Photoelectrocatalytic degradation of recalcitrant organic pollutants using TiO2 film electrodes: an overview

Photoelectrocatalytic (PEC) technology involved applying an electrical bias to a TiO₂ film electrode, has been widely applied to the degradation of refractory organic pollutants, owing to its high degradation efficiency. This paper reviews recent developments in the PEC degradation of recalcitrant organic contaminants using a TiO₂ film electrode. The preparation and application of various TiO₂ film electrodes have been investigated, as well as the parameters that influence PEC activity such as the crystal structure, the film thickness and substrate material, the applied electrical bias, the solution pH and conductivity. The improvement of PEC activity by doping the TiO₂ film electrode with metal and non-metal ions has been discussed. The mechanism and kinetics for the PEC degradation of organic pollutants have also been highlighted.     

适宜处理分散性生活污水的人工湿地除磷填料的筛选及改性

为提高人工湿地除磷效能,从沸石、陶粒、萤石、膨胀蛭石、石灰石、麦饭石、火山岩、牡蛎壳、钢渣和废砖块这10种具有较高磷素饱和吸附量的填料中,筛选出钢渣、沸石和石灰石3种适宜处理分散性生活污水的人工湿地填料,并分别使用不同浓度梯度的酸(碱)、盐对3种填料进行改性,以增强其除磷能力。研究结果表明,钢渣、沸石和石灰石分别经2 mol/L AlCl3、2 mol/L NaOH及2 mol/L AlCl3、0.5 mol/L AlCl3溶液改性后,磷素吸附量达到最高值(0.272、0.0801和0.351 mg/g),而双常数方程能更好地描述优选填料对生活污水中磷的吸附动力学过程,综合考虑填料的吸附效果、成本及来源,改性石灰石是人工湿地处理分散性生活污水时较为理想的除磷填料;此外,填料经铝改后,氮磷吸附效果普遍优于其他改性条件,且Al-P有利于植物直接吸收利用,含铝废水来源广泛,故利用铝改液处理人工湿地填料具有较高的应用推广价值。     

抗侵蚀型生态沟渠构建及其稻田应用效果

根据沟渠水力学和工程力学特征,通过引进三维植物网护坡技术,构建了一种抗侵蚀型稻田生态沟渠,横断面0.9 m2,沟壁和沟底水生植物覆盖度分别为62.8%和35.3%,沟壁抗坡面侵蚀强度较土质沟渠可提高2倍以上,在优化污染物拦截去除功能的同时,大大延长了其使用寿命。稻田应用实验表明,径流排水停留时间超过48 h后,SS、TN和TP去除率分别达59.5%、57.8%和45.3%,配置比例按照1 hm2水稻田配300 m该型生态沟渠实施,则超过80%以上的稻田径流排水能够得到有效处理。该型生态沟渠工程造价约245元/m,接近传统混凝土排水渠单价,经近2年的运行观测,沟渠系统结构稳定,净化植物长势良好。     

Phytostabilization potential of evening primrose (Oenothera glazioviana) for copper-contaminated sites

A field investigation, field experiment, and hydroponic experiment were conducted to evaluate feasibility of using Oenothera glazioviana for phytostabilization of copper-contaminated soil. In semiarid mine tailings in Tongling, Anhui, China, O. glazioviana, a copper excluder, was a dominant species in the community, with a low bioaccumulation factor, the lowest copper translocation factor, and the lowest copper content in seed (8 mg kg^?1). When O. glazioviana was planted in copper-polluted farmland soil in Nanjing, Jiangsu, China, its growth and development improved and the level of γ-linolenic acid in seeds reached 17.1 %, compared with 8.73 % in mine tailings. A hydroponic study showed that O. glazioviana had high tolerance to copper, low upward transportation capacity of copper, and a high γ-linolenic acid content. Therefore, it has great potential for the phytostabilization of copper-contaminated soils and a high commercial value without risk to human health.     

Determination of picogram quantities of chlortoluron in soil samples by luminol–chitosan chemiluminescence system

Based on the enhancing effect of chitosan (CS) on luminol-dissolved oxygen chemiluminescence (CL) reaction, a flow injection (FI) luminol–CS CL system was established. It was found that the increase of CL intensity was proportional to the concentrations of CS ranging from 0.7 to 10.0 μmol l^?1. In the presence of chlortoluron (CTU), the CL intensity of luminol–CS system could be obviously inhibited and the decrements of CL intensity were linearly proportional to the logarithm of CTU concentrations ranging from 0.01 to 70.0 ng ml^?1, giving the limit of detection 3.0 pg ml^?1 (3σ). At a flow rate of 2.0 ml min^?1, the whole process including sampling and washing could be accomplished within 36 s, offering a sample throughput of 100 h^?1. The proposed FI–CL method was successfully applied to the determination of CTU in soil samples with recoveries ranging from 95.0 % to 105.3 % and the relative standard deviations (RSDs) of less than 4.0 %.     

堆肥+零价铁可渗透反应墙修复黄土高原地下水中铬铅复合污染

为了研究堆肥+零价铁混合可渗透反应墙（PRB）修复黄土高原地下水中铬铅复合污染的可行性,分别用堆肥、零价铁、堆肥+ 零价铁、堆肥+ 零价铁+活性炭为反应介质,通过模拟柱实验考察PRB修复铬铅复合污染黄土高原地下水的效果。结果表明,在实验进行30 d后当反应柱1和2对六价铬的去除率接近于零,而且对二价铅的去除率迅速下降时,反应柱3对2种污染物仍保持较高的去除率;反应介质质量比为10：2：1的反应柱4和质量比为10：1：2的反应柱5对污染物的去除效果均优于质量比为10：1：1的反应柱3;反应50 d后,添加活性炭的反应柱6对2种污染物的去除率仍在90%。这说明使用堆肥+零价铁混合可渗透反应墙修复黄土高原地下水中铬铅复合污染是可行的;且以堆肥+零价铁作为介质的反应柱去除效果优于单独以堆肥或铁粉为介质的反应柱;增加铁粉或堆肥的用量有利于铬铅复合污染的去除;且同时添加活性炭更有助于污染物的去除。     

三乙胺降解菌SYA-1的分离、降解性能与动力学

从农药废水处理池的活性污泥中分离筛选得到1株高效三乙胺降解菌株SYA-1,根据菌株SYA-1的形态特征、生理生化特性和16S rRNA基因序列同源性分析,此菌株鉴定为Achromobacter sp.。菌株SYA-1能以三乙胺为惟一碳、氮源生长,并在24 h内完全降解200 mg/L的三乙胺。环境因素影响实验表明,在温度30℃,初始pH 7.0,NaCl浓度≤10 g/L条件下,菌株SYA-1生长良好且对三乙胺的降解效率最佳;金属离子对菌株生长和三乙胺降解的抑制程度表现为:Cu2+Co2+Ag+Cd2+Fe3+Pb2+。菌株SYA-1降解三乙胺的动力学过程可用Haldane模型模拟,其参数为μmax=0.123h-1;K s=82 mg/L;K i=215 mg/L。为含三乙胺废水的生物降解提供了理论依据和菌株资源。     

Air quality impacts of power plant emissions in Beijing

The CALMET/CALPUFF modeling system was applied to estimate the air quality impacts of power plants in 2000 and 2008 in Beijing, and the intake fractions (IF) were calculated to see the public health risks posed. Results show that in 2000 the high emission contribution induced a relatively small contribution to average ambient concentration and a significant impact on the urban area (9.52 microg/m(3) of SO(2) and 5.29 microg/m(3) of NO(x)). The IF of SO(2), NO(x) and PM(10) are 7.4 x 10(-6), 7.4 x 10(-6) and 8.7 x 10(-5), respectively. Control measures such as fuel substitution, flue gas desulfurization, dust control improvement and flue gas denitration planned before 2008 will greatly mitigate the SO(2) and PM(10) pollution, especially alleviating the pressure on the urban area to reach the National Ambient Air Quality Standard (NAAQS). NO(x) pollution will be mitigated with 34% decrease in concentration but further controls are still needed.     

Partitioning and source diagnostics of polycyclic aromatic hydrocarbons in rivers in Tianjin, China

Water, suspended particulate matter (SPM), and sediment samples were collected from ten rivers in Tianjin and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), dissolved organic carbon (DOC), particulate organic carbon (POC) in SPM and total organic carbon (TOC) in sediment. The behavior and fate of PAHs influenced by these parameters were examined. Generally, organic carbon was the primary factor controlling the behavior of the 16 PAH species. Partitioning of PAHs between SPM and water phase was studied, and K(OC) for some PAH species were found to be significantly higher than the predicted values. The source of PAHs contamination was diagnosed by using PAH isomer ratios. Coal combustion was identified to be a long-term and prevailing contamination source for sediment, while sewage/wastewater source could reasonably explain a short-term PAHs contamination of SPM.     

A cascade of anoxic and oxic fluidized bed biofilm reactors for treatment of synthetic municipal wastewater

In this study, a cascade of anoxic and oxic fluidized bed biofilm reactors system was carried out to treat synthetic municipal wastewater. The parameters of the influent flow rates and C/N ratios were discussed. System performance was acceptable for chemical oxygen demand (COD), ammonia, and total nitrogen removal. A decrease of ammonia and total nitrogen removal efficiencies, however, was observed when the influent flow rates increased to 5.04 and 6.12 1 h(-1). Total nitrogen removal decreased at the influent C/N ratio of 3:1. The measured ratios of COD reduction in the anoxic column to nitrogen removal through nitrification-denitrification were 3.7, 3.5, 3.3, and 3.1 g COD/g(-1) N on average when the influent C/N ratios changed from 6:1 to 3:1. The observed sludge yield (Yobs) was 0.169 g VSS g COD(-1) because of perfect denitrification in the anoxic column and the relatively long solids retention time.