Cu~(2+)助芬顿法处理高浓度邻苯二甲酸二甲酯废水

Cu2+可以与H2O2发生类Fenton反应,用Fenton法处理同时含有难降解有机物和Cu2+的工业废水时,Cu2+对于Fenton氧化难降解有机物的反应具有促进作用。本实验在高浓度邻苯二甲酸二甲酯(DMP)和Cu2+组成的模拟工业废水中投加Fenton试剂(Fe2++H2O2),利用Cu2+辅助Fe2+催化Fenton反应氧化难降解有机物。通过正交实验,优选反应条件,并进行单因素实验,分析不同Cu2+浓度、初始H2O2浓度、H2O2∶Fe2+(摩尔比)、pH及温度对DMP去除率的影响,以确定最佳的反应条件,并对反应机理进行了初步探讨。当Cu2+浓度为10 mg/L、DMP浓度为250 mg/L、初始H2O2的浓度为499.5 mg/L、H2O2∶Fe2+的摩尔比为4∶1、温度为20℃时,DMP的去除率最高可达到98.67%。本研究为类芬顿法处理难降解有机物和重金属离子共存的复杂工业废水奠定了基础。     

Detection of Escherichia coli in a cattle manure composting process by selective cultivation and colony polymerase chain reaction

Livestock manure is suitable for use as a composting material. However, various intestinal microbes, such as Escherichia coli, are significant components of such manures. Thus, it is desirable that the level of intestinal microbes, and particularly opportunistic pathogens, in compost is inspected and counted regularly. The sensitivity and specificity of detection of E. coli in compost have been improved by selective cultivation followed by colony polymerase chain reaction (PCR) using the ECO primer. Indeed, the sensitivity of this method is higher than that of DNA extraction from compost and PCR. In this study, changes in numbers of E. coli present in a field-scale composting process over time was assessed using selective cultivation and colony PCR. Numbers of ECO-positive colonies after 24 h decreased, with a concomitant rise in compost temperature. ECO-positive colonies were not detected from 33 to 48 h. However, ECO-positive colony numbers increased beginning on day 4 and continuing until day 42. Thus, it seems likely that the high temperatures reached during the composting process did not affect E. coli numbers in the final compost. Additionally, selective cultivation followed by colony PCR using specific primers is an appropriate method of determining levels of cultivable pathogens in composted materials.     

Nitrate reduction by green rusts modified with trace metals

A kinetic study of nitrate reduction by green rust (GR), a group of layered Fe(II)-Fe(III) hydroxide solids, was performed using a batch reactor system. The reduction rate of nitrate by GRs was affected by the anion content in the interlayer of GRs. GR containing F^- (GR-F) showed the fastest reduction rate while GR-SO₄ showed 9 times slower reaction rate than GR-F. The addition of 1 mM Pt or Cu to GR that contained 85 mM Fe(II) improved the reduction kinetics of nitrate by up to 200 times. Pt was an effective activating agent for all GRs. The sequential step reaction model that we proposed appropriately simulated the experimental data. The fastest nitrate reduction by GR-F with Pt was achieved at pH 9 among 7.5 to 11. At that condition, 1 mM nitrate transformed completely into ammonium within 23 min.     

Heterogeneous reactions of suspended parathion, malathion, and fenthion particles with NO(3) radicals

Organophosphorus pesticides (OPPs) emit into the atmosphere in both gas and particulate phases via spray drift from treatments and post-application emission, but most of their degradations in the atmosphere are not well known. In this study, the heterogeneous reactions of nitrate (NO₃) radicals with three typical OPPs (parathion, malathion, and fenthion) absorbed on azelaic acid particles are investigated using an online vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The reaction products observed with the VUV-ATOFMS are identified on the basis of GC/MS analysis of the products in the reaction between NO₃ radicals and the coating of the pesticide. Paraoxon is identified as the only product of parathion; malaoxon and bis(1,2-bis-ethoxycarbonylethyl)disulfide as the products of malathion; fenoxon, fenoxon sulfoxide, fenthion sulfoxide, fenoxon sulfone, and fenthion sulfone as the products of fenthion. The degradation rates of parathion, malathion, and fenthion under the experimental conditions are 5.5 × 10⁻³, 5.6 × 10⁻², and 3.3 × 10⁻² s⁻¹, respectively. The pathways of the heterogeneous reactions between the three OPPs and NO₃ radicals are proposed. The experimental results reveal the possible transformations of these OPPs through the oxidation of NO₃ radicals in the atmosphere.     

Magnetite/mesocellular carbon foam as a magnetically recoverable fenton catalyst for removal of phenol and arsenic

A magnetite-loaded mesocellular carbonaceous material, Fe₃O₄/MSU-F-C, exhibited superior activity as both a Fenton catalyst and an adsorbent for removal of phenol and arsenic, and strong magnetic property rendering it separable by simply applying magnetic field. In the presence of hydrogen peroxide, the catalytic process by Fe₃O₄/MSU-F-C completely oxidized phenol and As(III) under the conditions where commercial iron oxides showed negligible effects. Notably, the decomposition of H₂O₂ by Fe₃O₄/MSU-F-C was not faster than those by commercial iron oxides, indicating that hydroxyl radical produced via the catalytic process by Fe₃O₄/MSU-F-C was used more efficiently for the oxidation of target contaminants compared to the other iron oxides. The homogeneous Fenton reaction by the dissolved iron species eluted from Fe₃O₄/MSU-F-C was insignificant. At relatively high doses of Fe₃O₄/MSU-F-C, total concentration of arsenic decreased to a significant extent due to the adsorption of arsenic on the catalyst surface. The removal of arsenic by adsorption was found to proceed via preoxidation of As(III) into As(V) and the subsequent adsorption of As(V) onto the catalyst.     

北京市冬季空气中PM2.5对THP-1细胞焦亡的影响

为了验证PM_2.5进入肺部后,在肺巨噬细胞清除PM_2.5组分中是否发生细胞焦亡效应,本研究以THP-1细胞作为人巨噬细胞模型,以不同浓度PM_2.5暴露于THP-1细胞,采用CCK-8法检测细胞存活率,试剂盒检测乳酸脱氢酶(LDH)释放水平,荧光显微镜下观察细胞PI染色情况,流式细胞仪检测Annexin V/PI染色,蛋白免疫印迹(Western blotting)检测焦亡相关蛋白NLRP3、ASC、caspase-1、GSDMD的表达,以及ELISA法检测IL-1β、IL-18的分泌等来检测PM_2.5暴露诱导THP-1细胞的焦亡发生和炎症因子释放水平.结果显示：THP-1细胞暴露于PM_2.5后,细胞存活率的降低与PM_2.5暴露浓度的增加呈正相关;THP-1暴露PM_2.548 h后,细胞胀大并呈气泡状;与空白对照(PBS)组相比,PM_2.5暴露组与阳性对照组(1.0μg·mL^-1LPS+5.0...     

厌/缺氧时间对好氧颗粒污泥同步硝化内源反硝化和除磷的影响

选用4组同规格SBR反应器,在A/O/A模式下以水解酸化液为进水,调整厌/缺氧时间分别为50min/170min、90min/130min、130min/90min、180min/40min,探讨颗粒污泥在不同厌/缺氧时间下脱氮除磷特性.结果表明,厌氧时间从50min延长至90min时,污泥内碳源储存量和释磷量增加,同步硝化反硝化(SND)效率提高至62.65%,TN、TP去除率分别从81.1%、82.2%上升92.9%、98.5%.当厌氧时间从90min升至180min时,释磷量反而下降,厌氧内源性条件刺激胞外聚合物(EPS)增加造成聚羟基烷酸(PHA)合成下降,TP去除率降至88.1%;同时缺氧时间从130min降至40min,系统残留的NOX-较多,造成TN去除率降低至84%.机理分析表明系统中TN在好氧段由反硝化聚磷菌(DPAOs)和反硝化聚糖菌(DGAOs)利用PHA以SND方式消耗,并在缺氧段由DGAOs内源反硝化进一步去除,TP由PAOs和DPAOs去除,由批次实验估算得DPAOs占比在R2中最高,达41%,4组反应器运行期间颗粒均未发生解体,以水解酸化液为基质培养的颗粒...     

催化湿式氧化法处理废水的研究进展

介绍了催化湿式氧化（CWAO）法废水处理技术在催化剂开发、反应机理探讨和反应动力学研究等方面取得的进展;提出研制高效稳定的催化剂、探讨反应机理和研究反应动力学模型对于CWAO法的推广起着非常重要的作用。     

PCR技术在水体微生物检测中的应用

聚合酶链式反应(PCR)技术因其特异性强、灵敏度高以及快速简便等优点广泛应用于水体微生物的检测。综述了PCR技术的原理、方法及其在水体微生物检测中的研究进展。主要介绍了该技术应用于水环境中微生物病原体的检测、污水生物处理过程的监测与评价中的重要意义以及本实验室在该领域的研究进展。PCR技术为在分子水平上进行环境微生物的结构、多样性分析提供了有力的实验手段,有着广泛的应用前景。