1.5%, and 2% was from 89.5 to 93%, 74 to 87%, 62 to 84%, and 54 to 76%, respectively, compared to the existing treatment plant. [ABSTRACT FROM AUTHOR]

Industrial wastewaters are recognized as a valuable resource, however, their disposal without proper treatment can result in environmental deterioration. The associated environmental/operational cost of wastewater treatment necessitates upgrade of applied processes towards the goals of sustainability and mitigation of climate change. The implementation of cyanobacteria-based processes can contribute to these goals via resources recovery, production of high-value products, carbon fixation and green-energy production. The present study evaluates the cyanobacterium Synechococcus elongatus PCC 7942 (S7942) as a biological component for novel and sustainable alternatives to typical biological nutrient removal processes. Valuable results regarding cultivation temperature boundaries, applied disinfection techniques and analytical methods, as well as regarding relations between parameters expressing S7942 biomass concentration are presented. The results show that at typical industrial wastewater temperatures, S7942 efficiently grew and removed nitrates from treated snack-industry's wastewater. Moreover, in cultures with treated and relatively saline dairy wastewater, its growth rate slightly decreased, but nevertheless nitrates removal rate remained efficiently high. A comparison between typical denitrification processes and the proposed nutrient removal process indicated that a S7942-based system may constitute an alternative or a supplementary to denitrification process. Thus, Synechococcus elongatus PCC 7942 proved to be a potent candidate towards sustainable industrial wastewater treatment applications. HIGHLIGHTS Synechococcus elongatus PCC 7942 efficiently grows in treated industrial wastewater.; High rates of nitrates removal and growth at typical wastewater temperatures.; Efficient growth and high nitrates removal in saline industrial wastewater.; Filtration coupled with chlorination/dechlorination is effective for pre-treatment.;

It is still one of the significant solutions to treat saline wastewater with thermal desalination technology, especially falling film evaporators. To improve the performance of the falling film evaporator, a numerical study on the gas–liquid two-phase flow characteristics of saline wastewater in the vertical pipe was conducted using the VOF model. The results showed that the inlet velocity of the saline wastewater increased under the same operating conditions, resulting in the thickening of the liquid film and the increase of the average convective heat transfer coefficient. Increasing the inlet temperature of the working liquid reduced the temperature difference, which led to a decrease of the average convective heat transfer coefficient. In addition, as the inlet concentration of the working liquid increased, the film flow rate and the average convective heat transfer coefficient first decreased and then increased slightly. The experimental results verified the accuracy of the numerical simulation, and the average error was 9.27%. HIGHLIGHTS The study of fluid microflow combined with heat transfer was proposed.; The distribution of heat transfer coefficient based on numerical simulation.; The distribution of heat transfer coefficient is correctly verified by experiments.; The effects of the various operating parameters on the heat and mass transfer processes are studied.;

• A novel formation mechanism of ABGS with the algal barrier was revealed. • SMP was closely related to the assembly of the algal barrier. • Enriched TB-EP played a crucial role in the formation of ABGS. • The algal barrier provided stronger protection for ABGS under salinity stress. • Pseudofulvimonas and filamentous Streptophyta contributed to the granulation. Algal-bacterial granular sludge (ABGS) composed of microalgae and aerobic granular sludge, is a sustainable and promising technology for wastewater treatment. However, the formation mechanism of ABGS has not been clearly defined, and the direct formation of ABGS in saline wastewater has rarely been investigated. This study proposed novel insights into the granulation process of ABGS by assembling the algal barrier, which was successfully cultivated directly in saline wastewater. The results concluded that ABGS with the algal barrier maintained a higher biomass (MLSS of 7046 ± 61 mg/L), larger particle sizes (1.21 ± 0.06 mm), and better settleability (SVI 30 of 46 ± 1 mL/g), enabling efficient pollutants removal. Soluble microbial products (SMP) were found to be closely related to the emergence of the algal barrier. In addition, under salinity stress, the high production of extracellular polymeric substances (EPS, 133.70 ± 1.40 mg/g VSS), specifically TB-EPS (90.29 ± 1.12 mg/g VSS), maintained a crucial role in the formation of ABGS. Further analysis indicated that biofilm producing bacteria Pseudofulvimonas and filamentous eukaryote Streptophyta were the key players in ABGS formation with the algal barrier. Furthermore, the enhancement of key genes and enzymes involved in nitrogen metabolism, TCA cycle, and polysaccharide metabolism suggested a more robust protective effect provided by the algal barrier. This study is expected to advance the application of simultaneous ABGS formation and pollutant removal in wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

Background: Salicornia neei is a halophyte plant that has been proposed for use in the phytoremediation of the saline wastewater generated by land-based aquaculture. To identify the molecular mechanisms related to ammonium response, we analyzed the transcriptome of S. neei in response to growth in saline water containing 3 mM ammonium. Results: The RNA sequencing generated a total of 14,680,108 paired-end reads from the control and stressed conditions. De novo assembly using the CLC Genomic Workbench produced 86,020 transcripts and a reference transcriptome with an N50 of 683 base pair. A total of 45,327 genes were annotated, representing 51.2% of the contig predicted from de novo assembly. As regards differentially expressed genes, a total of 9,140 genes were differentially expressed in response to ammonium in saline water; of these, 7,396 could be annotated against functional databases. The upregulated genes were mainly involved in cell wall biosynthesis, transmembrane transport and antiporter activities, including biological Kyoto Encyclopedia of Genes and Genomes, pathways linked to the biosynthesis of secondary metabolites, plant hormone signal transduction, autophagy, and nitrogen metabolism. In addition, a set of 72 genes was directly involved in ammonium metabolism, including glutamine synthetase 1, glutamate synthase 1, and ferredoxin-dependent glutamate synthase chloroplastic. Conclusions: Our results support the hypothesis that an ammonium detoxification system mediated by glutamine and glutamate synthase was activated in S. neei when exposed to ammonium and saline water. The present transcriptome profiling method could be useful when investigating the response of halophyte plants to saline wastewater from land-based aquaculture. [ABSTRACT FROM AUTHOR]

Remote and mobile refineries are designed to utilize local groundwater (if abundantly available) to meet their industrial applications and inner uses. However, groundwater usually suffers hardness and salinity. Therefore, reverse osmosis (RO) technology is applied to treat the groundwater before use. The RO concentrate water stream is mixed with other refinery wastewater effluents resulting in a high saline wastewater. Upon discharging the refinery wastewater in constructed or natural lagoons, organic and non-organic pollutants permeate to groundwater reservoirs (aquifers) causing groundwater contamination build-up. The present study adopted the response surface methodology (RSM) to evaluate and optimize the simultaneous extraction of Pb2+, Cu2+, and Cd2+ ions from a refinery saline wastewater using emulsion liquid membrane (ELM). The experimental results were compared with those obtained from a previous study conducted for a simulated synthetic wastewater. Lower removal efficiencies of Pb2+, Cu2+, and Cd2+ ions were noticed for the refinery (real) wastewater due to possible interactions between dissolved salts of salinity, and metal ions. The lower removal efficiencies are due to the potential chemical complexation of the heavy metal ions with the petroleum organic and inorganic anions during the cations/carrier complexation at the wastewater/membrane interface which hinders the free migration of the metal ions. Also higher breakage was observed to cause lower stability of the ELM system in comparison with the simulated synthetic wastewater system. The impacts of the feed pH (2–6), homogenizer speed (5700–19,700 rpm), surfactant concentration (2–6%v/v), and carrier concentration (2–6%v/v) on the removal efficiencies of the Pb2+, Cu2+, and Cd2+ ions were investigated. The results of the regression analysis showed that experimental data could be fitted to quadratic models with values of determination coefficients (R2) equal to 91.18%, 88.91%, and 91.16% for Pb2+, Cu2+, and Cd2+ respectively. Maximum removal efficiencies of 92.33%, 88.98%, and 76.29% for Pb2+, Cu2+, and Cd2+ ions respectively were obtained at the optimum operating conditions of feed pH of 5.15, homogenizer speed of 5700 rpm, surfactant concentration of 3.97% v/v, and carrier concentration of 6% v/v. [ABSTRACT FROM AUTHOR]

The effects of pure oxygen aeration on organic pollutants removal performance and effluent soluble microbial products (SMP) characteristics of salt-tolerant sludge for the treatment of wastewater with the salinity from 1.0% to 3.5% were investigated. The results showed that the oxygen transfer efficiency of the pure oxygen aeration was higher than that of the air aeration. At the low salinities (0.5%, 1.0%, 1.5%), the total organic carbon (TOC) removal rates were 71.42%, 72.88% and 76.30%, respectively, much higher than those with air aeration. However, there were no significant differences of TOC removal efficiency between the air aeration and the pure oxygen aeration at high salinities (2.5% and 3.5%). The SMP contents showed a trend of first decline and then increase generally. The content of SMP with pure oxygen aeration was lower than that with air aeration at low salinity, whereas an opposite result was obtained for salinity above 2.5%. Five excitation–emission matrix (EEM) fluorescence peaks detected in the SMP with pure oxygen aeration and air aeration were assigned to tryptophan protein-like, tyrosine protein-like and humic acid-like substances. Humic acid-like fluorescence mainly appeared in the SMP with air aeration, which may be due to respiratory failure under air aeration conditions. [ABSTRACT FROM AUTHOR]

Desalination and industrial plants all around the world generate large amounts of saline wastewater (brine). The discharge of brine from facilities poses a severe environmental threat, while at the same time, the opportunity to recover resources is being lost as discharged brine is rich in valuable metals that could be recovered as salts/minerals. To this aim, this study presents and analyzes for the first time the characteristics of different brine effluents (from industries such as desalination, oil and gas production, petrochemical, aquaculture, pharmaceutical, textile) to prevent environmental pollution and to recover valuable resources (i.e., salts, minerals, metals, chemicals) enabling the concept of waste-to-resource (circular water economy model). The results revealed that the common salinity values in brine effluents range from 0.5 to 150 g/L, while the only exception is the produced water from the oil and gas industry (up to 400 g/L). Brine effluents from all sectors contain sodium, chloride, calcium, and potassium ions in high concentrations, while the production of common salts such as NaCl, CaCl2, and MgCl2 from brine can be economically profitable. Besides common ions, precious metals such as lithium, rubidium, and cesium are present in low concentrations (<25 mg/L); however, their extraction from brine effluents can be significantly profitable due to their very high sale price. The treatment and valorization of brine can be implemented by the hybridization of membrane-based, chemical, biological, and thermal-based technologies/processes in minimal and zero liquid discharge (MLD/ZLD) systems. [ABSTRACT FROM AUTHOR]

Worldwide, there is growing interest in achieving a meaningful use of natural resources, as epitomized in this work, which demonstrates the use of saline wastewater (WW) from the demineralization of cheese whey as the main component of a medium for cultivation of spirulina (Limnospira maxima). Based on Zarrouk medium and the fundamental composition of spirulina biomass, a novel cultivation medium for photoautotrophic cultivation of spirulina was developed. The wastewater medium (WWM) consisted of WW supplemented with NaHCO3, urea, K2HPO4, and FeSO4. The suitability of WWM was evaluated by comparison of spirulina growth in laboratory scale tubular or gas-lift photobioreactors in WWM and Zarrouk medium (ZM). The maximum biomass productivity of 0.36 g L−1 day−1 was achieved in WWM, compared with 0.24 g L−1 day−1 in ZM. The cost of WWM was less than 50% of the cost of ZM. [ABSTRACT FROM AUTHOR]