Study on fractions of adsorbed Pb and Cd onto natural surface coatings

The speciation and extent of migration of adsorbed Pb and Cd in natural surface coatings (NSCs) were investigated using sequential extraction procedure to provide an understanding of distribution of the adsorbed Pb and Cd. Extractions were conducted on NSCs before and after Pb and Cd adsorption treatment under controlled laboratory conditions with initial Pb and Cd concentrations ranging from 0.2-2.5 mol/l. The Langmuir adsorption isotherms were applied to estimate equilibrium coefficients of Pb and Cd adsorption to NSCs components. The results showed that 58.50% of adsorbed Pb in average existed in tightly adsorbed form, and the remaining Pb was mostly present as solid oxides/hydroxides (34.00%) and exchangeable and soluble form (7.50%) in NSCs, respectively. Large amount of adsorbed Cd (70.51% in average) was present in exchangeable and soluble form, following a decreasing order in tightly adsorbed form (18.61%), solid oxides/hydroxides (9.87%), and easily oxidizable solids/compounds (1.01%), respectively. No Cd was found in strongly held oxides and precipitates. Compared to the distribution of adsorbed Pb in NSCs, Cd distribution showed that less migration of Cd from exchangeable and soluble form to solid oxides/hydroxides after adsorbed to NSCs, indicating fewer sites for Cd to adsorb to NSCs and less affinity of Cd to the NSCs. These percent distributions of metals provided an additional interpretation to that Pb adsorption to the NSCs greater than that of Cd, less retention of Cd than that of Pb and less roles attributed for Pb/Cd adsorption by organic materials in NSCs, which were observed based on the selective extraction techniques in the independent investigations.     

Evaluation of PCDD/Fs patterns emitted from incinerator via direct ambient sampling and indirect serum levels assessment of Taiwanese

The aim of this study was to evaluate the PCDD/Fs patterns in ambient air based on data information emitted from incinerator generated from ambient air measurements and those in serum. Four circular zones, namely A, B, C, and D, were identified based on simulated ambient annual average PCDD/Fs concentrations, from a selected municipal waste incinerator. Sixteen ambient samples were taken from the 4 circular zones across 4-seasons. Eighty-nine volunteers were recruited according to the demographic distribution within each zone. PCDD/Fs profiles were documented both for air and serum samples collected. Comparing to the congener patterns from ambient air and serum samples, we found that OCDD, OCDF, 1,2,3,4,6,7,8-HpCDD, and 1,2,3,4,6,7,8-HpCDF were the predominant groups among 17 congeners from both the ambient air and serum sample. And, factor analysis showed the distribution patterns of PCDD/Fs from ambient air and serum samples are almost identical across different zones, except for congener patterns of serum samples from residents in zone C. In addition, the average PCDD/Fs level significantly reduced for about 10 folds than those of the other three seasons when the incinerator was shut down in one of sampling periods. We might conclude that ambient air exposure was the most important contributor to PCDD/Fs levels in ambient air but not the single in serum. Therefore, another or more powerful source, such as occupational exposure, dietary intake or the consumption of local food, should be further investigated at the same time.     

包埋固定化微生物法处理含油废水研究

本研究通过包埋固定化微生物法固定除油(Y1#菌),用于处理含油废水,并以水体中乳化油去除率为指标考察了影响乳化油降解的各种因素.选用聚乙烯醇(PVA)-海藻酸钠(SA)复配作为包埋固定化载体材料,制备成固定化微生物小球(IMB),通过实验优化了IMB制备的工艺条件.连续批次除油实验结果表明,在25～40℃,固液比1∶10,HRT为6 h的条件下,进水油含量在20～50 mg/L,乳化油去除率可达85%～90%,出水油含量低于5 mg/L.     

膜生物法降解TNT弹药销毁废水的重要影响因素

采用水解酸化一好氧膜生物工艺对弹药销毁废水中TNT进行降解试验研究。结果表明,共代谢外加碳源对TNT的生物降解影响显著。无共代谢外加碳源的情况下,HRT=40h,TNT的去除率仅为53．4％。有共代谢外加碳源的情况下,外加碳源COD与TNT提供COD比值宜大于4．8,系统对TNT的去除率可高达99％。温度对水解酸化影响重大,当温度低于15℃时,水解酸化对TNT去除率低于33．3％,而当温度高于20℃时,水解酸化对TNT的去除率不小于83％。     

气液混合脉冲放电等离子体再生活性炭系统优化研究

为了丰富活性炭再生方法,并拓宽脉冲放电等离子体技术的应用范围,研究建立了气液混合的脉冲放电等离子体体系,将其用于吸附酸性橙II (AO7)饱和活性炭的再生。通过实验,考察了气液混合方式、脉冲电压、脉冲频率和电极间距等关键参数对活性炭再生效果的影响规律,进而对该再生体系进行优化。研究结果表明,气液分离式的气液混合方式较利于该脉冲放电等离子体体系中活性炭的优化;在一定范围内提高脉冲电压,可以提高其中活性炭的再生效果;高的脉冲频率下活性炭再生效果好;气液混合脉冲放电等离子体体系中适宜于活性炭再生的电极间距为20 mm。     

Characterization of coal gangue and coal gangue-based sodalite and their adsorption properties for Cd2+ ion and methylene blue from aqueous solution

Journal of Material Cycles and Waste Management - Synthesis and development of high-efficiency and low-cost adsorbents for treating of the wastewater containing heavy metal ions and/or dyes has...     

Preparation of hydrogen-rich gas from waste polyurethane foam by steam gasification and catalytic reforming in a two-stage fixed bed reactor

Journal of Material Cycles and Waste Management - The reclamation of waste rigid polyurethane foam (WRPUF) is capable of realizing both circulations of waste and protection of the environment. In...     

NO oxidation performance and kinetics analysis of BaMO3 (M=Mn,Co) perovskite catalysts

Environmental Science and Pollution Research - Perovskite is an efficient and emerging catalyst for NO oxidation. In this study, BaMnO3 and BaCoO3 perovskite catalysts were synthesized by the...     

Antibiotic contamination in a typical water-rich city in southeast China: a concern for drinking water resource safety

Abstract

The occurrence and distribution in the aquatic environment of Nanjing of 49 antibiotics from seven therapeutic classes were investigated using an improved analytical method developed for multiclass target analysis. The results showed that these antibiotics are widely present in the water bodies of this city, with a total concentration of up to 1.958?μg L^?1. The most abundant class was tetracyclines, contributing 43.7% to the total antibiotic burden. Lincomycin was detected in all samples, and the detection rate of clindamycin was 90.5%. An exploratory analysis of the data points was performed by unsupervised pattern recognition (hierarchical cluster analysis, HCA) in an attempt to clarify the pollution level in different sampling areas, and robust cluster solutions grouped the data according to their different antibiotic contaminant profiles. The safety of drinking water resources was emphasized, and the rivers, as the main receiving water body for treated and untreated wastewater in this city, were more seriously contaminated than the surrounding lakes and reservoir, not only in concentration but also in detection frequency, in our study as well as in similar research studies. A correlation analysis between the presence of antibiotics and the environmental factors was conducted, and it was found that antibiotic contamination and water quality were closely connected; the better the water quality, the lower the antibiotic contamination. Positive correlations existed between the antibiotics and tested heavy metals, as well as between antibiotics and boron and arsenic. However, whether these correlations resulted from their reaction or a common source was difficult to determine, and the mechanism requires further exploration.