Search Results (15)

This study couples a carbon quantum dot photocatalyst with a proton relay installed (EDTA-CQDs) for efficient hydrogen peroxide (H₂O₂) production with an ozone (O₃) system. In situ activation of O₃ is achieved by the photogenerated H₂O₂, which integrates the photocatalytic hydrogen peroxide production (PHP) and advanced oxidation processes (AOPs) to form a new photocatalytic peroxone (H₂O₂/O₃) system, achieving highly efficient solar-driven degradation of recalcitrant organic pollutants in landfill leachate without the addition of external H₂O₂. The composite system exhibits efficient degradation ability for various typical pollutants in landfill leachate, among which the degradation percentage of 100 mg L⁻¹ hydroquinone (HQ) reaches 97% within 30 min. This is due to the synergistic effects of O₃ oxidation, photoactivation of O₃, activation of O₃ by EDTA-CQDs, and activation of O₃ by in situ-generated H₂O₂. In the EDTA-CQD-based H₂O₂/O₃ system, free radicals can be dynamically regenerated after the addition of pollutants, achieving sustained and efficient degradation. Therefore, in the treatment of actual leachate, the removal percentages of COD, TOC, and UV254 are nearly 90%, 70%, and 55%, respectively, demonstrating the significant advantage of this system in treating high-concentration recalcitrant organic pollutants in wastewater of complex quality. Full article

This paper presents a study on the optimization of 2,4-Dichlorophenoxyacetic (2,4-D) acid removal from synthetic wastewater by batch Fenton-Ozonation. The aim of this study is to evaluate the potential of the catalytic system Fe-L27 coupled to ozonation in the presence and absence of H₂O₂ as an effective and affordable technique for the treatment of organic pollutants in water. Fenton-like catalysts for the removal of 2,4-D in aqueous solutions were elaborated using catalysts synthesized by the wet impregnation method. The ACs and prepared catalysts were characterized by nitrogen adsorption–desorption isotherms at 77 K, TGA, XPS, SEM, and TEM. Their efficiency as Fenton-like catalysts was studied. In a first step, a response surface modeling method was employed in order to find the optimal parameters of the Fenton process, and then the optimal O₃/H₂O₂ ratio was established at laboratory scale. Finally, the investigated advanced oxidation processes were carried out at pilot scale. The results show that Fenton-like catalysts obtained by the direct impregnation method enhance the degradation rate and mineralization of 2,4-D. Full article

Electrochemical-based processes have shown great promise in removing organic pollutants such as non-steroidal anti-inflammatory drugs (NSAIDs) from wastewater due to their effectiveness in addressing environmental pollution. This study conducts a bibliometric analysis of the most-cited articles in the field to systematically evaluate the progress and current state of electrochemical methods for NSAID removal from wastewater. Additionally, it highlights the potential of combining electrochemical techniques with other treatment methods to enhance the overall efficiency of NSAID removal. Research in this field has mainly focused on three technologies: electro-peroxone process (E-peroxone), electro-Fenton (EF), and electrochemical oxidation (EO). Early studies prioritized EO-based treatments, but interest has gradually shifted toward EF and E-peroxone. Future research is expected to focus on the development of cost-effective electrode materials, improving energy efficiency, and exploring hybrid systems for more effective treatment of wastewater contaminated with NSAIDs. An integrated bibliometric and systematic review framework presented in this study provides the first comprehensive assessment of electrochemical strategies for NSAIDs removal, highlighting the evolution of research focus and the potential of hybrid approaches. Full article

The current work investigates the intensification process of the biological oxidation (BO) of a pharmaceutical effluent using ultrasound (US)-based pretreatment methods. US, in combination with chemical oxidants, like hydrogen peroxide (H₂O₂), Fenton, potassium persulphate (KPS), and peroxone, was used as a pretreatment technique to enhance the efficacy of BO, as BO alone could only bring about 16.67% COD reduction. The application of US under the optimized conditions of a 70% duty cycle, 120W of power, pH 2, and at a 30 °C temperature resulted in 12.3% COD reduction after 60 min, whereas its combination with oxidants at optimized loadings resulted in a higher COD reduction of 20% for H₂O₂ (2000 ppm), 23.08% for Fenton (1:1 Fe:H₂O₂), and 30.77% for the US + peroxone approach (400 mg/h of ozone with 2000 ppm H₂O₂). The pretreated samples did not produce any toxic by-products, as confirmed by a toxicity analysis using the agar well diffusion method. A cow-dung-based sludge was acclimatised specifically for use in BO. The treatment time for BO was set to 8 h, and the US + peroxone-pretreated samples showed a maximum overall COD reduction of 60%, which is about three times that observed with only BO. This work clearly demonstrates the enhancement of the biodegradation of a complex recalcitrant pharmaceutical effluent using a US-based pretreatment. Full article

The treatment of medical wastewater by the peroxone (AOP) and electro-peroxone (E-peroxone) processes was analyzed. The E-peroxone process is based on the production of hydrogen peroxide electrochemically from an O₂ and O₃ gas mixture produced in sparged ozone generator effluent using graphite-polytetrafluorethylene cathodes. The electrogenerated H₂O₂ reacts with sparged ozone to produce hydroxyl radicals. All advanced oxidation processes presented in this study effectively removed chemical oxygen demand (COD) by up to 87%. The use of E-peroxone showed 15% better results in COD reduction than conventional peroxone. The research suggests that E-peroxone is more sufficient at removing pollutants in wastewater than peroxone. Hence, E-peroxone was found to be more cost-effective than AOP in this case. Full article

A novel material of self-shaped ZnO-embedded biomass carbon foam pellets (ZnO@BCFPs) was successfully synthesized and used as fluidized particle electrodes in three-dimensional (3D) electro-peroxone systems for metronidazole degradation. Compared with 3D and 2D + O₃ systems, the energy consumption was greatly reduced and the removal efficiencies of metronidazole were improved in the 3D + O₃ system. The degradation rate constants increased from 0.0369 min⁻¹ and 0.0337 min⁻¹ to 0.0553 min⁻¹, respectively. The removal efficiencies of metronidazole and total organic carbon reached 100% and 50.5% within 60 min under optimal conditions. It indicated that adding ZnO@BCFPs particle electrodes was beneficial to simultaneous adsorption and degradation of metronidazole due to improving mass transfer of metronidazole and forming numerous tiny electrolytic cells. In addition, the process of metronidazole degradation in 3D electro-peroxone systems involved hydroxyethyl cleavage, hydroxylation, nitro-reduction, N-denitrification and ring-opening. The active species of ·OH and ·O₂⁻ played an important role. Furthermore, the acute toxicity LD₅₀ and the bioconcentration factor of intermediate products decreased with the increasing reaction time. Full article

A wastewater treatment configuration consisting of advanced oxidation pretreatment and biological wastewater treatment process (BWTP) was investigated to treat a reclaimer wastewater generated in a steel-making industry, which contained high concentration MDEA (N-methyldiethanolamine) of up to 20,548 mg/L and other pollutants such as formate, phenol, and thiocyanate. The Fenton, ozone, and peroxone methods were tested as candidates, and the peroxone method was chosen because it could selectively decompose MDEA resulting in the final MDEA and chemical oxygen demand (COD) removal efficiencies of 92.87% and 27.16%, respectively. Through the respirometer tests using the sludge of the BWTP, it was identified that the microbial toxicity of the peroxone-pretreated wastewater was negligible and the short-term biochemical oxygen demand (BOD) to COD ratio, indicating that the biodegradability of wastewater significantly increased from 0.103 to 0.147 by the peroxone pretreatment. Analysis of the oxygen uptake rate profiles also revealed that the microbial degradation rate of the pollutants present in the reclaimer wastewater was in the order of phenol > formate > thiocyanate > MDEA, which could be changed depending on the microbial community structure of the BWTP. Full article

The presence of emerging contaminant para-aminobenzoic acid (PABA) in the aquatic environment or drinking water has the potential to harm the aquatic ecosystem and human health. In this work, the removal of aqueous PABA by a compartmental electro-peroxone (E-peroxone) process was systematically investigated from the kinetic and mechanism viewpoints. The results suggest that single electrolysis or ozonation was inefficient in PABA elimination, and the combined E-peroxone yielded synergistic target pollutant degradation. Compared to the conventional E-peroxone oxidation, the sequential cathodic reactions, followed by anodic oxidations, improved the PABA removal efficiency from ~63.6% to ~89.5% at a 10-min treatment, and the corresponding pseudo first-order kinetic reaction rate constant increased from ~1.6 × 10⁻³ to ~3.6 × 10⁻³ s⁻¹. Moreover, the response surface methodology (RSM) analysis indicated that the appropriate increase of inlet ozone concentration, applied current density, initial solution pH value, and solution temperature could accelerate the PABA degradation, while the excess of these operational parameters would have a negative effect on the treatment efficiency. The comparation tests revealed that the coupling of electrolysis and ozonation could synergistically produce hydroxyl radicals (HO•) and the separation of cathodic reactions and anodic oxidations further promoted the HO• generation, which was responsible for the enhancement of PABA elimination in the compartmental E-peroxone process. These observations imply that the compartmental E-peroxone process has the potential for aqueous micropollutants elimination, and the reaction conditions that favor the reactive oxygen species generation are critical for the treatment efficiency. Full article

Electrochemical advanced oxidation processes (EAOP^®) are promising technologies for the decentralized treatment of water and will be important elements in achieving a circular economy. To overcome the drawback of the high operational expenses of EAOP^® systems, two novel reactors based on a next-generation boron-doped diamond (BDD) anode and a stainless steel cathode or a hydrogen-peroxide-generating gas diffusion electrode (GDE) are presented. This reactor design ensures the long-term stability of BDD anodes. The application potential of the novel reactors is evaluated with artificial wastewater containing phenol (COD of 2000 mg L⁻¹); the reactors are compared to each other and to ozone and peroxone systems. The investigations show that the BDD anode can be optimized for a service life of up to 18 years, reducing the costs for EAOP^® significantly. The process comparison shows a degradation efficiency for the BDD–GDE system of up to 135% in comparison to the BDD–stainless steel electrode combination, showing only 75%, 14%, and 8% of the energy consumption of the BDD–stainless steel, ozonation, and peroxonation systems, respectively. Treatment efficiencies of nearly 100% are achieved with both novel electrolysis reactors. Due to the current density adaptation and the GDE integration, which result in energy savings as well as the improvements that significantly extend the lifetime of the BDD electrode, less resources and raw materials are consumed for the power generation and electrode manufacturing processes. Full article

In keeping with the circular economy approach, reclaiming greywater (GW) is considered a sustainable approach to local reuse of wastewater and a viable option to reduce household demand for freshwater. This study investigated the mineralization of total organic carbon (TOC) in GW using TiO₂-based advanced oxidation processes (AOPs) in a custom-built stirred tank reactor. The combinations of H₂O₂, O₃, and immobilized TiO₂ under either dark or UVA irradiation conditions were systematically evaluated—namely TiO₂/dark, O₃/dark (ozonation), H₂O₂/dark (peroxidation), TiO₂/UVA (photocatalysis), O₃/UVA (Ozone photolysis), H₂O₂/UVA (photo-peroxidation), O₃/TiO₂/dark (catalytic ozonation), O₃/TiO₂/UVA (photocatalytic ozonation), H₂O₂/TiO₂/dark, H₂O₂/TiO₂/UVA, H₂O₂/O₃/dark (peroxonation), H₂O₂/O₃/UVA (photo-peroxonation), H₂O₂/O₃/TiO₂/dark (catalytic peroxonation), and H₂O₂/O₃/TiO₂/UVA (photocatalytic peroxonation). It was found that combining different treatment methods with UVA irradiation dramatically enhanced the organic mineralization efficiency. The optimum TiO₂ loading in this study was observed to be 0.96 mg/cm² with the highest TOC removal (54%) achieved using photocatalytic peroxonation under optimal conditions (0.96 mg TiO₂/cm², 25 mg O₃/min, and 0.7 H₂O₂/O₃ molar ratio). In peroxonation and photo-peroxonation, the optimal H₂O₂/O₃ molar ratio was identified to be a critical efficiency parameter maximizing the production of reactive radical species. Increasing ozone flow rate or H₂O₂ dosage was observed to cause an efficiency inhibition effect. This lab-based study demonstrates the potential for combined TiO₂-AOP treatments to significantly reduce the organic fraction of real GW, offering potential for the development of low-cost systems permitting safe GW reuse. Full article

Autopsies of exhumed bodies pose a risk of infections with environmental bacteria or fungi, which may be life-threatening. Thus, it is important to use effective methods of disinfection in forensic pathology facilities. In this study, we investigated the effectiveness of no-touch automated disinfection (NTD) system after autopsies of exhumed bodies. Directly after 11 autopsies of exhumed bodies, we used an NTD system based on a peroxone vapor to disinfect the air and surfaces. We measured microbial burden in the air and on surfaces before and after NTD. The NTD system reduced the mean bacterial burden in the air from 171 colony forming units (CFU)/m³ to 3CFU/m³. The mean fungal burden in the air decreased from 221 CFU/m³ to 9CFU/m³. The mean all-surface microbial burden was 79 CFU/100 cm² after all autopsies, and it decreased to 2 CFU/100 cm² after NTD. In conclusion, the peroxone-based NTD system was effective for decontamination of the air and surfaces in a dissecting room after autopsies of exhumed bodies. Full article

Background: Hospital-acquired infections (HAIs) remain a common problem, which suggests that standard decontamination procedures are insufficient. Thus, new methods of decontamination are needed in hospitals. Methods: We assessed the effectiveness of a no-touch automated disinfection (NTD) system in the decontamination of 50 surfaces in 10 hospital rooms. Contamination of surfaces was assessed with a microbiological assay and an ATP bioluminescence assay. Unacceptable contamination was defined as > 100 colony forming units/100 cm² in the microbiological assay, and as ≥ 250 relative light units in the ATP assay. Results: When measured with the microbiological assay, 11 of 50 surfaces had unacceptable contamination before NTD, and none of the surfaces had unacceptable contamination after NTD (p < 0.001). On the ATP bioluminescence assay, NTD decreased the number of surfaces with unacceptable contamination from 28 to 13, but this effect was non-significant (p = 0.176). On the microbiological assay taken before NTD, the greatest contamination exceeded the acceptable level by more than 11-fold (lamp holder, 1150 CFU/100 cm²). On the ATP bioluminescence assay taken before NTD, the greatest contamination exceeded the acceptable level by more than 43-fold (Ambu bag, 10,874 RLU). Conclusion: NTD effectively reduced microbiological contamination in all hospital rooms. However, when measured with the ATP bioluminescence assay, the reduction of contamination was not significant. Full article

Plastic products in municipal solid waste result in the extraction of phthalates in leachate that also contains large amounts of organic matter, such as humic substances, ammonia, metals, chlorinated organics, phenolic compounds, and pesticide residues. Phthalate esters are endocrine disruptors, categorized as a priority pollutant by the US Environmental Protection Agency (USEPA). Biological processes are inefficient at degrading phthalates due to their stability and toxic characteristics. In this study, the peroxone (ozone/hydrogen peroxide) process (O₃/H₂O₂), an O₃-based advanced oxidation process (AOP), was demonstrated for the removal of diethyl phthalate (DEP) in synthetic leachate simulating solid-waste leachate from an open dump. The impact of the O₃ dose during DEP degradation; the formation of ozonation intermediate by-products; and the effects of H₂O₂ dose, pH, and ultraviolet absorbance at 254 nm (UVC) were determined during ozonation. Removal of 99.9% of an initial 20 mg/L DEP was obtained via 120 min of ozonation (transferred O₃ dose = 4971 mg/L) with 40 mg/L H₂O₂ in a semi-batch O₃ system. Degradation mechanisms of DEP along with its intermediate products were also determined for the AOP treatment. Indirect OH radical exposure was determined by using a radical probe compound (pCBA) in the O₃ treatment. Full article

The electro-peroxone (E-peroxone) process is an emerging electrocatalytic ozonation process that is enabled by in situ producing hydrogen peroxide (H₂O₂) from cathodic oxygen reduction during ozonation. The in situ-generated H₂O₂ can then promote ozone (O₃) transformation to hydroxyl radicals (•OH), and thus enhance the abatement of ozone-refractory pollutants compared to conventional ozonation. In this study, a chemical kinetic model was employed to simulate micropollutant abatement during the E-peroxone treatment of various water matrices (surface water, secondary wastewater effluent, and groundwater). Results show that by following the O₃ and •OH exposures during the E-peroxone process, the abatement kinetics of a variety of model micropollutants could be well predicted using the model. In addition, the effect of specific ozone doses on micropollutant abatement efficiencies could be quantitatively evaluated using the model. Therefore, the chemical kinetic model can be used to reveal important information for the design and optimization of the treatment time and ozone doses of the E-peroxone process for cost-effective micropollutant abatement in water and wastewater treatment. Full article

A membrane ozonation contactor was built to investigate ozonation using tubular membranes and inform computational fluid dynamics (CFD) studies. Non-porous tubular polydimethylsiloxane (PDMS) membranes of 1.0–3.2 mm inner diameter were tested at ozone gas concentrations of 110–200 g/m³ and liquid side velocities of 0.002–0.226 m/s. The dissolved ozone concentration could be adjusted to up to 14 mg O₃/L and increased with decreasing membrane diameter and liquid side velocity. Experimental mass transfer coefficients and molar fluxes of ozone were 2.4 × 10⁻⁶ m/s and 1.1 × 10⁻⁵ mol/(m² s), respectively, for the smallest membrane. CFD modelling could predict the final ozone concentrations but slightly overestimated mass transfer coefficients and molar fluxes of ozone. Model contaminant degradation experiments and UV light absorption measurements of ozonated water samples in both ozone (O₃) and peroxone (H₂O₂/O₃) reaction systems in pure water, river water, wastewater effluent, and solutions containing humic acid show that the contactor system can be used to generate information on the reactivity of ozone with different water matrices. Combining simple membrane contactors with CFD allows for prediction of ozonation performance under a variety of conditions, leading to improved bubble-less ozone systems for water treatment. Full article