SBR法降解有机物规律的研究

本研究是以处理啤酒废水的试验为基础展开的。试验结果进一步验证了SBR法具有简易,快速、低耗等优点。除此之外,还得出以下结论:增加间歇反应时起始污泥浓度可以提高处理效率或减少反应时间;非限制曝气方式耐冲击负荷,需氧均匀,能缩短反应周期;间歇反应中微生物细胞的合成代谢占主导地位,对氮与磷的需要量大于传统的理论值。本文还指出SBR法是很适合我国国情的一种废水处理工艺,应当加强对它的研究和推广应用。     

利用磁信息研究潮滩重金属污染的探讨

本文以长江口潮滩沉积物的系统磁性测量为基础,对照化学分析和粒度分析等数据,初步探讨了潮滩沉积物的磁性特征与重金属元素含量的相关联系及其机理,建立了重金属元素含量与磁参数的定量关系模型,并揭示了长江口潮滩重金属污染的空间特征及其与沉积环境的联系。本项工作成功地探索了利用磁信息研究潮滩重金属污染的技术路线和应用前景,指出了在一定区域内,利用适量样品的磁性测量与重金属元素分析数据,建立其定量回归模型的可行性。从而可以在区域污染调查中,通过广泛的磁数据测量,由经验公式定量地估算不同滩地部分的重金属元素含量,以全面了解潮滩重金属污染的空间分布,分析其规律和机理。由于磁测方法具有快速、简便、经济、易行等特点,它为大范围的潮滩重金属污染研究提供了一项实用有效的辅助手段。     

Selectivity in the complexation of actinides by humic substances

The interactions of a range of actinide elements (Th, U, Np, Pu, Am) with humic substances from the Needle's Eye natural analogue site were studied by gel permeation chromatography. Bulk humic substances were isolated by ammonia extraction, followed by dialysis against distilled water and freeze-drying. The gel permeation results suggest that Needle's Eye humic substances can be fractionated into three incompletely resolved fractions with average molecular weights determined by analytical ultracentrifugation around 49 000 for Fraction 1, around 14 700 for Fraction 2 and around 8000 for Fraction 3. Although there are significant differences between the organic matter elution patterns in individual gel permeation experiments, presumably due to differences in column packing, these are much smaller than the differences between metal ions. The uranium that is naturally present in these humic substances is largely bound in the late-eluting fraction. Spikes of the early actinides, including Np and Pu in controlled valency states, have been added to the humic substances, and gel permeation of the spiked humic substances shows that the three humic fractions vary greatly in their effectiveness and selectivity as ligands for early actinides.     

制备ZnO/CdS/Au异质结用于可见光催化降解低浓度甲醛

采用水热法和化学浴沉积法制备了ZnO/CdS/Au异质结光催化剂,用于可见光下室温去除低浓度甲醛。通过XRD、SEM、TEM、XPS、UV、PL、PEC、EIS等手段对ZnO/CdS/Au异质结光催化剂的光学性能、光电性能进行表征。结果表明,Au负载的ZnO/CdS纳米棒组成的微米花状结构中,异质结和金属等离子体效应能拓宽光谱吸收范围,抑制半导体缺陷发光,促进光吸收以及光生电子空穴的分离和迁移;所制备的ZnO/CdS/Au异质结光催化剂对甲醛的去除具有优异性能,室温下2 h即可将反应舱内低质量浓度甲醛(1.25 mg·m⁻³)降至0.025 mg·m⁻³以下,且经过8次重复使用后催化剂活性没有明显下降。此外,影响甲醛去除的因素,如催化剂种类、光照波长、甲醛初始质量浓度、相对湿度也进行了研究和探讨。该研究结果对低浓度甲醛的室温去除具有理论指导意义。     

Fractionation of fulvic acids: characteristics and complexation with copper

Two fulvic acid samples isolated from Suwannee river (International Humic Substance Society) and Feeitsuey reservoir were subjected to gel filtration chromatography (GFC) for molecular size fractionation. The GFC-eluted samples were separated into three groups corresponding to the molecular weight ranges: < 220, 220-1000, and 1000-4000. Fluorescence quenching techniques were employed for determining the conditional stability coefficient and kinetic parameters of copper complexation with the three fractions of fulvic acids. Experimental conditions were pH 6, 5 x 10(-5)m total copper and 5 mg C litre(-1) of fulvic acids. The conditional stability coefficients of the fulvic acid fractions were in the order of 0.9-3.3 x 10(5)m(-1), and the forward and reverse rate constants were in the order of 6.9-12.4 x 10(3)m(-1) s(-1) and 3.5-8.0 x 10(-2) s(-1). Information could be useful in modelling copper transport in the hydrosphere.     

Methods for the preparation of a biodesulfurization biocatalyst using Rhodococcus sp

Several methods to prepare a biodesulfurization (BDS) biocatalyst were investigated in this study using a strain of Rhodococcus sp. 1awq. This bacterium could selectively remove sulfur from dibenzothiophene (DBT) via the "4S" pathway. DBT, dimethylsulfoxide (DMSO), sodium sulphate and mixed sulfur sources were used to study their influence on cell density, desulfurization activity, desulfurization ability, and the cost of biocatalyst production. In contrast to that observed from bacteria cultured in DBT, only partial desulfurization activity of strain 1awq was induced by DBT after cultivation in a medium containing inorganic sulfur as the sole sulfur source. The biocatalyst, prepared from culture with mixed sulfur sources, was found to possess desulfurization activity. With DMSO as the sole sulfur source, the desulfurization activity was shown to be similar to that of bacteria incubated in medium with DBT as the sole sulfur source. The biocatalyst prepared by this method with the least cost could remove sulfur from hydrodesulfurization (HDS)-treated diesel oil efficiently, providing a total desulfurization percent of 78% and suggesting its cost-effective advantage.     

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons

This study selected biosolids from a petrochemical waste-water treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl2) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl2-immersed biosolids pyrolyzed at 500 degrees C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high.     

Assessment of soil lead exposure in children in Shenyang, China

Soil lead pollution is serious in Shenyang, China. The paper brings together the soil work, the bioaccessibility, and the blood lead data to assess the soil lead exposure in children in Shenyang, China. Approximately 15.25% of the samples were above China Environment Protection Agency guideline concentration for soil Pb to protect human from health risk (350 mgkg(-1)). Pb concentrations varied among use scenarios. The main lead contamination sources are industry emission and automobile exhaust. Bioaccessibility also varied among use scenarios. Children, who ingested soil from industrial area, public parks, kindergarten playground, and commercial area, are more susceptible to soil lead toxicity. The industrial area soil samples presented higher bioaccessibility compared to the other use scenario soil samples contaminated by automobile exhaust. The result also suggested a most significant linear relationship between the level of Pb contamination and the amount of Pb mobilized from soil into ingestion juice. Soil pH seemed to have insignificant influence on bioaccessibility in the present study. Bioaccessibility was mainly controlled by other factors that are not investigated in this study. A linear relationship between children blood lead and soil intestinal bioaccessibility was present in the study. Children who are 4-5 years old are more likely to demonstrate the significant relationship between soil lead bioaccessibility and blood lead as their behaviors place them at greatest risk of soil lead toxicity, and their blood lead levels are more likely to represent recent exposure.     

Road grade estimation for on-road vehicle emissions modeling using light detection and ranging data

Vehicle-specific power (VSP) is useful for explaining a substantial portion of variability in real-world vehicle emissions, such as those measured with portable emissions monitoring systems (PEMS). VSP is a function of vehicle speed, acceleration, and road grade. Road grade is shown to significantly affect estimates of both VSP and of real-world emissions via sensitivity analysis and analysis of empirical data. However, road grade is difficult to measure reliably using PEMS. Therefore, alternative methods for estimating road grade were identified and compared. A preferred method for estimating road grade was explored in more detail based on light detection and ranging (LIDAR) data. The method includes buffering LIDAR data onto roadway maps using a geographic information system tool, defining segments of roadway based on criteria pertaining to vertical curvature, quantification of roadway elevations within the buffered segments, and estimation of road grade and banking by fitting a plane to each segment. Factors influencing errors in road grade estimates are discussed. The method was evaluated by application to selected interstate highways and comparison to design drawing data. The development and application of LIDAR-based road grade data are demonstrated via a case study using PEMS data collected in the Research Triangle Park, NC, area. LIDAR data are shown to be reliable and accurate for road grade estimation for vehicle emissions modeling.