Key Takeaways & Executive Findings
- •• • CA-FeCoCu catalyst achieved >66.7% COD removal in real industrial wastewater, reducing COD from 120 mg·L−1 to below 40 mg·L−1 in a 30-day continuous pilot test, demonstrating long-term stability and industrial viability. • • The O3 consumption ratio (O/C) was less than 1, indicating that the catalyst significantly improved ozone utilization efficiency, directly reducing operational costs compared to conventional ozonation. • • The catalyst exhibited high mechanical strength due to γ-Al2O3 support, overcoming the fragility of carbon-based catalysts, and maintained performance over 30 days, addressing a key bottleneck for industrial application. • • The synergistic effect of Fe, Co, Cu and carbon increased specific surface area and promoted ·OH generation, enhancing degradation efficiency in both simulated phenol wastewater and real industrial effluents.
Abstract
Advanced oxidation processes (AOPs) are promising for degrading organic pollutants in water treatment. Heterogeneous catalytic ozonation (HCO) has gained attention due to its high oxidation efficiency, strong interference resistance, and low secondary pollution. In this study, a series of trimetallic-carbon composite ozone catalysts were prepared via an organic precursor calcination method using γ-Al2O3 as support. This method enhanced catalytic activity and mechanical strength while overcoming the limitations of carbon materials (low mechanical strength) and metal-based materials (poor mass transfer). The optimized catalyst, CA-FeCoCu, comprising Fe, Co, Cu, carbon, and alumina, exhibited excellent performance in phenol degradation and real industrial wastewater treatment. Characterization revealed that the synergistic effect of trimetals and the introduction of multiple carbon types increased specific surface area and hydroxyl radical (·OH) generation. In a pilot-scale fixed-bed reactor, the CA-FeCoCu/O3 system reduced COD from 120 mg·L−1 to below 40 mg·L−1, with an O3 consumption ratio (O/C) of less than 1, effectively lowering operational costs. This work provides a new strategy for developing efficient and stable heterogeneous O3 catalysts and offers a reference for the practical application of HCO in industrial wastewater treatment.
1. Introduction
Industrial wastewater contains recalcitrant organic pollutants that resist conventional biological and physicochemical treatments, posing severe environmental and health risks. Advanced oxidation processes (AOPs), particularly heterogeneous catalytic ozonation (HCO), offer a robust solution by generating highly reactive hydroxyl radicals (·OH). However, traditional ozonation suffers from low ozone solubility, poor mass transfer, and limited oxidation selectivity. While various catalysts have been developed, nano/micro-scale catalysts face issues of agglomeration, difficult recovery, and complex synthesis, whereas millimeter-scale metal-based catalysts exhibit limited mass transfer. Carbon-based supports improve mass transfer but lack mechanical strength and durability. Moreover, most studies remain at laboratory scale, lacking validation in real industrial wastewater treatment.
This research addresses these bottlenecks by designing a trimetallic-carbon composite catalyst supported on γ-Al2O3, combining the high mechanical strength of alumina with the catalytic activity of Fe, Co, Cu, and the enhanced mass transfer properties of carbon. The organic precursor calcination method ensures uniform metal loading and introduces multiple carbon types, increasing specific surface area and ·OH generation. The catalyst demonstrated exceptional performance in both simulated and real wastewater, achieving >66.7% COD removal in a 30-day pilot trial with an O3 consumption ratio below 1, proving its industrial applicability and cost-effectiveness.
Loading authentic research manuscript (Pages 1–5)...
CAO Xu, MEI Hong, WANG Yan, PENG Lijing, LIU Xianwei, JU (2026). Preparation of Trimetallic-Carbon Composite Catalysts and Their Application in Catalytic Ozonation of Industrial Wastewater. Chinese Journal of Environmental Engineering. https://doi.org/10.12030/j.cjee.202506081
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the long-term stability of the CA-FeCoCu catalyst under continuous operation, and what are the deactivation mechanisms?
The catalyst maintained stable performance over a 30-day continuous pilot test, reducing COD from 120 mg·L−1 to below 40 mg·L−1. This suggests minimal deactivation under real wastewater conditions. Potential deactivation mechanisms include metal leaching or fouling by organic intermediates, but the observed stability indicates that the γ-Al2O3 support and carbon layer protect the active sites. Further studies on metal leaching and surface fouling are recommended.
How does the O3 consumption ratio (O/C) of less than 1 translate into operational cost savings compared to conventional ozonation?
An O/C ratio below 1 means that for every unit of COD removed, less than one unit of ozone is consumed. This indicates high ozone utilization efficiency, reducing the amount of ozone required and thus lowering energy and oxygen costs. In the pilot test, this ratio was achieved while meeting discharge standards, demonstrating significant cost savings for full-scale implementation.
What is the role of the carbon layer in enhancing catalytic activity, and how does it affect mass transfer?
The carbon layer, derived from glucose pyrolysis, increases the specific surface area and provides conductive pathways that facilitate electron transfer between ozone and the metal active sites. This promotes the homolytic cleavage of ozone to generate ·OH. Additionally, the carbon layer may enhance adsorption of organic pollutants, improving mass transfer to the catalytic sites. The combination of carbon and metals synergistically boosts catalytic performance.
How does the catalyst perform in treating real industrial wastewater compared to synthetic phenol solutions?
In synthetic phenol solutions, the catalyst achieved high degradation efficiency. In real industrial wastewater (biologically treated effluent), it reduced COD from 120 mg·L−1 to below 40 mg·L−1, demonstrating effectiveness against complex organic matrices. The performance in real wastewater was slightly lower due to the presence of refractory compounds, but the catalyst still met discharge standards, indicating its practical applicability.
What is the scalability of the catalyst synthesis method for industrial production?
The synthesis involves simple steps: impregnation of γ-Al2O3 spheres in a precursor solution, drying, and calcination under N2 atmosphere. This method is easily scalable, as it uses common metal salts and glucose, and does not require complex equipment. The use of millimeter-sized supports facilitates handling and recovery, making it suitable for large-scale fixed-bed reactors. The pilot test confirms the feasibility of scaling up.
Related Chinese Research & Cross-Citations
Analysis of National and Local Policies for Medical Waste Treatment and Disposal in China
The escalating generation of medical waste, driven by healthcare expansion and frequent medical activities, poses significant environmental and public health risks. Under the framework of ecological civilization, China is developing a comprehensive policy system for medical waste treatment and disposal, yet the current framework remains nascent and exhibits inconsistencies between national and local policies. This study systematically analyzes the status of national and local policies from 2003 to 2024, collecting 413 policy documents (166 from national ministries and 247 from provincial governments). The analysis examines temporal evolution, regional distribution, and policy focus, alongside the influence of medical waste output, treatment technologies, facility infrastructure, and major epidemic responses. Findings reveal distinct policy phases: initial self-disposal, exploratory management, foundational system building, and rapid development. Regional disparities are pronounced, with eastern coastal areas showing more advanced policies due to greater technical and financial resources. The surge in medical waste, particularly during the COVID-19 pandemic, underscores the need for enhanced regulatory guidance. Non-incineration technologies are gaining traction for their environmental and cost benefits, and facility coverage has improved but remains uneven. The study proposes five policy principles to foster technological innovation and industrial upgrading, ensuring safe medical waste management and environmental protection.
Kinetic Analysis and Simulation of Pollutant Removal in Sewage Networks
This study investigates pollutant removal characteristics and kinetic behaviors in sewage networks, and analyzes their impact on the carbon-to-nitrogen ratio (C/N, as COD/TN) of influent to wastewater treatment plants. Source water quality sampling at drainage outlets revealed spatial and temporal variations in C/N, with domestic sewage exhibiting higher C/N than industrial sewage, and diurnal peaks reaching 6.92 versus 4.71 during off-peak hours. Using a pilot-scale adjustable sewage network system in Kunshan, experiments were conducted under high (0.491 m·s−1) and low (0.089 m·s−1) flow velocities, monitoring pollutant removal over 144 hours. Pseudo-first-order kinetics were applied to model COD and TN removal. Results showed that COD (including SCOD and PCOD), BOD5, and SS achieved approximately 80% removal within 144 h, with higher removal at low flow velocity. TN, NH3-N, and TP exhibited lower overall removal rates. Kinetic fitting revealed that COD removal rate constants (kCOD) were significantly higher than those for TN (kTN), and both decreased with increasing flow velocity: at low velocity, kCOD=0.0167 h−1 and kTN=0.0029 h−1; at high velocity, kCOD=0.0127 h−1 and kTN=0.0020 h−1. Simulations based on actual source pollutant concentrations indicated that the time for C/N to drop to the denitrification critical value of 4.50 was 12.24 h at high velocity, but shortened to 9.49 h at low velocity. These findings demonstrate that increasing flow velocity effectively retards the decline of C/N. Therefore, regulating network flow velocity to reduce hydraulic retention time is a key strategy for maintaining adequate C/N at the terminal and ensuring denitrification efficiency in wastewater treatment plants.
Differentiated Characteristics of Suspended Particulate Matter and Their Effects on Water Quality in the Middle and East Routes of the South-to-North Water Diversion Project
This study investigates the spatiotemporal differentiation of suspended particulate matter (SPM) characteristics, sources, and their impacts on water quality between the Middle Route (closed artificial channel) and East Route (open natural water system) of the South-to-North Water Diversion Project. Thirty sampling sites (13 on the Middle Route, 17 on the East Route) were established, and samples were collected during dry and wet seasons. Water quality parameters and SPM characteristics were analyzed, including particle size distribution, total suspended solids (TSS), chlorophyll a, and stable carbon and nitrogen isotopes. Results show that the Middle Route maintains good and stable water quality, with SPM dominated by coarse particles (>63 μm, 61.43%–94.68%), total phosphorus (TP) <0.01 mg·L−1, and a significant positive correlation between chlorophyll a and coarse particles (r=0.60), indicating algal aggregation dominates particle formation. In contrast, the East Route exhibits high and fluctuating nitrogen and phosphorus concentrations, with SPM dominated by fine particles (<20 μm, 51.26%–88.61%), TP ranging from 0.03 to 1.11 mg·L−1, and a positive correlation with fine particles, suggesting significant external inputs. Carbon and nitrogen isotope analysis reveals that Middle Route SPM primarily originates from autochthonous algae (contribution >46.75%), while East Route SPM is influenced by both terrestrial C3 plants and algae. The distinct engineering and management approaches of the two routes lead to significant differences in SPM characteristics and sources, thereby affecting water quality dynamics. The Middle Route requires an 'algal reduction and hydrodynamic optimization' strategy to control algal-derived coarse particle deposition, whereas the East Route benefits from 'retention-sedimentation and wetland purification' to reduce external fine particles and pollutant inputs. This research provides theoretical support and practical guidance for differentiated SPM management in long-distance water diversion systems.
Combined Ozone Micro-Nano Bubble Oxidation and Powdered Activated Carbon Adsorption for Removal of Taste and Odor Compounds from Drinking Water
Algal-derived taste and odor compounds (2-methylisoborneol, 2-MIB, and geosmin, GSM) in drinking water sources are poorly removed by conventional treatment. This study systematically evaluated the standalone and combined performance of ozone micro-nano bubbles (O3-MNBs) oxidation and powdered activated carbon (PAC) adsorption for removing 2-MIB, GSM, and algal cells from source water. Results showed that O3-MNBs pre-oxidation achieved >97.5% removal of odorants at 400 ng·L−1 and 67.2% algal cell removal within 30 min. When applied as a deep treatment stage, the degradation rate constant (k) was 10.1%–25.6% higher than in pre-oxidation due to lower background matrix interference. Both pre-oxidation and deep treatment reduced effluent concentrations of 2-MIB and GSM to below 10 ng·L−1, with oxidation kinetics fitting pseudo-first-order models (R²>0.95). PAC adsorption of both compounds followed pseudo-second-order kinetics (R²>0.99), with GSM equilibrium adsorption capacity approximately 20.0% higher than that of 2-MIB. In pure water, adsorption capacity increased by >10.0% compared to raw water. Based on kinetic models, a quantitative prediction method was established for O3-MNBs oxidation and PAC adsorption processes, aiming to achieve efficient odorant removal and cost optimization, providing theoretical support for advanced drinking water purification and smart water plant construction.
Pulsed Electric Field Enhancement of Nitrogen Removal Performance and Microbial Community Structure Response in Anammox Granular Sludge
This study investigated the effects of a ring-shaped pulsed electric field (PEF) (1.5 V, 4 h on-time per cycle) on nitrogen removal performance and microbial community structure of anammox granular sludge (AnGS). Two anaerobic sequencing batch reactors (R1 control, R2 with PEF) were operated under stepwise increasing nitrogen loading rates (NLR). At NLR below 1,155 mg·(L·d)−1, R2 exhibited total nitrogen removal efficiency (TRE) 7.5%–17.0% higher than R1, with biomass, specific anammox activity (SAA), and extracellular polymeric substances (EPS) increased by 5%–7%, 21%–71%, and 54%–77%, respectively. However, at NLR above 1,320 mg·(L·d)−1, the toxic effect of nitrite dominated, and PEF enhancement diminished or even reversed to inhibition. Microbial community analysis revealed that at low-to-moderate NLR, PEF increased the relative abundance of Planctomycetes and key anammox bacteria (Candidatus Brocadia and Candidatus Jettenia), along with enhanced community richness (Chao1) and diversity (Shannon/Simpson indices). At high NLR, PEF decreased microbial richness compared to R1. Principal component analysis and redundancy analysis indicated that PEF was the key factor driving community differences at low-to-moderate NLR, whereas nitrite concentration became the dominant factor at high NLR. This study provides theoretical support for enhancing the resilience and engineering application of anammox processes.
Behavior and Mechanism of Uranium Removal from Acidic Uranium-Contaminated Groundwater by Sandstone Particle/Hydroxyapatite Composite
Acidic in-situ leaching of sandstone-type uranium deposits leaves residual acid and uranium in groundwater, posing environmental risks. This study investigated the feasibility of loading hydroxyapatite (HAP) onto aquifer sandstone particles for in-situ remediation. Sandstone particles were collected from an aquifer and reacted with a HAP-generating solution for 52 days to produce sandstone/HAP composite. Batch experiments examined the effects of initial pH, initial uranium concentration, composite dosage, and interfering ions on uranium removal. Results showed successful HAP loading on sandstone surfaces. At initial pH 3, uranium concentration 5 mg/L, composite dosage 3 g/L, and 24 h reaction, uranium removal reached 95.6%. Interfering ions suppressed removal in the order Fe3+ > Mn2+ > Ca2+ > Mg2+ > SO4^2-. Removal mechanisms included electrostatic adsorption, ion exchange, and dissolution-reprecipitation, with good stability of immobilized uranium. This work validates the concept of in-situ HAP loading in aquifers and provides a basis for practical application in acidic uranium-contaminated groundwater remediation.