Synthesis of residual carbon/transition metal silicate particle electrodes from coal gasification fine slag for electrocatalytic advanced treatment of coal chemical wastewater

Although physical, chemical, and biological wastewater treatment technologies have improved in recent years, their overall effectiveness remains limited by various challenges. This study evaluated the potential application of swine manure aerobic digestate effluent (SME) as an alternative medium for cultivating the cyanobacterium Arthrospira (Limnospira) maxima to meet the requirements for sustainable microalgae cultivation. A pilot-scale study was conducted using a 200-L photobioreactor to test the efficacy of SME dilutions of 30%, 50%, and 70% (v/v) over 30 days. The objective was to identify the optimal concentration for microalgae growth and nutrient removal. The 30% SME group showed the highest biomass productivity (1.04 ± 0.02 g L⁻1) and superior nutrient removal, with total nitrogen (T-N) and phosphate (PO₄-P) reduction rates of 42.46 ± 3.96% and 46.19 ± 1.36%, respectively, and chemical oxygen demand removal efficiency of 50.05 ± 6.04%. These findings indicate effective organic matter reduction under high-load conditions. The harvested biomass exhibited high protein content (~ 52%) and stable amino acid composition, supporting its potential as a protein-rich livestock feed. However, trace metal accumulation (Zn and Cu) increased at higher SME concentrations, highlighting the need for optimized dilution strategies. These results demonstrate the feasibility of integrating nutrient removal and biomass valorization using microalgae and show that swine manure-derived SME can be directly used without pretreatment as a scalable, eco-friendly approach in circular agriculture.

Multi-scale research on coal chemical wastewater treatment: Pollutant molecules, technologies, and process integration

The optimization of coal chemical wastewater treatment networks (WTNs) faces a critical conflict between model fidelity and computational tractability. Rigorous models capture essential nonlinearities but hinder system-wide optimization, whereas simplified models often yield suboptimal designs. This work proposes an integrated framework embedding high-fidelity “stage-wise” neural network surrogates into a novel sequential multi-stage superstructure. By incorporating domain-specific treatment hierarchies to prune infeasible connections, the framework significantly reduces the combinatorial search space. The developed surrogate captures discrete stage choices and nonlinear responses with a relative error below 4%, allowing for accurate process representation. Case studies reveal a critical coupling between unit operating conditions and global topology: a minor shift in the extraction phase ratio can trigger a drastic network reconfiguration, nearly doubling the total treatment flow (2550 to 4763 t/h). By minimizing the total hydraulic load—a primary determinant of system costs and resource consumption—the proposed framework effectively reduces the operational scale of treatment facilities. Ultimately, this study offers a practical pathway for the coal chemical industry to strictly meet environmental discharge limits with improved economic efficiency, thereby supporting sustainable wastewater management.

The synthesis of value-added ammonia (NH3) from nitrate-containing wastewater is crucial for green chemical manufacturing and wastewater treatment. However, achieving efficient electrocatalytic nitrate reduction reaction (NO3RR) under neutral conditions remains challenging because of an imbalance between the supply and demand of active hydrogen, insufficient active sites, and sluggish reaction kinetics. To address this challenge, plasma-assisted micro-modulation of ruthenium (Ru)-doped cobalt hydroxide (Co(OH)2) nanosheets induces surface restructuring under mild conditions. This process tunes the valence states of the constituent elements and creates abundant oxygen vacancies, thereby enhancing NO3RR performance under neutral conditions. The results demonstrate that the P-Ru-Co(OH)2@PCC catalyst, which was obtained following short-term treatment with H2/Ar plasma, exhibits significantly enhanced NO3RR activity. Specifically, the yield of ammonia reached 2.63mg h- 1 cm- 2. Theoretical calculations further confirmed that plasma regulation improved the catalyst's adsorption of NO3 -, lowered the reaction energy barrier, and ultimately enhanced the overall activity of the catalyst in the NO3RR process for ammonia synthesis.

Energy-efficient chlorine-mediated paired electrocatalysis for simultaneous H2O2 production and coal chemical wastewater purification.

Inhibitory effects and mechanisms of dichloromethane on a biological contact oxidation process for chemical wastewater treatment

Rapid start-up and microbial response strategies of an anaerobic digestion system for coal chemical wastewater treatment.

The treatment of real chemical industry wastewater is challenging due to its complex composition and high levels of resistant organic pollutants. This study assessed the effectiveness of Fenton and photo-Fenton processes for degrading chromophoric compounds in such wastewater. Four reagent doses were tested in the Fenton process, with the optimal condition (0.1 g/L Fe2+ and 4 g/L H2O2) selected for photo-Fenton experiments. The impact of UV fluence (250, 500, and 750 mJ/cm2) on pollutant removal was evaluated. Photo-Fenton treatment at 750 mJ/cm2 achieved the highest efficiencies: 72% COD, 95% color removal, outperforming classical Fenton oxidation. Acute toxicity tests with Daphnia magna showed reduced toxicity in all treated samples; however, only the 750 mJ/cm2 photo-Fenton effluent-maintained immobilization below 10%, indicating negligible toxicity. These results demonstrate that UV-assisted processes enhance pollutant degradation and ecological safety. The study underscores the value of combining chemical and biological assessments to ensure environmentally safe wastewater discharge.

Chemical laboratory wastewater is classified as hazardous due to the presence of compounds that can pose serious risks to both human health and the surrounding environment. Parameters such as Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), and heavy metal content serve as key indicators of water pollution, reflecting its quality and environmental impact. In this study, treatment of complex chemical laboratory wastewater was carried out through coagulation and flocculation processes using natural coagulants derived from chitosan and Abelmoschus leaf extract. The main objective of this research was to evaluate the effectiveness of these organic coagulants in reducing COD, BOD, and heavy metal concentrations. The experiment consisted of two stages: (1) optimization of treatment parameters using the Jar Test method, and (2) analysis of treated and untreated wastewater for COD, BOD, and heavy metals (Cr, Mn, Cu, Pb, Zn, Ni, and Fe) using Atomic Absorption Spectrophotometry (AAS). The results revealed that the treatment successfully reduced COD from 74,928 mg/L to 65,311 mg/L; Cr from 3.422 mg/L to 2.877 mg/L; Mn from 5.084 mg/L to 4.787 mg/L; Cu from 36.548 mg/L to 9.902 mg/L; Pb from 0.169 mg/L to 0.141 mg/L; Zn from 0.342 mg/L to 0.243 mg/L; Ni from 23.79 mg/L to 17.375 mg/L; and Fe from 13.615 mg/L to 7.697 mg/L. However, the BOD value increased from 383 mg/L to 453.5 mg/L, which is likely due to the introduction of organic matter from the natural coagulants and flocculants used. For improved treatment efficiency, further processes such as filtration or adsorption using activated carbon, zeolite, or bentonite, as well as biological treatment with activated sludge, are recommended..

To address the treatment of chemical wastewater containing the highly toxic and recalcitrant 2,4,6-trimethylpyridine (Col), this study evaluates the potential of hydrophobic deep eutectic solvents (HDESs) for Col removal via liquid–liquid extraction (LLE). thymol-decanoic acid (Thy-Dec) was selected as the optimal extractant via COSMO-RS and compared with methyl isobutyl ketone (MIBK) using multiscale simulations. Quantum chemical (QC) calculations revealed that Thy-Dec exhibits high selectivity due to its strong hydrogen-bond donor ability and electrostatic complementarity with Col. Molecular dynamics (MD) simulations dynamically elucidated the mass transfer behavior of Col across phases during LLE. An extraction-distillation integrated process modeled in Aspen Plus demonstrated that the Thy-Dec system outperforms MIBK in both environmental and economic performance, providing a theoretical basis for HDES-based recovery of pyridine compounds from aqueous streams.

Investigation of different activation methods in peroxymonosulfate oxidation for the treatment of chemical industry wastewater

Harnessing membrane and thermal processes for chemical industry wastewater treatment: A case study

ABSTRACT Coal chemical wastewater, characterized by high toxicity, salinity, and refractory organics (e.g. phenols), poses significant environmental challenges. An innovative system integrating micro-nano bubbles (MNBs) and acclimated bacterial consortia (DP-1) was developed in this study. It was designed to achieve efficient phenol degradation and chemical oxygen demand (COD) removal. DP-1 was domesticated under MNBs aeration, high phenol (up to 400 mg/L), and high-salt (1–15 g/L) conditions, exhibiting remarkable adaptability. The MNBs@DP-1 system achieved 100% phenol degradation and 88.9% COD removal within 24 h at 600 mg/L phenol, demonstrating robust performance across a wide pH range (6–9) and salinity (1–15 g/L). Notably, in a sequencing batch biofilm reactor (MNB-AR), long-term treatment of actual coal chemical wastewater (COD: 1300–1600 mg/L) yielded a stable average COD removal of 76.2% with <1.6% fluctuation. Microbial community analysis revealed Proteobacteria (99.1%) dominance post-acclimation, with Acinetobacter (65.7%) and Comamonas (29.7%) as key functional genera driving phenol mineralization. Comparative studies confirmed the superior efficacy of MNBs@DP-1 over conventional aeration systems, attributing enhanced degradation to MNBs-induced bacterial activity and biofilm stability. This work provides a scalable strategy for achieving ‘zero discharge’ in coal chemical wastewater treatment by synergizing bubble technology and microbial acclimation.

ABSTRACT In this study, the treatment of chemical industry wastewater, which is used in producing auxiliary chemicals for various industries, through coagulation and Fenton oxidation was examined. Coagulation studies with alum were done at various pH levels and doses to find the best conditions for wastewater treatment, and the pre‐treated wastewater was treated with Fenton oxidation using different chemical oxygen demand (COD)/Fe 2+ and COD/H 2 O 2 ratios (by weight). During coagulation (pH 5, 300 mg/L alum), COD, total suspended solids (TSS), color index (CI), and turbidity removal efficiency was obtained as 74.8%, 92.0%, 93.0%, and 93.3%, respectively. After coagulation, Fenton oxidation was achieved at a COD/Fe 2+ /H 2 O 2 ratio of 1:3:7.5, resulting in 89.2% TSS removal, 97.3% turbidity removal, 97.7% CI removal, and 74.8% COD removal. As a result, the treatment of chemical industry wastewater through coagulation and Fenton oxidation processes resulted in TSS, turbidity, CI, and COD removal of 99.0%, 99.8%, 93.0%, and 93.5%, respectively. As chemical industry wastewater has high COD and TSS content and toxic properties due to various chemicals, it was thought that applying Fenton oxidation after pretreatment with coagulation process would reduce the chemicals used in Fenton oxidation and thus reduce the cost. In summary, it has been shown in this study that complex chemical industry wastewater containing various chemicals can be effectively treated by alum coagulation followed by Fenton oxidation.

The article examines a mathematical model for porous catalysts incorporating nonlinear reaction kinetics. Central to this model is the nonlinear steady-state reaction-diffusion equation. The Taylor series method derives the analytical solution for species concentration in various nonlinear Langmuir-Hinshelwood-Haugen-Watson (LHHW) models, each characterized by distinct fundamental rate functions. From this analysis, we derive both straightforward and approximate polynomial expressions for concentration and effectiveness factors. Furthermore, we compare numerical simulations to the analytical approximations, demonstrating a strong correlation between the numerical results and theoretical predictions. We also compute the concentration and effectiveness factors for the LHHW-type models. The analytical solutions offer valuable insights for optimizing catalytic and biochemical system designs, such as fixed/fluidized-bed reactors, fuel cells, and catalytic converters. They support advances in sustainable chemical production, wastewater treatment, biomedical devices, and energy systems. These results reduce reliance on trial-and-error methods, enabling cost-effective scale-up and improved catalyst longevity. Overall, the findings align well with the aim of statistics, optimization, and information computing for efficient system modeling and design.

In recent times, oscillatory baffled reactors have been gaining acceptance for use in various industrial processes due to their appealing mixing and mass transfer characteristics. In addition to the baffles, which are artificially attached, oscillatory baffled reactors produce additional fluid turbulence that is very useful in improving chemical reaction, fermentation, and wastewater treatment processes. This study describes in detail a simulation of the gas-liquid flow inside an Oscillatory Multi-orifice Baffled Reactor (OMOBR), focusing on the hydrodynamic aspects of different oscillation scenarios and baffle spacing as performed using the COMSOL Multiphysics software. The study explains the patterns of flow, bubble size, and pressure drop using oscillatory Reynolds numbers and advanced computational tools. The findings reveal that increased oscillatory Reynolds numbers enhance turbulent flow and bubble size, thus improving the homogeneity of the gas-liquid system. With lower oscillatory Reynolds numbers, the flow becomes smooth, and bubbles are larger and more stable without the violent pulsations typical of a bubble column reactor. However, when the oscillatory Reynolds number increases, the flow induces violent turbulence, and this reduces the bubble diameter and increases the pressure drop. Also, the baffle spacing (l=1.0D) causes comparatively lesser pressure drop with smaller bubble sizes than the other dimensions utilized. These studies bring to light useful information regarding the conditions of oscillation that can allow reaching the optimal parameters and efficiency of an industrial reactor.

The rapid development of the chemical industry has caused serious environmental problems, among which chemical wastewater discharge has become a key problem that needs to be solved urgently. Compared with traditional treatment technologies, emerging technologies such as advanced oxidation and bioelectrochemical systems have been widely adopted due to their advantages of low energy consumption and high efficiency. This article aims to briefly analyze the principles, advantages, disadvantages and application scenarios of emerging treatment technologies, and points out a series of challenges facing the development of chemical wastewater treatment technology. This paper concludes that traditional water treatment methods face the challenge of energy conservation and consumption reduction. Compared with traditional technologies, emerging technologies have the advantages of being energy-saving and efficient, and are suitable for meeting increasingly stringent environmental protection standards. In the future, innovation and integration of a variety of technologies can be carried out, and combined processing technology not only reduces equipment costs but also improves processing efficiency and quality. The analysis in this article can provide some reference and inspiration for the selection and improvement of chemical wastewater treatment technologies in related industries.

Selective removal of organic matters from high-salinity chemical industrial wastewater: Ultrafiltration or nanofiltration?

As a result of global urbanization and industrialization, heavy metals are one of the hazardous contaminants facing the world. The adsorption process using agricultural wastes can achieve one of the sustainable development goals for wastewater treatment and resource recovery. Moringa and tea extracts were utilized to synthesize iron nanoparticles for the treatment of aqueous solutions containing heavy metal ions (Cu2+, Pb2+, Se2+, Zn2+, and Cr6+). This method offers a sustainable substitute for conventional chemical wastewater treatment methods. Furthermore, the use of magnetic iron nanoparticles reduces the need for extra separation processes by making it simple to separate the adsorbent from the treated waste using a magnetic field. Various techniques were employed to characterize the prepared nanoparticles, such Fourier-transform infrared spectroscopy (FT-IR), energy dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), x-ray diffraction (XRD), and x-ray fluorescence (XRF). The XRD analysis confirmed the crystalline phase of alpha-FeNPs in the synthesized nanoparticles. The EDX analysis verified the presence of oxygen and iron in the nanoparticles, indicating that the iron was in an oxide form. This study aimed to investigate the removal of heavy metals using nano-magnetic composites of moringa (FeNPs-M) and tea (FeNPs-T). To assess the effectiveness of the FeNPs-M several parameters were tested, including pH, contact time, initial concentration, and nanoparticle dosage. The results indicated that the efficiency of FeNPs-M was significantly higher than that of FeNPs-T for the removal of heavy metals from synthetic solutions, achieving removal efficiency are 96.5% 99.71%, 96.73%, 93.16%, and 91.83% of Cu2+, Pb2+, Se2+, Zn2+, and Cr6+, respectively, when using FeNPs-M, while the removal efficiency are 96.36%, 93.40%, 79.83%, 78.6%, and 77.77% of Cu2+, Pb2+, Se2+, Zn2+, and Cr6+, respectively, 25 °C, with a contact time of 45 min, a pH of 3.0, concentration 3.0 mg/L, a sorbent dose of 0.8 g/L, and 200 rpm at 25 °C.