【作者】 张华峰；

【导师】 李进；

【作者基本信息】 北京交通大学 ， 环境工程， 2008， 硕士

【摘要】 生物吸附剂作为一种新兴的吸附剂，在重金属废水处理方面有着广阔的研究前景和巨大的优势，同时已有众多学者证明生物吸附剂应用于实际过程是可行的，具有良好的社会和经济效益。本文选择SBR活性污泥法对微量重金属进行动态吸附研究，探讨SBR反应器中活性污泥作为吸附剂吸附脱硫废水中重金属的可能性及应用性。在SBR反应器中对活性污泥吸附脱硫废水溶液中Cr（Ⅲ）、Cd（Ⅱ）、Pb（Ⅱ）的行为进行研究。通过研究各种不同条件：HRT，污泥浓度，溶液起始重金属浓度以及pH对吸附的影响，确定了动态吸附下的最佳条件。研究结果如下：（1）在HRT=16h的情况下，吸附率达到71％，保证了活性污泥对重金属充分的吸附时间并且不会发生重金属离子的解析，吸附效果最佳。（2）在污泥浓度为5000～5500mg/L时，COD去除率达到88．7％，活性污泥对有机物降解能力达到最高；并且对Cr（Ⅲ）去除率达到了70％。（3）溶液起始重金属浓度（1～1000μg／L）范围内，在Cr（Ⅲ）为1～600μg／L时，活性污泥对Cr（Ⅲ）的吸附量和吸附率在不断增大，在Cr（Ⅲ）浓度=600μg／L时吸附率达到最大，为85％；当Cr（Ⅲ）达到600～1000μg／L时，活性污泥对Cr（Ⅲ）的吸附量仍旧增大，吸附效率开始下降，到Cr（Ⅲ）浓度=980μg／L时吸附率已经下降到了78％。（4）pH值对活性污泥吸附重金属的影响最为显著，当pH（?）3时，过低的pH会导致污泥的直接死亡；当pH>7时，由于吸附点位的减少和点位吸附能力的降低又会影响吸附效果；经过试验研究，在pH=6时，活性污泥对重金属吸附量和吸附率分别达到了12．82μg／g和72．3％，为最佳的吸附条件。（5）在多种重金属的共存于溶液中的情况下，会引起对吸附点位的竞争，不同的重金属离子之间的竞争产生对吸附的抑制作用，在有其他干扰重金属离子存在的情况下，目标离子的吸附效率会降低。向Cr（Ⅲ）浓度为600μg／L的废水中分别加入Pb（Ⅱ）和Cd（Ⅱ）后，Cr（Ⅲ）的去除率为56％和68％，同溶液中只存在Cr（Ⅲ）时相比，Cr（Ⅲ）的去除率分别下降了41％和22％，Pb（Ⅱ）和Cd（Ⅱ）的存在均影响了Cr（Ⅲ）的吸附效果。（6）通过对比拟和出活性污泥吸附重金属的Langmuir吸附模型和Freundlich吸附模型。得到活性污泥对Cd（Ⅱ）和Pb（Ⅱ）的吸附适合用Langmuir吸附模型解释，对Cr（Ⅲ）的吸附适合用Freundlich吸附模型解释，活性污泥对不同重金属离子的吸附能力顺序为：Pb（Ⅱ）>Cd（Ⅱ）>Cr（Ⅲ）。（7）SBR活性污泥法运用于实践当中，可以将实际脱硫废水中的重金属离子处理到国外排放标准。其中主要的重金属离子Cd²⁺、Cr³⁺、Hg²⁺、Pb²⁺、Zn²⁺的出水浓度分别为21μg／L、17μg／L、8μg／L、13μg／L、215μg／L，出水中各种金属浓度均低于国外重金属排放标准。（8）通过对活性污泥中的微生物进行研究，发现前期的累枝虫对活性污泥吸附重金属起到了主要的吸附作用。同时污泥中存在大量原、后生动物，有助与食物链的延长和增强，便会使生物量减少理论上能够达到污泥减量的目的。更多还原

【Abstract】 As an advanced absorbent, biological absorbent which has been proved to be engineering feasible and economical beneficial, has an extensive vista of research and large advantages in the treatment of wastewater that contains heavy metals.An SBR reactor was used to discuss the feasibility and utility of heavy metal biosorption by activated sludge in the treatment of desulfurization wastewater which contains traces of heavy matals. The biosorption capacities of activated sludge towards Cr（Ⅲ）, Cd（Ⅱ） and Pb（Ⅱ） in the desulfurization wastewater were observed. In this study, the influences of different hydraulic retention times（HRT）, MLSS, initial concentrations of heavy metals and pH on the heavy metal biosorption process were assessed and an optimum operation condition of heavy metal biosorption by activated sludge process were obtained. The research results are as follows:（1） HRT=16h is an optimum operation time for sufficient biosorption and at the same time non-desorption towards heavy metals, the biosorption efficiency is at its best with a value of 71 %.（2） When the concentrations of activated sludge （MLSS） are 5000～5500 mg/L, the metal biosorption capacity of activated sludge reaches a highest value, with COD removal rate of 88.7% and Cr （Ⅲ） removal rate of 70%.（3） when the initial Cr（Ⅲ） concentrations are 1～600μg /L, the capacity and efficiency of Cr biosorption are increasing constantly with the increase of initial Cr（Ⅲ） concentrations and reaches an extreme of 85% by biosorption efficiency at the Cr（Ⅲ） concentration of 600μg /L. However, the biosorption efficiency of Cr begins to drop when the initial Cr（Ⅲ） concentrations are 600～1000μg/L while the biosorption capacity remains to increase. The biosorption efficiency lowered to 78% at the initial Cr（Ⅲ） concentration of 980μg/L.（4） pH values influence heavy metal biosorption by activated sludge most. When pH<4, the out-lowered pH leads to the death of activated sludge; when pH>7, biosorpation capacity is affected by reducing the adsorption points and weakening the adsorption capability of points.In the experiment, pH=6 is optimal for heavy metal biosorption of activated sludge with the biosorption capacity and biosorption efficiency of 12.82μg/g and 72.3 %, respectively.（5） Heavy metals compete for binding sites of activated sludge in case that several metals are contained. This competition leads to the inhibition of heavy metal biosorption, and the biosorption capacity of target ions will be lowered. The Cr（Ⅲ） removal rates are lowered to 44% and 63%, compare to the condition of only existing Cr（Ⅲ）,which are fell by 41% and 22%, when Pb （Ⅱ） and Cd （Ⅱ） are added to the system, respectively. The existence of Pb （Ⅱ） and Cd （Ⅱ） affects the biosorption of activated sludge towards Cr（Ⅲ）.（6） Simulate the heavy metal biosorption of activated sludge using Langmuir and Freundlich adsorption models. It’s obtained that Cd（Ⅱ） and Pb（Ⅱ） biosorptions fit Langmuir adsorption model and Cr（Ⅲ） biosorption fits Freundlich adsorption model. The metal-sludge affinity order is obtained as follow: Pb（Ⅱ）>Cd（Ⅱ）>Cr（Ⅱ）.（7） An SBR activated sludge process is practical for heavy metal treatment in full-scale desulfurization wastewater to the discharge standard abroad. In this study, the main heavy metals in the desulfurization wastewater such as Cd²⁺, Cr³⁺, Hg²⁺, Pb²⁺ and Zn²⁺ are treated to 21μg /L, 17μg /L, 8μg /L, 13μg /L and 215μg /L, resbectively, which are all lower than the discharge standard abroad.（8） Through the research on microorganism of activated sludge, founding that the Epistylis Vrceolata played a major role in the absorption of heavy metal by activated sludge. At the same time there are a lot of Protozoans and Epigenetic animals exist in the activated sludge, it will reduce the amount of sludge theoretically and able to achieve the objective of reducing.更多还原