Sorption of 3,4-dichloroaniline on four contrasting Greek agricultural soils and the effect of liming

Sorption of 3,4-dichloroaniline (3,4-DCA) on four typical Greek agricultural soils, with distinct texture, organic matter content and cation exchange capacities, was compared by using sorption isotherms and the parameters calculated from the fitted Freundlich equations. The sorption process of 3,4-DCA to the soil was completed within 48–72 h. The 3,4-DCA sorption on all soils was well described by the Freundlich equation and all sorption isotherms were of the L-type. The sandy clay loam soil with the highest organic matter content and a slightly acidic pH was the most sorptive, whereas the two other soil types, a high organic matter and neutral pH clay and a low organic matter and acidic loam, had an intermediate sorption capacity. A typical calcareous soil with low organic matter had the lowest sorption capacity which was only slightly higher than that of river sand. The 3,4-DCA sorption correlated best to soil organic matter content and not to clay content or cation exchange capacity, indicating the primary role of organic matter. The distribution coefficient (K _d) decreased with increasing initial 3,4-DCA concentration and the reduction was most pronounced with the highly sorptive sandy clay loam soil, suggesting that the available sorption sites of the soils are not unlimited. Liming of the two acidic soils (the sandy clay loam and the loam) raised their pH (from 6.2 and 5.3, respectively) to 7.8 and reduced their sorption capacity by about 50 %, indicating that soil pH may be the second in importance factor (after organic matter) determining 3,4-DCA sorption.     

高碱度水库水混凝过程中残留铝控制

针对高碱度水库水源的某水厂残留铝超标问题,选取碱化度(B)与Alb含量不同的3种铝盐絮凝剂,研究不同投量与pH值下混凝效果与残留铝浓度水平。结果表明,碱化度和Alb含量显著影响混凝效果。DOC和浊度的去除率随着3种絮凝剂AlCl3(B=0)、PACl-1(B=1.2)、PACl-2(B=2.2)投量增大而升高。3种絮凝剂投量在1.5～2.0 mg/L(以铝计)范围内,总铝和溶解铝含量最低。对于该水厂自制的絮凝剂PACl-2,可通过降低絮凝剂碱化度,或将水的pH值降低至7～7.5之间,以此可以提高PACl-2混凝效果,而且可以降低出厂水残留铝浓度。考虑工程应用可行性,可优先考虑调整絮凝剂生产工艺。     

常温低基质厌氧氨氧化反应器启动及其稳定性

以上向流生物滤池为反应器,以实验室内氧化沟回流污泥为接种污泥,采用先培育好氧生物膜,后转为厌氧环境培育厌氧氨氧化生物膜的方式,成功实现了常温低基质浓度下厌氧氨氧化反应器的启动。控制反应器进水pH为7.50～7.80,NH4+-N为30～40 mg/L,NO2--N为35～50 mg/L,温度为20～25℃。224 d以后,反应器启动成功。在稳定运行阶段,出水亚硝氮和氨氮的平均浓度分别为1.4 mg/L和4.6 mg/L,平均去除率分别为95.3%和90.1%,去除比例为1～1.8∶1,主要集中在1.4～1.5∶1,亚硝氮和氨氮去除的容积负荷分别为104.2 mg/(L.d)和146.0 mg/(L.d)。     

不同流量分配比对多级A/O工艺去除有机物及脱氮的影响

采用三级A/O工艺分段进水工艺处理低碳源生活污水,考察了进水流量分配比对系统去除有机物、硝化反硝化能力以及去除TN的影响。通过对水质指标沿程监测结果表明,不同流量分配比(4∶3∶3,5∶3∶2,6∶3∶1)对系统去除有机物及硝化效率影响不大,出水COD、氨氮分别均在30 mg/L、1 mg/L以下。但反硝化效果受流量分配比的影响较大,在流量比为5∶3∶2时,有效利用原水中碳源进行反硝化,反硝化效果最好。在流量比为5∶3∶2的情况下,TN出水为5.7 mg/L去除率为82.9%,优于流量分配比为6∶3∶1和4∶3∶3时的脱氮效果。总体而言,分段进水工艺在对碳源的有效利用及能耗节省方面优于单点进水。     

某生活垃圾卫生填埋场渗滤液的梯度分离与表征

目前,渗滤液中污染物的粒度分布及其在渗滤液污染控制中的作用日益受到关注。通过系列微滤膜(1.2μm及0.45μm)对某生活垃圾卫生填埋场渗滤液各处理单元的渗滤液进行梯度分离,发现悬浮物对COD、浊度的影响较大;COD主要在胶体态和可溶解态间分配,不同渗滤液中的分配情况不同;磷主要与胶体、悬浮物以各种形式结合而存在;细胶粒和溶解态等小分子对TN的贡献大;不同粒度物质对pH的影响不明显;总残渣在可溶态组分中所占比例较大。膜微滤处理渗滤液可以有效的去除一部分物质,使COD、TP、TN、浊度、电导率都有不同程度的降低,pH逐渐升高,但对总N、残渣的去除效果不好。     

碳源类型及进水量分配对CMICAO工艺脱氮除磷的影响

研究了分别以葡萄糖和乙酸钠为碳源时多点交替进水阶式A2/O(CMICAO)工艺氮磷的去除效果,以及在不同进水C/N比时各进水量分配对脱氮除磷效果的影响.结果表明,在相同的进水COD浓度下,乙酸钠比葡萄糖更适合作为碳源,更能提高脱氮除磷效率.以葡萄糖为碳源时,COD为200 mg/L、C/N比为5、缺氧池与厌氧池进水配比为1∶2时,出水COD、TN、氨氮和TP浓度分别为28.5、10.8、2.1和0.5 mg/L,均达到国家一级A排放标准.若采用葡萄糖作为碳源,投加量以使进水C/N比为5～7.5为宜,外加碳源时缺氧池与厌氧池进水分配比可统一采用1∶1.     

土壤镉处理对棉花镉吸收及分布规律的影响

用CdCl2将盆栽土壤Cd浓度处理为1mg／kg、5mg／kg、10mg／kg、20mg,／kg、30mg／kg种植棉花,研究棉花对镉的吸收及镉在棉花体内的分布规律。结果表明,当土壤镉浓度小于30mg／kg时,镉在棉花体内的分布呈现不同的规律。当土壤镉浓度小于5mg／kg时,镉主要分布在棉花的地上部;当土壤镉浓度大于20mg／kg时,镉主要分布在棉花的叶片、根、茎中,其中叶片的镉含量最高,棉絮镉含量最低。不同镉污染水平下,棉花的镉富集系数均小于1。当土壤镉污染浓度为5mg／kg时,棉花叶片的镉富集系数为0．76。在同一镉污染水平下,棉花叶片的镉转运系数最高。当土壤镉含量小于20mg／kg时,棉花茎、叶、棉絮的转运系数平均为4．63。     

Sexual difference in PCB congener distributions of burbot (Lota lota) from Lake Erie

Concentrations of 86 congeners of polychlorinated biphenyls (PCBs) were determined for 25 adult female and 25 adult male burbot (Lota lota) from Lake Erie. Significant differences in mean proportions of total PCB concentration between males and females ages 14–17 were found for 26 congeners. Males generally had higher mean proportions of hexachloro congeners, whereas females had higher mean proportions of more highly chlorinated congeners. In contrast, only four congeners exhibited differences between males and females ages 6–13 in mean proportions of total PCB. Therefore, the sexual difference in PCB congener distribution widened for older burbot. Males ages 14–17 also had higher proportions of certain hexachloro congeners than the other three demographic groups (males ages 6–13, females ages 6–13, and females ages 14–17) we examined. The reverse was true for more highly chlorinated congeners. The results supported a previous hypothesis that older male burbot spent a substantial amount of time feeding in the vicinity of mouths of rivers with sediment contaminated with PCBs. However, additional studies are needed to clarify and corroborate this apparent “hot spot” effect, such as seasonal movements, spatial distributions, and diet of burbot; and PCB congener distributions of various species of prey fishes captured at various locations throughout the eastern basin of Lake Erie and at different locations in the contaminated rivers.     

Hexabromocyclododecanes in limnic and marine organisms and terrestrial plants from Tianjin,China: Diastereomer- and enantiomer-specific profiles,biomagnification, and human exposure

To interpret the distribution of hexabromocyclododecanes (HBCDs) in various organisms, we measured the concentrations and diastereomer and enantiomer profiles of HBCDs in 21 different species of limnic and marine cohorts from Tianjin, China. The concentration ranges of HBCDs in limnic and marine organisms were 64.3–1111 ng g⁻¹ lw and 85.5–989 ng g⁻¹ lw, respectively. Living habitat and feeding habits had important impacts on HBCD diastereomer distribution. Most of the species appeared to preferentially select (+)-α-, (−)-β- and (−)-γ-HBCD. There is a tendency that the total and α-HBCDs were magnified as trophic level increased with trophic magnification factors (TMFs) around 2. The concentrations of HBCDs in the limnic and marine fishes were highest in the liver, followed by the gill, skin, and muscle. In terrestrial plants, the highest concentrations of HBCDs were observed in the leaf, followed by the root and the rhizosphere soil. Plants showed enantioselectivity for HBCD enantiomers, which varied with plant species and organs (leaf vs. root) of the same plant. Higher estimated daily intakes (EDIs) of HBCDs were observed from fish than from wheat.