Coal Wastewater Research Articles

Synergistic flocculation performance and underlying mechanisms of a novel bioflocculant flocan with coagulant iron salt

Flocculation is an integral part of wastewater treatment units and various flocculants have been employed to strengthen the flocs formation and produce clean water. Natural polysaccharides have been employed as eco-friendly bioflocculants for the treatment of turbid water. In the study, flocan is a named exopolysaccharide (EPS) isolated from a coastal mudflat with a high yield of 8.3g/L. Flocan consisted of glucose, mannose, galactose, and glucuronic acid in a molar ratio of 2:3:1:1, along with pyruvate modifications. As the bioflocculant agent, flocan exhibited more than 85% removal efficiency in kaolin suspension in terms of a concentration of 10mg/L at pH 3. The addition of iron salts with flocan showed high flocculation efficiency in acidic kaolin suspension (99.37%) and acidic coal wastewater (99.44%). The carboxyl/hydroxyl groups and branched structure of flocan provided ionic interactions and promoted higher bridging between bioflocculants and negatively charged particles. Coagulants FeCl3 enhanced the flocculating activity via neutralizing and stabilizing the residual negative charge of functional groups. Treatment with EDTA decreased the ionic interactions and reversed the flocculation significantly. Compared with the current bioflocculants, the superior production, low dosage, and excellent flocculating activity implied that flocan showed great potential in acidic wastewater treatment industrially. The coagulants/bioflocculants combination appears to be a promising and sustainable technology for wastewater flocculation.

Waste to energy-study on the optimal types and dosage of additives for coal wastewater slurry

Abstract As a clean and efficient fuel derived from coal, coal water slurry can be produced by using industrial wastewater, promoting resource recirculation and environmental preservation. To maintain fluidity and stability during industrial applications of coal wastewater slurry, stabilizers play a crucial role. To promote the energy utilization of industrial wastewater, this article conducted a comparative study on different stabilizers for coal wastewater slurry. The results are as follows: (a) Compared with other stabilizers, xanthan gum makes the water separation rate of the coal wastewater slurry the lowest, and the slurry still maintained good stability after standing for 1 week and 1 month; (b) If the coal wastewater slurry requires a short storage time, the slurry properties with a blending ratio of 0.05% of xanthan gum will be the best; if the coal wastewater slurry requires a longer storage time, it can be made with a blending ratio of 0.10% of xanthan gum. The conclusion presented in this paper offers valuable insights for selecting stabilizers during the preparation of coal wastewater slurry.

Encapsulating Fe-Co bimetal inside carbon aerogel to boost electron transfer for efficient heterogeneous electro-peroxone oxidation of organic pollutants

We fabricated a novel Fe-Co bimetal encapsulated inside carbon aerogel sphere (Fe2Co@CS) to improve the electro-peroxone (EP) process. The degradation and mineralization of p-nitrophenol (p-NP) were 100% (15 min) with rate constant of 0.314 min−1 and 83.8% (60 min) in Fe2Co@CS/EP, respectively. Fe2Co@CS was composed of defective graphite carbon and Fe2Co alloy. The presence of metal–oxygen-carbon (M-O-C, MFe/Co) bonds promoted interface electron transfer from carbon layer towards Fe2Co alloy, which was advantageous to the reduction of ≡Fe3+/≡Co3+. Moreover, the Fe-Co synergistic effect also accelerated the interfacial catalytic reaction for activating O3 and H2O2. The quenching experiment and EPR test indicated that ·OH, ·O2- and 1O2 were main reactive oxygen species (ROSs). DFT calculations showed that O3 had lower adsorption energy on Fe2Co@CS than H2O2, manifesting that catalytic ozonation played the key role in ROSs generation. In addition, ozone utilization efficiency in Fe2Co@CS/EP (ΔTOC/ΔO3 = 1.23–0.68) revealed 66-36% increase relative to those of EP (0.74–0.5). Fe2Co@CS was an efficient catalyst over a wide pH range (3–11) with permissible iron and cobalt releases. The Fe2Co@CS/EP process exhibited high-performance for degrading different pollutants under high salinity condition with coexistence of Cl−, NO3− and SO42−. For treating real coal wastewater, the TOC removal was 52.7% at 4 h with low EEC (0.038 kWh (g TOC)−1). This study provided an efficient method for the development of EP in wastewater treatment.

Mechanistic insight into the adsorption and interaction of lignite, organic ingredients, and dispersant in coal wastewater slurry

The conversion of coal gasification wastewater into coal wastewater slurry (CWWS) for combustion and gasification fuels is a promising approach that combines resource recovery with effective wastewater management. In this work, the influence of organic ingredients derived from coal gasification wastewater on the slurrying capabilities of lignite, particle dispersion/aggregation behavior, and adsorption characteristics between lignite and sodium methylene dinaphthalene sulfonate (NNO) in CWWS was thoroughly investigated. The interaction mechanism of lignite, NNO, and the organic ingredients in the slurry systems revealed subsequently by molecular dynamics (MD) simulations. Results indicated that the maximum solid concentration for coal gasification wastewater simulated by organic ingredients increased by 1.64% with a decrease in pseudo-plasticity and stability. The presence of dodecane, phenolic and heterocyclic nitrogen compounds caused the dissociation and coalescence of particles in the CWWS and further formation of creaming or clarifying layer. The adsorption processes of NNO and the organic ingredients on lignite particles exhibited competitive adsorption, following the pseudo-second-order kinetic and the Freundlich thermodynamic models. The adsorbed organic ingredients enhanced the hydrophobicity and electrostatic repulsion of the particle surface in CWWS, increasing the hydrophobic C-C/C-H content from 64.73% to 71.27%. Moreover, the MD simulation results revealed that the adsorption conformations at the lignite-water interface in CWWS changed from “single-point and single-layer” adsorption of NNO to “multi-point and multi-layer” adsorption of NNO and organic ingredients driven by hydrophobic effect, van der Waals force, π-π stacking effect, and hydrogen bonding.

Effect of oxygen-containing functional groups and pore structure characteristics of coal on the slurryability of coal wastewater slurry

The physical and chemical characteristic of coal have an important influence on the slurryability of coal wastewater slurry. In this paper, eight different coals are used to make coal wastewater slurry, and the effects of oxygen containing functional groups and pore structure characteristics of different coal samples on the slurryability are analyzed. Results show that (a) Coal with more oxygen-containing functional groups on surface have stronger hydrophilicity, higher surface activity and have stronger adsorption capacity for water molecules, this will lead to the reduction of free water and the increase of viscosity of the slurry. (b) Coal with larger BET specific surface area and pore volume and smaller average pore diameter have the stronger ability to adsorb and store water in coal wastewater slurry, thus the concentration of coal wastewater slurry prepared from these coal is low. The conclusion of this paper can provide reference for coal selection in the preparation of coal wastewater slurry.

Analysis of the Contribution of TSS, pH, Fe, and Mn Parameters to the Pollution Load Capacity of Coal Mines in the Oal River, South Sumatra

The Oal River receives coal wastewater input at several companies. Coal mining in the vicinity of the location adds to the burden of water pollution in the Oal River due to waste water disposal activities. The increase in the concentration of coal waste and the pollution load that enters the Oal River water body will have an impact on the reducing capacity of the pollution load. This study aim to provide information on the condition of the pollution load carrying capacity of the Oal River. Determination of the carrying capacity of water pollution loads at water sources using the mass balance method. The characteristic of the Oal River water with the parameters TSS, pH, Fe and Mn have not yet passed the quality standards for river water and wastewater, both according to PP No. 22 of 2021 and South Sumatra Governor Regulation No. 8 of 2012. The Oal River still has the capacity to accommodate TSS and pH parameters.

Preparation and application of low-cost fibers for efficient adsorption of oil from coal pyrolysis wastewater and establishment of quantitative equation for calculating oil contact angle under water

The removal of oil from coal pyrolysis wastewater persists to be a challenging problem. Thus, this study proposes a new scheme that integrates the adsorption of oil using fibers and subsequent centrifugation or elution to achieve efficient oil–water separation. Based on their stable chemical property, PP and were selected as the substrates for drawing the fibers. In addition, PVDF and PTFE were explored to modify the wettability of PP and PE. The performances of as-prepared fibers were tested for removing oil from wastewater in both batch and continuous modes. Among all the fibers, the PVDF-modified PP fibers exhibited the best performance. For PP-based fibers with 5 wt% PVDF, the saturated oil-removal efficiency reached 92.24 % in case of the simulated wastewater and 81.10 % for the actual wastewater. Given that the oil content in coal pyrolysis wastewater was ~2000 ppm, the residual oil content in the outlet water would be ~380 ppm, which satisfies the requirement of the subsequent treatment process. Furthermore, the PVDF-modified PP fibers exhibited excellent reusability and stability to defy various environmental corrosions. The separation of oil and water based on the adsorption by fibers offers promising prospect to remove oil from coal pyrolysis wastewater. In addition, we derived a formula to calculate the oil contact angle under water based on Young's equation using several measurable parameters. As the calculation results were consistent with real scenarios, this derived formula can provide quantitative guidance for material modification in coal wastewater treatment.

Boosting singlet oxygen generation for salinity wastewater treatment through co-activation of oxygen and peroxymonosulfate in photoelectrochemical process

High concentrations of inorganic ions in saline wastewater pose adverse effects on hydroxyl radical (HO•)-dominated technologies. Here, we report a unique strategy for boosting singlet oxygen (1O2) generation via coactivation of oxygen and peroxymonosulfate (PMS) by regulating the electron transfer regime in the photoelectrochemical process. The Fe-N bridge in atomic Fe-modified graphitic carbon nitride (denoted SA-FeCN) favors the construction of electron-defective Fe and electron-rich N vacancies (Nvs) to accelerate directional electron transfer. The produced intermediate (HSO4O···Fe−Nvs···OO) as a chemical channel accelerates the directional electron transfer from PMS to further reduce O2 to form activated products (SO5•−, O2•−), thereby transforming O2 into 1O2. An optimized 1O2 generation rate of 39.4 μmol L−1s−1 is obtained, which is 15.7–945.0 times higher than that in traditional advanced oxidation processes. Fast kinetics are achieved for removing various phenolic pollutants in a nonradical oxidation pathway, which is less susceptible to the coexistence of natural organic matter and inorganic ions. The COD removal for coal wastewater and complex industrial wastewater in real scenarios is found to reach a value of 90%-96% in 3 h. This work provides a new direction for boosting the 1O2 generation rate, especially for the selective degradation of target electron-rich contaminants in saline wastewater.

The Synergistic Effects of Al3+ and Chitosan on the Solid-Liquid Separation of Coal Wastewater and Their Mechanism of Action.

It is important to identify an environmentally friendly and efficient flocculant that can replace polyacrylamide for the solid–liquid separation of coal wastewater. In this study, to explore whether chitosan can be used as an environmentally friendly and efficient flocculant for the solid–liquid separation of coal wastewater, AlCl3–chitosan was used to conduct flocculation–sedimentation and dewatering tests under different chitosan dosages and shear-strength conditions for the prepared coal wastewater. Focused beam reflectance was measured to dynamically monitor the number of refractory fine particles, and the settled flocs were photographed and analyzed with microscopy to explore the effect of AlCl3–chitosan on the flocculation settlement effect and floc characteristics. The synergistic mechanisms of AlCl3 and chitosan were investigated using quartz crystal dissipative microbalance and zeta potential measurement. The results showed that the addition of chitosan can significantly improve the flocculation–sedimentation and dewatering effects of coal wastewater. A reasonable dosage under a certain shear strength is conducive to the reduction of fine slime particles, which results in a compact floc structure, increases the floc size, and improves the settling effect. The synergistic effect of AlCl3–chitosan improved the electric neutralization and adsorption bridging abilities of the chitosan, and the mixed solution of AlCl3 and chitosan had stronger adsorption on the carbon surface. This study provides a new approach to the selection of flocculants for coal wastewater treatment.

Assessing the environmental performance of a novel coal mine brine treatment technique: A case in Poland

Although the energy transition results in decreased use of coal for power production, hard coal extraction will continue due to its importance in steel production and coal mine wastewater will continue generating after mines closure. The coal mining sector produces wastewater which results in environmental burdens and often contains valuable materials that can be treated to eliminate effluent discharge and recover contained materials. The aim of this study is to determine whether the implementation of a novel wastewater treatment technique in an existing coal wastewater treatment plant (WWTP) can improve both environmental performance and resource recovery potential. Our study assesses for the first time the environmental performance of the WWTP of Dębieńsko at the Upper Silesian Coal Basin, in Poland because coal mine effluents need to be treated to eliminate current environmental impacts on surface water bodies (rivers). The existing wastewater treatment system comprises reverse osmosis, evaporation and crystallization technologies. In the case of the novel ZERO BRINE technique, lab performance data is scaled-up and used for nanofiltration, reverse osmosis, electrodialysis and crystallization technologies. The environmental impacts analysis is performed with life cycle assessment (LCA) by considering mid-point impact categories (climate change, terrestrial acidification and fossil resource scarcity) and end-point damages (human health, ecosystems and resources). The functional unit is 1 m3 of coal mine wastewater input and a scenario is developed where the plant functionality concerns salt production. Results show that the implementation of the ZERO BRINE technique can improve the environmental performance of the WWTP for all considered impact categories due to a reduction in electricity consumption by 13% in the entire plant. Climate change, acidification, fossil resources scarcity, human health, ecosystems, and resources were improved by 16%, 13%, 12%, 25%, 21% and 13%, respectively. A sensitivity analysis is performed on the electricity consumption of electrodialysis which shows an additional improvement by 7% on all impacts. The ZERO BRINE technique produces both water and different types of salts. In this case, the multi-functionality of the system is addressed through substitution, while sensitivity analyses are carried out using mass and economic allocation methods.

The utilization of moringa (moringa oleifera) seed powder as a biocoagulant and flocculant in waste water treatment coal mining industry

Mineralogically, acid mine drainage consists of minerals such as silica, iron silicate, magnesium, sodium, potassium and sulfide. These minerals can undergo oxidation (especially pyrite oxidation) to form acidic salts with a pH of 2.8-3.4. Moringa seed powder activity test were performed by adding 30% H2O2 to coal waste water treatment; Moringa seed powder was added to 2 L of coal waste water and stirred for 50, 100, 150, 200, and 250 minutes. Observations were analyzed using the AAS (Atomic Absorption Spectofotometry) to measure the quality of degraded waste water and X-Ray Diffraction (XRD). The results showed that the pH value reached 7.6 in the addition of H2O2 at the mixing time of 250 minutes, the TSS level reached 0 at the stirring period of 250 minutes without the addition of Moringa oleifera powder, while the addition of H2O2 and Moringa oleifera seed powder decreased heavy metals with an average of 69.06%at the stirring period of 100 minutes. Â

Laboratory Simulation for Reducing Water Turbidity by Water Hyacinth to Meet Coal Wastewater Discharge in Paringin Pit Lake

Coal mining with an open-pit mining method can created the formation of pit lake filled with high turbidity water which has the potential to pollute and cannot be utilized if not managed properly. Treatment to reduce water turbidity to meet quality standards with chemicals is a common, but during post mining period, it is necessary to reduce the processing, which is expensive and uncertain, turning into a natural process and lower cost. The aim of this study is to analysis on the role of water hyacinth as macrophytes in reducing water turbidity on three different water sources for treatment. Water hyacinth is an aquatic plant that can be used to reduce water pollution such as high levels of turbidity in water quality. The experimental results showed that not significant on TSS < 200 mgL-1 but significantly different results, on TSS values between 200 - 400 mgL-1 and TSS > 400 mgL-1 and to be the basic reference data of the number of plants used in experiment to enlarge it on a field scale

The structure and flocculation characteristics of a novel exopolysaccharide from a Paenibacillus isolate

Bioflocculants like polysaccharides are excellent alternatives to harmful synthetic flocculants and usability under stricter levels of ecosystem protection. In this study, an exopolysaccharide producing strain Paenibacillus sp. M21629 was isolated. The exopolysaccharide was abundant in carboxylic groups and named floccuronic acid with a high weight average molecular weight of 2.38 × 108 Da. The hexasaccharide repeating units of floccuronic acid were →3)-α-D-Manp-(1 → 3)-4-Suc-β-D-Manp-(1 → 3)-β-D-Glcp-(1 → 4)-β-D-GlcpA-(1 → 4)[4,6-Pyr-β-D-Galp-(1 → 3)]-β-D-Galp-(1→. The floccuronic acid at 0.5–1 ppm showed high turbidity removal efficiency in kaolin suspension (99.8%), coal wastewater (98.8%), and high-turbidity drinking water (89.2%). The flocculation ability of floccuronic acid depended on the instability of solid particles. Owing to these encouraging results, floccuronic acid is expected to be a useful bioflocculant applied in wastewater treatment and the utilization of water resources.

CARRIER FLOTATION BY CHAR SLIME - WASHING OF ŞIRNAK ASPHALTITE SLIMES

Şırnak asphaltite slime below 200 micron size is processed. The clean coal products of the column flotation are received with mid-products and shale settlements in the modified column cell in the baffled form. The use of hydrocyclone, agglomerate thickener and wash decantation has been a suitable potential method after the driven and internal loop column flotation. With this method, ultrafine sized oily sludges with high efficiency and low solid rate coal washing are provided. It also enabled highly efficient wastewater treatment as a result of separating the oil with czar foam. Therefore, the method applied in this study can be designed as an optimum wastewater treatment technology for the treatment of oily wastewater in the oil and drilling industry. The aeration process in internal loop column flotation with air jet is widely used in lake water treatment and fresh water treatment. In this study, internal loop carrier column flotation, hydrocyclone overflows and agglomeration process are optimized for coal washing and environmental wastewater treatment. The ash and sulfur contents decreased to a level of 48% ash reduction and a 34% sulphur reduction

Study on the preparation of coal wastewater slurry from salt/alkali wastewater

Combining experimental research and simulation calculation, the effect of high-concentration salt/alkali wastewater on the preparation of coal wastewater slurry (CWWS) was studied. The research on the slurry-ability of CWWS shows that Na+ in NaCl will be electrically neutralized with the negative charge on the coal, the electrostatic repulsion of particles will decrease, and the viscosity will increase. In the presence of HCO3c, negative charge increases on coal particles, the apparent viscosity decreases by 42 mPa·s compared with the absence of HCO3−. In the CO32− systems, the pH is 8.25. Higher pH indicates that there are more OH−. Because CO32− is easy to combine with water to form a stable structure, and the strong polar effect of OH− is also easy to bind water molecules, forming a stable water molecule layer configuration on the coal, which hinders the adsorption of sodium lignosulfonate (SL), resulting in a decrease in steric hindrance effect, which is not conducive to the dispersion of particles. The molecular dynamics (MD) simulation results confirmed the existence of the neutralization of Na+ and the negative charge on coal in the NaCl system. The adsorption energies (Eadsorption) of each system were negative, indicating that the dispersant was easily adsorbed on the coal. However, in the CO32− system, the absolute value of Eadsorption was lower than that the pure water system, indicating that the presence of CO32− is not conducive to the adsorption of SL. The self-diffusion coefficient(D) of Na2CO3 system is lower than that of coal/water/SL system, NaCl system, and NaHCO3 system. It shows that the presence of CO32− can significantly reduce the migration rate of water molecules and is easy to bind water molecules. The presence of HCO3− is also easy to bind water molecules, but it is weaker than CO32−. The migration and diffusion rate of water molecules in the saline-alkali mixed system decrease. This may be mainly affected by CO32−, which easily binds water molecules on the coal surface and hinders the adsorption of SL.

Supercritical Water Gasification of Phenol with Metal Cations-A Way to Degrade Coal Industrial Wastewater and Metal-Contaminated Wastewater Simultaneously

Supercritical Water Gasification of Phenol with Metal Cations-A Way to Degrade Coal Industrial Wastewater and Metal-Contaminated Wastewater Simultaneously

Treatment of reverse osmosis concentrate from industrial coal wastewater using an electro-peroxone process with a natural air diffusion electrode

• Electro-peroxone (EP) treated reverse osmosis concentrate (ROC) for the first time. • The use of natural air diffusion electrode in EP was studied for the first time. • EP could remove refractory substances in ROC within 2 h. • The EP process had high tolerance to wastewater quality. • The combination of peroxi-coagulation (PC) and EP outperformed EP. Reverse osmosis concentrate (ROC) produced in the RO treatment of coal chemical wastewater is highly toxic and difficult to degrade. In this study, an electro-peroxone (EP) process was applied to treat ROC with a natural air diffusion electrode (NADE), which was used as the cathode to efficiently generate H 2 O 2 . The treatment efficiency of EP, electro-Fenton, electro-oxidation (EO), peroxi-coagulation (PC) and ozonation for the removal of total organic carbon, colour and UV 254 in ROC were studied and compared, confirming that EP was the most efficient process. The EP process as well as electric energy consumption (EEC) were optimized, and an optimum reaction conditions (current of 200 mA, pH of 4 and O 3 dose of 6 mg/min) were selected. The production of ⋅ OH in EP was much higher than that in ozonation and EO, as indicated by the EPR measurement. Excitation-emission matrix spectra of ROC after EP treatment verified that all the fluorescent contaminants in ROC was removed within 2 h. Further, the combination of PC and EP processes (2 h + 3 h) significantly reduced EEC by 58% as compared with EP (6 h), realizing complete decolouration. This study declared the potential of using EP and the combined PC-EP process to effectively treat the real ROC wastewater.

Modification of Cu2+ in polyphenol oxidase extract from purple eggplant for phenol degradation in coal wastewater treatment

Cracking coal-forming organic compounds during the gasification process produces liquid waste containing phenolic compounds that require special handling based on their toxicity. As one of the components, there is liquid waste resulting from the coal gasification process. The purpose of this research was to study the activity of polyphenol oxidase (PPO) on phenol after the addition of Cu2+ to purple eggplant (Solanum melongena L.) extract and its potential to work more effectively in phenol biodegradation for coal wastewater containing phenol. Enzyme activity and phenol determination were carried out spectrophotometrically. The results showed PPO activity of 25.90-38.10 U/mL; 4.0 mM phenol and the activity of PPO-Cu2+ was 21.58-46.32 U/mL; 2-10 mM CuSO4; 2.0-4.0 mM phenol. Based on Michaelis Menten’s graph, the initial rate of PPO-Cu2+ was 0.015 mM/min and the initial rate of PPO was 0.15 mM/min using 2 mM phenol as a substrate. Lineweaver-Burk’s graph shows the KM of PPO-Cu2+ = 6.92 mM, which is lower than KM of PPO = 13.05 mM. Its means that the phenol response has a higher affinity for PPO-Cu2+ than PPO. The application of PPO-Cu2+ in purple eggplant extract works effectively as much as 46.7% for artificial coal liquid waste containing phenol.

Maximum solid concentrations of coal wastewater slurries predicted by optimized neural network based on wastewater composition data

AbstractA variety of wastewaters can be generated in the coal chemical industry, and their treatment processes are complicated and have difficulty meeting standards. Using wastewater to prepare coal water slurry is an efficient and convenient new approach. The concentration of coal wastewater slurry is related to the content of the main wastewater components. A backpropagation neural network is developed to predict the maximum slurry concentration and analyze the mechanism at the data level according to the main component indicators, and a particle swarm algorithm is used to improve the neural network. The results are as follows: (a) it is feasible to predict the maximum concentration of coal wastewater slurry by a neural network, and a particle swarm algorithm can effectively improve the prediction accuracy in different models, reducing mean absolute error by up to 0.44%; (b) different input factors have different impacts on model prediction results—organic matter, ammonia nitrogen, and monovalent metal ions content as input factors to predict the maximum slurry concentration can get the most accurate results, obtaining a mean absolute error of 0.16% for the optimized backpropagation neural network and the lowest mean square error; and (c) divalent metal ions and phenols content are not suitable as input factors for predicting, as they all cause an increase in model error due to their weak or complex effects on the slurryability.

Selectively photoelectrocatalytic reduction of oxygen to hydroxyl radical and singlet oxygen: Mechanism and validation in coal wastewater

The fine-tuning of generating hydroxyl radical (OH) and singlet oxygen (1O2) was firstly proposed via the selectively photoelectrochemical (PE) reduction of oxygen with Cu-coordinated carbon-nitride-electrode (CuCN). Complete removal efficiency and trace Cu leaching (<0.01 ppm) were achieved during treatment of dimethyl phthalate and atrazine, which were mainly oxidized by OH and 1O2, respectively. Besides, no toxic intermediates was detected in the whole degradation process. The overall oxygen reduction pathway in PE system was demonstrated by electron paramagnetic resonance measurements and quenching tests. The valence band position of CuCN was designed to be more negative (−1.5 VSHE) for favoring the photocatalytic oxygen reduction. Specifically, Cu-N2-C as active sites optimized the Gibbs free energy of intermediate *OOH (ΔG*OOH = 3.99 eV) to improve the reactivity of two-electron oxygen reduction. The CuCN/photoelectrochemical system is applied for treatment of coal water slurry gasification (CWS) wastewater with high concentration of salt. The TOC of CWS was successfully decreased from 127 to 1.9 mg·L−1 in 3 h with a low specific energy consumption of 0.024−0.05 kW·h·g−1·TOC−1. The treated CWS wastewater can be used for recovery and utilization of salt as chemical raw materials. This work highlights the important role of synergistic photo-electro-catalytic effect in regulating the generation of active oxygen species via oxygen reduction pathway, which can be a promising way especially for salinity coal wastewater remediation.