Photosensitized degradation of bisphenol A involving reactive oxygen species in the presence of humic substances

The photodegradation of endocrine disrupter bisphenol A (BPA) in the presence of natural humic substances (HS) under simulated solar irradiation was studied. BPA underwent slow direct photolysis in neutral pure water, but rapid photosensitized degradation in four kinds of HS, following pseudo-first-order reaction. Reactive oxygen species (ROS) formed from HS were determined, including OH, (1)O(2) and H(2)O(2). The enhancement of BPA degradation by adding Fe(III) was primarily attributed to the oxidation of OH produced from photo-Fenton-like reaction. And the joint effects of HS and nitrate ions coexisting on BPA degradation appeared to depend on respective concentration levels. The effects of dissolved oxygen suggested that the energy transfer between excited state of SRFA and NOFA likely occurred, while the abstraction of phenolic hydrogen atom to reactive triplet state of NOHA possibly took place. Based on the structural analyses of main intermediates and degradation products of BPA detected by GC-MS, the possible photodegradation pathways were proposed, involving the alky cleavage, alkyl oxidation and OH addition. This study gave a better understanding for the photochemical transformation of BPA induced by ROS generated from natural water composition under sunlight irradiation.     

1,2,4-三氯苯环境污染修复技术研究进展

综述了物理修复、化学修复、微生物修复及联合修复等几种主要的1,2,4-三氯苯(1,2,4-TCB)环境污染修复技术的研究进展。阐述了各种修复方法的反应原理、修复条件和效果,对比了各种修复方法的优缺点。提出今后的研究方向:解决物理吸附法修复1,2,4-TCB污染后的吸附剂的后续处理问题;优化化学降解1,2,4-TCB的工艺条件,避免二次污染,进行现场试验,实现工程应用;分离、培育1,2,4-TCB的优势降解菌种;深入研究联合修复技术的降解机理,实现1,2,4-TCB的高效、彻底降解。     

曝气对电解除磷的影响研究

针对高浓度含磷废水,重点分析了电解除磷工艺中曝气对磷去除率、pH、电导率、电极钝化的影响.结果表明:(1)在电流密度为20 mA/cm2、磷初始质量浓度为200 mg/L,初始pH为5.5～6.5的条件下,当曝气量为1.0、1.5、2.0 L/min时,60 min内磷去除率均接近100%,而且出水中未检测出磷,符合<污水综合排放标准>(GB 8978-1996)中一级标准,30～40 min内,磷去除率达到了95%以上,磷残余质量浓度小于10 mg/L,相比未曝气的情况,磷去除率有了显著提高;(2)在电流密度为20 mA/cm2、磷初始质量浓度为200 mg/L、初始pH约为3的条件下,曝气溶液的pH在前30 min呈上升趋势.30 rain后趋于平缓,最终停留在8左右;(3)在电流密度为20 mA/cm2、磷初始质量浓度为200 mg/L、初始pH约为3的条件下,曝气溶液的电导率在整个电解除磷过程中先逐步下降,30～40 min后逐步趋于稳定;(4)曝气对于抑制电极钝化、提高磷去除率有着显著效果.     

生态修复水生植物根际氨氧化细菌的研究

为研究水生植被恢复对底泥氨氧化细菌(ammonia-oxidizing bacteria,AOB)种群的影响,选取在生态修复中广泛使用的4种水生植物,芦苇(Phragmites communis)、窄叶香蒲(Typha angustifolia L.)、菹草(Potamogeton crispus L.)和荇菜(Limnanthemun nymphoides),采用最大可能数法(most pmbable number,MPN)计数AOB的数量,巢式聚合酶链式反应-变性梯度凝胶电泳(nested polymerase chain reaction-denaturing gradienl gel electmphoresis,nested PCR-DGGE)及条带回收测序的方法分析AOB的主要种类.结果显示,水生植物根际AOB密度显著高于无水生植物的表层底泥,而芦苇(2.8×105cells/g)和菖蒲(4.3×10'celts/g)又明显高于菹草(9.3 x 104cells/g)和荇菜(7.7×104 cells/g).水生植物根际呈氧化环境,而NH 4的浓度低于无水生植物的对照区.DNA测序结果显示尽管不同植物根际AOB主要种类有所区别,但基本属于亚硝化单胞菌属(Nitrosomonas).此类微生物群落在水生植物根际的聚集对促进生态修复中N元素的循环具有重要作用.     

折流式水解反应器处理印染废水水温影响研究

在水温为5℃、9.7℃、14.9℃、19.7℃、23.5℃和31.1℃6种温度的条件下,应用折流式水解反应器对印染废水进行水解试验研究.结果表明,提高水温可增大COD、色度及UVA254的去除效率,相应的ORP值变小,pH值升高,水解程度加深.水温5℃时,水解效果较差;水温在10～23.5℃内,水解效果相对较好,31.1℃水解效果最好,研究结果能为工程应用提供一定的参考.     

生物标志物在水源地风险评价中的作用与展望

针对肿瘤高发区饮用水污染和南水北调水质的风险评价问题,提出了可用生物标志物检测水中的“环境诱变剂量”来作为评价水体中有毒有害污染物潜在遗传危害的综合指标。简要介绍了生物标志物在国内外的研究动态及其在环境监测、环境风险评价中的应用前景。     

新型滤槽除尘器配套脱硫工艺试验研究

采用半干法脱硫系统与新型滤槽除尘器相结合 ,可有效提高系统的脱硫、除尘效率。研究了影响该技术脱硫效率的主要因素。该技术集脱硫、除尘于一体 ,工艺简单 ,运行成本较低 ,尤其适用于燃煤含硫量≤ 1 .2 %的锅炉烟气的脱硫。     

Using the multiple cell balance method to solve the problem of two-dimensional groundwater flow and contaminant transport with nonequilibrium sorption

The problem of large-scale contamination of groundwater by relatively low levels of organic contaminants is most frequently addressed by extracting and treating the impacted groundwater. This pump-and-treat strategy is often unsuccessful because of difficulties encountered in recovering the contaminants from relatively immobile zones within the porous medium. These zones can exist at the particle scale, as intraparticle or intra-aggregate porosity, and at the larger scales, as low-permeability layers or lenses interspersed in substantially more permeable layers. This work focuses on achieving an efficient numerical solution to a system of groundwater flow and contaminant transport equations that sufficiently captures the dynamics of slow desorption in a two-dimensional porous medium. The conceptual model and governing equations are presented. A numerical method for solving the governing equations, the upstream-weighted, multiple cell balance (UMCB) method, is proposed. The UMCB algorithm has been employed previously for the case of solute transport with equilibrium sorption, and is extended here to the nonequilibrium case. The approach employs a finite-element basis function and a finite-difference local mass balance, and is designed to reduce computational and storage requirements, while minimizing the mass balance error. The computational grid is formed by division of the flow domain into triangular elements. An invented node at the center of each element divides the element into three subtriangular regions. By linking the center of each triangular element and the mid-point of each elemental side, a multiangular region, referred to as an exclusive subdomain, is defined. The discretized system of governing equations is derived from the integral form that describes the mass balance in the exclusive subdomain of each node. The paper details the application of the numerical method, and demonstrates that the method is reasonably accurate and computationally efficient for a two-dimensional domain subject to nonequilibrium sorption.     

钝顶螺旋藻和小球衣藻富集Cd2+

为了探究我国北方水体中藻类对Cd2+的富集行为,选取常见的蓝藻(钝顶螺旋藻)和绿藻(小球衣藻),模拟天然藻类对Cd2+的吸附和吸收,研究藻液浓度、时间、pH值、温度、共存阳离子类型对富集过程的影响。结果发现:2种藻对Cd2+的富集性能优于活性炭,富集量高出2~17倍左右。藻对Cd2+的富集率随着藻液浓度的增加而升高,而单位富集量则呈现下降趋势;8 h后富集达到饱和;当pH值在3.0~9.0范围内,富集量随着pH值的升高而增加;在室温25℃时富集量最高,低温或高温时富集量都有明显下降;Fe3+对钝顶螺旋藻富集Cd2+几乎没有影响,但对小球衣藻有拮抗作用,Na+、Ca2+对2种藻类富集Cd2+均表现为拮抗作用,且价态越高,拮抗作用越明显。因此,在适宜的环境中,钝顶螺旋藻和小球衣藻对Cd2+具有良好的富集效果。     

黄磷废水中氟化物的物化处理研究

本文利用向含氟废水中加入适量石灰和聚合氯化铝PAC ,然后投加适量钙盐、磷酸和聚丙烯酰胺PAM的二级处理工艺除氟。通过控制合适的 pH、钙盐和磷酸的投加量、反应时间、反应温度、搅拌强度和絮凝剂的投加量 ,确定了最佳的除氟工艺 ,可以使氟的浓度降至 5mg/L ,达到国家一级排放标准GB8978 1996。