UV/TiO2/Fenton光催化氧化垃圾渗滤液的研究

采用UV/TiO2与Fenton法的联合工艺处理垃圾渗滤液,考察了反应温度、pH值、TiO2投加量、H2O2用量等对COD去除率和脱色率的影响,比较了单一的Fenton法、UV/TiO2法和UV/TiO2/Fenton法处理垃圾渗滤液的效果.结果表明,反应温度越高,对垃圾渗滤液中COD的去除率和脱色率也越高;pH值为4时处理效果较好,pH值过低会抑制·OH的产生,pH值过高则水中胶体不易被去除,且Fe2+易失去催化活性;TiO2投加量需适当,TiO2过量会引起光散射,降低紫外光辐射效率;过量的H2O2会引发自由基链反应终止;UV/TiO2与Fenton试剂耦合,可促进TiO2表面羟基化,提高·OH的生成效率,加快自由基的链传递,提高对污染物的降解速率.     

Heterogeneous UV/Fenton degradation of TBBPA catalyzed by titanomagnetite: catalyst characterization, performance and degradation products

Tetrabromobisphenol A (TBBPA), a widely used brominated flame retardant, could negatively affect various aspects of mammalian and human physiology, which triggers effective techniques for its removal. In this work, the degradation characteristics of TBBPA in heterogeneous UV/Fenton reaction catalyzed by titanomagnetite (Fe_3−xTi_xO₄) were studied. Batch tests were conducted to evaluate the effects of titanomagnetite dosage, H₂O₂ concentration and titanium content in magnetite on TBBPA degradation. In the system with 0.125 g L⁻¹ of Fe_2.02Ti_0.98O₄ and 10 mmol L⁻¹ of H₂O₂, almost complete degradation of TBBPA (20 mg L⁻¹) was accomplished within 240 min UV irradiation at pH 6.5. The titanium incorporation obviously enhanced the catalytic activity of magnetite. As shown by the XRD and XANES results, titanomagnetite had a spinel structure with Ti⁴⁺ occupying the octahedral sites. On the basis of the degradation products identified by GC-MS, the degradation pathways of TBBPA were proposed. TBBPA possibly underwent the sequential debromination to form TriBBPA, DiBBPA, MonoBBPA and BPA, and β-scission to generate seven brominated compounds. All of these products were finally completely removed from reaction solution. In addition, the reused catalyst Fe_2.02Ti_0.98O₄ still retained the catalytic activity after three cycles, indicating that titanomagnetite had good stability and reusability. These results demonstrated that heterogeneous UV/Fenton reaction catalyzed by titanomagnetite is a promising advanced oxidation technology for the treatment of wastewater containing TBBPA.     

Kinetics of aniline degradation by Fenton and electro-Fenton processes

Aniline degradation at pH 2 by Fenton and electro-Fenton processes was kinetically investigated in this study. Electro-Fenton process was found to be superior to ordinary Fenton process with the current impacts of 1.2 to 3.1 for removal efficiency and 1.2 to 5.8 for degradation rate depending on initial Fe2+ concentration. This is mainly due to the rapid electrochemical regeneration of Fe2+. Overall rate equations for aniline degradation by Fenton and electro-Fenton processes (in units of molar and minute) are: [EQUATION: SEE TEXT]. With current application, aniline degradation rate seems to be autonomous from Fenton's reagent concentrations and approaching a half order with respect to aniline. In addition, for complete removal of 0.01 M aniline, the delay in current supply at the initial stage could save up to one-third of the total energy required by the ordinary electro-Fenton process. As a result, significant reduction in energy consumption and operating cost could be obtained by the current-delay operating mode.     

Anodic Fenton process assisted by a microbial fuel cell for enhanced degradation of organic pollutants

The electro-Fenton process is efficient for degradation of organic pollutants, but it suffers from the high operating costs due to the need of power investment. Here, a new anodic Fenton system is developed for energy-saving and efficient treatment of organic pollutants by incorporating microbial fuel cell (MFC) into an anodic Fenton process. This system is composed of an anodic Fenton reactor and a two-chamber air-cathode MFC. The power generated from a two-chamber MFC is used to drive the anodic Fenton process for Acid Orange 7 (AO7) degradation through accelerating in situ generation of Fe²⁺ from sacrificial iron. The kinetic results show that the MFC-assisted anodic Fenton process system had a significantly higher pseudo-first-order rate constant than those for the chemical Fenton methods. The electrochemical analysis reveals that AO7 did not hinder the corrosion of iron. The anodic Fenton process was influenced by the MFC performance. It was also found that increasing dissolved oxygen in the cathode improved the MFC power density, which in turn enhanced the AO7 degradation rate. These clearly demonstrate that the anodic Fenton process could be integrated with MFC to develop a self-sustained system for cost-effective and energy-saving electrochemical wastewater treatment.     

光化学氧化降解水中有机微污染物试验研究

通过室内试验研究了溶液浊度、流速、光源和pH值等因素对2,4-二氯酚(2,4-DCP)光降解速率的影响,确定了光化学氧化降解2,4-DCP的主要影响因素和最佳操作条件.结果表明,反应器的最佳流速为0.31 mL/s,并且在酸性条件下2,4-DCP更易于光降解,紫外光解产生的活性·OH自由基是2,4-DCP降解的直接原因.     

铁炭微电解/Fenton/生物接触氧化处理电镀废水

某电镀废水处理回用改造项目,采用TMF+RO处理工艺实现废水再生回用,回用率为60%。剩余40%的浓水通过铁炭微电解/Fenton氧化/生物接触氧化工艺处理,系统稳定运行后出水各项指标均可达到《电镀污染物排放标准》(GB 21900—2008)表3的标准。     

ME/Fenton/AF/BAF工艺处理炼油废水研究

采用微电解/芬顿/厌氧/好氧生物滤池工艺(ME/Fenton/AF/BAF)处理炼油废水,探讨了各工段的工艺参数及工艺整体运行效果。试验得到最佳工艺参数如下:微电解单元的初始pH值为3,Na₂SO₄投加量为0. 05 mol/L;双氧水的投加量为1. 5 m L/L; AF/BAF工段的水力停留时间为(2+2) h。在上述工艺条件下,ME/Fenton/AF/BAF工艺连续运行处理炼油废水时对COD、氨氮、油的平均去除率分别为85. 2%、85. 0%、90. 1%。     

Adsorption effect on the degradation of 4,6-o-dinitrocresol and p-nitrophenol in a montmorillonite clay slurry by AFT

The adsorption and degradation of 4,6-o-dinitrocresol (DNOC) and p-nitrophenol (PNP) in SWy-2 montmorillonite clay slurry were investigated. The pH and type of cation of the slurry were varied. Results showed that adsorption of DNOC and PNP increased at lower pH values, and when pH < pK_a (4.4) of DNOC, DNOC was almost completely adsorbed on the clay under given experimental conditions. The specific cation also had a significant effect on adsorption, which was dramatically enhanced in the presence of K⁺ and NH₄⁺, compared with the presence of Na⁺ or Ca²⁺. Anodic Fenton treatment (AFT) degradation of DNOC and PNP in the clay slurry was studied, and it was found that DNOC degradation rates were greatly affected by the initial pH and the types of electrolytes. Due to the higher adsorption, the degradation rate substantially decreased in the clay slurry system in the presence of K⁺ and low pH, with a large amount of DNOC residue remaining after 60 min treatment. AFT degradation of PNP was completed within 30 min treatment. Based on LC-MS data, a DNOC degradation pathway was proposed. Overall, the results showed the inhibition effect of adsorption on the degradation of nitroaromatic compounds in montmorillonite clay slurry by AFT, providing important implications for water and soil remediation.     

Effect of O2 exposure on perchlorate reduction by Dechlorosoma sp. KJ

Anaerobic bioreactors have been developed to remove perchlorate from water, but backwashing and operational interruptions can expose biofilms to oxygen. While it is well known that oxygen is a preferential electron acceptor to perchlorate for perchlorate-respiring bacteria, little is known about the effect of oxygen exposure or redox potentials on perchlorate reduction. Four different dissolved oxygen scavengers were tested for their ability to quickly restore anaerobic conditions and allow perchlorate reduction by a facultative, perchlorate respiring bacterium Dechlorosoma sp. KJ. Of the four different oxygen scavengers tested (Oxyrase trade mark, L-cysteine, Na2S and FeS), only Oxyrase trade mark was able to rapidly (<30 min) scavenge dissolved oxygen and allow cell growth. There was no cell growth after addition of Na2S and FeS, and l-cysteine produced a long lag in cell growth. To investigate the effect of dissolved oxygen on perchlorate reduction, anaerobically grown cultures Dechlorosoma sp. KJ, were exposed to dissolved oxygen for various periods ranging from 1 to 32 h. Perchlorate reduction and redox potential were then measured for cells returned to an anaerobic environment containing an oxygen scavenger. It was determined that cells exposed to dissolved oxygen for more than 12h were incapable of reducing perchlorate. Cells exposed to dissolved oxygen for less than 12h quickly reduced the redox potential to negative values (-127 mV to -337 mV) and were able to reduce perchlorate or chlorite. Our results suggest that aeration during backwashing of biofilm reactors, or exposure of perchlorate-degrading cell suspensions to dissolve oxygen for less than 12h, will not be detrimental to the ability of perchlorate-degrading bacteria to use perchlorate as an electron acceptor.     

4D模型技术在绿色施工中的应用

对4D模型与4D模型技术作了概述,针对4D模型技术应用于绿色施工的必然性和可行性,分析了其在绿色施工中的应用及发展状况以及一些缺点,最后提出了加快4D模型技术在绿色施工中应用步伐的途径,从而保证绿色施工的顺利进行。     

Simultaneous degradation of disinfection byproducts and earthy-musty odorants by the UV/H2O2 advanced oxidation process

Advanced treatment technologies that control multiple contaminants are beneficial to drinking water treatment. This research applied UV/H₂O₂ for the simultaneous degradation of geosmin, 2-methylisoborneol, four trihalomethanes and six haloacetic acids. Experiments were conducted in de-ionized water at 24 ± 1.0 °C with ng/L amounts of odorants and μg/L amounts of disinfection byproducts. UV was applied with and without 6 mg/L H₂O_2. The results demonstrated that brominated trihalomethanes and brominated haloacetic acids were degraded to a greater extent than geosmin and 2-methylisoborneol. Tribromomethane and dibromochloromethane were degraded by 99% and 80% respectively at the UV dose of 1200 mJ/cm² with 6 mg/L H₂O₂, whereas 90% of the geosmin and 60% of the 2-methylisoborneol were removed. Tribromoacetic acid and dibromoacetic acid were degraded by 99% and 80% respectively under the same conditions. Concentrations of trichloromethane and chlorinated haloacetic acids were not substantially reduced under these conditions and were not effectively removed at doses designed to remove geosmin and 2-methylisoborneol. Brominated compounds were degraded primarily by direct photolysis and cleavage of the C-Br bond with pseudo first order rate constants ranging from 10⁻³ to 10⁻² s⁻¹. Geosmin and 2-methylisoborneol were primarily degraded by reaction with hydroxyl radical with direct photolysis as a minor factor. Perchlorinated disinfection byproducts were degraded by reaction with hydroxyl radicals. These results indicate that the UV/H₂O₂ can be applied to effectively control both odorants and brominated disinfection byproducts.     

Solar Fenton and solar TiO2 catalytic treatment of ofloxacin in secondary treated effluents: Evaluation of operational and kinetic parameters

Two different technical approaches based on advanced oxidation processes (AOPs), solar Fenton homogeneous photocatalysis (hv/Fe²⁺/H₂O₂) and heterogeneous photocatalysis with titanium dioxide (TiO₂) suspensions were studied for the chemical degradation of the fluoroquinolone ofloxacin in secondary treated effluents. A bench-scale solar simulator in combination with an appropriate photochemical batch reactor was used to evaluate and select the optimal oxidation conditions of ofloxacin spiked in secondary treated domestic effluents. The concentration profile of the examined substrate during degradation was determined by UV/Vis spectrophotometry. Mineralization was monitored by measuring the dissolved organic carbon (DOC). The concentrations of Fe²⁺ and H₂O₂ were the key factors for the solar Fenton process, while the most important parameter of the heterogeneous photocatalysis was proved to be the catalyst loading. Kinetic analyses indicated that the photodegradation of ofloxacin can be described by a pseudo-first-order reaction. The rate constant (k) for the solar Fenton process was determined at different Fe²⁺ and H₂O₂ concentrations whereas the Langmuir-Hinshelwood (LH) kinetic expression was used to assess the kinetics of the heterogeneous photocatalytic process. The conversion of ofloxacin depends on several parameters based on the various experimental conditions, which were investigated. A Daphnia magna bioassay was used to evaluate the potential toxicity of the parent compound and its photo-oxidation by-products in different stages of oxidation. In the present study solar Fenton has been demonstrated to be more effective than the solar TiO₂ process, yielding complete degradation of the examined substrate and DOC reduction of about 50% in 30 min of the photocatalytic treatment.     

O3/H2O2对水中微量2,4-D的降解效果

研究了O3／H2O2工艺对水中微量农药2，4-D的氧化效果，探讨了H2O2投量和溶液pH值对2，4-D氧化效率的影响规律，利用LC-MS和GC-MS等手段对降解产物进行了定性分析，并在此基础上提出了2，4-D的氧化降解途径。     

采用TUD模型动态模拟倒置A2/O工艺运行工况

在进行动态模拟前,首先对3组现场检测的水质、水量数据进行物料平衡检查,目的是校核实测数据的准确度。通过物料平衡分析发现,只有2组数据的物料平衡准确度合格,另外1组为无效数据。利用静态模拟建立并校正过的工艺模型对2组有效数据进行动态水质模拟,发现预测结果与实测值的吻合度至少为80％～90％。在此基础上,对典型水量日变化曲线（24h）下的动态进水负荷进行模拟以预测出水水质的变化趋势,揭示动态负荷下出水水质的变化规律以及保持良好水质所应采取的运行对策。动态模拟结果具有较高吻合度这一事实表明,数学模拟技术完全可用于我国污水处理厂运行问题诊断以及运行优化方案的制定与实施。     

Kinetics and mechanisms of DMSO (dimethylsulfoxide) degradation by UV/H(2)O(2) process

The objective of this study was to elucidate the degradation pathways of dimethylsulfoxide (DMSO) during its mineralization caused by UV/H(2)O(2) treatment. In order to accomplish this, we measured the concentration time-profiles of DMSO and its degradation intermediates during the UV/H(2)O(2) treatment. In addition, we proposed a kinetic model that could account for the degradation pathways of DMSO during its UV/H(2)O(2) treatment. The results show that the degradation of DMSO by the UV/H(2)O(2) treatment can be classified into two major pathways, and this is supported by both the analysis of the intermediates and total organic carbon (TOC) measurements. Firstly, DMSO was degraded into sulfate (SO(4)(2-)) through the formation of methansulfinate (CH(3)SO(2)(-)) and methansulfonate (CH(3)SO(3)(-)) as sulfur-containing intermediates. One of the two carbon constituents of DMSO was highly resistant to mineralization, due to the formation of methansulfonate, which reacted very slowly with (.-)OH k = 0.8 x 10(7) M(-1)s(-1)). Secondly, the other carbon constituent of DMSO was relatively easily mineralized through the formation of formaldehyde (HCHO) and formate (HCO(2)(-)) as non-sulfur-containing intermediates. The kinetic model proposed in this study for the degradation of DMSO by (.-)OH in the UV/H(2)O(2) process was able to successfully predict the patterns of concentration time-profiles of all components during the UV/H(2)O(2) treatment of DMSO.     

Oxidative decomposition of atrazine by a Fenton-like reaction in a H2O2/ferrihydrite system

The oxidation of atrazine (ATZ) was studied in the presence of hydrogen peroxide (H(2)O(2)) and ferrihydrite at different concentrations and pHs. The rate of ATZ oxidation increased with H(2)O(2) concentration and is independent of pH ranging from 4 to 8. However, at pH 3 an increase of ten times in the rate of ATZ oxidation was observed due to the mineral dissolution. The decomposition rate of H(2)O(2) was three times higher at pH 8 than 3 and increased with increase of both H(2)O(2) and ferrihydrite concentrations. The results indicate that ferrihydrite controls oxidation of ATZ by H(2)O(2) in two different ways: (i) mineral dissolution at low pH allowing the Fenton reaction to proceed in solution and (ii) surface-mediated decomposition of H(2)O(2) producing non-reactive oxygen species in particular at higher pH. Three degradation products (desethylatrazine, desisopropylatrazine, and 2-hydroxyatrazine) were identified and corroborate with a Fenton reaction taking place in solution.     

Paracetamol oxidation from aqueous solutions by means of ozonation and H2O2/UV system

Paracetamol oxidation from aqueous solutions is studied by means of ozonation and H(2)O(2) photolysis. Both oxidative systems are able to destroy the aromatic ring of the substrate with a partial conversion of the initial carbon content into carbon dioxide. For the adopted experimental conditions mineralization degrees up to 30% and 40% are observed with ozonation and H(2)O(2) photolysis, respectively. Main reaction intermediates and products are identified for both systems by HPLC and GC-MS analyses and a kinetic characterization is achieved.     

4D信息模型对施工过程的影响分析

针对建设工程项目的特点,对4D信息模型作了介绍,从施工过程模拟、分析、管理方面阐述了4D模型对施工过程的影响,对施工项目的进度、成本、管理水平、生产效率起到一定的作用。     

Kinetic model of thermophilic l-lactate fermentation by Bacillus coagulans combined with real-time PCR quantification

A simple l-lactate fermentation of organic wastes at pH 5.5 and 55 °C under nonsterile conditions using Bacillus coagulans can be suitable for l-lactate fermentation of garbage. A mathematical model that simulated the lactate fermentation characteristics of B. coagulans was developed by focusing on the inhibitory effects of substrate, lactate (product) and NaCl, and bacterial growth. Basic fermentation experiments were performed using simple substrates to derive fundamental parameters of growth rate and inhibition effects. The model was then applied to fermentations using simple substrates and artificial kitchen garbage in order to verify its applicability. Microbial concentration, a key state variable of the model was measured using both real-time polymerase chain reaction (PCR) and traditional methods. The results of these methods were compared for experimental cases in which only soluble substrates were used. B. coagulans concentrations were suitably measured using real-time PCR, even when traditional measurement methods for microbial concentrations cannot be used. The results indicate that the developed model and biomass measurement can be used to evaluate lactate fermentations using both simple and complex substrates. These proposed methods would be useful for developing a new bacterial function-based mathematical model for more complex acid fermentations.     

Efficiency and energy requirements for the transformation of organic micropollutants by ozone, O3/H2O2 and UV/H2O2

The energy consumptions of conventional ozonation and the AOPs O₃/H₂O₂ and UV/H₂O₂ for transformation of organic micropollutants, namely atrazine (ATR), sulfamethoxazole (SMX) and N-nitrosodimethylamine (NDMA) were compared. Three lake waters and a wastewater were assessed. With p-chlorobenzoic acid (pCBA) as a hydroxyl radical (^•OH) probe compound, we experimentally determined the rate constants of organic matter of the selected waters for their reaction with ^•OH (k_OH,DOM), which varied from 2.0 × 10⁴ to 3.5 × 10⁴ L mgC⁻¹ s⁻¹. Based on these data we calculated ^•OH scavenging rates of the various water matrices, which were in the range 6.1-20 × 10⁴ s⁻¹. The varying scavenging rates influenced the required oxidant dose for the same degree of micropollutant transformation. In ozonation, for 90% pCBA transformation in the water with the lowest scavenging rate (lake Zürich water) the required O₃ dose was roughly 2.3 mg/L, and in the water with the highest scavenging rate (Dübendorf wastewater) it was 13.2 mg/L, corresponding to an energy consumption of 0.035 and 0.2 kWh/m³, respectively. The use of O₃/H₂O₂ increased the rate of micropollutant transformation and reduced bromate formation by 70%, but the H₂O₂ production increased the energy requirements by 20-25%. UV/H₂O₂ efficiently oxidized all examined micropollutants but energy requirements were substantially higher (For 90% pCBA conversion in lake Zürich water, 0.17-0.75 kWh/m³ were required, depending on the optical path length). Energy requirements between ozonation and UV/H₂O₂ were similar only in the case of NDMA, a compound that reacts slowly with ozone and ^•OH but is transformed efficiently by direct photolysis.