模拟酸雨对污染土壤中Cd、Cu和Zn释放及其形态转化的影响

研究了模拟酸雨连续浸泡下污染红壤和黄红壤中重金属释放及形态转化．结果表明。随着模拟酸雨pH值下降,污染土壤中重金属释放强度明显增大;Cd、Zn释放量与酸雨pH值呈线性极显著负相关．Cu与酸雨pH值呈线性显著负相关．模拟酸雨作用下,污染红壤和黄红壤中Cd均以交换态为主;Cu则以有机结合态和氧化锰结合态为主;Zn在污染红壤中以残留态和交换态为主．在污染黄红壤中以残留态和有机结合态为主．土壤有机质含量和阳离子交换量对Cd、Cu、Zn的释放产生一定的影响并影响Cd、Zn的形态转化,但对Cu形态转化影响不明显,随着模拟酸雨酸度增大,污染红壤和黄红壤中重金属Cd、Cu的生物可利用态明显增多,但难解吸态Zn向生物有效态转化效应不明显．     

模拟酸雨条件下Pb2+和Cr6+对蕹菜光合作用及品质的影响

以蕹菜（Ipomoea aquatica Forsk．）为供试对象,通过盆栽试验,研究了不同酸度模拟酸雨（AR）条件下,Pb^2＋和Cr^6＋对其光合作用、营养品质及食用安全性的影响。结果表明：酸雨条件下,重金属对蕹菜叶片光合作用和品质的胁迫表现为Pb〉Pb＋Cr〉Cr;随酸度增加,AR＋Pb和AR＋Pb＋Cr处理的危害性显著增加,pH=3．5时,AR＋Pb＋Cr处理的胁迫性明显大于其他处理水平,对蔬菜造成伤害;3个光合作用参数均随酸雨酸度增加有不同程度的下降,但对胁迫的敏感性存在差异;pH〈5．6时,蕹菜中蛋白质和游离氨基酸含量与pH值呈正相关;随酸度增加,可溶性糖含量增加,而还原性糖含量下降,表现出对环境胁迫的应激反应;除了Cr污染处理外,Pb污染和Pb＋Cr污染都能显著促进蕹菜中硝态氮积累,其含量随酸雨酸度上升而增加;蕹菜中Pb和Cr存在竞争吸附作用,且随着酸雨酸度下降,蕹菜对2种重金属的富集有加快趋势。     

柠檬酸、草酸和乙酸对污泥中镉、铅、铜和锌的去除效果

研究了柠檬酸、草酸和乙酸对污泥中Cd、Pb、Cu和Zn等重金属的去除效果,并分析了污泥中重金属的形态变化和生物有效性.结果表明,随着反应时间和酸浓度的增加,污泥中重金属（Cu除外）的去除率也相应增加.污泥加入柠檬酸溶液反应7h即可去除污泥中52.0%的Pb和74.2%的Zn,24h后可去除76.0%的Pb和92.5%的Zn,草酸和乙酸对重金属的去除率较低.柠檬酸去除的Pb和Zn主要以稳定态存在,并导致污泥中不稳定态重金属的比例上升,其中可交换态重金属浓度有不同程度的增加.虽然有机酸对Cd和Cu的去除率较低,但反应后可交换态Cd和Cu的浓度仍有小幅增加.     

钙的光释放技术及其在细胞研究中的应用

Ca²⁺的光释放技术通过光解作用使预先引入细胞内的光敏感性螯合剂对Ca²⁺的亲和性改变,从而实现对细胞内游离钙离子浓度的调控,有助于阐明Ca²⁺作为第二信使对电兴奋性、肌肉收缩、神经分泌等细胞功能的调制作用.     

微嗜酸寡养单胞菌EFS1的产电性能及在污水处理中的应用

【背景】微生物燃料电池(Microbial Fuel Cell,MFC)作为一种新型的燃料电池资源,在产电的同时可应用于污水处理领域,达到资源最大化的目的。【目的】从MFC中分离获得一株可培养微生物,研究其产电特性及在污水处理中的微生物絮凝、重金属耐受、苯酚降解性能,为扩展产电菌资源库提供理论基础。【方法】利用WO_3纳米探针从MFC阳极中筛选获得一株具备产电和絮凝性能的菌株,命名为EFS1。运用循环伏安分析结合扫描电镜观测阳极电极;改变外电阻测定极化曲线和功率密度曲线。测定菌株的絮凝、重金属耐受及苯酚降解性能。【结果】经16S rRNA基因序列分析,结合形态学和生理生化鉴定菌株EFS1为微嗜酸寡养单胞菌(Stenotrophomonas acidaminiphila)。菌株EFS1具有稳定的产电周期,周期电压最高可达300m V,功率密度可达56.25m W/m~2;扫描电镜发现菌株存在直接接触电极及分泌电子中介体传递电子的方式;MFC内阻为1 000Ω左右。有氧条件下菌株的絮凝率可达到70%,存在电子受体的无氧环境中可达到80%;该菌株还具有良好的Cd~(2+)、Cu~(2+)、Mn~(2+)耐受性及苯酚降解性能,在48 h、2–4 mg/L时苯酚降解率达到了100%。【结论】研究验证了产电菌EFS1具备絮凝能力、重金属耐受、苯酚降解的可能性,为产电菌的开发及污水处理方面提供理论依据。     

临床路径的应用效果和存在的问题

临床路径是一种包含了质量保证、循证医学、整体护理、持续质量改进的诊疗标准方法。它应用与临床工作中,在一定程度上能够降低医疗费用,节省卫生资源,提高病人满意度,促进医护间的相互协作。但同时,在其推广和发展的过程中,也存在一些问题。     

股票期权制在我国应用中存在的问题

股票期权作为一种企业长期激励制度从20世纪90年代在我国实现试点,至今以逐步为高新技术企业所推崇。随着我国股票市场的扩大和投资机构的增加,信息制度披露的不断完善,其实施可行性已经明确。但目前其在应用中存在一些与国情相关的具体问题,仍需进一步的完善。     

景深合成技术在植物光学微形态研究上的应用

介绍了利用电脑景深合成技术在光学显微镜上获得植物标本大景深图片的摄影方法。概述了此方法获取植物光学微形态特征清晰图片的基本步骤和优缺点。该方法制片简单,可利用最普通的生物显微镜、电子目镜结合计算机进行摄影,成本低,观察特征明显,获得的图片具有真色彩,并可拍出植物最鲜活的状态。此方法有可能成为未来植物微形态研究的一个重要手段。     

藻类胞外聚合物的产生因素及其在污水处理和生物絮凝方面的应用

藻类胞外聚合物(extracellular polymeric substances, EPS)是一种复杂的高分子聚合物,主要由多糖、蛋白质等物质组成。由于EPS具有独特的结构、大的比表面积及含有大量官能团等物理-化学特性,使其在污水处理及微藻生物质的絮凝回收等方面都有着非常重要的作用。本文系统介绍了EPS的组成及特性,重点论述了影响藻类EPS产生的生物因素及非生物因素,如光照、营养盐、pH及温度等,并对EPS在污水处理及生物絮凝方面的应用进行了总结。对藻类EPS产生机制及机理的深入研究有望为微藻提供更广阔的应用前景。     

Aerobic granular sludge: characterization,mechanism of granulation and application to wastewater treatment

Aerobic granular sludge can be classified as a type of self-immobilized microbial consortium, consisting mainly of aerobic and facultative bacteria and is distinct from anaerobic granular methanogenic sludge. Aerobic granular technology has been proposed as a promising technology for wastewater treatment, but is not yet established as a large-scale application. Aerobic granules have been cultured mainly in sequenced batch reactors (SBR) under hydraulic selection pressure. The factors influencing aerobic granulation, granulation mechanisms, microbial communities and the potential applications for the treatment of various wastewaters have been studied comprehensively on the laboratory-scale. Aerobic granular sludge has shown a potential for nitrogen removal, but is less competitive for the high strength organic wastewater treatments. This technology has been developed from the laboratory-scale to pilot scale applications, but with limited and unpublished full-scale applications for municipal wastewater treatment. The future needs and limitations for aerobic granular technology are discussed.     

城市污水土地处理专家系统研究

在进行污水土地处理适宜性调查和研究基础上,应用ＴｕｒｂｏＰｒｏｌｏｇ和Ｃ程序语言建立了污水土地处理专家系统（ＬＴＥＳ）．通过测试表明,该系统能对土地处理系统的进水水质、场地适宜性、出水目标等指标进行快速准确的判断和预测,解决了污水土地处理的选址、处理工艺类型选择等问题,是科学设置污水生态工程的重要工具．     

Biocatalyst behavior under self-induced electrogenic microenvironment in comparison with anaerobic treatment: evaluation with pharmaceutical wastewater for multi-pollutant removal

Biocatalyst behavior was comparatively evaluated under diverse microenvironments viz., self-induced electrogenic (bioelectrochemical treatment, BET) and anaerobic treatment (AnT) microenvironments, with real-field pharmaceutical wastewater. Relatively higher treatment efficiency was observed with BET (COD removal, 78.70%) over AnT (32%) along with the power output. Voltammetric profiles of AnT showed persistent reduction behavior, while BET depicted simultaneous redox behavior. BET operation documented significantly higher bio-electrocatalytic activity (k_app, 245.22 s⁻¹) than AnT (k_app, 7.35 s⁻¹). The electron accepting conditions due to the presence of electrode in the BET might contributed to higher electrogenesis leading to enhanced substrate degradation along with the removal of multiple pollutants accounting for the effective reduction of toxicity levels of wastewater. Even at higher organic loads, BET operation showed good treatment efficiency without process inhibition. Introduction of electrode-membrane assembly in anaerobic microenvironment showed significant change in the electrocatalytic behavior of biocatalyst resulting in enhanced treatment of complex wastewater.     

Removal of natural and xeno-estrogens during conventional wastewater treatment

The ecological impacts of natural estrogens and xenoestrogens in treated wastewater include altered sexual development and sex ratios among continuously exposed organisms. The primary sources of estrogenic activity in wastewater are natural estrogens such as estrone, 17β-estradiol and estriol and synthetic compounds like 17α-ethinylestradiol, alkylphenols and alklphenol ethoxylates. Precursors in raw wastewater can yield estrogenic intermediates during wastewater treatment. All these compounds can be destroyed by biochemical processes, albeit at significantly different rates or under different conditions. That is, estrogenic compounds can be, but are not always, destroyed by conventional wastewater treatment processes, suggesting that conventional processes can be optimized for removal of estrogenic activity from wastewater. Sorption to sludges derived from wastewater treatment affects the fates of hydrophobic xenoestrogens such as nonylphenol, in part because the biodegradability of sorbed contaminants is limited. It may also be possible to tailor sludge stabilization processes to remove trace contaminants, including estrogens. For example, there are significant differences in the efficiencies of aerobic and anaerobic digestion for destruction of alkylphenols and probably other estrogenic compounds with aromatic moieties. Because advanced wastewater treatment is not economically feasible for most communities, there is ample incentive to develop accurate relationships between operational parameters and removal of estrogenic compounds during secondary wastewater treatment.     

Critical review of the influences of nanoparticles on biological wastewater treatment and sludge digestion

Nanoparticles (NPs), with at least one dimension less than 100?nm, are substantially employed in consumer and industrial products due to their specific physical and chemical properties. The wide uses of engineered NPs inevitably cause their release into the environment, especially wastewater treatment plants. Therefore, it is essential to systematically assess their potential impact on biological wastewater treatment and subsequent sewage sludge digestion. This review aims to provide such support. First, this paper reviews the recent advances on the analytical developments and nano–bio interface of NPs in wastewater and sewage sludge treatment. The effects of NPs on biological wastewater treatment and sewage sludge digestion and related mechanisms are discussed in detail. Finally, the key questions that need to be answered in the future are pointed out, which include on-line revelation of the changes of NPs in sewage and sludge environments, in situ assessment of the variations of microorganisms involved in these biological systems after they are exposed to NPs. Differentiation of the contribution of individual toxicity mechanisms to these systems, and the identification of under what conditions the nanoparticle-induced toxicity will be increased or decreased are also considered.     

Reduction in excess sludge production in a dairy wastewater treatment plant via nozzle-cavitation treatment: Case study of an on-farm wastewater treatment plant

Nozzle-cavitation treatment was used to reduce excess sludge production in a dairy wastewater treatment plant. During the 450-d pilot-scale membrane bioreactor (MBR) operation, when 300 l of the sludge mixed liquor (1/10 of the MBR volume) was disintegrated per day by the nozzle-cavitation treatment with the addition of sodium hydrate (final concentration: 0.01% W/W) and returned to the MBR, the amount of excess sludge produced was reduced by 80% compared with that when sludge was not disintegrated.     

Characteristics of PAHs adsorption on inorganic particles and activated sludge in domestic wastewater treatment

The occurrence of polycyclic aromatic hydrocarbons (PAHs) in a domestic wastewater treatment plant (WWTP) was investigated in a 1 year period. In order to understand how PAHs were removed at different stages of the treatment process, adsorption experiments were conducted using quartz sand, kaolinite, and natural clay as inorganic adsorbents and activated sludge as organic adsorbent for adsorbing naphthalene, phenanthrene, and pyrene. As a result, the adsorption of PAHs by the inorganic adsorbents well followed the Langmuir isotherm while that by the activated sludge well followed the Freundlich isotherm. By bridging equilibrium partitioning coefficient with the parameters of adsorption isotherm, a set of mathematical models were developed. Under an assumption that in the primary settler PAHs removal was by adsorption onto inorganic particles and in the biological treatment unit it was by adsorption onto activated sludge, the model calculation results fairly reflected the practical condition in the WWTP.     

污水渗滤湿地处理系统技术的研究进展

由于渗滤湿地污水处理系统具有很高的净化效率和相对较低的基建投资和处理成本,目前正渐渐在许多国家得到较为广泛的应用．本文简要论述了渗滤湿地的构造与渗滤介质、N和P的去除过程与净化机理、技术性能、现行的设计方法、运行与调控机制、土壤堵塞问题与解决途径、垂直流与水平流人工湿地处理系统的组合及其在不同类型废水处理中的应用等．最后,探讨了这一技术的研究发展方向．     

人工湿地污水处理工艺设计关键及生态学问题

人工湿地污水处理系统是一种经济高效的污水生态处理技术方式．然而,湿地污水处理技术在性能上仍须有待发展与完善,尤其需要对其处理工艺参数进行不断改进和系统优化．本文针对人工湿地污水处理工程中有关水力停留时间、水传导因素、表面负荷率和工程构筑物设计等技术参数,概括性地剖析、探讨了国内外人工湿地污水处理工艺的设计关键及其主要技术内涵,给出了一些重要的优化模型与最佳数值;与此同时,分析、提出了利用生态学方法克服人工湿地工程运行中所涉及的野生生物管理与蚊蝇控制等问题。