Chemical Oxidation Demand Removal Research Articles

Photoelectrocatalytic treatment of municipal wastewater with emerging concern pollutants using modified multi-layer catalytic anode

Municipal wastewater contains emergent chemical and biological pollutants that are resistant to conventional wastewater treatments. Therefore, the focus of the current study was to address the challenge of removing emergent chemical and biological pollutants present in municipal wastewater. To achieve this, a photo electro-catalytic (PEC) treatment approach was employed, focusing on the removal of both micro and biological pollutants that are of emergent concern, as well as the reduction of Chemical Oxidation Demand (COD) and Total Organic Carbon (TOC). The treatment involved the use of a modified multi-layer catalytic anode photo-electroactive anode as an effective anode for PEC treatment of municipal wastewater. In the continuous mode of operation, %COD removal was optimized for the treatment of municipal wastewater under Ultra-Violet C (UVc), 280 nm, and Visible (Vis) radiation, 400 nm. Therefore, a comparative study was performed to investigate the effect of Vis radiation on %COD removal, micropollutants removal, and disinfection of municipal wastewater. Micropollutants present in municipal wastewater were effectively oxidized/degraded with the highest reduction rate between 100% and 80% under the influence of UVc and Vis radiation respectively by the PEC treatment process. Disinfection of various microorganisms present in the wastewater with the effect of UVc and Vis assisted PEC treatment was also monitored. Overall, 75–80% of the disinfection of municipal wastewater was contributed by the modified multi-layer catalytic anode. The UVc in the PEC system, contributes approximately 20–25% to the overall disinfection of municipal wastewater.

Boosting sunlight-powered photocatalytic fuel cell with S-scheme Bi2WO6/ZnO nanorod array composite photoanode

The construction of intimate contact and effective segregation of charge carrier is a prominent approach to ameliorate the photoactivity of heterojunction catalyst. Herein, a S-scheme flake ball-like Bi2WO6 loaded on ZnO nanorod array (Bi2WO6/ZnO NRA) composite photoanode has been fabricated via a two-step electrochemical-hydrothermal technique and utilized in a sunlight-powered photocatalytic fuel cell (PFC) for the first time. Incorporation of Bi2WO6 can prolong the visible light response range and improved the electrochemical traits of the composite photoanode. The photoelectric test and chemical oxidation demand (COD) measurement on municipal wastewater treatment have been entirely recorded under direct sunlight. The maximum power density of the Bi2WO6/ZnO NRA was 2.707 µW/cm2, which was 1.8 times than that of the pure ZnO NRA in treating municipal wastewater. The COD removal efficiency of municipal wastewater using 2-Bi2WO6/ZnO NRA PFC was 100% over 180 min period. The boosted photoactivity of the composite was accredited to the one-dimensional nanorod array morphology and the formation of S-scheme heterojunction structure between the Bi2WO6 and ZnO NRA, which tremendously segregated charge and retained high redox potential. The postulated S-scheme mechanism was supported by the radical quenching test and Mott-Schottky analyses. Consistent photocatalytic performance of Bi2WO6/ZnO NRA photoanode was also found after five cyclic runs. This work sheds light on the potential applications of efficient sunlight-activated catalysts in water decontamination and energy recovery.

Performance of coagulation-flocculation followed by ultra-violet/ultrasound activated persulfate/hydrogen peroxide for landfill leachate treatment

The advanced oxidation processes (AOPs) were assessed for enhancing the treatment of stabilized landfill leachate previously pretreated using coagulation-flocculation (C-F).The primary treatment by C-F using 20 g.L−1 of FeCl3 (optimal coagulant dosage) has removed 71% of chemical oxidation demand (COD) and 95% of turbidity. Thereafter, secondary treatment was applied using different system combinations of two inorganic oxidants (potassium persulfate, K2S2O8 (PS) (1500 mg. L−1) and hydrogen peroxide, H2O2 (1327 mg. L−1)) that were used simultaneously or separately with UV-A and/or ultrasonic (US) irradiations.The obtained results indicated that the oxidation systems with the presence of H2O2 were more efficient than other systems. Indeed, the H2O2-PS-US-UV-A system reached the highest COD removal of 89%, while PS-based combinations were the less efficient (PS alone 19%, PS-UV-A 22%, PS-US 32%, and PS-US-UV-A 35%).Hence, the sequential process including C-F as pretreatment followed by the application of the H2O2-PS-US-UV-A system has proven high efficiency for COD removal, absorbance at 254 nm, and color number of 97%, 97%, and 99%, respectively.The sequential application of AOPs after preliminary treatment using coagulation-flocculation is a promising alternative to reducing the high organic load of stabilized leachate and that could be largely applied to other types of effluents.

An electro-Fenton process to treat waste liquor of a hyperaccumulator that contains potentially toxic elements and the COD

Rapid and safe treatment of harvested fresh biomass of hyperaccumulators is essential for phytoremediation of metal-contaminated soils. Here, an electro-Fenton (EF) process was used to remove cadmium (Cd) and chemical oxidation demand (COD) from waste liquor from the dewatering of biomass of the hyperaccumulator Sedum plumbizincicola after flocculation precipitation. The results showed that the order of impact of the factors on the removal rate of COD and Cd was pH > electrical current density > H2O2 dosage. Increasing pH promoted Cd removal but hindered COD removal. As current density and H2O2 dosage increased the removal rates of both Cd and COD initially increased and then decreased. Compared to an electrocoagulation process, the addition of H2O2 in EF process greatly enhanced Cd and zinc (Zn) removal. Speciation analysis showed that most of the Cd and Zn in the initial liquor were organically and inorganically complexed. At optimal conditions, e.g., pH 5, current density 15 mA cm−2 and H2O2 dosage 9 g L−1, the removal efficiencies of Cd, Zn and COD reached 99.4, 99.9 and 55.5% after 80 min of EF treatment. Electro-Fenton process can therefore be used to quickly remove trace metals from the waste liquor of the hyperaccumulator.

Comparison of COD removal from petrochemical wastewater by electro-Fenton and electro oxidation processes: optimization and kinetic analyses

ABSTRACT This study reveals comparison between electro-Fenton (EF) and electro-oxidation (EO) methods to study chemical oxidation demand (COD) removal from synthetic petrochemical wastewater. Initially 54.60% of COD removal was found by acid precipitation treatment at optimum conditions. Subsequently, electrochemical treatments such as EF and EO using graphite electrodes were imposed to the supernatant and process parameters such as time (20→80 min), current density (60.97→121.95 A/m2), pH (2→6), Fe2+concentration (1→2 mmole/L), electrolyte concentration (), and electrode gap (1→5 cm) were optimized by Box Behnken Design. Maximum removal of COD was obtained 66.23% and 56.57% with electric energy-consumption (kWh/kg CODremoved): 33.30 and 35.27 during EF and EO treatments respectively at optimum conditions.

Degradation of Methylene Blue via Dielectric Barrier Discharge Plasma Treatment

The degradation of methylene blue (MB) using an upgraded dielectric barrier discharge (DBD) plasma reactor was investigated in this paper. Air plasma was generated in the glass bead packed bed in the reactor, which was propagated into MB solution through a microporous diffuser plate. Microdischarge phenomenon can be observed on the interface of MB solution and the diffuser plate, where plasma active species were generated. The effects of air flow rate, initial solution concentration, initial solution pH, and initial solution conductivity on MB degradation were examined. Experimental results indicated that the proposed plasma reactor was effective for MB degradation. No obvious change in MB degradation efficiency was obtained for solution with various initial pH and conductivities, which suggested the potential of the reactor in actual wastewater treatment. The possible mechanism of the generation of plasma active species for MB degradation was proposed. In addition, the total organic carbon removal and chemical oxidation demand removal after 30 min treatment were 38.5% and 48.3%, which was higher than that obtained by ozone. The energy yield for MB degradation reached up to 9.3 g/kWh. Finally, a possible degradation pathway of MB solution was proposed.

Removal of Reactive Dyes in Textile Effluents by Catalytic Ozonation Pursuing on-Site Effluent Recycling.

The textile wash-off process consumes substantial amounts of water, which generates large volumes of wastewater that pose potential pollution issues for the environment. In the present study, catalytic ozonation was applied to degrade residual dyes present in rinsing effluents from wash-off processes towards the aim of recycling the waste effluents. A magnetic catalyst was prepared for promoting dye degradation by catalytic ozonation. Via a hydrothermal reaction, highly magnetic manganese ferrite (MnFe2O4) particles were successfully loaded on carbon aerogel (CA) materials (MnFe2O4@CA). The results showed that the developed catalyst strikingly promoted the degradation of dye contaminants by catalytic ozonation, in terms of color removal and reduction of chemical oxidation demand (COD) in rinsing effluents. COD removal efficiency in catalytic ozonation was enhanced by 25% when compared with that achieved by ozonation alone under the same treatment conditions. Moreover, we confirmed that after catalytic ozonation, the rinsing effluents could be recycled to replace fresh water without any evident compromise in the color quality of fabrics. The color difference (ΔEcmc(2:1)) between fabrics treated with recycled effluents and water was not more than 1.0, suggesting that the fabrics treated with recycled effluents displayed acceptable color reproducibility. Although colorfastness and color evenness of fabrics treated with recycled effluents were slightly poorer than those of fabrics treated with water, they were still within the acceptable tolerance. Therefore, the present study validated that catalytic ozonation was a promising technology for saving water and wastewater elimination in textile dyeing. It provides a feasibility assessment of catalytic ozonation for recycling waste effluents to reduce water dependence in textile production. Furthermore, we show a new perspective in on-site recycling waste effluents by catalytic ozonation and enrich the knowledge on feasible approaches for water management in textile production.

Low frequency ultrasonic‐assisted Fenton oxidation of textile wastewater: process optimization and electrical energy evaluation

AbstractWorldwide, there is a continuous need to develop alternative treatment methods to replace conventional processes for textile wastewater. In this regard, Fenton oxidation, with the potential of hydroxyl radical production, is an efficient method. Nevertheless, pH dependence, high chemical consumption and sludge production are a few aspects that limit its wide application. Therefore, to overcome these limits, integration of Fenton oxidation with other advanced oxidation processes is considered a viable option. Therefore, in this study, Ultrasonic‐assisted Fenton oxidation was investigated to observe the increase in degradation efficiency of Fenton oxidation. For this purpose, low frequency ultrasonic water bath was used and malachite green dye was used as a model pollutant. Central composite design was used for experimental design, and [OP]ini, OP:Fe+2 (wt/wt), H2O2:Fe+2 (wt/wt) and pH were used as control factors. Based on experimental results, maximum of 97.5% Chemical Oxidation Demand (COD) reduction was obtained at the process conditions of [OP]ini: 100 mg/L, OP:Fe+2: 50, H2O2:Fe+2: 1.5 and pH:3. Furthermore, 10 times reduction in the consumption of hydrogen peroxide was obtained. According to Pareto analysis, organic pollutant (OP) in interaction with OP is the most significant while pH was identified as the least. The process followed pseudo‐first order kinetics (k = 0.0196 min−1) with electrical energy order of 26.21 kWh/m3 and the maximum energy consumption per COD removal of 0.8 kJ/COD, lower than those available in the literature. The results suggested that US‐assisted Fenton oxidation could be considered as an efficient method for treating the recalcitrant wastewater.

Optimization of US-Electropersulfate Process for Leachate Treatment by Response Surface Methodology

Introduction: Chemical Oxidation Demand (COD) is an important parameter in treatment of leachate. Leachate from solid waste has a high pollutants that must be treatment before discharge to environment. The aim of this study was optimization of US-Electro/persulfate process, predicate of optimum conditions by RSM for landfill leachate treatment. Methods and materials: In this experimental study used to sonochemical-reactor with one liter volume that equipped with 40 KHz and two Iron electrodes as an anode and two Copper electrodes as a cathode that connected to direct current supply source. In final step of study pH (2-4), S2O82- (1- 2gr/L), direct electrical current (1/5-3 A) and reaction time parameters as an independent parameters were studied. In optimum condition, corrosion of the electrodes in anode and energy consumption were measured. Sludge properties before and after the process were analyzed by SEM / EDAX and FT-IR spectroscopy. Results: By using this software (design Expert), the optimum condition was done at PH=3/41, S2O82- dose=1.2 gr, current density=2/41 A, and reaction time were 70 min. In this condition the efficiency of COD removal was 75 . The R-squared and Adj R-squared process is 0/78 and 0/88 respectively. The electrodes corrosion in optimum condition were 0.77 gr and energy consumption was 9/23 KW/kg COD. The results of analysis indicate that change in sludge during the process happened and elements structure in leachate has observed, the most obvious oxygen and iron increase in sludge after the process. Conclusion: The US-Electro/persulfate has a good efficiency in COD removal and with this model can be tested with a few run and high accuracy to optimize the process.

Comparison of Photocatalytic activity of Various Metallic and Non-metallic doped TiO2 Nano Particles for Treatment of Pharmaceutical Effluent

The use of semiconductor oxide particles such as TiO 2 as photo catalysts has shown great utility in the complete mineralization of organic compounds present in effluent. The dopant maximize the electron trapping for further inhibiting excitation recombination and thereby enhancing the oxidation of organic compounds. A pilot scale synthesis of TiO 2 nano particles has been carried out using the Sol-gel method with various metallic dopants like Iron, Copper, Cobalt, Vanadium, silver and non-metallic dopants like Boron, Phosphorus and Nitrogen. The obtained doped TiO 2 was characterized by X-ray Diffraction (XRD) to determine size, Morphology Index and Dislocation Density in order to analyze the structural, optical and surface properties of the synthesized materials. Photocatalytic activity of the various doped TiO 2 are assessed by the photocatalytic degradation of pharmaceutical effluent under ultraviolet light and Hydrogen Peroxide to compare treatment efficiency in terms of maximum removal of Chemical Oxidation Demand (COD) of pharmaceutical waste water having initial COD of 40000 mg/L. Comparison between TiO 2 nano particles and doped TiO 2 nano particles has also been carried out. From this we conclude that Ag doped TiO 2 nano particles is best among all dopants when amount of photocatalyst was 0.5 gm and H 2 O 2 (30 %) was 25 ml. Ag doped TiO 2 shows maximum COD removal efficiency of 84 % where as Boron doped TiO 2 shows minimum efficiency of 31 %. Keywords: TiO 2 Nano particles; Metallic and Non-metallic Dopants; X-ray Diffraction; Sol-Gel method; photocatalytic Oxidation

Parametric study of electro-Fenton treatment for real textile wastewater, disposal study and its cost analysis

Treatment of real textile wastewater by electro-Fenton method was investigated using Ti/RuO2 electrodes. The performance of the treatment process was evaluated in terms of %chemical oxidation demand removal; %color removal; and energy consumed, at three electro-Fenton process parameters: current, electrolysis time and ferrous sulfate concentration. To determine the optimum operating conditions, multiple responses optimization based on Box–Behnken design with desirability function was used. The optimum value of parameters were found to be current= 0.32 A, time = 90 min and ferrous sulfate concentration = 0.53 mM. Box–Behnken design suggested the %chemical oxidation demand removal; %color removal; and energy consumed were 100%, 90.30% and 1.27 Wh, respectively at optimized process parameters. The predicted performance parameters agree well with the experimental data. Second-order kinetic model was fitted to the experimental data, at optimum conditions. GC–MS analysis confirmed that dye components were totally eliminated after electro-Fenton treatment of textile effluent. To determined the toxicity of the treated textile effluent bioassay analysis was performed. It was identified that the generated by-products were non-toxic in nature. The total cost to treat the 1 m3 of real textile wastewater by electro-Fenton at optimum conditions was $ 3.13.

Effects of a polymeric organic coagulant for industrial mineral oil wastewater treatment using response surface methodology (RSM)

In this study, treatment of a local South African oil refinery effluent using a coagulation flotation process is designed using response surface methodology (RSM). A Box-Behnken design (BBD) implementing the RSM is applied to evaluate the effects and interactions of three operating parameters, viz., pH, coagulant dosage and flotation time, on the treatment of mineral oil wastewater (MOW). Polyacrylamide (Zetag-FS/A50), which is a water-soluble compound, is applied to enhance the adsorption mechanism and intermolecular bridging to minimise the amount of oil droplets. In addition, due to the monomeric nature and the charge density of the Zetag-FS/A50, its efficiency was evaluated to serve as an alternative coagulant for the pretreatment of the MOW. The removal of chemical oxidation demand (COD), soap oil and grease (SOG), total suspended solids (TSS) and turbidity from the MOW were used as the response variables for the coagulation flotation process. This was done with a standard dissolved air flotation jar test. The results show that the actual COD, SOG, TSS and turbidity percentage removal at optimised conditions with a coagulant dosage of 50 mg/L were 82%, 83%,70% and 83% respectively, while the predicted response was 92%, 96%, 73% and 87% for COD, SOG, TSS and turbidity, respectively. The analysis of variance (ANOVA) showed that the proposed models are significant at a 95% confidence level. A quadratic model was generated for response variables COD and SOG, while TSS and turbidity produced a linear model. The models fitted well with the experimental data with correlation coefficients (actual R2) of 0.94 for COD, 0.91 for SOG, 0.81 for TSS, and 0.75 for turbidity. The outcome of the study shows that the RSM has merit to optimise and identify the most important factor to control and the Zetag-FS/A50 coagulant has the potential to adsorb the oil droplets in order to enhance the treatment efficiency of the process.

OPTIMIZATION OF ANAEROBIC BAFFLED REACTOR (ABR) USING ARTIFICIAL NEURAL NETWORK IN MUNICIPAL WASTEWATER TREATMENT

This study is focused on simulating and optimizing design and configuration of anaerobic baffled reactor (ABR) by means of artificial neural network (ANN). This approach is aimed to assess an efficient ABR performance in various operational conditions treating municipal wastewater. For this purpose, to analyze comprehensively on a base of experimental data, the system is operated in two pilots of 48 liters net volume made of 8 compartments. In 7 months, more than 130 sets of data are obtained to be introduced to MATLAB neural network. These include removal efficiency of chemical oxidation demand (COD) and volatile fatty acids (VFAs) parameters. The finest correlative architecture obtained consists of 12 neurons along with 1 hidden and 1 output layer. It can be concluded from predicting simulation diagrams that the most favorable design and operation can be achieved in 10 to 12 hours hydraulic retention time with a six-compartment configuration. Besides, to make reactor resistant against shock loads and environmental changes, two supplementary baffles are recommended. Accordingly, soluble COD removal efficiency of more than 90% is anticipated to be achieved and VFAs fully digested even in incompatible operating conditions. Finally, the study confirms the considerable role of artificial neural network in prediction and optimization of ABR.

Landfill Leachate Treatment by Fenton and Fenton‐Like Oxidation Processes

The treatment of landfill leachate with physico‐chemical and Fenton and Fenton‐like processes was investigated. Additionally, the acute toxicities of the raw, the physico‐chemical pre‐treated, and the Fenton and Fenton‐like oxidation treated leachates on activated sludge microorganisms are given (determined by the ISO 8192 (respiration inhibition test)). Pre‐treatment with lime positively affected the biodegradability of the sludge by preventing inhibition. The Fenton and Fenton‐like processes resulted in high chemical oxidation demand (COD) (>80%) removal performance from leachate samples. The inhibitory effects of the Fenton and Fenton‐like reagents on activated sludge mixtures decreased. In addition to toxicity, the COD removal efficiencies and the operation costs of the applied processes were determined.

Application of Fered-Fenton and chemical precipitation process for the treatment of electroless nickel plating wastewater

Electroless nickel plating wastewaters commonly contain the citrate chelating complex and the coexisting hypophosphite, which is a scavenger of hydroxyl radicals, typically lowers the catalytic efficiency of H2O2 by Fe2+ in Fenton reaction. Hence, in this work, the Fered-Fenton method was adopted to remediate the citrate, and then alkaline precipitation was utilized to remove the freed nickel ions. The chemical oxidation demand (COD) of citric acid could be efficiently reduced by approximately 95% using 1080mM H2O2 (dosed in continual mode) and 20mM ferrous ions at a current density of 190Am−2 ([citric acid]=100mM and [Ni]=100mM). Meanwhile, 99.9% of the nickel that was liberated from the chelation of citric acid was removed by the cathodic deposition and the sequential precipitation. The hypophosphite did not significantly influence the COD or nickel removal efficiency. Finally, those optimal conditions for the successful management of simulated electroless plating wastewater consisted of citric acid and nickel ions coexisting with hypophosphite were then used to demonstrate the treatment of real wastewater (45,000ppm COD and 8000ppm nickel ions). The high COD removal, 93%, from the effluents of the electroless nickel plating process verified that the Fered-Fenton process can be practically applied.

Chemical and toxicological evaluation of an emerging pollutant (enrofloxacin) by catalytic wet air oxidation and ozonation in aqueous solution

This study evaluates the degradation efficiency of enrofloxacin (ENR) by catalytic wet air oxidation (CWAO) and ozonation. Results obtained by CWAO experiments show that 99.5% degradation, 37.0% chemical oxidation demand (COD) removal and 51.0% total organic carbon (TOC) conversion were obtained when 100mol% FeCl3 and 25mol% NaNO2 at 150°C under 0.5MPa oxygen pressure after 120min are used. The degradation products are identified by liquid chromatography–tandem mass spectrometry (LC–MS/MS), gas chromatography–mass spectrometry (GC–MS) and ion chromatography (IC). The oxidation end products, F−, NO3- and NH4+ were determined by IC. The BOD5/COD ratio as a measure of the biodegradability of the parent compound increased from 0.01 to 0.12 after 120min of reaction time, indicating an improved biodegradability of the parent compound. The inhibition of bioluminescence of the marine bacteria V. fischeri decreased from 43% to 12% demonstrating a loss in toxicity of ENR during CWAO. Ozonation of 0.2mM ENR was carried out with an ozone concentration of 7.3gm−3 at pH 7. ENR decomposition with a degradation rate of 87% was obtained corresponding to the reaction time. Moderate changes in COD (18%) and TOC (17%) removal has been observed. The bioluminescence inhibition increased from 8% to 50%, due to the generation of toxic degradation products during ozonation. In comparison to the widely use of well developed method of ozonation CWAO exhibits better performance in terms of COD, TOC removals and generates less toxic products.

Effects of inorganic anions on Fenton oxidation of organic species in landfill leachate

Fenton oxidation typically achieves only a moderate removal efficiency of chemical oxidation demand (COD) in treatment of a landfill leachate, incomparable to some other chemical oxidation processes (e.g. electrochemical oxidation). A traditional viewpoint is that the remaining highly oxidized organic species become recalcitrant to hydroxyl radical (OH·)-induced oxidation at a higher degree of Fenton oxidation. Although this may, at least partially, be true, the effects of inorganic anions, which are abundant in leachate, on Fenton oxidation have been largely ignored. The objective of this study is to assess the roles of three inorganic anions (nitrate, sulfate, and chloride) originally present in or externally added to leachate during Fenton oxidation of refractory organic species in leachate. Nitrate (NO₃⁻) did not significantly affect the COD removal rate. In contrast, sulfate (SO₂⁴⁻) and chloride (Cl⁻), particularly the latter, inhibited Fenton oxidation. Their inhibiting effect may be ascribed to: (1) scavenging of OH·; and (2) competition with H₂O₂ to form Fe(III) complexes, thus preventing the Fe(II) regeneration from Fe(III) reduction. At 2.125H₂O₂:initial COD(COD(0)) = 9.0, [H₂O₂]:[Fe²⁺] = 3, and pH = 3.0, 96, 62, 49, and 37% of COD(0) (1,254 mg L(-1)) were removed in the presence of 0, 1270, 5000, and 10, 000 mg L⁻¹ Cl⁻, respectively.

Oxidative Degradation of Organic Pollutants Catalyzed by Trace Manganese(II) Ion in Sodium Bicarbonate Solution

Catalytic degradation of organic pollutants in a sodium bicarbonate solution with Mn2+ ion (0.004-0.1 mmol/L) as the catalyst has been studied using H2O2 as the oxidant.Complete decoloration of methylene blue was achieved in 180 min with 44.0% chemical oxidation demand removal at 25 oC at the NaHCO3,MnCl2 and H2O2 concentrations of 25,0.1,and 100 mmol/L,respectively.The total organic carbon measurement indicated that 13.8% of the carbon was mineralized.The Mn2+/HCO3-+ H2O2 system also showed high ability for oxidative degradation of methyl orange,rhodamine B,and even landfill leachate.The analysis of UV-Vis spectroscopy and reaction kinetics indicated that the MnIV=O intermediate is the key active species in methylene blue degradation.

Ozonation of Dyes and Textile Wastewater in a Rotating Packed Bed

This study investigates the ozonation of Reactive Red 120 and Acid Red 299 dyes in the synthesized solution and textile wastewater by using a rotating packed bed. The decomposition rate of Reactive Red 120 and Acid Red 299 dyes via ozonation can be described by the pseudo-first-order kinetics. Ozonation of Reactive Red 120 exhibited the higher mineralization rate compared with that of Acid Red 299. The biodegradability of the two dyes could be significantly promoted during the ozonation. The BOD5/TOC (5-day biological oxygen demand/total organic carbons) ratios of the ozonated Reactive Red 120 and Acid Red 299 solutions would increase and have the maximum values. Moreover, the oxidized textile wastewater revealed the fast decolorization and moderate COD (chemical oxidation demand) removal rates. The optimal ADMI (American Dye Manufactures Institute) and COD removal of the textile wastewater were 93% and 37% in 30 minutes ozonation time, respectively. The performance evaluation of ozonation in the rotating packed bed indicated that the higher water flow rate, gas ozone concentration and rotational rotating speed would increase the efficiency of mineralization.