Optimization of methyl orange removal from aqueous solution by response surface methodology using spent tea leaves as adsorbent

The effective disposal of redundant tea waste is crucial to environmental protection and comprehensive utilization of trash resources. In this work, the removal of methyl orange （MO） from aqueous solution using spent tea leaves as the sorbent was investigated in a batch experiment. First, the effects of various parameters such as temperature, adsorption time, dose of spent tea leaves, and initial concentration of MO were investigated. Then, the response surface methodology （RSM）, based on Box- Behnken design, was employed to obtain the optimum adsorption conditions. The optimal conditions could be obtained at an initial concentration of MO of 9.75 mg·L-1, temperature of 35.3℃, contact time of 63.8 min, and an adsorbent dosage 3.90 g· L-1. Under the optimized condi- tions, the maximal removal of MO was 58.2%. The results indicate that spent tea leaves could be used as an effective and economical adsorbent in the removal of MO from aqueous solution.     

Modeling of Ce（IV） transport through a dispersion flat combined liquid membrane with carrier P507

A mathematical model for the transport of Ce （IV） from hydrochloric acid solutions through dispersion flat combined liquid membrane （DFCLM） with contain 2- ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester （P507） as the carrier, dissolved in kerosene as the membrane solution have been studied. This process of facilitated transport, based on membrane technology, is a variation on the conventional technique of solvent extraction and may be described mathematically using Fick＇s second law. The equations for transport velocity are derived considering the diffusion of P507 and its metallic complexes through the liquid membrane. In this work, the system is considered to be in a transient state, and chemical reaction between Ce（IV） and the carrier to take place only at the solvent-aqueous interfaces. Model concentration profiles are obtained for the Ce（IV）, from which extraction velocities are predicted. The experimental and simulated Ce（IV） extractions showed similar tendencies for a high Ce （IV） concentration and acidity case.The model results indicate that high initial Ce（IV） concentrations and acidity both have detrimental effects on Ce（IV） extraction and stripping. The diffusion coefficient of Ce（IV） in the membrane and the thickness of diffusion layer between feed phase and membrane phase are obtained and the values are 6.31 × 10-8m2·s-1 and 31.2 μm, respectively. The results are in good agreement with experimental results.     

In vitro agonistic and antagonistic endocrine disrupting effects of organic extracts from waste water of different treatment processes

Effluents from wastewater treatment plant （WWTP） have been reported to have a broad spectrum of endocrine disrupting compounds （EDCs）. The majority of studies have focused on the occurrence of estrogenic activity, while ignoring nuclear hormone receptors （NRs） pathways. In the present study, a battery of in vitro yeast bioassays and a cell bioassay, including antagonistic and agonistic effects on estrogen receptor （ER）, androgen receptor （AR）, progesterone receptor （PR）, estrogen- related receptor （ERR） and aryl hydrocarbon receptor （AHR）, were conducted to evaluate the removal efficien- cies of EDCs by different treatment processes of a WWTP located in Beijing. Estrogenic, anti-estrogenic, anti- androgenic, anti-progesteronic, anti-ERR and the activa- tion of AHR activities were detected in samples from all treatment processes and the receiving water. The concen- tration of estrogenic contaminants with estradiol （E2） equivalent concentrations ranged from 0.82 x 10-9 to 3.54 x 10 9g Ee_EQ.L-1. The concentration of anti-estrogenic contaminants with 4-hydroxytamoxifen （4-OHT） equiva- lent concentrations ranged from 1.24 × 10-6 to 2.36 x 10-6 g 4-OHT-EQ.L-1. The concentration of anti-androgenic contaminants ranged from 2.21 x 10-s to 3.52 × 10-6g flutamide-EQ. L-1. The concentration of anti-progesteronic contaminants ranged from 3.15 x 10^-5 to 2.71 x 10^-4g RU486-EQ. L-1. The concentration of anti-ERR contami- nants ranged from 7.09 x 10-5 to 6.50 x 104 g 4-OHT-EQ × L^-10. The concentration of AHR activators ranged from 1.7 × 10-10 to 3.4 × 10^-10g TCDD-EQ-L-1. These processes including secondary clarifier, coagulation, as well as coal and sand filtration could eliminated 67.2% of estrogenic contaminants, 47.0% of anti-estrogenic contaminants, 98.3% of anti-androgenic contaminants, 88.4% of anti- progesteronic contaminants, 65.4% of anti-ERR contami- nants and 46.9% of AHR activators. WWTP effluents contain multiple receptor disruptors may have very complex adverse effects on exposed organisms.     

Enhanced dewatering characteristics of waste activated sludge with Fenton pretreatment: effectiveness and statistical optimization

In this work, the enhanced dewaterabing characteristics of waste activated sludge using Fenton pretreatment was investigated in terms of effectiveness and statistical optimization. Response surface method （RSM） and central composite design （CCD） were applied to evaluate and optimize the effectiveness of important operational parameters, i.e., H202 concentrations, Fe2＋ concentrations and initial pH values. A significant quadratic polynomial model was obtained （R2= 0.9189） with capillary suction time （CST） reduction efficiency as the response. Numerical optimization based on desirability function was carried out. The optimum values for H202, Fe2, and initial pH were found to be 178 mg-g-1 VSS （volatile suspended solids）, 211mg.gI VSS and 3.8, respectively, at which CST reduction efficiency of 98.25% could be achieved. This complied well with those predicted by the established polynomial model. The results indicate that Fenton pretreatment is an effective technique for advanced waste activated sludge dewatering. The enhancement of sludge dewaterability by Fenton＇s reagent lies in the migration of sludge bound water due to the disintegration of sludge flocs and microbial cells lysis.     

Detailed analysis of PCBs and PCDD/Fs impurities in a dielectric oil sample （ASKAREL Nr 1740） from an imported transformer in China

Homolog and congener profiles of polychlori- nated biphenyls （PCBs）, polychlorinated dibenzo-p- dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） in commercial PCBs formulations are useful information for the source appointment of PCBs contam- ination as well as the risk assessment caused by potential exposure. Dielectric oil （ASKAREL Nr 1740） in an imported transformer found in China was sampled and analyzed by isotope dilution technology using high resolution gas chromatography-high resolution mass spectrometry （HRGC/HRMS）. The detailed homolog and congener profiles of PCBs obtained were compared with those of known Aroclor formulations. High similarity in the homolog profile between the oil sample and Aroclor 1260was found, with the hexachlorinated and hepta- chlorinated biphenyls accounting for more than 80.2% of the total PCBs concentration. Severn indicator PCBs contribute about 30%, while 12 PCB congeners （i.e., # 153, #143, #168, #180, #149, #165, #138, #170, #190, #187, #174, #181） account for more than 50% of the total PCB concentrations. Total concentration ofPCDDs, PCDFs and dioxin-like PCBs （DL-PCBs） was found to be 740 ng TEQ/g, of which 620 ng TEQ/g came from DL-PCBs. The contribution of PCDDs to the total TEQ was neglectable. The concentration of PCDFs homologs follows the order of OCDF 〉 HxCDFs 〉 HpCDFs 〉 PeCDFs 〉 TeCDFs, which is in consistence with the previous study on Aroclor 1260. Three DL-PCBs congeners （i.e., #118, #156, #157） accounted for 77% of the total concentration of DL-PCBs, also they contribute 72% in the TEQ caused by DL-PCBs.     

基于ISM法的矿工安全心理影响因素分析

运用ISM法建立了矿工安全心理影响因素的三层递阶结构模型,分析矿工安全心理影响因素,明晰各因素之间的层次递阶关系。结果显示,表层直接影响因素为个体心态、生理疲劳和工作应激;中层间接影响因素主要涉及个性气质、作业环境、组织公平等因素;深层根本影响因素为安全教育培训、生产组织管理及生产工艺技术这三项因素。煤矿企业可从影响矿工安全心理的根本因素出发,寻找增强矿工安全心理的有效途径。研究结果为煤矿安全管理、矿工不安全心理预防提供了一定的参考。     

焦化厂多环芳烃污染场地的环境评价实证研究

通过实地调查某焦化厂污染场地污染现状,结果表明：该场地土壤和地下水以多环芳烃（PAHs）有机类污染为主,土壤中苯并（仅）芘和多环芳烃污染以1．5m以内表层土污染为主,随着深度的增加浓度逐渐降低,弱透水层表现出良好的阻隔作用。沿着地下水流动方向,地下水中多环芳烃浓度逐渐降低,经过约400m的迁移,由17296μg／L降至111μg/L;苯并（α）芘经过200m的迁移,由18．3μg／L降至0,地下水流动导致污染物在包气带横向扩散。1号孔、3号孔和4号孔所在地表层土壤中苯并（α）芘的单个污染物的致癌风险分别为0．0278、0．0209和1．496,远远超出可接受水平,因此上述孔位所在地附近表层土壤需重点治理。     

低温贫营养好氧反硝化细菌SY13的反硝化特性

从底泥中分离出1株低温贫营养好氧反硝化细菌SY13,经常规生理生化鉴定和16SrDNA测序,鉴定出细菌SY13属于Acinetobactersp．。考察了温度、pH、C／N比及接种量对菌株SY13硝酸盐还原活性的影响,初始硝酸盐浓度为15mg／L左右,温度为15℃时低温贫营养好氧反硝化细菌SY13的硝酸盐去除率为49．26％,在中性环境适应性较强,pH值为7．0时72h的硝氮去除率达到58．08％,随着C／N比不断增加,菌株SY13硝酸盐的去除效果逐渐增强,接种量为10％时,菌株SY13培养72h后的硝氮去除率可达到59．62％。     

焊接防护具抗热穿透性能测试仪的研制

焊接防护具是指一种保护佩戴者免受由焊接或相关作业所产生的有害光辐射及其他特定有害因素的装置。它是从事焊接与热切割作业人员必备的个体防护装备。抗热穿透性能是表征焊接防护具产品质量和安全性能的最重要技术指标之一。然而,如何快速、便捷、节能、准确地对焊接防护具抗热穿透性能进行检测,是迫切需要解决的技术难题。本文在简要分析国内外眼面部防护标准中抗热穿透性能技术要求和测试方法的基础上,提出了一种测试焊接防护具抗热穿透性能的方法,并成功研制了焊接防护具抗热穿透性能测试仪。     

行为安全管理在施工中的应用分析

不良的行为习惯是导致事故的主要原因。为加强员工行为管理,提高安全行为意识,减少危险行为,本文简要介绍了建筑施工安全的管理现状,说明了行为安全管理的应用程序和方法,并将以人为中心的行为安全管理模式引入建筑施工企业,对行为安全管理提高安全的有效性进行了研究。通过在工程现场就危险因素进行为期4周的行为观察,分析发现,行为安全管理方法的实施对纠正不安全行为、提高安全管理水平效果明显,它有助于预防事故。同时,要保持较高的安全水平,应延长行为观察周期。行为安全管理是传统安全管理的补充,它的有效实施还需要员工直接参与行为观察、管理者支持以及相互的信任。