Mobilities and leachabilities of heavy metals in sludge with humus soil

Chemical forms of Zn, Ni, Cu, and Pb in municipal sewage sludge were investigated by adding humus soil to sludge and by performing sequential extraction procedures. In the final sludge mixtures, Zn and Ni were mainly found in Fe/Mn oxide-bound (F3) and organic matter/sulfide-bound (F4) forms. For Zn, exchangeable (F1), carbonate-bound (F2), and F3 forms were transformed to F4 and residual forms (F5). For Ni, F1 and F2 forms were transformed to F1, F2, and F3 forms. Both Cu and Pb were strongly associated with the stable forms F4 and F5. For Cu, F2 and F3 forms were major contributors, while for Pb, F3 and F4 forms were major contributors to F5. Humus soil dosage and pH conditions in the sludge were strongly correlated with the forms of heavy metals. Five forms were used to evaluate metal mobilities in the initial and final sludge mixtures. The mobilities of the four heavy metals studied decreased after 28 days. The metal mobilities in the final sludge mixtures were ranked in the following order: Ni > Zn > Cu = Pb. Leaching tests showed that the mobilities of Zn and Ni in lower pH conditions (pH 4) were higher than those in higher pH conditions (pH 8).     

Remediation of copper polluted red soils with clay materials

Attapulgite and montmorillonite were utilized to remediate heavy metal polluted red soils in Guixi City, Jiangxi Province, China. The e ects of clay minerals on availability, chemical distribution, and biotoxicity of Cu and Zn were evaluated. The results provided a reference for the rational application of clay materials to remediate heavy metal contaminated soils. From the sorption experiment, the maximum adsorbed Cu2+ by attapulgite and montmorillonite was 1501 and 3741 mg/kg, respectively. After polluted red soil was amended with attapulgite or montmorillonite and cultured at 30 and 60 days, soil pH increased significantly compared to the control. An 8% increase in the amount of montmorillonite in soil and 30 days incubation decreased acid exchangeable Cu by 24.7% compared to the control red soil. Acid exchangeable Cu decreased with increasing amounts of attapulgite and montmorillonite, with best remediation e ect reached at a dose of 8%. Results also showed that the Cu poisoning e ect on earthworms was reduced with the addition of attapulgite and montmorillonite. Montmorillonite showed the best e ect, with the addition of a 2% dose the mortality of earthworms decreased from 60% to zero compared to the control. Our results indicated that the bioavailability of Cu in soils was reduced more e ectively with the application of montmorillonite than attapulgite.     

Removal of heavy metal ions from aqueous solution using red loess as an adsorbent

The adsorption behaviors of heavy metals onto novel low-cost adsorbent, red loess, were investigated. Red loess was characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectra. The results indicated that red loess mainly consisted of silicate, ferric and aluminum oxides. Solution pH, adsorbent dosage, initial metal concentration, contact time and temperature significantly influenced the efficiency of heavy metals removal. The adsorption reached equilibrium at 4 hr, and the experimental equilibrium data were fitted to Langmuir monolayer adsorption model. The adsorption of Cu(II) and Zn(II) onto red loess was endothermic, while the adsorption of Pb(II) was exothermic. The maximum adsorption capacities of red loess for Pb(II), Cu(II) and Zn(II) were estimated to be 113.6, 34.2 and 17.5 mg/g, respectively at 25°C and pH 6. The maximum removal efficiencies were 100% for Pb(II) at pH 7, 100% for Cu(II) at pH 8, and 80% for Zn(II) at pH 8. The used adsorbents were readily regenerated using dilute HC1 solution, indicating that red loess has a high reusability. All the above results demonstrated that red loess could be used as a possible alternative low-cost adsorbent for the removal of heavy metals from aqueous solution.     

COD/SO42-对硫酸盐有机废水处理效率的影响

以人工配制的含硫酸盐有机废水作为原水,研究不同COD/SO42-值下厌氧折流板反应器(ABR)处理含硫酸盐有机废水去除率.试验结果表明:当COD/SO42-＜14.8时COD的去除率可达95%,SO42-的去除率在86%～96%之间;当COD/SO42-在14.8～4.0之间时,COD的去除率有所下降但仍能保持在94%...     

土壤pH、Eh对土壤-苦丁茶树系统中铅分布的影响

以苫丁茶冬青(Ilex kudingcha C.J.Tseng)扦插苗(15个月生)进行盆栽实验,通过土施H2SO4、Ca(OH)2和复合肥,改变土壤pH和氧化还原电位(Eh),研究土壤pH、Eh条件对土壤-苦丁茶树系统中铅分布的影响.结果表明:在所研究的土壤pH范围内,从酸性到碱性变化,铅在土壤中含量分布趋于减少,在...     

V(Ⅴ)与V(Ⅳ)在不同土壤中的吸附-解吸行为研究

选择四川攀枝花地区广泛分布的3种土壤,研究五价钒[V(Ⅴ)]与四价钒[V(Ⅳ)]在土壤中的吸附-解吸行为。分别运用Langmuir模型和Freundlich模型对V在黄棕壤、紫色土和水稻土中的等温吸附线进行拟合,计算出这2种价态的V在各土壤中的最大吸附量,比较不同土壤对不同价态V的吸附能力,同时分别分析3种土壤吸附平衡液与解吸液pH的变化。结果表明:(1)2种价态的V在3种土壤中的等温吸附线与两模型均基本吻合;(2)3种土壤对2种价态的V的吸附能力大小顺序一致,依次为:黄棕壤>水稻土>紫色土;(3)3种土壤对V(Ⅳ)的最大吸附量基本一致,但紫色土与水稻土对V(Ⅴ)的最大吸附量高于黄棕壤;(4)V(Ⅳ)在3种土壤中的解吸率高于V(Ⅴ),最高可达48.93%;(5)V(Ⅴ)的吸附平衡液与解吸液pH均随V浓度增加呈上升趋势,而V(Ⅳ)的吸附平衡液与解吸液pH均随V(Ⅳ)浓度增加呈下降趋势,且3种土壤的吸附平衡液pH变化幅度较解吸液大。     

基于熵值法新疆循环经济发展综合评价分析

根据循环经济理论,针对新疆循环经济的发展,从资源可承载能力、环境发展、社会经济发展三个方面考虑建立新疆循环经济发展的综合评价指标体系,运用熵值法对新疆10年循环经济的发展水平进行综合评价,进而提出了相应的措施,包括完善法律法规体系、加快产业结构调整、加大政策鼓励力度、促进产业集聚等。     

丹东市降水pH值及酸雨分析

分析2013年大气降水pH值及近10年历史演变的方法分析丹东市酸雨污染现状、特征,并从污染源和气候条件解释酸雨形成的原因,确定酸雨的形成受外来空气污染物影响较大,而酸雨强度的大小具有本地环境条件和环境污染特征。     

泥炭碱提取液E4/E6值表征泥炭腐殖化度及其古气候意义

采用AMS14C测年技术建立了哈尼泥炭地的年代序列,以泥炭碱提取液的E4/E6值(400nm和600nm处吸光度比值)来表征泥炭腐殖化度,并探讨其指示的古气候意义。研究结果表明:根据泥炭碱提取液E4/E6值与校正年龄的变化曲线,以及将其与哈尼泥炭400nm处吸光度直接表征腐殖化度的曲线进行对比,发现哈尼泥炭碱提取液的E4/E6值对古气候具有很好的指示意义,对全新世以来的气候突变事件以及前人研究的气候时期划分都能得到很好的对应,即哈尼泥炭碱提取液E4/E6值高,泥炭腐殖化度低,指示气候干冷,其E4/E6值低,泥炭腐殖化度高,指示气候暖湿。在今后的研究中,可结合E4/E6值来表征泥炭腐殖化度,并结合磁化率、孢粉等化学物理生物因子以及温度、湿度、水文、地质条件等其他因素来探讨泥炭腐殖化度对古气候的指示意义。     

土壤pH对东南景天修复镉污染土壤的影响研究

东南景天是一种镉和锌的超积累植物,改变土壤p H能否有效提高其吸收镉的效率,需要进一步验证。采用盆栽实验研究不同土壤p H下东南景天吸收和积累Cd的差异以及对Ca Cl2提取有效态镉的影响。结果表明,降低土壤p H值显著提高了土壤镉的有效态含量。弱酸性土壤即p H接近5.5时东南景天生物量及累积镉的量最大,土壤镉去除率也最高,达6.6%。强酸性即当p H接近4时,虽然植物地上与地下镉含量均最高,但生物量最小,植物去除率较其他处理低。研究证实降低土壤p H是提高植物提取效率的有效办法,这为进一步利用东南景天修复镉污染土壤,提高修复效率提供了科学依据。