Occurrence of organic contaminants in sewage sludges from eleven wastewater treatment plants, China

This study presents the occurrence of 43 semi-volatile organic compounds (SVOCs) listed as priority pollutants by both China and the United States Environmental Protection Agency, in sewage sludges collected from eleven wastewater treatment plants (WWTPs) of mainland and Hong Kong, China. Thirty-six SVOCs were detected by gas chromatography coupled with mass spectrometer (GC-MS) and at least 14 in each sample. The most abundant compounds were phthalic acid esters (PAEs) and polycyclic aromatic hydrocarbons (PAHs) with total concentrations ranging from 10 to 114mgkg(-1) dry weight (d.w.) (with a mean of 30mgkg(-1) d.w.) and from 1.4 to 33mgkg(-1)d.w. (with a mean of 16mgkg(-1) d.w.), respectively, followed by chlorobenzenes, nitroaromatics, haloethers and halogenated hydrocarbons which occurred generally at concentrations lower than 10mgkg(-1) d.w. Large variations were observed between the concentrations of individual compounds as well as their total concentrations in sludge samples from different WWTPs. The highest values of sum concentration of 16 PAHs and of 6 PAEs were found in sewage sludge from Beijing. The mean total concentration of each class of SVOCs in sewage sludge from mainland was remarkably higher than that from Hong Kong. The concentrations of di(2-ethylhexyl) phthalate in 91% sludge samples met the limit (100mgkg(-1)d.w.) proposed by the Europe Union for land application, whereas the PAH concentrations of 64% sludge samples exceeded the maximum permissible concentration (6.0mgkg(-1)d.w.). The occurrence of SVOCs in this study are compared with other studies and their sources are discussed.     

The influence of storage on the morphology and physiology of phthalic acid-degrading aerobic granules

The precultured aerobic granules with special degradabilities could be used as a feasible bioseed for enhancement of aerobic granulation systems. In practice, the storage stability, physicochemical characteristics, and recovering efficiency of granules are crucial for a long-distance transportation and successful application. In this study, phthalic acid (PA)-degrading aerobic granules were cultivated and stored for 8 wk at 4 °C. The granular size, settling ability as well as structure integrity was found stable during the storage period. It was observed that the upper 1/3 part of granules stored in the reagent bottle turned to black color, while the lower 2/3 part granules did not significantly change color (brown–yellow) after the 8-wk storage. The black and brown–yellow color PA-degrading granules were manually separated and re-inoculated into two identical sequencing batch reactors for reviving the PA degradation capability. After a 7 d operation, both black and yellow granules restored their activities to the levels before storage, in terms of total organic carbon removal efficiency (100%), specific oxygen uptake rate (59 mg g VSS⁻¹ h⁻¹), and adenosine triphosphate content (0.016 mg g VSS⁻¹). This study demonstrated that aerobic granules grown on a complex substrate could tolerate storage conditions and rapidly restored their bioactivities toward the target pollutant. The results also shed the light on the future application of precultured aerobic granules with unique functions for biodegradation and bioremediation purpose.     

The influence of iron and sulfur mineral fractions on carbon tetrachloride transformation in model anaerobic soils and sediments

The objective of this research was to identify the dissolved species or solid phase mineral fraction(s) best correlated with rates of carbon tetrachloride (CT) reductive transformation in systems modeling sulfate-reducing and iron oxide-rich soils and sediments. We used sulfide (S(-II))-treated goethite as our model system, but also studied Fe(II) and S(-II)-treated goethite, Fe(II)-treated goethite, pure FeS, and Fe(II)-treated FeS in order to isolate and evaluate the influence of different mineral fractions on reaction rates. Initial rates of CT transformation were measured for different pH values and concentrations of added Fe(II), as well as different aging times and conditions. The following dissolved species and iron and sulfur mineral fractions were quantified and compared with CT transformation rates: aqueous Fe(2+) and S(-II), surface associated Fe(II) (including weakly and strongly bound Fe(II)), FeS(s), and Cr(II) reducible solid phase S. Over the pH range of 6-10, CT transformation rates were correlated with surface associated Fe(II), while at pH 8, rates were correlated with weakly bound Fe(II). Aging of S(-II)-treated goethite led to oxidation of surface sulfur and a change in the concentration of weakly bound Fe(II), but did not change the relationship between initial rates and weakly bound Fe(II). The results of this research suggest that surface associated Fe(II) and weakly bound Fe(II) could serve as indicators of the potential for abiotic CT dechlorination in natural soils under sulfate-reducing conditions.     

新型湿法除尘除有害气体斜板塔的流场分析

研究对象为2种新型湿法除尘除有害气体的斜板塔:矩形斜板塔和伞罩形斜板塔.为了观察塔内流场分布规律,运用CFD(计算流体力学)软件,气相采用标准K-ε湍流模型描述,液相采用颗粒轨道模型描述,对2种新型塔内气液两相流动进行了数值模拟.预测了无喷淋和有喷淋两种情况下的气相湍流流场,不同空塔气速不同液气比的塔内压力损失.结果表明:采用中心出口的圆柱型塔可以有效地避免气体"死区"的产生;新型斜板塔能有效地增大气液接触面积,延长气体的塔内停留时间;加入喷淋液体以后,气相流场明显均匀化.该模拟也为塔体的进一步优化设计提供了依据.     

催化臭氧氧化法处理甲醛废水

用异丙醇钛盐表面改性法制备TiO2／SiO2催化剂，对甲醛废水进行催化臭氧氧化处理。通过比表面积的BET测定法、X射线衍射和拉曼光谱等分析方法对TiO2／SiO2催化剂进行了表征，考察了TiO2／SiO2催化剂加入量、臭氧流量及溶液pH等因素对甲醛催化臭氧氧化效果的影响。实验结果表明，在SiO2表面，TiO2微晶粒子以锐钛矿型高度分散；在甲醛质量浓度700mg／L、COD1000mg／L、TiO2／SiO2催化剂加入量2．0g、臭氧流量2．5mg／min、溶液pH8．5的条件下，催化臭氧氧化反应30min后，甲醛质量浓度由700mg／L降至39mg／L，COD去除率认到87．5％．     

降低超稳分子筛生产污水中氨氮含量工艺研究

通过对催化裂化催化剂活性组分──超稳分子筛的生产工艺过程铵盐消耗的分析,在小试试验的基础上,结合装置实际情况,经优化工艺条件,改进工艺流程,降低交换过程铵盐投料比,并用后工序废液代替化学水用于前工序浆液的调配等手段,使铵盐消耗量由1.8t/t降至0.95t/t,每年可节约467.5万元;同时采用氨氮回收技术将高氨氮污水中氨氮含量由原来的5000mg/L降至200mg/L以下,为最终采用生物法将污水氨氮含量降至15mg/L以下达标排放奠定了坚实基础。     

生物工程对提高路基安全稳定的研究

详细阐述了路基边坡遭受侵蚀破坏的机理及边坡破坏的表现方式 ;着重分析了植被措施对路基的重要防护作用 ;提出了综合生物工程技术应在路基工程中广泛应用。     

TiO2光催化脱除NOx的研究进展

利用TiO2的光催化效应脱除大气污染物是近十年来国内外学术界的研究热点之一.本文对TiO2光催化脱除NOx方面的研究工作进行了综述,着重论述了光催化氧化反应及光催化还原反应脱除NOx的反应机理及影响因素,并对应用前景作出展望.     

茅田冲2号隧道洞门安全与质量事故的分析及整治方案

通过对茅田冲 2号隧道洞门处安全与质量事故的形态、变形特征的勘察 ,判断事故形成原因 ,然后应用抗滑桩和注浆等工程措施进行综合治理。为常见的隧道洞门安全与质量事故提供了可参考的治理方法     

Combined amendment reduces soil Cd availability and rice Cd accumulation in three consecutive rice planting seasons

The scientific application of stabilized materials has been considered an effective method for the in situ remediation of Cd-contaminated soil. This study aimed to investigate the persistence of the effect of a combined amendment of limestone and sepiolite(LS) on soil Cd availability and accumulation in rice grown in a mildly Cd-contaminated paddy field(0.45 mg/kg of Cd) over three consecutive rice seasons. 1125–4500 kg/ha of LS was applied to the soil before the first rice planting season and 5...