Fluoride removal performance of a novel Fe-Al-Ce trimetal oxide adsorbent

A trimetal oxide was developed as a fluoride adsorbent by coprecipitation of Fe(II), Al(III) and Ce(IV) salt solutions with a molar ratio of 1:4:1 under alkaline condition. The material retained amorphous structure and maintained relatively stable fluoride adsorption performance at calcination temperatures lower than 600 degrees C. The optimum pH range for fluoride adsorption was 6.0-6.5 and the adsorbent also showed high defluoridation ability around pH 5.5-7.0, which is preferable for actual application. A high fluoride adsorption capacity of 178 mg g(-1) was acquired under an equilibrium fluoride concentration of 84.5 mg l(-1), adsorbent dose of 150 mg l(-1) and pH 7.0. The adsorption isotherm could be better described by the two-site Langmuir model than the one-site model, suggesting the existence of two types of active sites on the adsorbent surface. Coexistence of high concentrations of phosphate or arsenate only led to partial inhibition of fluoride adsorption, which further suggests the existence of heterogeneous adsorption sites. Sulfate and chloride did not affect fluoride adsorption, and nitrate influenced it only when the concentration of NO(3)(-)-N exceeded 50 mg l(-1). A high desorption efficiency of 97% was achieved by treating fluoride loaded Fe-Al-Ce oxide with NaOH solution at pH 12.2. A column experiment using the adsorbent fabricated into 1mm pellets was performed at an initial fluoride concentration of 5.5 mg l(-1), space velocity of 5h(-1) and pH of 5.8, and 2240 bed volumes were treated with the effluent fluoride under 1.0 mg l(-1).     

Determination of benzene, toluene, ethylbenzene, xylenes in water at sub-ng l-1 levels by solid-phase microextraction coupled to cryo-trap gas chromatography-mass spectrometry

A trace analytical method of benzene, toluene, ethylbenzene and xylenes (BTEX) in water has been developed by using headspace solid-phase microextraction (HS-SPME) coupled to cryo-trap gas chromatography-mass spectrometry (GC-MS). The chromatographic peak shape for BTEX was improved by using cryo-trap equipment. The HS-SPME experimental procedures to extract BTEX from water were optimized with a 75 microm carboxen/polydimethylsiloxane (CAR/PDMS)-coated fiber at a sodium chloride concentration of 267 g l(-1), extraction for 15 min at 25 degrees C and desorption at 290 degrees C for 2 min. Good linearity was verified in a range of 0.0001-50 microg l(-1) for each analyte (r(2)=0.996-0.999). The limits of detection (LODs) of BTEX in water reached at sub-ng l(-1) levels. LODs of benzene, toluene, ethylbenzene, m/p-xylene and o-xylene were 0.04, 0.02, 0.05, 0.01 and 0.02 ng l(-1), respectively. The proposed analytical method was successfully used for the quantification of trace BTEX in ground water. The results indicate that HS-SPME coupled to cryo-trap GC-MS is an effective tool for analysis of BTEX in water samples at the sub-ng l(-1) level.     

建筑行业农民工的职业安全健康现状及对策

通过分析现阶段我国建筑行业农民工的常见职业性伤害事故以及职业安全健康现状,从教育、技术、监管3个方面提出了引导农民工学会利用法律、通过合法渠道维护自身权益;改善农民工的就业环境,加强个体防护,讲究文明礼貌,遵守职业行为准则,培养科学、文明、健康的生活方式等具体措施,为农村富余劳动力转移提供更多的就业机会,增加农民收入促进城乡经济协调发展,保障建筑行业农民工的职业安全健康提供科学依据。     

Isolation,identification, and acetochlor-degrading potential of a novel Rhodococcus sp. MZ-3

A new species of Rhodococcus, designated strain MZ-3, which could degrade acetochlor efficiently were isolated and identified. The isolate could degrade and utilize acetochlor as the sole source of carbon, nitrogen, and energy for growth. The optimal conditions for the degradation and growth of MZ-3 were pH 7.0 and 30°C. Under these conditions, this strain could completely degrade 200 mg/L of acetochlor within 12 h of incubation. During the biodegradation process, the enantioselectivity of the strain was investigated using a chiral high-performance liquid chromatography (HPLC) system. However, no obvious enantioselectivities were found. 2-chloro-N-(2-methyl-6-ethylphenyl) acetamide (CMEPA) was detected as the intermediate using liquid chromatography-mass spectrometry (LC-MS) analyses. Our results suggest that strain MZ-3 might be a promising microorganism for the bioremediation of acetochlor-contaminated environments because of its acetochlor-degrading performance.     

不同温度下曝气生物滤池运行效能与微生物群落结构

采用Biostyr 曝气生物滤池(BAF)处理城市污水,研究了温度变化对其处理效果与微生物群落结构的影响。结果表明,温度低于18℃(低温)时,BAF对COD和NH4+-N去除率均低于60%;当水温在18~22℃(中温)之间变化时,BAF对COD 和NH4+-N的去除效果稳定且明显高于低温时的去除率;当水温高于22℃(高温)后,BAF对COD和NH4+-N去除率与水温正相关,去除率随温度的升高而显著提高。PCR-DGGE分析表明,温度越高BAF内总细菌微生物群落多样性越好;定量PCR分析表明,BAF内总细菌、氨氧化细菌和硝化细菌的菌群密度均随温度升高而增大,与其对污染物的去除率变化趋势一致。BAF在低温环境下,滤池内的菌群结构变得简单、菌群密度降低,但出水水质仍能满足要求,表明BAF工艺具有良好的抗低温冲击能力。     

四川地区高含硫化氨气田钻完井风险因素分析

通过对川东北地区钻完井事故资料的统计,分析了影响高含硫化氢气田钻完井安全的主要风险因素。     

农用地土壤重金属生态安全阈值确定方法的研究进展

农用地土壤重金属生态安全阈值作为农用地土壤环境质量基准制定的重要依据,近年来随着多学科的共同发展,农用地土壤重金属生态安全阈值的确定方法变得越来越完善,但目前对其的研究综述却鲜见报道。因此,文章综述了农用地土壤重金属生态安全阈值的确定方法,详细阐述了点模型、概率模型以及经验模型中的代表方法在确定农用地土壤重金属生态安全阈值方面的概念、原理、发展及应用,并深入探讨了各方法的适用情况和优缺点,系统分析了各方法在确定农用地土壤重金属生态安全阈值时的不确定性及影响因素,最后在前人的研究基础上提出了今后的主要发展方向,以期为我国农用地土壤环境质量标准的完善与细化及农用地土壤其他污染物生态安全阈值的确定提供参考依据。     

汉江上游罗家滩剖面晚更新世以来沉积物粒度端元分析

通过对汉江上游旬阳段开展野外考察,在罗家滩(LJT)发现夹有古洪水滞流沉积层(slackwater deposits,SWD)的风成黄土-古土壤剖面。对采集的沉积学样品进行粒度分析,利用Gen.Weibull函数分布的参数化端元模型反演得出4个端元,结合吸湿水等环境替代指标分析,探讨了各个端元所指示的不同沉积动力环境和物质来源。结果表明:在黄土层和土壤层中,EM1代表的主要是沉积物沉积后在亚洲夏季风影响下,经历强烈风化成壤作用形成的次生黏土矿物组分;EM2代表高空西风和东亚冬季风翻越秦岭而搬运的远源细粉砂组分;EM3代表山谷风从河谷中分布的河流沉积物和坡积碎屑物中以低空短距离形式搬运而来的粉尘物质,并且受到后期气候变化控制下的淋溶作用影响;EM4则代表山谷风从近源的河流沉积物和坡积碎屑物中搬运而来的粗颗粒物质。在古洪水SWD层中,EM1、EM2和EM3主要来源于汉江上游暴雨洪水侵蚀搬运的河谷两岸分布的表层沉积物;而EM4则明确代表河流特大/大洪水环境下搬运沉积的粗颗粒悬移质泥沙。该成果能够为区域环境变化研究提供指导和借鉴。     

提高静电除尘器粉尘驱进速度方法研究

由Deutsch公式可知,尘粒驱进速度的大小直接决定着电除尘器除尘效率的高低。从提高驱进速度的角度入手,通过分析影响电除尘器除尘效率的主要因素与驱进速度的关系,得出提高电除尘器除尘效率的方法,为设计合理、高效、节能的静电除尘器提供指导。     

碱性工业废水在燃煤锅炉烟气脱硫中的应用

阐述了碱性工业废水脱硫的机理以及p H值、液气比、进气SO2浓度等对脱硫效率的影响。利用碱性工业废水对燃煤锅炉烟气脱硫,其脱硫效率平均可达70%～80%。