Industrial Wastewater Research Articles

Interface engineering of laminated redox-copolymers for electrochemical remediation of perfluoroalkyl substances

Redox polymers now show promise for selective removal of perfluoroalkyl substances from a complex aqueous matrix at high energy efficiency and no secondary pollution. However, self-agglomeration of redox polymers is a dominating barrier to constructing a low-cost, stable system in practical applications. Herein, we introduce polymer interface engineering strategy to enhance the activity of amine functionalities and nitrous oxide radicals in copolymers composed of 4-methacryloyloxy-2,2,6,6-tetramethylpiperidin-1-oxyl and 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine. The grafted laminated redox polymer on multi-walled carbon nanotubes (termed MWCNT-g-P(TMPMA-co-TMA)) via free-radical polymerization demonstrated a 19.1–59.9 % increase in the electrosorption capacity with a maximum value (Qm) of 725.09 mg g−1 and a pseudo-first-order rate constant k1 = 1.46 min−1 and sustainable regeneration efficiency at ∼80 %. The core–shell structure of MWCNT-g-P(TMPMA-co-TMA) with a laminated redox polymer layer of ∼5 nm processed a low charge transfer resistance, which is expected to contribute to the enhanced capture performance and stability. An integrated system consisting of a MWCNT-g-P(TMPMA-co-TMA) electrode and a boron-doped diamond electrode can efficiently separate and degrade trace-concentration PFOA from industrial wastewater at high mineralization efficiency. This work provides insight into the design and optimization of redox active materials for water purification and beyond.

A critical review of ozone-based electrochemical advanced oxidation processes for water treatment: Fundamentals, stability evaluation, and application

In recent years, electrochemical advanced oxidation processes (EAOPs) combined with ozonation have been widely utilized in water/wastewater treatment due to their excellent synergistic effect, high treatment efficiency, and low energy consumption. A comprehensive summary of these ozone-based EAOPs is still insufficient, though some reviews have covered these topics but either focused on a specific integrated process or provided synopses of EAOPs or ozone-based AOPs. This review presents an overview of the fundamentals of several ozone-based EAOPs, focusing on process optimization, electrode selection, and typical reactor designs. Additionally, the service life of electrodes and improvement strategies for the stability of ozone-based EAOPs that are ignored by previous reviews are discussed. Furthermore, four main application fields are summarized, including disinfection, emerging contaminants treatment, industrial wastewater treatment, and resource recovery. Finally, the summary and perspective on ozone-based EAOPs are proposed. This review provides an overall summary that would help to gain insight into the ozone-based EAOPs to improve their environmental applications.

Triple strategies for process salt reduction in industrial wastewater treatment: The case of coking wastewater

Human activities introduce nutrient elements into wastewater, yet the saline byproducts from treatment are poorly managed. Selecting a low-salt process, without compromising treatment efficacy, is essential for reaching the zero-discharge goal in water treatment. Based on the engineering treatment process of coking wastewater, the source and reduction strategy of salts were studied. The results showed that 73.21 % of the residual salt originated from raw coal, 10.87 % from raw water, and 15.92 % from chemicals, respectively. Triple strategies for process salt reduction (PSR): load salt reduction, technology salt reduction and cyclic salt reduction can bring 0.411 mS/cm·m3, 0.217 mS/cm·m3 and −0.070 mS/cm·m3 salt reduction, and also bring 1.455 CNY/m3, 0.836 CNY/m3 and 0.360 CNY/m3 net present value, respectively. Meanwhile, PSR is also a low-carbon strategy, which will bring about carbon emission reduction of 1.6948 kg CO2-eq/m3, 0.4898 kg CO2-eq/m3 and 1.4082 kg CO2-eq/m3 respectively. The Resource/Carbon source Management-Oxic − Hydrolytic & Denitrification − Oxic (A-OHO) process, incorporating PSR, cuts costs by 27.83–31.66 % and carbon emissions by 18.68–19.54 % compared to conventional wastewater treatment methods. It can be predicted that the PSR in the standard treatment stage can provide a guarantee for the subsequent water reuse and desalination process to reduce project investment and operating costs, and at the same time benefit the macro environment from the aspects of carbon emission reduction and sludge reduction.

Chloride-mediated transformation of sulfate radicals to hydroxyl radicals for enhanced contaminant degradation in high-temperature wastewater

Using the excess heat in high-temperature industrial wastewater to activate oxidant precursors for organic contaminant degradation would make advanced oxidation processes more sustainable in the context of carbon neutrality, while the salt-mediated radical transformation chemistry in such wastewater is poorly understood. We herein demonstrate that chloride (Cl–) in the range of 0.28–56.34 mM accelerates the degradation of organic contaminants in the heat activated persulfate process in both synthetic and authentic wastewater. We use laser flash photolysis technique together with kinetic modeling to directly determine the bimolecular rate constants of radical–radical (e.g., kSO4·--SO4·- = 2.50 × 109 M−1 s−1), Cl–-radical (e.g., kSO4·--Cl- = 3.75 × 108 M−1 s−1), and radical-contaminant (e.g., kHO·-BA = 1.02 × 1010 M−1 s−1) reactions at 55 °C, which are substantially higher than those at ambient water temperature (25 °C). We also combine experimental and modelling results to calculate the contribution of different radicals to contaminant removal at 55 °C. The results clearly demonstrate that Cl– in the range of 0.28–56.34 mM promotes the transformation of SO4– to HO at 55 °C, with reactive chlorine species involved as the intermediates. The findings improve fundamental understanding of Cl–-mediated radical chemistry in high-temperature water and provide an engineering strategy to recycle the heat in wastewater to enhance contaminant remediation.

Recycling of Sewage Sludge: Synthesis and Application of Sludge-Based Activated Carbon in the Efficient Removal of Cadmium (II) and Lead (II) from Wastewater.

The limited supply of drinking water has aroused people's curiosity in recent decades. Adsorption is a popular method for removing hazardous substances from wastewater, especially heavy metals, as it is cheap, highly efficient, and easy to use. In this work, a new sludge-based activated carbon adsorbent (thickened samples SBAC1 and un-thickened samples SBAC2) was developed to remove hazardous metals such as cadmium (Cd+2) and lead (Pb+2) from an aqueous solution. The chemical structure and surface morphology of the produced SBAC1 and SBAC2 were investigated using a range of analytical tools such as CHNS, BET, FT-IR, XRD, XRF, SEM, TEM, N2 adsorption/desorption isothermal, and zeta potential. BET surface areas were examined and SBAC2 was found to have a larger BET surface area (498.386 m2/g) than SBAC1 (336.339 m2/g). While the average pore size was 10-100 nm for SBAC1 and 45-50 nm for SBAC2. SBAC1 and SBAC2 eliminated approximately 99.99% of Cd+2 and Pb+2 out the water under all conditions tested. The results of the adsorption of Cd+2 and Pb+2 were in good agreement with the pseudo-second-order equation (R2 = 1.00). Under the experimental conditions, the Cd+2 and Pb+2 adsorption equilibrium data were effectively linked to the Langmuir and Freundlich equations for SBAC1 and SBAC2, respectively. The regeneration showed a high recyclability for the fabricated SBAC1 and SBAC2 during five consecutive reuse cycles. As a result, the produced SBAC1 and SBAC2 are attractive adsorbents for the elimination of heavy metals from various environmental and industrial wastewater samples.

Ultrahigh-purity ammonia recovery from synthetic coke wastewater via membrane contactor: Overcoming phenolic interference and assessing cost efficiency

Ammonia recovery from industrial wastewater using membrane contactor processes is emerging as a promising method owing to the diverse applications of ammonia. This study uniquely addressed ammonia recovery from coke plant wastewater, which is challenging due to the presence of numerous toxic and volatile phenolic compounds. Experiments were conducted using a synthetic coke plant effluent to assess the effects of various pH levels and temperatures on ammonia recovery. Specifically, the aim was to achieve high-purity ammonia recovery while minimizing the permeation of phenolic compounds. The results demonstrate that ammonia recovery in the membrane contactor processes is highly efficient, even in the presence of phenolic compounds. During temperature variations at 25 °C and 40 °C, the recovery of ammonia increased from 42.36% to 52.97% at pH 11. Additionally, increasing the pH of a feed solution from 7 to 12 significantly increased the ammonia content to 58.3%. At this pH, the recovered ammonia was of exceptional purity (>99%), with phenol, p-Cresol, and 2,4-xylenol present at negligible concentrations (0.001%, 0.002%, and 0.004%, respectively). This was attributed to the ionization of phenolic compounds at higher pH levels, which prevents their permeation through the hydrophobic membrane. The estimated cost analysis revealed that the membrane contactor process at pH 12 was approximately 1.41 times more cost-effective than conventional air-stripping processes over eight years of operating period (pH-12 membrane contactor: $19.79; pH-12 air stripping: $23.75). This study provides a detailed analysis of the optimal conditions for selective ammonia recovery from complex wastewater, highlighting both effective treatment and sustainable resource recovery and offering a superior alternative to traditional methods.

Development of high flux photocatalytic agcl-cooh-mwcnt/pes ultrafiltration membranes for enhanced waste water treatment and fouling mitigation

A structurally stable AgCl-COOH MWCNT/PES composite membrane was designed and fabricated by combining phase conversion and post-treatment techniques, which can solve the serious membrane fouling in industrial wastewater treatment. The carboxylation of MWCNTs not only enhanced their dispersion but also facilitated their binding with silver chloride, resulting in a stable composite structure that significantly improved contaminant degradation capabilities. The post-treatment technique increased the membrane’s water purification flux by 150 % (reaching 520 L·m2·h−1·bar−1) while maintaining a high BSA retention rate of 95 %. Additionally, the composite membrane demonstrated excellent photocatalytic antifouling properties, with a flux recovery rate of 91.8 % under UV irradiation, and exhibited more than 99 % inhibition of Escherichia coli. This method provides a scalable solution for enhancing the performance of PES membranes in wastewater treatment applications.

Fertilizer-driven FO and MD integrated process for shale gas produced water treatment: Draw solution evaluation and PAC enhancement

It is a great challenge for effective treatment of shale gas produced water (SGPW), a typical industrial wastewater with complex composition. Single forward osmosis (FO) or membrane distillation (MD) process has been widely used for desalination of SGPW, with membrane fouling not well addressed. Fertilizer draw solution (DS) with high osmotic pressure is less likely to cause FO fouling and can be used for irrigation. An integrated process using fertilizer-driven FO (FDFO) and MD process was proposed for the first time for SGPW treatment, and characteristics of fertilizer DS and powdered activated carbon (PAC) enhancement were assessed. The DS using KCl and (NH4)2SO4 had high MD fluxes (36.8–38.8 L/(m2·h)) and low permeate conductivity (below 50 μS/cm), increasing the contact angle of the MD membrane by 113 % than that without FO, while the DS using MgCl2 and NH4H2PO4 produced a lower reverse salt flux (0.9–3.2 g/(m2·h)). When diluted DS was treated using PAC, the MD permeate conductivity was further reduced to 35 μS/cm without ammonia, and the membrane hydrophobicity was maintained to 71–83 % of the original. The mechanism of the FDFO-MD integrated process for mitigating MD fouling and improving permeate quality was analyzed, providing guidance for efficient SGPW treatment.

Insights into the individual and combined effects of Cu(Ⅱ) and Ni(Ⅱ) on anammox: Nitrogen removal performance, enzyme activity and microbial community

Anaerobic ammonium oxidation (anammox) is an efficient and economical nitrogen removal process for treating ammonium-rich industrial wastewaters. However, Cu(Ⅱ) and Ni(Ⅱ) present in industrial wastewaters are toxic to anaerobic ammonium-oxidizing bacteria (AnAOB). Unfortunately, the effects of Cu(Ⅱ) and Ni(Ⅱ) on anammox have not been thoroughly investigated, especially when Cu(Ⅱ) and Ni(Ⅱ) coexist. This work comprehensively investigated the individual and combined effects of Cu(Ⅱ) and Ni(Ⅱ) on anammox and revealed the inhibitory mechanisms. With the influent NH4+-N and NO2−-N concentration of 230 and 250 mg L−1, the inhibition thresholds on anammox are 2.00 mg L−1 Cu(Ⅱ), 1.00 mg L−1 Ni(Ⅱ) and 1.00 mg L−1 Cu(Ⅱ) + 1.00 mg L−1 Ni(Ⅱ), and higher Cu(Ⅱ) or Ni(Ⅱ) concentrations resulted in sharp deteriorations of nitrogen removal performance. The inhibition of Ni(Ⅱ) on anammox was mainly attributed to the adverse effect on NiR activity, while the inhibition mechanism of Cu(Ⅱ) seemed to be unrelated to the four functional enzymes, but associated with disruption of cellular and organellar membranes. The behavior of extracellular polymeric substances (EPS) contributed to the antagonistic effect between Cu(Ⅱ) and Ni(Ⅱ) on anammox. In addition, the niche of Candidatus Brocadia and Candidatus Jettenia shifted under the Cu(II) and Ni(II) stress, and Candidatus Jettenia displayed greater tolerance to Cu(II) and Ni(II) stress. In conclusion, this research clarified the combined effect and the inhibitory mechanism of multiple heavy metals on anammox, and provide the guidances for anammox process application in treating high-ammonium industrial wastewaters containing heavy metals.

Synthesis and characterization of AlxCu0.7Mn0.3Fe2-xO4 ferrite and its application in adsorption of dyes

The increasing presence of artificial dyes in industrial wastewater has necessitated the development of efficient and sustainable adsorption materials. This work explores the synthesis and characterization of Al-doped Cu-Mn (AlxCu0.7Mn0.3Fe2-xO4, where x = 0.1, 0.3, 0.5, 0.7, and 0.9) ferrite as a new adsorbent for the removal of dyes from aqueous solutions. The Al-doped Cu-Mn ferrite was prepared using the solution combustion method and meticulously characterized using various physiochemical techniques, including scanning electron microscopy (SEM) analysis, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffractometer (XRD), vibrating sample magnetometer (VSM), and Brunauer-Emmer-Teller (BET). Adsorption studies tested the material's ability to remove hazardous dyes such as congo red, methyl orange, methylene blue, and crystal violet from aqueous solutions. The effects of various parameters, including temperature, contact time, and initial dye concentration, were systematically studied. To understand the mechanism of interaction between the adsorbent and the dyes, the adsorption isotherms were examined using the Langmuir, Temkin, D-R, and Freundlich models. The Freundlich isotherms provided the best fit for the experimental data. To clarify the kinetics of the adsorption process, kinetic experiments were conducted using pseudo-first and pseudo-second-order. According to the results of the kinetics analysis, pseudo-second-order kinetics fit the data better, with a higher coefficient of determination values (R2 = 0.981, 0.983, 0.984 & 0.984). Thermodynamic parameters, including enthalpy, Gibbs free energy, and entropy changes, were calculated to determine the nature of the adsorption process, and the result demonstrates that the adsorption process was endothermic and naturally spontaneous. The results indicate that Al-doped Cu-Mn ferrite exhibits high adsorption capacities and favourable thermodynamic properties, making it a promising material for the removal of dyes from industrial wastewater effluents. The study contributes to the field by providing insights into the adsorption mechanisms and potential applications of Al-doped Cu-Mn ferrite in environmental remediation.

Sustainable Removal of Cr(VI) from Wastewater Using Green Composites of Zero-Valent Iron and Natural Clays

Composites for efficient removal of hexavalent chromium Cr(VI) from industrial wastewater were obtained by deposition of nano-zero-valent iron (nZVI), synthesized by environmentally friendly synthesis using oak leaf extract, on inexpensive, natural, readily available and cheap natural raw materials, sepiolite (SEP) or kaolinite/illite (KUb) clay, as support. nZVI particles were deposited from the FeCl3 solution of different concentrations, with the same volume ratio extract/FeCl3 solution (3:1), and with different masses of SEP or KUb. Physico–chemical characterization (SEM/EDS, FTIR, BET, determination of point of zero charge) of the composites and nZVI was performed. The results of SEM and BET analyses suggested more homogeneous deposition of nZVI onto SEP than onto KUb, which ensures greater availability of the nZVI surface for Cr(VI) anions. Therefore, the higher Cr(VI) removal at all investigated initial pH values (pHi) of the solution (3, 4 and 5) was achieved with the SEP composites. The adsorption results indicated that the elimination of Cr(VI) was achieved via the combined effect of reduction and adsorption. The removal of total chromium at pHi = 3 was approximately the same as that of Cr(VI) removal for the KUb composites, but lower for the SEP composites, indicating lower removal of Cr(III) compared to the reduced Cr(VI). The SEP/nZVI composite with the highest removal efficiency was applied for Cr(VI) removal from real wastewater at pHi = 3 and pHi = 5. The results demonstrated the high Cr(VI) removal capacity, validated the assumption that a good dispersion of nZVI particles is beneficial for Cr(VI) removal and showed that the produced green composites can be efficient materials for the removal of Cr(VI) from wastewater.

Identification and screening of priority pollutants in printing and dyeing industry wastewater and the importance of these pollutants in environmental management in China

At present, priority pollutants in printing and dyeing wastewater have attracted increasing attention, but their types and limits in the wastewater discharge standards for China's dyeing and finishing industry are still lacking. This study selected 9 printing and dyeing enterprises in a region of Zhejiang Province as the research objects. Through literature collection, field investigations, and chemical analysis, combined with industry priority pollutant screening technology, 103 and 21 characteristic pollutants were selected as preliminary and supplementary lists of priority pollutants, respectively. The results of the pollutant category analysis revealed that 55% of the pollutants on the preliminary list included carcinogens, and 29% of the pollutants on the supplementary list included alcohols. According to the four rules for in-depth screening, a total of 23 indicators (excluding those in GB 4287-2012 and its revised versions) were selected as the final list of priority pollutants, most of which were polycyclic aromatic hydrocarbons (PAHs) but also included a small number of lipid substances, such as bis (2-ethylhexyl) phthalate. The screening of these indicators not only provides data support for the expansion of water pollution control indicators and the determination of their limits in China's printing and dyeing industry, but also promotes the supplementation and improvement of the sewage discharge standard system in related industries.

Sequential use of coagulation and adsorption methods for COD removal from soft drink industry wastewater

Sequential use of coagulation and adsorption methods for COD removal from soft drink industry wastewater

The Used of Variuos Biomass Waste as Raw Material Biogass Production using Cow Dung as Source of Microbe by Continuously-Anaerobic Fermentation on the 15 Liter Reactor

In Indonesia, there were some biomass wastes if there not treatment, will cause quality- environmental decreasing. It is need effort to minimalize negative effect of those biomass wastes by treating to higher value product. The organic materials in the biomass waste could be anaerobically fermentatation degradated to produce biogass. The anaerobic fermentation were depended on the use of raw materials and microorganism. The organic wastes that use as raw material on this research were (1) tapioca industrial wastewater,(2) tofu industrial wastewater, (3) fruits-peel wastes and (4) vegatable wastes. The source of microbe were found from cow dung The reaserch purpose were to know the influence of the kind of raw materials on the biogas production using cow dung as source of microbe. The research were done at Engineering Faculty Laboratry, Malahayati University Bandarlampung on the 15 liter continuously-anaerobic bioreactor with 15 days retention time. The influen were added 2 liter/2days continuously. The tested variable were COD and biogas composition. The research result showed that the COD in the tapioca industrial wastewater were reduced 71.00 – 89.5 %, in the tofu industrial wastewater reduced 70.00 – 75.00 %, in the fruit-peel waste reduced 7.00-86.00 % andin the vegetable waste reduced 65.00 – 67 %. The CH4 concentration in the produced biogas were 57.63 % ; 40,75 %; 41,41 % and 40.64 %. The C/N ratio effluent between 7.94 – 14.08 could be used directly as liquid organic fertilizer The research conclusion were the production biogas using tapioca industrial wastewater showed the best result . That cause tapioca industrial wasterawte contain high carbohydrate concentration. In the anaerobic digestion, the carbohydrate material were degradated to CH4 (methane)

ADDITIONAL PURIFICATION BY ULTRAVIOLET RADIATION OF RED SPD DYE AFTER ELECTROCHEMICAL DESTRUCTION

Surface water pollution by industrial wastewater is one of the serious environmental problems of the Republic of Uzbekistan. A significant source of pollution is the textile industry, whose wastewater contains organic dyes and various related substances. This article presents the results of a study of the photooxidation of the active dye Red SPD after electrochemical degradation in an electrolytic cell with insoluble anodes. Studies have been carried out to determine the efficiency of active chlorine synthesis in the process of electrolysis of chloride solutions, the effect of active chlorine concentration, electrolyte composition, power consumption when using the combined electrochemical/ultraviolet irradiation process, and changes in the spectral characteristics of the dye solution for carrying out the photooxidation process have been studied. The technological parameters of the method of photooxidative post-treatment in treated water after electrochemistry are established, considering the concentration of oxidizing agents. The maximum current output of active chlorine occurs at a treatment time of 10 minutes. The use of NaCl as an electrolyte in comparison with Na2SO4 showed the best result in the purification process. When using NaCl with a concentration of 1.625 g L-1 in the composition of a sulfate-containing electrolyte, it can reduce the concentration of Red SPD to 1.0 mg L-1. Photooxidative degradation can become an alternative for post-treatment of wastewater from textile enterprises. The developed technology confirms the efficiency of using the combined cleaning method.

Fixed-bed adsorption for industrial wastewater purification: An in-depth review

Fixed-bed adsorption for industrial wastewater purification: An in-depth review

Application of Reduced Graphene Oxide-Zinc Oxide Nanocomposite in the Removal of Pb(II) and Cd(II) Contaminated Wastewater

Toxic metal wastewater is a challenge for exposed terrestrial and aquatic environments, as well as the recyclability of the water, prompting inputs for the development of promising treatment methods. Consequently, the rGO/ZnONP nanocomposite was synthesized at room temperature for four hours and was tested for the adsorption of cadmium and lead in wastewater. The optimized nanocomposite had the lowest band gap energy (2.69 eV), and functional group interactions were at 516, 1220, 1732, 3009, and 3460 cm−1. The nanocomposite showed good ZnO nanoparticle size distribution and separation on rGO surfaces. The nanocomposite’s D and G band intensities were almost the same, constituting the ZnO presence on rGO from the Raman spectrum. The adsorption equilibrium time for cadmium and lead was reached within 10 and 90 min with efficiencies of ~100%. Sips and Freundlich best fitted the cadmium and lead adsorption data (R2 ~ 1); therefore, the adsorption was a multilayer coverage for lead and a mixture of heterogenous and homogenous coverage for cadmium adsorption. Both adsorptions were best fitted by the pseudo-first-order model, suggesting the multilayer coverage dominance. The adsorbent was reused for three and seven times for cadmium and lead. The nanocomposite showed selectivity towards lead (95%) and cadmium (100%) in the interfering wastewater matrix. Conclusively, the nanocomposite may be embedded within upcoming lab-scale treatment plants, which could lead to further upscaling and it serving as an industrial wastewater treatment material.

Comparative Study of Adsorbents for Treatment of Industrial Effluent

Water contaminated with various impurities is considered as wastewater and industrial wastewater obtainedfrom industries is known as effluent. The industrial effluent adversely affects the aquatic ecosystems,deteriorate human health, and degrades overall environmental quality. Treatment of such effluent withadsorbent is one of the most efficient and cost-effective method. In the present study, industrial effluent wastreated with various bio-adsorbents obtained from orange peels, cotton, neem tree bark. Effect of adsorptionon parameters like pH, COD, BOD, TDS and TSS were determined and their results were compared withcommercial grade activated charcoal. For majority of the parameters, the effectiveness of adsorbent varied as:activated charcoal > tree bark-based adsorbent > cotton-based adsorbent > orange peels-based adsorbent.Effect of pretreatment- acid treatment- was also examined for cotton and tree bark-based adsorbent.Phosphoric acid was proven to be better acid for pretreatment in comparison with sulfuric acid. For tree barkbased adsorbent treated with phosphoric acid, % removal for COD, BOD, TDS and TSS were 46.5 %, 57.06%, 35.51% and 90.43% respectively

APPLICATION OF PLANT SEED BIO-COAGULANT IN THE REMEDIATION OF ENVIRONMENTAL PAINT EFFLUENT

The discharge of industrial effluents into the environment has been a growing concern worldwide due to its adverse impacts on human health and the ecosystem. Paint effluent, in particular, poses a significant threat due to its high chemical oxygen demand (COD), total suspended solids (TSS), and colour. Conventional methods of treating paint effluent discharge require the use of chemical coagulants, which are expensive, non-sustainable, and can generate hazardous waste. The search for alternative and sustainable methods for treating industrial effluent has led to the exploration of natural coagulants derived from plant sources. One such source is watermelon seeds, which contain significant amounts of proteins that possess coagulating properties. This study aimed to investigate the potential of watermelon seed bio-coagulant (WSB) for the remediation of paint effluent discharge. The effects of the watermelon seed bio-coagulant dosage, pH, and agitation rate on the removal efficiency of the treatment process were evaluated. These results revealed that the bio-coagulant was effective. The optimum coagulant dosage, pH, and agitation rate were found to be 300mg/L,4, and a treatment time of 45 min, respectively, with BOD and COD removal efficiencies of 88.47% and 90.41%, respectively. Statistical optimization of the treatment process was performed using the response surface methodology (RSM). The results revealed that the quadratic model developed using RSM was statistically significant with a high coefficient of determination (R2 = 0.9958). The analysis also revealed that bio-coagulant dosage and pH are the major factors affecting the efficacy of the treatment process. The optimized conditions led to removal efficiencies of88.95% and 90.61% for BOD and COD, respectively, indicating that watermelon seed bio-coagulant could be an effective and sustainable alternative for treating paint effluent. The results of this study suggest that the use of watermelon seed bio-coagulant is a promising approach for optimizing the paint effluent treatment process. It is a cost-effective and eco-friendly alternative to conventional coagulants used in wastewater treatment and has demonstrated efficacy in treating industrial wastewater. This study presents a sustainable and eco-friendly approach to the treatment of paint effluent discharge using a natural coagulant derived from a waste product.

Enhanced 3D electrochemical degradation of acrylonitrile with Fe-Cu@CB nanoparticles via the hydrogenation-oxidation synergistic processes

Acrylonitrile is a highly toxic and hazardous pollutant present in industrial wastewater at high concentrations, posing significant environmental and health risks. There is an urgent need for efficient, cost-effective, and environmentally friendly treatment methods for acrylonitrile. The electron-withdrawing –CN group in acrylonitrile offers potential pathways for degradation via superoxide radicals (O2•-), but this approach remains underexplored with limited research efforts. To investigate the degradation mechanism of acrylonitrile by O2•-, we synthesized particle electrodes Fe-Cu@CB using a novel one-step co-hydrolysis method and applied them for the 3D electrochemical degradation of acrylonitrile. Batch experiments showed that acrylonitrile with an initial concentration of 100 mg·L−1 was removed by 95 % at a voltage of 2.73 V (vs. RHE) for one hour. Compared with 2D electrochemical degradation, 3D electrochemical degradation of acrylonitrile increased the removal rate from 57 % to 95 %, and the TOC removal rate was also enhanced from 23.59 % to 88.33 %. Additionally, the energy consumed by this system was remarkably lower than the reported 3D electronic reaction system. Based on electron paramagnetic resonance (EPR), oxygen species (ROS) quenching experiments, and GC–MS results, we proposed a new hydrogenation-oxidation synergistic pathway for acrylonitrile removal, which could be depicted as that acrylonitrile suffered hydrogenation, followed by O2•- reduction, and finally the intermediate products were degraded speedily. Other pollutants in acrylonitrile wastewater such as acrylic acid, acrylamide, and fumaronitrile could also be eliminated in this reaction system, and the degradation efficiency varied with the electronic structure of the pollutants. These findings offer new insights into the treatment of acrylonitrile wastewater and present a highly efficient, sustainable solution for industrial pollutant degradation.