Ozone Oxidation Process Research Articles

Preparation of Co-Ce@RM catalysts for catalytic ozonation of tetracycline.

In this work, a Co-Ce@RM ozone catalyst was developed using red mud (RM), a by-product of alumina production, as a support material, and its preparation process, catalytic efficiency, and tetracycline (TCN) degradation mechanism were investigated. A comprehensive assessment was carried out using the 3E (environmental, economic, and energy) model. The optimal production conditions for Co-Ce@RM were as follows: The doping ratio of Co and Ce was 1:3, the calcination temperature was 400°C, and the calcination time was 5h, achieving a maximum removal rate of 87.91% of TCN. The catalyst was characterized using different analytical techniques. Under the conditions of 0.4L/min ozone aeration rate, with 9% catalyst loading and solution pH9, the optimal removal rates and chemical oxygen demand by the Co-Ce catalytic ozonation at RM were 94.17% and 75.27%, respectively. Moreover, free radical quenching experiments showed that superoxide radicals (O2 -) and singlet oxygen (1O2) were the main active groups responsible for the degradation of TCN. When characterizing the water quality, it was assumed that TCN undergoes degradation pathways such as demethylation, dehydroxylation, double bond cleavage, and ring-opening reactions under the influence of various active substances. Finally, the 3E evaluation model was deployed to evaluate the Co-Ce@RM catalytic ozonation experiment of TCN wastewater. PRACTITIONER POINTS: The preparation of Co-Ce@RM provides new ideas for resource utilization of red mud. Catalytic ozonation by Co-Ce@RM can produce 1O2 active oxygen groups. The Co-Ce@RM catalyst can maintain a high catalytic activity after 20 cycles. The degradation pathway of the catalytic ozonation of tetracycline was fully analyzed. Catalytic ozone oxidation processes were evaluated by the "3E" (environmental, economic, and energy) model.

Catalytic Ozonation Treatment of Coal Chemical Reverse Osmosis Concentrate: Water Quality Analysis, Parameter Optimization, and Catalyst Deactivation Investigation.

Catalytic ozone oxidation, which is characterized by strong oxidizing properties and environmental friendliness, has been widely used in organic wastewater treatments. However, problems such as a low organic pollutant removal efficiency and unstable operation during the catalytic ozone treatment process for wastewater remain. To address these disadvantages, in this study, the treatment efficacy of catalytic ozone oxidation on a coal chemical reverse osmosis concentrate was investigated. The basic water quality indicators of the chemical reverse osmosis concentrate were analyzed. The effects of initial pollutant concentration, pH, ozone concentration, and catalyst concentration on the COD removal rate from the coal chemical reverse osmosis concentrate were explored. Water quality indicators of the chemical reverse osmosis concentrate before and after the catalytic ozone treatment were studied using spectroscopic analysis methods. The RO concentrate demonstrated large water quality fluctuations, and the catalytic ozonation process removed most of the pollutants from the treated wastewater. A possible deactivation mechanism of the ozone catalyst was also proposed. This study provides a theoretical reference and technical support for the long-term, efficient, and stable removal of organic pollutants from coal chemical reverse osmosis concentrate using a catalytic ozone oxidation process in practical engineering applications.

Treatment of aircraft maintenance wastewater by coupling low-temperature evaporation with Fe–C micro-electrolysis-configured ozonation

ABSTRACT A novel approach combining low-temperature evaporation with Fe–C micro-electrolytic ozone oxidation has been devised for treating substantial volumes of high-concentration organic cleaning wastewater generated during aircraft maintenance activities. The findings from experiments demonstrate impressive average removal rates for various contaminants, including chemical oxygen demand (93.1%), oil concentration (94.0%), suspended solids (98.9%), turbidity (98.8%), chroma (93.8%), total nitrogen (93.7%), and total phosphorus (99.2%). Within this integrated system, the synergistic effects between ozone oxidation, catalytic fillers, and electrochemical processes significantly enhance pollutant removal efficiency. The chemical oxygen demand reduction rates of the cleaning wastewater derived from engine maintenance, mechanical and electrical maintenance, aircraft accessory maintenance, and mixed wastewater exceed 98%. The optimal reaction times for four types of wastewater are 150, 120, 90, and 120 min, respectively. The time can be adjusted according to the different treatment objects in actual operation projects. Moreover, the average concentration efficiency achieved surpasses 92% while meeting all effluent quality standards set forth by municipal sewage networks, and it has reduced the disposal cost of the enterprise by about 80%. This technology provides enterprises with an effective way to reduce energy consumption and expenses.

Pilot testing and engineering application of O3/H2O2 process for 2-methylisoborneol and geosmin removal in drinking water treatment

Microorganisms in source water, including algae, actinomycetes and other microbes, produce secondary metabolites during growth, particularly 2-methylisoborneol (2-MIB) and geosmin (GSM), which emerge as the primary contributors to taste and odor issues in drinking water. Although the conventional ozone (O3) oxidation process has been widely adopted to address the odor issue, it frequently exhibits inadequate removal efficiency for 2-MIB and GSM, and presents the risk of bromate formation exceeding regulation limit when processing bromine-enriched water. In this study, a pilot study applying the O3/H2O2 advanced oxidation process (AOP) was conducted to overcome the above problems. The influence of variables, including O3 dosage, O3/H2O2 ratio, etc., on the removal efficiency of 2-MIB, GSM, natural organic matter as the permanganate index (PI), and bromate formation was investigated, and compared with the conventional ozonation process. According to the pilot-scale experiments, the O3/H2O2 AOP demonstrated remarkable efficacy in effectively eliminating odorous substances and inhibiting bromate formation. The full-scale application of the O3/H2O2 AOP at a 120,000 m3/d water plant in Shandong, China also showed that while the 2-MIB and GSM concentrations in raw water were up to 260 and 33 ng/L, respectively, the treated water had 2-MIB and GSM concentrations <10 ng/L, which fulfills the “Standards for Drinking Water Quality” of China (GB 5749-2022). Meanwhile, bromate remained undetectable.

Comparison on the formation and toxicity for chlorinated products during the oxidation of acetic acid (CH3COOH) by three widely used advanced oxidation processes (AOPs) at the presence of [formula omitted

As a technology for industrial wastewater advanced treatment, there is a lack of relevant information the impacts of the treated effluents by advanced oxidation processes (AOPs) on ecological environment. Therefore, this study mainly compared the differences of the formation types and concentrations of chlorinated organic products（COPs）and active inorganic chlorine species (AICS) and toxicity changes in the oxidation of CH3COOH by three commonly used AOPs technologies as Fenton, ozone and electrochemical advanced oxidation process (EAOP) with the addition of Cl−. The results illustrate that in the EAOP process, trichloromethane (TCM) and Chloroacetic acids (CAAs) were the main COPs in the oxidation of CH3COOH by EAOP at 120 min. CCl4 was major COPs for the Fenton and ozone oxidation of CH3COOH, respectively. Through the algae growth inhibition experiment and the toxicity evaluation by using ECOTOX toxicity database, the toxicity of EAOP oxidation of CH3COOH to algae and fish were much higher than those from Fenton and ozone oxidation as the highest formation concentrations of inorganic by-products. Considering the toxic effects on the environment, when choosing the AOPs for the further treatment of wastewater containing Cl−, try to avoid the use of EAOP technology, and it is better to choose Fenton and ozone oxidation.

Degradation of Odor Compounds in Drinking Water by Ozone and Ozone-Based Advanced Oxidation Processes: A Review

Degradation of Odor Compounds in Drinking Water by Ozone and Ozone-Based Advanced Oxidation Processes: A Review

Treatment of Landfill Leachate Reverse Osmosis Concentrates by Advanced Oxidation-Heterotrophic Nitrification-Aerobic Denitrification Combination process.

This study aimed to develop a multistage treatment system for highly toxic wastewater named reverse osmosis concentrates of landfill leachate. Therefore, a combination of the ammonia stripping process (ASP), catalytic ozone oxidation process (COP), and heterotrophic nitrification-aerobic denitrification process (HNADP) was proposed and the quality of effluent was evaluated for the concentration of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and total nitrogen (TN). ASP had moderate removal efficiency of NH4+-N, and TN in the effluent. COP was catalyzed by cerium-supported-activated carbon achieved good performance in disposal of COD. The effluent of HNADP had the most significant removal efficiency of COD, NH4+-N, and TN. As a result, the effluent of combined process successfully met the discharge standards for NH4+-N and TN according to Table 1 of GB 16889-2008 in China. To investigate the microbial mechanism of pollutant removal in HNADP, 16S rRNA high-throughput sequencing was performed and the results suggested that the relative abundance and diversity of microorganisms fluctuated with the changes of COD/TN ratio in HNADP. Truepera and Halomonas were identified as the key genera involved in the simultaneous degradation of COD and nitrogen-containing pollutants, the functional genes (hao, amoA, nirS, and nirK) were predicted in nitrification and denitrification process. Overall, this study demonstrates a feasible multistage system for treatment of concentrates and propose that further explorations of combined techniques may lead to even more satisfactory removal efficiencies.

Ozone pretreatment combined with partial denitrification-anammox process for efficient nitrogen removal from nanofiltration concentrate of landfill leachate

Treatment of nanofiltration concentrate (NFC) from landfill leachate is challenging due to its complex composition and high concentration of refractory organic matter. This study proposed a combined process of ozone pretreatment and partial denitrification/anammox (PD/A) for treating NFC, exploring the feasibility of using ozone-oxidized NFC as a carbon source for partial denitrification. The ozone oxidation process was employed to degrade the refractory organic compounds. With an ozone flow rate of 1.2 L/min and a reaction time of 50 min, the chemical oxygen demand (COD) removal efficiency of NFC was 20.83%, and the volatile fatty acid (VFA) content reached a maximum value of 104.37 mg/L. Meanwhile, the process significantly increased the ammonia and nitrate concentrations in the NFC. Then, PD/A process was applied to remove nitrogen from the NFC. Results showed that PD/A can effectively remove nitrogen from the NFC without additional carbon source. Using VFA produced in the ozone oxidation stage as carbon source, the reactor achieved a nitrogen removal efficiency of approximately 70%, resulting in an effluent with a total nitrogen below 40 mg/L, which satisfied the relevant standards in China. This study provides new insights into the application of ozone oxidation and PD/A in treating NFC from leachate.

Research Progress of Iron-Based Catalysts in Ozonation Wastewater Treatment

On account of the rich contents of iron-based catalysts, low preparation costs, and good effects, they play important roles in various fields of water treatment. There are many kinds of iron oxides, which have been employed in catalytic ozone oxidation processes. However, a thorough analysis of their syntheses, characterization techniques, reactions affecting variables, and mechanistic applications is lacking in the catalytic ozone oxidation sector. It is necessary to search for the catalytic efficiencies of different types of iron-based catalysts in the ozone system and elucidate the activation mechanisms of hydroxyl radicals by iron-based catalysts. In this paper, the synthesis methods, characterization techniques, and practical application fields are summarized in detail. The catalytic performances of iron-based catalysts in the ozone system are explored. The effects of solution pH, reaction temperature, catalyst addition amount, ozone concentration, and inorganic anions on the degradations of organic pollutants and the stability of an iron-based catalyst/oxidant system are also discussed. The activation mechanisms of free radicals and the removal mechanisms of organic pollutants in the iron-based catalyst/ozone system are revealed by a detection method, characterization technology, and theoretical analysis. The potential preparation methods, practical applications, auxiliary technologies, and influences on ozone catalysis are prospected.

Effects of atmospheric oxidation processes on the latitudinal distribution differences in MSA and nss-SO42- in the Northwest Pacific

Dimethyl sulfide (DMS) derived aerosols play an important role in the oceanic atmosphere. The methanesulfonic acid (MSA)/non-sea-salt sulfate (nss-SO42-) ratio is often used to determine the contribution of the DMS sulfate source. However, there is competition between the pathways of DMS to MSA and sulfate, and the importance of the differences in the reaction pathways for MSA/nss-SO42- remains unclear. Here, the MSA, nss-SO42-, and other environmental data from the Northwest Pacific Ocean in July and September were used to evaluate the impact of atmospheric oxidation processes on the ratio. In July, nss-SO42- was mostly contributed by anthropogenic sources, and in September, it was mostly produced mainly from DMS (biogenic sulfate [bio-SO42-]). Differences in sources explain most of the spatiotemporal distribution characterization of MSA and nss-SO42-. However, the atmospheric oxidation process was the main factor responsible for the difference in the spatial distribution of MSA and bio-SO42- in September. The air temperature, surface incoming shortwave flux, ozone and relative humidity affect atmospheric oxidation processes and thus the MSA/bio-SO42– ratio. Therefore, when nss-SO42- is mainly from the DMS source and the net primary production (NPP) is similar between sea areas, the MSA/nss-SO42- ratio needs to be used carefully to evaluate the sulfate contribution from the DMS source. In addition, it should be noted that the contribution of the DMS source aerosol to the Northwest Pacific is not negligible (up to 45%) with gentle wind and high NPP.

Characteristics of TOC Treatment for Industrial Wastewater Treatment -Characteristics of Industrial Wastewater TOC Treatment Status and TOC Treatment by Ozone and Advanced Oxidation Process-

Objectives:As the organic pollutant indicator is changed from COD&lt;sub&gt;Mn&lt;/sub&gt; to TOC and the demand for TOC treatment of industrial wastewater increasing, the current situation of TOC treatment of wastewater discharge facilities of each industrial category is analyzed, and it is intended to consider the possibility of residual TOC treatment by ozone and advanced oxidation process.Methods:To review the TOC treatment situations of wastewater discharge facilities of each industrial category, the field survey data (46 sites) by Environment Ministry and Korea Environment Corporation were analyzed according to inflow TOC concentrations, direct/indirect discharge type, and main treatment process of wastewater treatment facilities. To review the characteristics of TOC treatment by ozone and advanced oxidation processes, previous studies and the results of field pilot tests conducted by ozone companies were comprehensively analyzed.Results and Discussion:The TOC treatment level varies depending on the inflow TOC concentrations to each industrial wastewater treatment facility, direct/indirect discharge type depending on the location of the wastewater treatment facilities, and the main treatment process of the wastewater treatment facility. In particular, the TOC removal rate differed by more than 20% depending on the presence or absence of biological treatment. The wastewater treatment facilities that require additional treatment of residual TOC were divided as follows (1) when the facility has biological treatment as main process, increasing unexpected inflow TOC load in treatment facilities or the condition of the biological treatment become worsen. (2) when the facility has phy-chemical treatment as main process, increasing unexpected inflow TOC load. (3) extending the replacement cycle of activated carbon to save maintenance cost. The advance oxidation process decomposes easily by OH radicals through the radical substitution of unsaturated hydrocarbons and aromatic compounds, so the removal rate of TOC by the O&lt;sub&gt;3&lt;/sub&gt;+H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; advanced oxidation pilot test was 14.7~93.5%, higher than that of ozone oxidation. The specific ozone consumption per TOC removal amount (O&lt;sub&gt;3&lt;/sub&gt;/ΔTOC) by O&lt;sub&gt;3&lt;/sub&gt;+H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; advanced oxidation is 8.5~22.5mgO&lt;sub&gt;3&lt;/sub&gt;/mgTOC, which is 1/5 of that of ozone oxidation only. In addition, comparing ozone demand by COD&lt;sub&gt;Mn&lt;/sub&gt; and TOC removal, ozone demand of O&lt;sub&gt;3&lt;/sub&gt;+H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; advanced oxidation to remove TOC is 2.7 to 4.3 times compared to that by O&lt;sub&gt;3&lt;/sub&gt; oxidation to remove COD&lt;sub&gt;Mn&lt;/sub&gt;.Conclusion:In order to reduce residual TOC from industrial wastewater effluent, it is necessary to secure stability of the existing main treatment process in preparation for load fluctuations, and the technologies research on complex advanced oxidation processes, hybrid advanced oxidation processes, and pretreatment technology to reduce ozone demand is needed for economical field application.

Removal trends of typical priority control pollutants in wastewater treatment plant tailwater: Mechanisms clarifying and optimal process selection

Priority control pollutants (PCPs) have attracted much attention due to their safety concerns during effluent recycling in wastewater treatment plants (WWTPs). To clarify the removal characteristics of typical PCPs in WWTP effluent, the removal rates of eight typical PCPs during coagulation, ozonation, ultrafiltration (UF) and their combined processes were investigated. Experimental results revealed that single advanced treatment could not efficiently remove all PCPs within the WWTP effluent, whereas the combined processes significantly improved the removal rates due to the synergy of different treatment units. Specifically, ATZ exhibited the highest removal efficiency of 72.45 % when the coagulation-ozonation progressed, owing to the strong attacking of ozone onto the reactive groups (CC bond, aniline, amido group). Similarly, >93.4 % of SMZ, DCF, NaP, and Ant were efficiently removed during the ozonation-UF treatment. By contrast, adsorption by membrane was the main reason for the excellent removal of BaA (95.32 %) during ozonation-UF process and BaP (96.28 %) in coagulation-UF treatment. The optimized selective strategies for different treatment processes for the above-mentioned eight PCPs reduction were proposed based on analytical hierarchical processes, and the simulation results revealed that: ozone oxidation and UF process were more feasible for the tertiary treatment of PCPs characterized by two rings linked by NH bonds, as well as those PAHs with three or more benzene rings; whereas coagulation-ozone and coagulation-UF were for PCPs with triazine rings and monocyclic aromatic compounds with carboxyl groups.

Beneficial role of pre- and post-ozonation in a low rate biofiltration-ultrafiltration process treating reclaimed water

Previous studies have shown that the combination of biological and ozone oxidation processes can achieve a greater performance in treating natural surface water than each process individually. In this work, we designed and tested an ozonation–gravity-driven up-flow slow rate (0.01 m/h) biofiltration–ozonation (O3–GUSB–O3) process for the pre-treatment of reclaimed water prior to ultrafiltration (UF), with the aim of producing high quality drinking water and a significantly reduced degree of UF fouling. Results showed that O3 coupled with GUSB can effectively remove aromatic compounds (∼ 84.8%), dissolved organic carbon (DOC, ∼ 83.4%), and biopolymers in surface water. In addition, post-ozonation greatly contributed to the reduction of the UF membrane fouling (∼ 6 times greater flux). With regard to the disinfection by-product formation potential (DBPFP) of the final treated water, both trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP) were greatly reduced (86.4% and 84.8% for THMs and HAAs, respectively). The relationship between DBPFP and various spectral indexes revealed that aromatic compounds and amino acids were more likely to generate DBPs during the disinfection stage. Among these, humic substances were more likely to generate THMs, while low molecular weight carboxylate and carbonyl organic compounds were associated with the generation of HAAs. Moreover, the dosage of O3 during the post-ozonation stage was found to influence directly the generation of DBPs. Overall, this study has conducted a detailed evaluation of a novel multi-ozone biofilter UF process for treating surface water, and the results provide a valuable basis for subsequent studies at larger scale to demonstrate the potential of the treatment process for practical applications.

Study on ultrasonic enhanced ozone oxidation of cyanide-containing wastewater

Gold smelting wastewater contains cyanide ions and copper ions, which may cause potential risks to the environment. In this study, a new ultrasonic enhanced ozone (US/O3) oxidation method was developed for the comprehensive treatment of cyanide-containing wastewater, destruction of cyanide and further recovery of copper. The cyanide removal rate and copper recovery rate reached 99.96 % and 99.3 % under the optimum conditions of ozone flow rate of 80 L/h, temperature of 25 °C, reaction time of 15 min and ultrasonic power density of 80 W/L, respectively. The dried sediment was characterized by XRD, SEM and particle size analysis, the results showed that the dry sediment was Cu slag. The experimental results were in accordance with the pseudofirst-order kinetic model with apparent rate constants of 0.1662 L/(mg·min) and 0.2056 L/(mg·min) for ozone oxidation and ultrasonic enhanced ozone (US/O3) oxidation, respectively. The mechanism of ultrasonic enhanced ozone was studied by FT-Raman, FT-IR, EPR and Gas chromatography. Ultrasonic enhanced ozone (US/O3) oxidation process for treatment of cyanide containing wastewater is characterized by rapid and complete decomposition of cyanide in wastewater and efficient recovery of valuable element copper.

Changes in Organics and Nitrogen during Ozonation of Anaerobic Digester Effluent

The objective of this study is to investigate the consequence of ozone dosage rate on the qualitative change in organic compounds and nitrogen in anaerobic digester effluent during the ozone process. Therefore, ozonation improves the biodegradability of recalcitrant organic compounds, quickly oxidizes the unsaturated bond, and forms radicals that continue to deteriorate other organic matter. In this study, ozonation was performed in a microbubble column reactor; the use of microbubble ozone improves the status of chemical oxygen demand (COD) and changes of organic nitrogen to inorganic compounds. The ozone injection rates were 1.0, 3.2, and 6.2 mg/L/min. The samples obtained during the ozone treatments were monitored for CODMn, CODCr, TOC, NO2−-N, NO3−-N, NH4+-N, T-N, and Org-N. The ozone dose increased 1.0 to 6.2 mg/L and it increased the degradation ratio 40% and the total organic carbon 20% during 20 min of reaction time. During the ozonation, the CODCr and CODMn values were increased per unit of ozone consumption. The ozone treatment showed organic nitrogen mineralization and degradation of organic compounds with the contribution of the microbubble ozone oxidation process and is a good option for removing non-biodegradable organic compounds. The original application of the microbubble ozone process, with the degradation of organic compounds from a domestic wastewater treatment plant, was investigated.

The degradation of printing and dyeing wastewater by manganese-based catalysts

Printing and dyeing wastewater generally has high pH, high turbidity, poor biodegradability, complex composition, and high chroma, which make it one of the most difficult industrial wastewaters to treat. Herein, heterogeneous ozone oxidation technology is applied to oxidize and degrade printing and dyeing wastewater. A metal oxide catalyst supported on activated carbon (γ-MnO2/AC) was prepared by hydrothermal synthetic method and shown to enable synergistic catalysis involving MnO2 metal sites and N/C sites. A simulated methyl orange solution was used to determine the effects of various preparation and operation parameters. The results confirmed that the γ-MnO2/AC catalyst exhibited good chemical oxygen demand (COD) removal and reusability. Additionally, γ-MnO2/AC demonstrated excellent degradation of the secondary biochemical effluent of printing and dyeing wastewater (COD removal = 72.45% within 120 min). The γ-MnO2/AC catalyst was fully characterized, and the mechanism governing its catalytic ozone oxidation process was investigated experimentally.

Ozone oxidation of 2,4,6-TCP in the presence of halide ions: Kinetics, degradation pathways and toxicity evaluation

2,4,6-Trichlorophenol (2,4,6-TCP) is extensively consumed in industrial production and may cause environmental damages. The effect of halide ions on the decomposition of 2,4,6-TCP has often been overlooked. In this study, the bromide ion was found to have a stronger negative impact on 2,4,6-TCP degradation than chloride ion in the O3 system, and led to the formation of adsorbable organic halogens (AOX). Kinetic modeling demonstrated that the concentration of various radicals was largely depended on the solution pH, and stronger basicity not only contributed to the mineralization of 2,4,6-TCP, but also inhibited the formation of halogenated by-products. Combining the intermediate identification and quantum chemical calculation, the degradation pathways of 2,4,6-TCP during ozone oxidation process were proposed. The toxicity test and ECOSAR simulation demonstrated that the acute toxicity of some 2,4,6-TCP degradation intermediates was relatively higher than their parent compound. With high concentrations of halide ions, the ozone-treated solution showed greater toxicity than the originator 2,4,6-TCP solution. These results illustrate that the ozone treatment of the halide-containing wastewater may cause potential ecological hazards and its application needs to be more cautious.

Bioaugmentation Technology for Treatment of Toxic and Refractory Organic Waste Water Based on Artificial Intelligence.

With the development of modern chemical synthesis technology, toxic and harmful compounds increase sharply. In order to improve the removal efficiency of refractory organic matter in waste water, the method of adding powdered activated carbon (PAC) to the system for adsorption was adopted. Through the analysis of organic matter removal rule before and after waste water treatment, it can be found that PAC is easy to adsorb hydrophobic organic matter, while activated sludge is easy to remove hydrophilic and weakly hydrophobic neutral organic matter. Powdered activated carbon-activated sludge SBR system (PAC-AS) system is obviously superior to AS and PAC system in removing organic matter of hydrophilic and hydrophobic components, that is, biodegradation and PAC adsorption are additive. Compared with the control system, the Chemical Oxygen Demand (COD) removal rate of refractory substances increased by 8.36%, and PAC had a good adsorption effect on small molecular weight organic compounds, but with the increase of molecular weight of organic compounds, the adsorption effect of PAC gradually weakened, and it had no adsorption effect on macromolecular organic compounds. Based on the research of fuzzy control theory, an Agent control system for ozone oxidation process of industrial waste water based on Mobile Agent Server (MAS) theory was established, which was realized by fuzzy control method. The simulation results showed strong stability and verified the feasibility and adaptability of the distributed intelligent waste water treatment system based on MAS theory in the actual control process.

Ozone direct oxidation pretreatment and catalytic oxidation post-treatment coupled with ABMBR for landfill leachate treatment

In order to treat the high concentration landfill leachate, ozone direct oxidation pretreatment and catalytic oxidation post-treatment coupled with anaerobic baffled membrane bioreactor (ABMBR) system was proposed in this study. For pretreatment, ozone direct oxidation could remarkably reduce UV254, 3D fluorescence peak value and fluorescence regional integration (FRI) of organic pollutants. For ABMBR treatment, the removal efficiencies of COD and ammonia nitrogen were 80.38% and 21.56%, respectively. Post-treatment included struvite precipitation, ozone catalytic oxidation and membrane bioreactor (MBR) treatment. Finally, the total removal efficiencies of COD and ammonia nitrogen were 91.2% and 99.4%, respectively. The chroma was remarkably decreased from 1250 times to 40 times after a series of treatments. The acids in ABMBR could be degraded by microorganisms of Proteobacteria and Chloroflexi. The cellulose and polysaccharides could be decomposed by Bacteroidetes and ketones could be decomposed by Brevundimonas in ABMBR. Electron paramagnetic resonance (EPR) analysis indicated that the hydroxyl radicals were the main reactive oxygen species during the direct ozone oxidation process, while the superoxide radicals played an important role in the ozone catalytic oxidation process.

Study on the Removal of Fluorescent Whitening Agent from Paper-Mill Wastewater Using the Submerged Membrane Bioreactor (SMBR) with Ozone Oxidation Process

In this study, paper-mill wastewater was treated using the Submerged Membrane Bioreactor (SMBR) process. In particular, the ozone oxidation treatment process is applied after SMBR to remove the fluorescent whitening agent, which is a trace pollutant and non-biodegradable. Fluorescent whitening agent concentration was indirectly measured by UV scanning and COD concentration. The concentration of COD before SMBR and ozone oxidation was 449.3 mg/L, and the concentration of treated water was 100.3 mg/ℓ. The COD removal efficiency of paper-mill wastewater through SMBR and the ozone oxidation process was about 77.68%. The optimized amount of ozone was required for the removal of the fluorescent whitening agent after SMBR was 95 mg·O3/ℓ calculated by UV scan results. Additionally, the optimized amount of required ozone to remove COD was calculated to 0.126 mg·COD/mg·O3.