刁江底泥砷形态的化学分级法与XANES方法比较

采用XANES(X射线近边分析)方法和化学分级法,研究了刁江污染源区尾砂及刁江底泥的砷形态组成特征. XANES方法结果表明,尾砂中砷的形态主要以毒砂(FeAsS)存在,其相对百分含量为63%~99%;而刁江底泥中的砷形态主要是毒砂、砷酸盐和亚砷酸盐,其中毒砂的比例较高,表现出典型的尾砂污染特征. 化学分级法结果表明,尾砂中砷形态主要是残渣态砷(Res-As),而底泥中的砷主要以铁合态、钙合态及残渣态形式存在. 刁江底泥中毒砂相对百分含量和残渣态砷随着与污染源区距离的增大而减小,砷酸盐和亚砷酸盐则呈相反的趋势. 化学分级法和XANES方法所反映的刁江底泥和污染源的砷形态组成和变化趋势总体上较为一致,但这2种方法所获得的定量数据存在一定的差异.      

Tenax萃取技术用于养殖底泥中有机氯农药的生物有效性研究

本研究以经济底栖生物菲律宾蛤仔和河蚬为受试生物,分别对不同浓度梯度的海洋和淡水底泥中9种代表性有机氯农药(OCPs)进行累积实验;同时采用Tenax连续萃取法研究2类底泥中OCPs的脱附动力学,提供简单、快速评价养殖底泥中OCPs生物有效性的方法,并将Tenax萃取结果与2种底栖生物的累积结果进行比较。结果表明,菲律宾蛤仔和河蚬对OCPs的生物-底泥富集因子(BSAF)分别为0.31~1.89和0.12~2.12,且底泥中有机碳标化的OCPs浓度与生物体内脂肪标化的OCPs浓度之间的相关性较差。Tenax脱附动力学的结果表明,2类底泥中OCPs的快速脱附比例(F_(rap))均在50%左右,其快速、慢速和极慢速脱附速率常数数量级分别为10~(~(-1))、10~(-2)和10~(-4)。Tenax快速脱附组分与2种底栖生物累积结果之间具有良好的相关性(r~2=0.75,P0.0001),表明Tenax萃取技术可以预测OCPs在底栖生物体内的累积量,并且该方法克服了大型底栖生物累积实验结果重复性较差等缺点。另外通过与基于热力学平衡的方法对比发现,Tenax萃取技术更适用于滤食性或可消化底泥的底栖生物对底泥污染物的富集;同时Tenax 6 h和24 h单点萃取技术可以作为简单快速评价底泥疏水性有机污染物(HOCs)生物有效性的替代方法,进一步为养殖领域的底泥污染状况以及相关水产品的质量安全和食用风险提供生物有效性评价依据。     

Eco-friendly approach for leaching out heavy metals from sewage sludge

Sewage sludge contains rich organic matter and nutrients essential for the growth of plants but the presence of toxic heavy metals restricts its land application. To overcome this, the study aims an eco-friendly approach for leaching out heavy metals. Sewage sludge from sewage treatment plant, Chennai, India was characterised. The analysis of total heavy metal concentration was done by digesting in nitric acid and different forms were extracted by community bureau of reference sequential method. Heavy metals: As, Cd, Cr, Cr, Ni, Pb and Zn were determined using inductively coupled plasma optical emission spectrometry Perkin Elmer Optima 5300 DV. The experimental set-up for heavy metal leaching was held for five consecutive days at different concentrations of humic acid (0.1%, 0.5% and 1%) at varied pH (5–9). Results revealed that at the end of fifth day at pH 8, 1% humic acid is capable of leaching out 75.5% cadmium, 66.0% nickel, 52.0% lead, 51.2% zinc, 31.2% copper and 8.5% cadmium from sewage sludge. Statistically positive correlation (0.7088) existed between the percentage of heavy metals leached out and the sum of soluble and reducible fractions. Thus, from ecological point of view, humic acid can be used to leach out heavy metals from sewage sludge serving the need in restoration of soil fertility upon land application.     

Utilization of aluminum hydroxide waste generated in fluoride adsorption and coagulation processes for adsorptive removal of cadmium ion

Although Al-based coagulation and adsorption processes have been proved highly efficient for fluoride (F) removal, the two processes both generate large amount of Al(OH)₃ solid waste containing F (Al(OH)₃-F). This study aimed to investigate the feasibility of utilizing Al(OH)₃-F generated in Al(OH)₃ adsorption (Al(OH)₃-F_ads) and coagulation (Al(OH)₃-F_coag) for the adsorption of cadmium ion (Cd(II)). The adsorption capacity of Al(OH)₃-F_ads and Al(OH)₃-F_coag for Cd(II) was similar as that of pristine aluminum hydroxide (Al(OH)₃), being of 24.39 and 19.90 mg·g^–1, respectively. The adsorption of Cd(II) onto Al(OH)₃-F_ads and Al(OH)₃-F_coag was identified to be dominated by ion-exchange with sodium ion (Na⁺) or hydrogen ion (H⁺), surface microprecitation, and electrostatic attraction. The maximum concentration of the leached fluoride from Al(OH)₃-F_ads and Al(OH)₃-F_coag is below the Chinese Class-I IndustrialWastewater Discharge Standard for fluoride (<10 mg·L^–1). This study demonstrates that the Al(OH)₃ solid wastes generated in fluoride removal process could be potentially utilized as a adsorbent for Cd(II) removal.     

Speciation of particulate trace metals in sediments of Anarbe reservoir∗

Total concentration and chemical forms of heavy metals in samples of sediment from a drinking water reservoir have been analysed. The result of total metal contest shows Fe and Mn concentration increase along the reservoir, from 4.4% in Fe and 0.07% in Mn in the end part to 6.4% Fe and 0.22% Mn at the dam. However, a decrease in organic matter along the reservoir is observed. In order to test the accuracy of the digestion methods used, a standard reference material was also analysed.

Trace metal concentrations, with exception of Cadmium, Pb and Mn, found in fraction 5 are higher than those observed in the others extractions, Fe, Ni, Zn, Cr and Cu content in non‐residual fraction is found mainly in moderately reducible fraction, but the percentage of this fraction in each metal is very different.     

The determination of partition coefficients of organic compounds in technical products and waste waters for the estimation of their bioaccumulation potential using reversed phase thin layer chromatography

Reversed phase thin layer chromatography (RPTLC) has been investigated for the estimation of octanol/water partition coefficients (P), an important parameter for the prediction of the environmental behaviour of organic chemicals. A strong correlation between P derived from the traditional octanol/water system and RPTLC has been established over five orders of magnitude. RPTLC data are likewise correlated to results obtained by high performance chromatography (HPLC). Due to the low costs, simplicity and separation power RPTLC is especially suited for the investigation and screening of mixtures of compounds before more complicated tests are involved.

Results from a round robin test on the determination of partition coefficients by HPLC, RPTLC and the batch method indicate the simplicity and accuracy of the RPTLC technique. Applications of the RPTLC‐technique on technical products and industrial waste waters are described.     

Medium ‐ pressure ‐ liquid ‐ extraction (MPLE) of selected polychlorinated biphenyls from soil (MPLE II) 1

The extraction of PCBs from spiked soils using the Medium‐Pressure Liquid‐Extraction method showed good recovery rates. Comparison of MPLE and Soxhlet extraction of naturally contaminated soil showed similar results. However, too large quantities of solvents have to be used in MPLE procedure and the elution profile makes it unlikely, that the aspired separation from PAHs would be sufficient.     

进水氨氮浓度对静置/好氧/缺氧SBR脱氮除磷性能的影响

在4个序批式反应器(SBR)R1、R2、R3和R4中,以静置段代替传统厌氧段,采用后置缺氧,考察进水氨氮浓度分别为20,30,40,50mg/L对静置/好氧/缺氧SBR脱氮除磷性能的影响.结果表明,R1、R2、R3和R4长期运行中磷去除率分别为82.3%、92.8%、92.6%和89.1%,总氮(TN)去除率分别为97.2%、88.6%、84.5%和72.6%.静置段省却搅拌,但仍起厌氧段作用,仍可实现生物强化除磷.4个反应器好氧段均发生同步硝化-反硝化(SND),分别贡献14.7%、16.6%、17.8%和14.8%的进水后TN量,且后置缺氧段利用糖原驱动反硝化,脱氮效果较好,出水TN分别为0.57,4.43,6.61,13.70mg/L.研究表明,进水氨氮浓度可影响静置释磷、好氧摄磷、反硝化除磷.静置段代替厌氧段的后置缺氧工艺可取得较好脱氮除磷效果,且节约成本,简化工艺.     

高瓦斯低透气性煤层水力压裂技术的试验研究

由于某矿煤层透气性低、瓦斯含量高,现有瓦斯抽采技术不能满足瓦斯抽采的需要,因而采用了水力压裂技术增透措施进行试验。通过该矿11-2煤层的工业试验,分析了水力压裂技术的参数选择、压裂范围、煤层透气性、压裂后抽采效果等。试验研究得出,经过水力压裂,煤层的透气性提高了2246倍,煤层瓦斯抽采效率也大幅提高     

Speciation of heavy metals in sediments from the Scheldt estuary,Belgium

A simple three-step sequential extraction procedure was applied to study the speciation of heavy metals in sediment from Scheldt estuary, and their relationship to sediment grain size and organic matter content. The sedimentary metal content was fractionated into carbonate and exchangeable, metals bound to organic matter and residual fractions. Sedimentary total metal content was also determined using an industrial microwave (ETHOS 900) HF/HNO₃ extraction method. The extracts were analysed for metals using inductively coupled plasma atomic emission spectrometry. The bioavailable fraction (exchangeable and metals bound to organic matter) comprised less than the other forms. Residue metals were the dominant form of metals in almost all studied sites. The average total metal content for the studied sites decreased in the order Fe>Cr>Cu>Co>Zn>Pb>Cd. Based on average values for the studied sites, the highest bioavailable metals in sediments were Cd (38%) from Westkapelle, Zn (17%) from Yerseke, Co (12%) from Domburg, Cr (9%) from Vlissingen, Fe and Pb each (2%) from Yerseke, and Cu (1%) from Domburg. Metal recovery was good, with<10% difference between the total metal recovered through the extractant steps and the total metal determined using HF/HNO₃ extract.