Real Wastewater Research Articles

Impact of the Anaerobic Feeding Strategy on the Formation and Stability of Aerobic Granular Sludge Treating Dairy Wastewater

Industrial activated sludge plants in many sectors, including the dairy industry, face sludge separation problems caused by sludge bulking. Aerobic granular sludge (AGS) could be a solution by forming well-settling granules. The key to successful granulation is the microbial selection of slow-growing glycogen-accumulating organisms (GAOs) by introducing an anaerobic feeding/reaction step. The objective of the current study was to investigate the impact of two slow feeding strategies to achieve granulation in existing sequencing batch reactors treating real dairy wastewater, by microbial selection only. The first strategy consisted of slow 90 min mixed feeding. The second strategy combined 45 min static and 45 min mixed feeding to build up a substrate gradient. The feeding strategies did not affect the effluent quality, but significantly impacted the sludge morphology, settling properties, and microbial community composition. Mixed feeding led to filamentous overgrowth by Thiothrix species, up to 45% abundance, and deteriorating settling, with sludge volume index (SVI) values up to 125 mL/g. In contrast, static feeding yielded densified sludge with SVI values below 45 mL/g and up to 35% GAO abundance. In conclusion, the results show successful granulation when using a simple static slow feeding mode, which could benefit the industrial application of AGS technology.

Optimized Solar-Simulated Photocatalysis of Congo Red Dye Using TiO2: Toward a Sustainable Water Treatment Approach.

This study investigates a sustainable approach to the photocatalytic degradation of Congo red (CR) dye using titanium dioxide (TiO2) under simulated solar radiation, with a specific focus on the UV-A component of the radiation. The aim was to optimize reaction conditions to maximize dye removal efficiency while promoting environmentally friendly wastewater treatment practices. A central composite design (CCD) was implemented, and results were analyzed using analysis of variance (ANOVA). The key factors examined included TiO2 concentration, UV-A radiation intensity, CR dye concentration, and suspension depth. The optimal conditions determined were 222.37 mg/L TiO2, 20 W/m2 UV-A irradiation, 25 µmol/L CR dye concentration, and a suspension depth of 29 mm. Under these conditions, decolorization was achieved with the lowest absorbance (0.367 at 498 nm) and total organic carbon (0.805 mg/L) values, indicating effective dye degradation. The findings confirm that TiO2-assisted photocatalysis is a green and promising method for wastewater treatment. The potential use of natural solar radiation could reduce operational costs, making the process more sustainable. However, challenges such as photocatalyst recovery, aggregation, and the impact of the real wastewater matrices need further investigation.

Characterization and Treatment Pharmaceutical Wastewater by Photo-Fenton Process

The characteristics of the PT X pharmaceutical wastewater influent were a pH of 7.18, a COD of 384 mg/L, and a red-brown color. The Chemical Oxygen Demand (COD) has not met the quality standards based on the Ministry of Environment and Forestry Regulation No. 5 of 2014. The red-brown color was caused by wastewater containing rifampicin as a component of the tuberculosis drug. The objectives of this study were treating the real pharmaceutical wastewater to reduce COD and color by varying the molar ratio of the Fenton reagents and to identify the influence of the neutralization process. The Fenton reagents were FeSO4.7H2O and H2O2 with a molar ratio of 1:1.5, 1:2, and 1:3. The process was conducted with the help of UV light and acidic conditions. The photo-Fenton process produced residues, which can be neutralized by using 0.1 NaOH solution and coagulated by using NaCl. The neutralization process successfully decreases the amount of Fe, H2O2, and COD on liquid. The results showed that the best molar ratio is 1:2, which can be seen from the removal efficiency of organic compounds of 89.58%, and the color decrease is seen from the decrease in absorbance value.

Superhydrophilic Quaternized Electrospun Nanofibers for Fast and Efficient Removal of Cr(VI) from Metallurgical Wastewater.

Due to the low adsorption capacity, slow adsorption kinetics, and insufficient selectivity of conventional adsorbents in highly acidic environments, therefore, the removal of highly toxic Cr(VI) from industrial metallurgical wastewater remains a great challenge. Herein, a novel superhydrophilic quaternized nanofiber adsorbent was synthesized using electrospinning technology. The superhydrophilic nanofiber adsorbent facilitated water molecule movement during the adsorption process, which increased the system's free energy and thus promoted the efficient and rapid selective removal of Cr(VI). The adsorbent was completely wetted within 0.06 s and reached a maximum adsorption capacity of 450.33 mg/g in a Cr(VI) solution with an initial concentration of 400 mg/L and equilibrated within 20 min. Adsorption experiments showed that the correlation coefficients of the pseudo-secondary kinetics and Langmuir model of the process were as high as R22 = 0.994 and RL2 = 0.971-0.993, respectively, suggesting that the adsorption process is mainly surface adsorption driven by chemisorption. Moreover, the adsorption mechanism by Zeta potential analysis and XPS and DFT simulations revealed that the selective adsorption for Cr(VI) is the synergistic action of ion exchange and coordination by electrostatic attraction. In addition, the dynamic column adsorption test demonstrated that the adsorbent could adsorb 6000 times its own mass of Cr(VI) ions in metallurgical wastewater, the recovery of Cr(VI) by nanofibers could still reach 89.7% after five cycles, and the removal efficiency was as high as 95.64% in real metallurgical wastewater, which highlighted the potential of its practical application.

Efficient removal of 137Cs isotope from real radioactive wastewater by magnetic nanocomposite zeolite NaA

ABSTRACT A magnetic Fe3O4@ zeolite NaA was prepared using a hydrothermal method to provide magnetic, high surface area cation – exchange material for radioisotope removal from real radioactive wastewater. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), and Bruner Emmett Teller (BET) were used to investigate the Fe3O4@ NaA composite structure, elemental composition, and surface characterisation, respectively. The effect of adsorption parameters including adsorbent dosage, initial concentration of 137Cs isotope, pH, and contact time were investigated. The optimum removal parameters were found to be 10 g L−1, pH 7, and 60 min with a high concentration of caesium. Despite using actual radioactive wastewater and removing Cs radioactive isotope, the composite achieved a high adsorption capacity of 2744.444 mg g−1 which is on par with the reported capacities of synthetic samples with stable Cs salts. The adsorption was categorised as chemisorption on the surface with minimal heterogeneity driven by cation exchange between 137Cs+ and Na+ and entrapments in the pores available on the zeolite structure. These adsorption mechanisms made it easy to regenerate the adsorbent with a small loss of ~ 5% capacity after using it for three cycles. This material exhibited rapid performance in the treatment of radioactive water, as compared to conventional techniques, owing to its magnetic properties. Consequently, this meets the principles of radioactive waste management by minimising the risk posed by substantial amounts of this isotope in water and transforming it into a tiny solid state that can be simply managed when stored as radioactive waste, based on its measured quantity in the contaminated water. As a result, our investigated study presents a simple, efficient, and scalable synthesis procedure that delivers viable applications of the magnetic Fe3O4@zeolite NaA nanocomposite as a lower-cost adsorbent for hazardous liquid radioactive waste treatment.

Porous Carbon Derived from Pumpkin Tissue as an Efficient Bioanode Toward Wastewater Treatment in Microbial Fuel Cells

A novel three-dimensional porous biocarbon electrode with exceptional biocompatibility was synthesized via a facile approach using pumpkin as the precursor. The obtained pumpkin-derived biocarbon features a highly porous architecture and serves as an efficient biocarbon electrode (denoted as PBE) in a microbial fuel cell (MFC). This PBE could form robust biofilms to facilitate the adhesion of electroactive bacteria. When used in the treatment of real wastewater, the assembled PBE-MFC achieves a remarkable power density of 231 mW/m2, much higher than the control (carbon brush—MFC, 164 mW/m2) under the identical conditions. This result may be attributed to the upregulation of flagellar assembly pathways and bacterial secretion systems in the electroactive bacteria (e.g., Hydrogenophaga, Desulfovibrio, Thiobacillus, Rhodanobacter) at the anode of the PBE-MFC. The increased abundance of nitrifying bacteria (e.g., Hyphomicrobium, Sulfurimonas, Aequorivita) and organic matter-degrading bacteria (e.g., Lysobacter) in the PBE-MFC also contributed to its exceptional wastewater treatment efficiency. With its outstanding biocompatibility, cost-effectiveness, environmental sustainability, and ease of fabrication, the PBE-MFC displays great potential for application in the field of high-performance and economic wastewater treatment.

Fe2+-Coupled Organic-Substrate-Enhanced Nitrogen Removal in Two-Stage Anammox Biofilm Reactors

Anammox is a novel and energy-efficient biological nitrogen removal technology. Enhancing its performance in treating low-strength nitrogen wastewater is essential for expanding its practical applications. In response to challenges such as low nitrogen removal efficiency (NRE), poor operational stability, limited environmental resistance, and the interference of organic compounds commonly found in real wastewater, this study developed a two-stage upflow anammox biofilm reactor system (R1 and R2) enhanced by an Fe2+-coupled organic substrate strategy for deep nitrogen removal under low-nitrogen conditions. Results showed that sodium acetate at a chemical oxygen demand (COD) concentration of 40 mg/L provided the greatest enhancement to anammox activity, achieving an average total nitrogen removal efficiency (NRE) of 90.02%. However, the reactor performance was significantly inhibited under higher COD conditions (e.g., COD = 60 mg/L). Under an influent Fe2+ concentration of 10 mg/L, the reactors’ NRE increased and then decreased as the COD concentration rose from 0 to 100 mg/L, resulting in the highest efficiency being achieved at an average NRE of 94.11%, observed under 10 mg/L Fe2+ coupled with 60 mg/L of COD in the two-stage anammox system. Scanning electron microscopy revealed that the co-addition of Fe2+ and organic substrates led to the formation of granular protrusions and pores on the sludge surface, which favored the structural stability of the biomass. At a COD level of 40 mg/L, the contents of extracellular polymeric substances and heme c in anammox biofilm were significantly higher compared to the addition of 10 mg/L Fe2+ alone, whereas excessive COD inhibited both indicators. These findings suggest that moderate levels of Fe2+ coupled with organic matter can promote anammox activity for deep nitrogen removal, while excessive organics have inhibitory effects. This study provides theoretical support for enhancing nitrogen removal from low-strength wastewater using Fe2+ and organic-substrate-assisted anammox processes.

Valorization of Golden Mussel Shells for Sustainable Phosphorus Recovery in Wastewater Treatment

The golden mussel (Limnoperna fortunei) poses environmental and infrastructural challenges due to its ability to attach to various substrates and form dense colonies. These colonies are difficult to remove and threaten hydroelectric power stations, water treatment plants and fishing activities. However, the high calcium carbonate content of golden mussel shells (GMSs) presents an opportunity for phosphorus (P) recovery from wastewater, addressing both waste management and resource scarcity. This study evaluated the effectiveness of GS for P recovery from synthetic and real wastewater. Batch experiments were conducted to assess P recovery capacity under varying adsorbent dosages, pH levels, contact times and isotherm conditions (Langmuir, Freundlich and Temkin). Also, the chemical and physical analyses of GMSs were performed to elucidate the mechanisms of P recovery. The Freundlich isotherm model best describes the process, while the Langmuir model suggests a maximum recovery potential of approximately 59.9 mg P g−1 of GMS, demonstrating a P recovery efficiency of up to 60.7% at a P concentration of 40–50 g L−1 and a contact time of 3 h. Due to the predominance of negative charges, it was concluded that the precipitation was the major mechanism for P recovery by GS. This study highlights the potential of GMSs as a sustainable and low-cost material for phosphorus recovery in wastewater treatment, offering a promising solution for both waste valorization and environmental management contributing to a circular economy.

The hidden toxicity of Solid Phase Extraction blanks in water analysis.

Non-toxic blank samples are a prerequisite in Effect Directed Analysis (EDA) to ensure that any measured bioassay activity stems from chemicals in the environmental sample, and not from chemicals added through the sampling and sample preparation procedures. In a study on wastewater, solid phase extraction (SPE) blank samples, prepared by extracting clean water (such as tap water, demineralized water etc) using the same methodology as real wastewater, showed toxic effects in algae, daphnia and in vitro bioassays. The aim of this study was to pinpoint the origin of the chemicals responsible for the observed toxicity, and to provide guidance on how to remediate their occurrence. Analysis revealed that the elution solvents optimized for SPE, composed of methanol (MeOH), NH4OH, and formic acid (FA), constituted a significant source of toxicity, even when evaporated to dryness. Ammonium was the primary source of toxicity in the algae assay. FA released toxic metal ions from the system and SPE materials, particularly Cu and Zn, which strongly affected daphnia. Switching to pure MeOH as the elution solvent alleviated most of the toxicity, although some metals remained. Further reductions in toxicity were achieved by replacing ultra-pure water with an ion-rich artificial freshwater medium for preparing blank samples. Three tested SPE materials (GCB, HLB and ENV+) released unidentified toxic chemicals correlating with algae toxicity and estrogen receptor activity, but these could be eliminated through extensive MeOH washing before packing the cartridges. Non-toxic levels of plasticizers were detected from system components. In conclusion, altering SPE elution solvents, washing SPE materials, and using artificial freshwater as blanks minimized the release of chemicals and ensured non-toxic blank samples.

A Novel Green In Situ Amine-Functionalized Aerogel UiO-66-NH2/TOCNF for the Removal of Azo Anionic Dyes.

UiO-66-NH2 is a metal-organic framework (MOF) with open metal sites, making it a promising candidate for adsorption and catalysis. However, the powdery texture of MOFs and the use of toxic solvents during synthesis limit their application. A novel solution to this issue is to create a layered porous composite by encasing the MOF within a flexible and structurally robust aerogel substrate using safe, eco-friendly, and green solvents such as ethanol. The fibrous MOF aerogels, characterized by a desirable macroscopic shape of cylindrical block and hierarchical porosity, were synthesized by two approaches: in situ growth of amine-functionalized UiO-66-NH2 crystals on a TEMPO-oxidized cellulose nanofiber (TOCNF) and ex situ crosslinking of UiO-66-NH2 crystals onto a TOCNF network to form UiO-66-NH2/TOCNF. The incorporation of MOF into the cellulose nanofibrils via the in situ method reduces their aggregation potential, alters the nucleation/growth balance to produce smaller MOF crystals, and enhances mechanical flexibility, as evidenced by SEM images. The three adsorbents, including UiO-66-NH2, ex situ UiO-66-NH2/TOCNF, and in situ UiO-66-NH2/TOCNF, were synthesized and used in this study. The effects of pH, time, temperature, and initial concentration were studied. A maximum adsorption capacity (Qmax) of 549.45 mg/g for Congo Red (CR) and 171.23 mg/g for Orange II (ORII) was observed at pH 6, using 10 mg of in situ UiO-66-NH2/TOCNF at 40 °C with a contact time of 75 min for CR and 2 h for ORII. The adsorption of both dyes primarily occurs through monolayer chemisorption on the in situ UiO-66-NH2/TOCNF. The main removal mechanisms were hydrogen bonding and surface complexation. The noteworthy adsorption capacity of in situ UiO-66-NH2/TOCNF coupled with environment-friendly fabrication techniques indicates its potential applications on a large scale in real wastewater systems.

Effects of Chemical Pretreatment on Natural Fibers Removal and Microplastics Integrity for Wastewater Characterization.

Nine digestion protocols were tested to quantify microplastics in wastewater using nine polymeric and three natural fiber controls representative of common microplastics in wastewater. Protocols were also evaluated for their impact on natural fibers, which can interfere with microplastic quantification. Control size change and visual integrity were assessed, revealing that a sequential 24-h treatment with 6% NaClO at room temperature (RT) followed by 24 h with 30% H2O2 at 40 °C preserved polymer integrity while fully oxidizing natural fibers, even when preincubated in real wastewater samples. A Fourier-transform infrared spectroscopy (FTIR) validation using the carbonyl index (CI) and carbon-oxygen index (COI) showed significant changes in poly-(ethylene terephthalate) (PET) and polyvinyl chloride (PVC) after digestion but did not compromise FTIR spectrum recognition. The protocol applied to raw wastewater samples showed optimal performance at 300 mg Cl2/L, achieving up to 95% Chemical Oxygen Demand (COD) and 92% turbidity reduction. No further improvements in COD or turbidity removal were observed beyond this dose, regardless of initial COD levels. The present approach affords greater comparability with existing studies thanks to a large range of polymeric, natural controls, and oxidant dose investigations regarding common water quality parameters.

Synthesis of Lanthanum-Modified Natural Magnetite: Characterization and Valorization for Phosphorus Recovery from Aqueous Solutions.

In this research work, a natural sample from an Omani magnetite (MG) deposit was used for the synthesis of a magnetite decorated with ferrihydrite (MG-Fh), and two lanthanum (La)-modified materials at mass percentages of 5% (MG-Fh-La-5) and 15% (MG-Fh-La-15). These materials were first characterized using various analytical techniques. Then, their phosphorus (P) recovery efficacy from aqueous solutions was studied in batch mode under a wide range of experimental conditions. The characterization results show that compared to the raw feedstock, MG-Fh, MG-Fh-La-5, and especially MG-Fh-La-15 have improved structural, textural, and surface chemistry properties. Adsorption tests indicate that due to the deposition of high contents of lanthanum oxides on its surface, the MG-La-15 exhibited a large P uptake capacity (34.5 mg g-1), which is significantly superior to those determined for MG-La-5 (24.3 mg g-1), MG-Fh (12.4 mg g-1), and various engineered materials published in the literature. Moreover, these materials retain an interesting ability to recover P from real wastewater with a highest adsorbed mass of 27.3 mg g-1, observed for MG-La-15. The P recovery seems to involve both physical and chemical mechanisms, including electrostatic interactions and complexation. This research work shows that La-modified magnetite can be considered a promising and eco-friendly material for P recovery from liquid effluents.

Synthesis and Characterization of MAPTAC-Modified Cationic Corn Starch: An Integrated DFT-Based Experimental and Theoretical Approach for Wastewater Treatment Applications

Phosphorus contamination in water bodies is a major contributor to eutrophication, leading to algal overgrowth, oxygen depletion, and ecological imbalance. Conventional treatment methods, including chemical precipitation and synthetic adsorbents, are often limited by high operational costs, low biodegradability, and secondary pollutant generation. In this study, a cationic starch was synthesized through free radical graft polymerization of 3-methacrylamoylaminopropyl trimethyl ammonium chloride (MAPTAC) onto corn starch. The modified polymer exhibited a high degree of substitution (DS = 1.24), indicating successful functionalization with quaternary ammonium groups. Theoretical calculations using zDensity Functional Theory (DFT) at the B3LYP/6-311+G(d,p) level revealed a decrease in chemical hardness (from 0.10442 eV to 0.04386 eV) and a lower ionization potential (from 0.24911 eV to 0.15611 eV) in the modified starch, indicating enhanced electronic reactivity. HOMO-LUMO analysis and molecular electrostatic potential (MEP) maps confirmed increased electron-accepting capacity and the formation of new electrophilic sites. Experimentally, the cationic starch showed stable zeta potential values averaging +15.3 mV across pH 5.0–10.0, outperforming aluminum sulfate (Alum), which reversed its charge above pH 7.5. In coagulation-flocculation trials, the modified starch achieved 87% total suspended solids (TSS) removal at a low coagulant-to-biomass ratio of 0.0601 (w/w) using Scenedesmus obliquus, and 78% TSS removal in real wastewater at a 1.5:1 ratio. Additionally, it removed 30% of total phosphorus (TP) under environmentally benign conditions, comparable to Alum but with lower chemical input. The integration of computational and experimental approaches demonstrates that MAPTAC-modified starch is an efficient, eco-friendly, and low-cost alternative for nutrient and solids removal in wastewater treatment.

Biomarker Detection in the Wastewater Phantom.

Research trends are focused on developing solutions that monitor public health utilizing sewage surveillance, as wastewater can provide valuable information on the presence of specific biomarkers. Such information can serve as an indication of immune response at the community level, delivering a noninvasive measure of e.g., vaccination effectiveness. In this paper, we present an optical wastewater phantom fabrication, characterization, and comparison to real wastewater samples. Raman spectroscopy was used for the investigation of the molecular compositions of treated wastewater and artificial wastewater phantoms, and the refractometer to investigate refractive index values dependence on temperature. Selected biomarkers concentrations (10-6 to 10-1 mg/mL) were added to the validated phantoms. The selective detection of SARS-CoV-2 immunoglobulin G (IgG) was achieved through specific surface modification of the fiber-optic probe, allowing only targeted biomarkers to attach and influence the measurement signal. Successful detection of 10-6 mg/mL IgG concentration in the wastewater phantom was achieved within 5 min.

Flowing Microreactors for Periodate/H2O2 Advanced Oxidative Process: Synergistic Degradation and Mineralization of Organic Dyes

The periodate/hydrogen peroxide (PI/H2O2) system is a recently developed advanced oxidation process (AOP) characterized by its rapid reaction kinetics, making it highly suitable for continuous-flow applications compared to conventional batch systems. Despite its potential, no prior studies have investigated its performance under flowing conditions. This work presents the first application of the PI/H2O2 process in a tubular microreactor, a promising technology for enhancing mass transfer and process efficiency. The degradation of textile dyes (specifically Basic Yellow 28 (BY28)) was systematically evaluated under various operating conditions, including reactant concentrations, flow rates, reactor length, and temperature. The results demonstrated that higher H2O2 flow rates, increased PI dosages, and moderate dye concentrations (25 µM) significantly improved degradation efficiency, achieving complete mineralization at 2 mM PI and H2O2 flow rates of 80–120 µL/s. Conversely, elevated temperatures negatively impacted the process performance. The influence of organic and inorganic constituents was also examined, revealing that surfactants (SDS, Triton X-100, Tween 20, and Tween 80) and organic compounds (sucrose and glucose) acted as strong hydroxyl radical scavengers, substantially inhibiting dye oxidation—particularly at higher concentrations, where nearly complete suppression was observed. Furthermore, the impact of water quality was assessed using different real matrices, including tap water, seawater, river water, and secondary effluents from a municipal wastewater treatment plant (SEWWTP). While tap water exhibited minimal inhibition, river water and SEWWTP significantly reduced process efficiency due to their high organic content competing with reactive oxygen species (ROS). Despite its high salt content, seawater remained a viable medium for dye degradation, suggesting that further optimization could enhance process performance in saline environments. Overall, this study highlights the feasibility of the PI/H2O2 process in continuous-flow microreactors and underscores the importance of considering competing organic and inorganic constituents in real wastewater applications. The findings provide valuable insights for optimizing AOPs in industrial and municipal wastewater treatment systems.

Study on the recycling strategy of wastewater algae by extracting bio-oil from Dunaliella salina and combining it with pyrolysis biochar

Background The sustainable utilization of Dunaliella salina biomass for biochar and bio-oil production offers a promising approach for pollutant removal and biofuel generation. This study aimed to optimize pyrolysis conditions and evaluate the physicochemical properties of biochar and bio-oil derived from D. salina under real wastewater treatment conditions. Methods D. salina was cultivated in wastewater under controlled aeration (2 L/min) and continuous illumination (100 µmol photons m−2 s−1) for 21 days. Biomass was harvested via centrifugation, dried at 60 °C, and subjected to pyrolysis at temperatures ranging from 400 °C to 900 °C under a nitrogen atmosphere. Biochar yield was determined gravimetrically, and adsorption efficiency was assessed by treating metal-contaminated water with biochar. Bio-oil composition was analysed using GC-MS and NMR spectroscopy, while biochar structural properties were characterized via FE-SEM, XPS, and FTIR. Gas chromatography quantified gas composition, and a life-cycle assessment evaluated environmental impacts. Results Biochar yield decreased from 48.6% at 400 °C to 20.8% at 900 °C, with a corresponding decline in activation energy from 162.3 to 121.9 kJ/mol. DTG analysis showed peak decomposition temperatures shifting from 325 °C to 415 °C, indicating progressive thermal degradation. Bio-oil yield peaked at 45.3% at 550 °C, with dominant compounds including 29.4% aromatics, 22.5% phenols, and 18.3% ketones. Biochar adsorption efficiency reached 95.0% for Pb2+, 96.0% for Cd2+, and 90.0% for As³+, with a maximum surface area of 600 m2/g at 650 °C. Life-cycle analysis indicated a 60.9% reduction in GWP and a 73.3% decrease in fossil resource depletion for biochar compared to bio-oil production. Conclusion Biochar and bio-oil from D. salina demonstrated high adsorption efficiency and fuel potential, supporting their application in environmental remediation and sustainable energy production.

Unlocking single-atom induced electronic metal-support interactions in electrocatalytic one-electron water oxidation for wastewater purification

Electro-oxidation is a promising green technology for decentralized wastewater purification. However, its efficacy is primarily constrained by the selectivity and efficiency of hydroxyl radical (•OH) generation through one-electron water oxidation. In this study, we elucidate the mechanism of electronic metal-support interactions (EMSI) of Ni single-atoms on antimony-doped tin oxide anode (Ni/ATO) to enhance •OH production and overall water treatment efficiency. We experimentally and theoretically investigate both the structural evolution process and micro-interface mechanisms associated with the EMSI effects induced by Ni single-atoms. The optimized electronic structures in the interfacial catalysts under EMSI conditions and the co-catalytic role of Ni single-atoms synergistically facilitate selective and efficient •OH generation, resulting in over a fivefold increase in its steady-state concentration and tenfold enhancement in pseudo-first-order rate constant of sulfamethoxazole degradation compared to those on bare ATO. With the EMSI, rapid electron transfer channels were established for a marked enhancement in the adsorption, conversion, and dissociation of interfacial H2O molecules. Notably, it is revealed that Ni single-atoms serve as co-catalytic sites, exhibiting a “H-pulling effect” that is crucial for •OH generation. The Ni/ATO anode demonstrates great efficiency in degrading various refractory organic pollutants, and effectively treats real pharmaceutical wastewater with low energy consumption. Furthermore, it presents remarkable stability and adaptability, while maintaining a minimal environmental footprint during wastewater treatment processes. This work addresses the theoretical gaps between EMSI effects and co-catalysis in electro-oxidation systems, while providing a robust technological solution for wastewater purification.

Strengthened pollutants abatement in wastewater through electrocoagulation and zeolite adsorption: analytical and microbial assessment.

As the global population rapidly increases, so does the water demand, making effective wastewater treatment essential to mitigate pollutants, including heavy metals, organic compounds, and microbial contaminants. These pollutants pose significant health risks, exacerbate environmental crises, and disrupt ecosystems, emphasizing the urgent need for sustainable solutions. This study explores the electrocoagulation-adsorption (EC-Ads) integrated treatment process as a promising approach for contaminant removal from wastewater. The method simultaneously generates in situ coagulants while leveraging the retention capabilities of zeolite. A NaOH-prefusion-mediated hydrothermal synthesis was employed to convert clay-rich illite and fumed silica by-product into pure analcime-C zeolite. This material demonstrated high crystallinity (89%), a specific surface area of 23.76 m2/g, and a cation exchange capacity (CEC) of 510 meq/100g. Initially, the EC process was optimized for chromium (VI) removal from synthetic solutions, achieving an 85% removal efficiency at an energy consumption of 0.5 kWh/g under optimal conditions (initial pH 5, current density 10 mA/cm2, and electrolysis time 40 min). Subsequently, the EC and EC-Ads processes were applied to real wastewater samples. Under optimized conditions, the EC-Ads process achieved 97.85% chromium removal with an energy consumption of 7.32 Wh/L. Additionally, reductions in chemical oxygen demand (COD) and total organic carbon (TOC) were observed at 60.19% and 94.09%, respectively. Notably, complete eradication (100%) of microbial contaminants, including microflora, fungi, and coliforms, was achieved. These findings highlight the efficiency and sustainability of the EC-Ads integrated approach in removing diverse pollutants from wastewater, offering a reliable solution to enhance water quality in treatment facilities.

Mitigating the Challenges of Textile Wastewater Treatment in Saudi Arabia Utilizing Electrocoagulation Process: Optimization of Operating Parameters

The increasing importance of treating industrial effluents for environmental and public health protection has necessitated reliable and economical treatment methods capable of meeting stringent effluent quality standards. This study aimed to evaluate the effectiveness of the electrocoagulation (EC) process using iron electrodes for treating real textile wastewater by removing total solids (TS), COD, colour, and turbidity. Various operating parameters, including treatment time, initial pH, current density, stirring speed, and inter-electrode spacing (IES), were investigated to optimize removal efficiency. The results demonstrated that the optimal conditions for maximum pollutant removal were achieved at a treatment time of 60 minutes, a current density of 6.2 mA/cm², a solution pH of 8-8.5, a stirring speed of 150 rpm, and an IES of 5 cm. Under these conditions, the removal efficiencies reached 79.2% for TS, 92.7% for COD, 88.9% for turbidity, and 98.7% for colour. The findings of this research indicate that the EC process is a simple, quick, and economically viable method for effectively removing pollutants from textile wastewater. Additionally, it is recommended that a coupled treatment unit, such as filtration or adsorption, be employed following the EC process to enhance pollutant removal. Saudi Arabia’s Vision 2030 aims to address environmental pollution from industrial wastewater, including textile wastewater, highlighting the importance of balancing industrial growth with environmental stewardship. Present study offers the first thorough analysis of textile wastewater treatment utilizing EC process in the region, enhancing understanding of effective strategies for sustainability and compliance with effluent quality standards.

Advanced treatment of tannery effluent from Fez City (Morocco) using a sequence of aerobic and sono-photo-Fenton processes

This work aims to purify real tannery wastewater (TWW) after a physicochemical characterization. A pretreatment using air stripping (aerobic pretreatment; AP) was first applied and compared to anaerobic pretreatment (ANP). The COD and BOD5 were highly removed by AP, reaching 86% and 88% compared to ANP, which only achieved 48% and 55%, respectively. Following the AP, the sono-photo-Fenton (SPF) process was applied as post-treatment. The optimal conditions pH = 3, [H2O2] = 1834 mg/L, and [Fe2+] = 1281 mg/L improved the COD, color and BOD5 removal of 96%, 98%, and 98%, respectively. Turbidity, N-NO3 -, and N-NO2 - were completely removed (100%) by the combined processes (AP+SPF), while Cr, Cl-, and N-NH4 + were reduced to 99%, 97%, and 99%, respectively. Finally, phytotoxicity tests were performed to confirm the efficiency of the sequential processes. The highest germination percentage, germination rate index, and seedling vigor index for the grains wheat and Medicago sativa were observed using the TWW treated by the AP+SPF, followed by those treated by AP alone. In contrast, no germination indicators were noticed in raw TWW. These findings highlight the significant purification effectiveness of the sequential processes of AP and SPF post-treatment, which suggests the potential use of this combination for the efficient treatment of real liquid effluents.