用UV/H2O2,UV/O3,UV/H2O2/O3催化处理城市固体垃圾填埋渗出物

The performance of UV/H2O2, UV/O3, and UV/H2O2/O3 oxidation systems for the treatment of municipal solid-waste landfill leachate was investigated. Main objective of the experiment was to remove total organic carbon (TOC), non-biodegradable organic compounds (NBDOC) and color. In UV/H2O2 oxidation experiment, with the increase of H2O2 dosage, removal efficiencies of TOC and color along with the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) of the effluent were increased and a better performance was obtained than the system H2O2 alone. In UV/H2O2 oxidation, under the optimum condition H2O2 (0.2 time), removal efficiencies of TOC and color were 78.9% and 95.5%, respectively, and BOD/COD ratio was significantly increased from 0.112 to 0.366. In UV/O3 oxidation, with the increase of O3 dosage, removal efficiencies of TOC and color along with BOD/COD ratio of the effluent were increased and a better performance was obtained than the system O3 alone. Under the optimum condition UV/O3     

超声波-Fenton法协同降解含表面活性剂SDS弱酸艳红染料废水的研究

采用Fenton氧化、超声辐射和超声-Fenton氧化三种方法处理含阴离子表面活性剂SDS的弱酸艳红B染料废水,考察溶液初始pH、H2O2投加量、FeSO4投加量、反应时间和超声功率对废水色度和COD的影响。结果表明:单独超声对废水色度和COD的去除没有效果,超声-Fenton氧化法对废水COD的去除效果明显优于Fenton氧化法。在pH 2.5,温度50℃,H2O2投加量4 mL/L,FeSO4投加量300 mg/L,反应时间90 min及超声功率400 W的条件下,废水色度去除率为98%,COD去除率为72%,比单独Fenton氧化法COD去除率提高25%。     

Pd-based catalysts for catalytic wet oxidation of combined Kraft pulp mill effluents in a trickle bed reactor

Catalytic wet oxidation of combined pulp mill effluents was studied in a trickle bed reactor. Two types of supported Pd-based catalysts, eggshell and uniform catalysts, and a supported Pd–Pt uniform catalyst were employed. Supported Pd catalysts showed high activity for total organic carbon (TOC) and color removal at temperatures of 353–448 K and 1.84 MPa. Compared to uniform catalysts, the eggshell catalysts with a 0.2 wt.% Pd loading show promise for treatment of combined pulp mill effluents. High activity for TOC and color removal can be attributed to the high density of active Pd sites in the shell area and to the decrease of diffusion path for reactants and intermediates. No apparent deactivation of eggshell catalysts was observed after 40 h on stream. Potential application of the supported Pd catalysts for treatment of combined pulp mill effluents is discussed.     

Decomposition of nonionic surfactant in a labyrinth flow photoreactor with immobilized TiO2 bed

The photocatalytic oxidation of nonionic surfactant polyoxyethylene nonyl phenyl ether (Rokafenol N9) in water in the labyrinth flow reactor with immobilized catalyst bed was investigated. Tytanpol A11 titanium dioxide supplied by Chemical Factory “Police” S.A. (Poland) was used as a photocatalyst. The influence of various factors, including reaction mixture flow rate, initial surfactant concentration and time of the process performance on the photodegradation of model compound were examined. It was found that the effect of the initial surfactant concentration on the effectiveness of Rokafenol N9 removal was practically negligible in the range of the investigation, whereas the reaction mixture flow rate has a significant effect on the effectiveness of Rokafenol N9 decomposition. The highest surfactant photodegradation (92%) was obtained at the solution flow rate equal to 11.98 dm³/h and the lowest (86%) at 1.64 dm³/h. The apparent rate constant k was linearly dependent on the reaction mixture flow rate. Extension of the reaction time from 5 to 60 h did not result in a complete mineralization of Rokafenol N9 to CO₂ and water.     

Modeling of a continuous photocatalytic reactor for isovaleraldehyde oxidation: Effect of different operating parameters and chemical degradation pathway

An investigation of isovaleraldehyde (ISOV) photocatalytic oxidation was conducted at initial concentrations ranging from 25 to 150 mg/m³ and different relative humidities (5–90% RH) in order to characterize the process performances close to indoor air conditions. Experiments were carried out in two different reactors: cylinder and flat-plate photoreactor (planar reactor) at different air gap (20–60 mm) and gas residence times (0.67–5.0 s). A plug flow reactor system was developed in order to perform kinetic studies of (i) isovaleraldehyde removal, (ii) selectivity of CO₂, (iii) by-products formation and removal. It appears that ISOV removal efficiencies increased with lower inlet concentrations, lower air gap and higher gas residence times.     

The dependence on temperature of gas-phase photocatalytic oxidation of methyl tert-butyl ether and tert-butyl alcohol

The influence of temperature on the mechanism and kinetics of gas-phase photocatalytic oxidation (PCO) and thermal oxidation (TO) of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) over TiO₂ was studied in a continuous flow annular reactor. The reaction products of PCO of both substances included acetone, water, carbon dioxide and carbon monoxide. Volatile TO products of MTBE included 2-methyl-1-propene (2-MP), carbon monoxide, carbon dioxide and water; TBA decomposed to 2-MP and water. Thermal oxidation of MTBE became noticeable at 388 K, TBA started to decompose thermally at 393 K. Both PCO and TO fit well to the Langmuir–Hinshelwood (L–H) model for monomolecular reactions. The dependence of the kinetic constants on temperature was established in the form of an Arrhenius equation. The TiO₂ catalyst showed no deactivation at temperatures above 373 K but gradually lost its activity below 373 K.     

Influence of Experimental Parameters in the Treatment of Distillery Effluent by Electrochemical Oxidation

The electrochemical oxidation of distillery effluent was studied in a batch reactor in the presence of supporting electrolyte NaCl using Mixed Metal Oxide (MMO) electrode. The effect of operating parameters such as current density, initial pH, and initial electrolyte concentration on the percentage of Chemical Oxygen Demand (COD) removal, power consumption, and current efficiency were studied. The maximum percentage removal of COD was observed to be 84% at a current density of 3 A/dm²at an electrolyte concentration of 10 g/l with an effluent COD concentration of 1000 ppm and at an initial pH of 6. The operating parameters for the treatment of distillery effluent by electrochemical process were optimized using response surface methodology by CCD. The quadratic regression models with estimated coefficients were developed for the percentage removal of COD and power consumption. It was observed that the model predictions matched with experimental values with an R² value of 0.9504 and 0.9083 for COD removal and power consumption respectively. The extent of color removal and oxidation of organic compounds were analyzed using UV spectrophotometer and HPLC.     

Anaerobic-aerobic processes for the treatment of textile dyeing wastewater containing three commercial reactive azo dyes: Effect of number of stages and bioreactor type

In this study, the effect of number of stages and bioreactor type on the removal performance of a sequential anaerobic-aerobic process employing activated sludge for the treatment of a simulated textile dyeing wastewater containing three commercial reactive azo dyes was considered. Two stage processes performed better than one stage ones, both in terms of overall organic and color removal, as well as the higher contribution of anaerobic stage to the overall removal performance, thereby making them a more energy efficient option. The employment of a moving bed sequencing batch biofilm reactor, which uses both suspended and attached biomass, for the implementation of the anaerobic stage of the process, was compared with a sequencing batch reactor that only employs suspended biomass. The results showed that, although there was no meaningful difference in biomass concentration between the two bioreactors, the latter reactor had better performance in terms of chemical oxygen demand (COD) removal efficiency and rate and color removal rate. Further exploratory tests revealed a difference between the roles of suspended and attached bacterial populations, with the former yielding better color removal whilst the latter had better COD removal performance. The sequential anaerobic-aerobic process, employing an aerobic membrane bioreactor in the aerobic stage resulted in COD and color removal of 77.1±7.9% and 79.9±1.5%, respectively. The incomplete COD and color removal was attributed to the presence of soluble microbial products in the effluent and the autoxidation of dye reduction metabolites, respectively. Also, aerobic partial mineralization of the dye reduction metabolites, was experimentally observed.     

Photoelectrocatalytic and photocatalytic disinfection of E. coli suspensions by titanium dioxide

This paper reports studies of the photoelectrocatalytic and photocatalytic disinfection of E. coli suspensions by titanium dioxide in a sparged photoelectrochemical reactor.

Two types of titanium dioxide electrode have been used. ‘Thermal’ electrodes were made by oxidation of titanium metal mesh; ‘sol–gel’ electrodes were made by depositing and then heating a layer of titania gel on titanium mesh. Cyclic voltammetry was used to carry out an initial characterisation and optimisation of both electrode types. The best ‘thermal electrodes’—i.e. those with the highest photocurrents—were prepared by heating titanium mesh at 700 °C in air. For sol–gel derived electrodes, optimum performance was obtained by heating at 600 °C. These electrodes were then used, in a gas sparged reactor, to disinfect E. coli suspensions with an initial concentration of 10⁷ colony forming units (cfu) ml⁻¹. Films prepared by the oxidation of titanium metal were shown to be superior to sol–gel derived films. Direct experimental comparison demonstrates that the photoelectrochemical system is more efficient than photocatalytic disinfection effected by slurries of Degussa P25 titanium dioxide.

Since in practical systems the TiO₂ would be exposed to a variety of species additional to those that are targeted, we also examined the effects of H₂PO₄⁻ and HCO₃⁻ ions on the measured disinfection rates. Phosphate addition poisons both the electrode and particulate-slurry systems and is only partially reversible. By contrast, although bicarbonate addition affects all three systems, the effects are reversible.     

Hydroxyapatite photocatalytic degradation of calmagite (an azo dye) in aqueous suspension

The hydroxyapatite (HAP) is prepared by precipitation method and examined for the photocatalytic degradation of calmagite, a toxic and non-biodegradable azo-dye compound. The physicochemical properties of hydroxyapatite material were characterized using BET surface area, XRD, FT-IR, and SEM analysis. The FT-IR analysis of the hydroxyapatite revealed that the peak intensity due to absorbance of surface PO₄³⁻ group centered at wave number 1030 cm⁻¹ is drastically decreased upon exposure to UV for 1 h. The study includes dark adsorption experiments at different pH conditions, influence of the amount of catalyst, and effect of pH on photocatalytic degradation of dye, chemical oxygen demand (COD) removal, biological oxygen demand (BOD₅) increase and SO₄²⁻ and NO₃⁻ ions evolution during the degradation. At optimum photocatalytic experimental conditions the same is compared with commercial degussa P-25 TiO₂. The photocatalytic treatment significantly reduced the COD (92% removal) and increased the BOD₅/COD ratio to 0.78. Considerable evolution of SO₄²⁻ (8.5 mg L⁻¹) and NO₃⁻ (12.2 mg L⁻¹) ions are achieved during the degradation process, thus reflecting the usefulness of the hydroxyapatite photocatalytic treatment in calmagite removal in wastewater.     

ANAMMOX反应器快速启动及对反硝化聚磷的影响研究

硝化菌的生长快于厌氧氨氧化菌,通过培育硝化生物膜,利用硝化菌的基质多样性和代谢多样性,可使生物膜由催化硝化反应过渡到催化厌氧氨氧化反应,加速ANAMMOX反应器的启动。经过2个月的运行,成功地启动了ANAMMOX反应器,而且反应器运行性能稳定。将厌氧氨氧化引入反硝化聚磷系统中,试验结果表明,在COD和TP的去除率保持基本不变的情况下,NH4+-N的去除率从23%上升到87%,TN的去除率从88%提高到93%,出水NH4+-N和NO2--N的质量浓度均低于2mg/L。     

Performance of a ZVI‐UASB reactor for azo dye wastewater treatment

BACKGROUND: Zero valent iron (ZVI) is expected to be helpful for creating an enhanced anaerobic environment that might improve the performance of the anaerobic process. Based on this idea, a ZVI packed upflow anaerobic sludge blanket reactor (ZVI‐UASB) was developed to enhance azo dye wastewater treatment. RESULTS: The ZVI‐UASB reactor was less influenced by a decrease in the operational temperature from 35 °C to 25 °C than a reference UASB reactor that did not contain ZVI. In addition, chemical oxygen demand (COD) and color removal efficiencies of the ZVI‐UASB reactor at an HRT of 12 h exceeded those of the reference reactor at an HRT of 24 h. The hydraulic circulation in the ZVI bed enhanced the function of ZVI so that it improved the COD and color removal efficiencies. Moreover, fluorescence in situ hybridization experiments revealed that the abundance of Archaea in the sludge of the ZVI bed was significantly higher than that at the reactor bottom, which made the reactor capable of greater COD removal under low temperature and short HRT conditions. CONCLUSION: This ZVI‐UASB reactor could adapt well to changes in the operational conditions during wastewater treatment. Copyright © 2010 Society of Chemical Industry     

螺旋升流式反应器系统较长泥龄时运行效果及其流态释因

结合螺旋升流式反应器（SUFR）的特性,通过对比试验分析SUFR系统在较长泥龄时（主要在32 d左右）营养物去除的工艺特点。试验结果表明,SUFR系统（θ_c=32 d）出水COD和TN分别小于40 mg·L^-1﹑10 mg·L^-1,SUFR系统（θ_c=32 d）除磷率随着泥龄的延长有一定的下降,但出水TP一直稳定在1 mg·L^-1内, SUFR系统（θ_c=32 d）的SOUR值为10～18 mg·g^-1·h^-1。流态模拟结果表明,SUFR系统中单元反应器的推流流态容积利用率为63%。这说明SUFR系统反应器以活塞流为主要特征的流态特性有助于减轻较长泥龄对污水处理的负影响。该系统具有更宽的泥龄适宜范围。     

Effect of pre‐treatments based on UV photocatalysis and photo‐oxidation on toluene biofiltration performance

BACKGROUND: The integration of UV photocatalysis and biofiltration seems to be a promising combination of technologies for the removal of hydrophobic and poorly biodegradable air pollutants. The influence of pre‐treatments based on UV_{254 nm} photocatalysis and photo‐oxidation on the biofiltration of toluene as a target compound was evaluated in a controlled long‐term experimental study using different system configurations: a standalone biofilter, a combined UV photocatalytic reactor‐biofilter, and a combined UV photo‐oxidation reactor (without catalyst)‐biofilter. RESULTS: Under the operational conditions used (residence time of 2.7 s and toluene concentrations 600–1200 mg C m^?3), relatively low removal efficiencies (6–3%) were reached in the photocatalytic reactor and no degradation of toluene was found when the photo‐oxidation reactor was operated without catalyst. A noticeable improvement in the performance of the biofilter combined with a photocatalytic reactor was observed, and the elimination capacity of the biological process increased by more than 12 g C h^?1 m^?3 at the inlet loads studied of 50–100 g C h^?1 m^?3. No positive effect on toluene removal was observed for the combination of UV photoreactor and biofilter. CONCLUSIONS: Biofilter pre‐treatment based on UV_{254 nm} photocatalysis showed promising results for the removal of hydrophobic and recalcitrant air pollutants, providing synergistic improvement in the removal of toluene. Copyright © 2011 Society of Chemical Industry     

NOx removal from the flue gas of oil-fired boiler using a multistage plasma-catalyst hybrid system

The study on removal of NO_x from the flue gas of oil-fired boiler has been carried out using non-thermal plasma cum catalyst hybrid reactor at 150 °C. Propylene (C₃H₆) was used as a reducing agent. A multistage plasma-catalyst hybrid reactor was newly designed and successfully operated to clean up the flue gas stream having a flow rate of 30 Nm³/h. TiO₂ and Pd/ZrO₂ wash-coated on cordierite honeycomb were used as catalysts in the present study. Though the plasma-catalyst hybrid reactor with TiO₂ showed good activity on the removal of NO yet it removed only 50–60% of NO_x because a significant portion of NO oxidized to NO₂. On the contrary, the plasma-catalyst hybrid reactor with Pd/ZrO₂ removed about 50% of inlet NO with a negligible amount of NO oxidation into NO₂. The plasma/dual-catalysts hybrid system (front two units of plasma-Pd/ZrO₂ + rear two units of plasma/TiO₂) proved to be very promising in NO_x removal in the presence of C₃H₆. DeNO_x efficiency of about 74% has been achieved at a space velocity of 3300/h at 150 °C.     

浆态光催化反应器有机模拟废水光催化氧化特性与动力学

采用循环式浆态光催化反应器对苯甲酰胺模拟废水光催化氧化特性和动力学进行了研究,系统地考察了操作条件对模拟污染物光催化降解的影响,并与搅拌式和鼓泡床式浆态光催化反应器中苯甲酰胺的降解效果进行对比.结果表明,循环式浆态光催化反应器中光催化剂的用量、污染物的初始浓度和初始pH值对模拟污染物光催化降解性能的影响存在适宜值;体系中H₂PO^-₄、Cl^-、Cu²⁺、Al³⁺对其光催化降解过程有明显的抑制作用.与传统的搅拌式和鼓泡床式浆态光催化反应器相比,循环式浆态光催化反应器中催化剂和废水的混合效果较好,光利用率高,较大程度上减少催化剂的用量和提高废水处理能力.同时,对不同催化剂的用量和污染物初始浓度下的光催化氧化反应动力学研究表明,此过程符合拟一级动力学,催化剂表面反应速率常数k₀和催化剂吸附平衡常数K_TiO2分别为0.0279 min^-1和17.99 L•g^-1.     

A photocatalytic membrane reactor for gas-phase reactions using porous titanium oxide membranes

Photocatalytic membrane reactors using porous titanium oxide membranes having pore sizes of several nanometers were utilized for a gas-phase reaction of methanol. Air mixed with methanol (MeOH) vapor, the concentration of which was controlled in the range of 500–6000 ppm, was fed to the photocatalytic membrane reactor in the range of 50–500 cm³/min using several types of flow patterns. Photocatalysis with membrane permeation resulted in a large decomposition rate, compared to photocatalysis without membrane permeation. The characteristics of the reaction such as decomposition ratio of MeOH, the conversion of the decomposed MeOH to CO₂ and H₂O were found to be a function of the residence time in the reactor. The photocatalytic reaction was analyzed based on pseudo-first-order kinetics to ascertain its simplicity, and the fitted curves were found to be in a relatively good agreement with the experimental data. Apparent rate constants with and without membrane permeation were 2.5 and 1.5×10⁻⁶ m s⁻¹, respectively, indicating that the performance of the photocatalytic reaction system with membrane permeation was enhanced.     

Catalytic ozonation with non-polar bonded alumina phases for treatment of aqueous dye solutions in a semi-batch reactor

Semi-batch experiments were conducted to investigate the effects of catalyst type, pH, initial dye concentration and production rate of ozone on the catalytic ozonation of the dyes, namely Acid Red-151 (AR-151) and Remazol Brilliant Blue R (RBBR). The used catalysts were alumina, 25% (w/w) perfluorooctyl alumina (PFOA), 50% (w/w) PFOA and 100% (w/w) PFOA. The results showed that the overall percent dye removal after 30 min of the reaction was not affected significantly by the catalyst type. However, highest COD reduction was achieved by ozonation with alumina for AR-151, and 100% PFOA for RBBR at pH 13. The behavior of COD reduction with the increasing amount of perfluorooctanoic (PFO) acid amount can be explained by the enhancement of catalytic activity of PFOA with alkyl chains. For both of the dyes, the highest dye and COD removals were reached at pH 13. The overall dye reduction after 30 min of ozonation was almost independent of the initial dye concentration at relatively low values while at the higher concentrations, it changed with the initial dye concentration for both of the dyes. Similarly, COD reduction changed on a limited scale with the increasing initial dye concentration from 100 mg/L to 200 mg/L; however, an increase of initial dye concentration to 400 mg/L decreased the COD reduction significantly. All the studied production rates of ozone were sufficient to provide almost 100% dye removal in 30 min, whereas the COD removal percentage was increased gradually by the increasing ozone input to the reactor. The reaction kinetics for the ozonation of each dye with and without catalyst was investigated and discussed in the paper.     

反应器型式对有机废水光催化氧化特性的影响

采用浆态光催化反应器对苯甲酰胺模拟废水光催化氧化特性进行了研究。探讨了催化剂的用量、污染物的初始浓度、反应时间、空气流量等操作参数对鼓泡式、循环式等形式的浆态光催化反应器内苯甲酰胺模拟废水光催化氧化特性和动力学的影响。结果表明,浆态光催化降解过程中污染物的浓度越低效果越好,催化剂的用量存在适当值;不同操作条件对不同形式浆态光催化反应器内苯甲酰胺模拟污染物光催化降解性能的影响不近相同。在所考察的污染物初始浓度、催化剂量和空气流量范围内,反应器中苯甲酰胺光催化氧化速率均符合拟一级动力学方程。与鼓泡式浆态光催化反应器相比,所开发的循环式浆态光催化反应器在空气作用下能更好地改善催化剂与气体和废水的混合效果,进而提高了光催化剂的利用效率,能更有效降解有机污染物;而且空气利用量小,能够大大降低浆态床光催化氧化处理废水的运行成本。     

Kinetics of wet oxidation of black liquor over a Pt–Pd–Ce/alumina catalyst

The catalytic oxidation of industrial wastewater from paper and pulp mills has been investigated in a slurry reactor at a temperature range 433–463 K and at pressures from 1.5 to 2.2 MPa. Adding Ce on alumina support promotes the catalytic activity for oxidation of black liquor. Pt–Pd–Ce/alumina catalyst shows a promising activity for wet catalytic oxidation of black liquor. The oxidation reaction over a Pt–Pd–Ce catalyst is characterized by an initial fast reaction step followed by a slow reaction step. The rate of total organic carbon (TOC) reduction was described by first-order kinetics with respect to TOC concentration in black liquor for both initial and later reaction steps. The activation energies were determined to be 54.53 and 50.13 kJ/mol for the initial and later oxidation steps, respectively. Comparison of the data with the generalized kinetic model was also presented.