粗粒包气带结构对地下水氮污染影响的模拟实验研究

用两个砂柱模拟实验研究了非均质及均质粗粒包气带结构对地下水氮污染的影响．结果表明，以蒸馏水混合液注入的Ⅰ号柱的ＮＯ３ － 的去除率为８５６９ ％ ；Ⅱ号柱的ＮＯ３ － 的去除率为３８２５ ％ ．以地下水混合液注入的Ⅰ号柱的ＮＯ３ － 的去除率为３２４８ ％ ；Ⅱ号柱的ＮＯ３ － 的去除率为２８９２ ％ ．上述数据说明，Ⅰ号柱的反硝化作用要强于Ⅱ号柱，在注入液都相同的情况下。

CFD based extraction column design-Chances and challenges

This paper shows that one-dimensional （I-D） [and three-dimensional （3-D） computational fluid dynamics （CFD）] simulations can replace the state-of-the-art usage of pseudo-homogeneous dispersion or back mixing models. This is based on standardized lab-scale cell experiments for the determination of droplet rise, breakage, coalescence and mass transfer parameters in addition to a limited number of additional mini-plant experiments with original fluids. Alternatively, the hydrodynamic parameters can also be derived using more sophisticated 3- D CFD simulations. Computational 1-D modeling served as a basis to replace pilot-plant experiments in any column geometry. The combination of 3-D CFD simulations with droplet population balance models （DPBM） increased the accuracy of the hydrodynamic simulations and gave information about the local droplet size. The high computational costs can be reduced by open source CFD codes when using a flexible mesh generation. First combined simulations using a three way coupled CFD/DPBM/mass-transfer solver pave the way for a safer design of industrial-sized columns, where no correlations are available.

Experimental Investigation and Numerical Simulation for Bacteria Transport in Soil

A thorough understanding of bacteria transport in soil and groundwater is vital to the successful practice of environmental bioremediation.In this work,a dual-process adsorption with growth and decay model of bacterial transport was proposed.The onsite soil and the high efficiency methyl tertbutyl ether （MTBE） degrading bacterium Chryseobacterium sp.A-3,was used in the experiments.The model was validated using one-dimensional soil column experiments.The results show that the dual-process adsorption with growth and decay model proposed well describes the migration mechanism of microorganisms in soil and groundwater environment.According to the model analysis and simulation,the bacterial transport is enhanced as flow velocity and inlet cell concentration increase.Compared with the contaminant MTBE,the bacteria show stronger transport capacity but the irreversible straining in soil prevents the bacteria from transporting longer than MTBE.The results have certain instructive significance to the insitu contamination remediation operation.

垃圾填埋场生物覆盖材料筛选及甲烷减排

通过模拟柱实验研究了消化污泥、矿化垃圾和黏土作为垃圾填埋场生物覆盖材料的甲烷氧化能力。3种材料的甲烷日氧化率平均值、总氧化率和氧化速率V(CH4)分别是:消化污泥10.27%、75.82%、1.76 mmol/(kg·d);矿化垃圾11.05%、75.61%、2.04 mmol/(kg·d);黏土9.05%、68.15%、1.33 mmol/(kg·d),消化污泥和矿化垃圾对甲烷的氧化能力均大于黏土。进一步探讨了消化污泥中添加粉煤灰、建筑垃圾和黏土进行改性后对甲烷的氧化能力,考察了改性污泥的渗透系数和抗压强度。结果表明:粉煤灰对消化污泥的改性效果最好,其日氧化率平均值、总氧化率和V(CH4)分别达到17.27%、92.37%和2.35 mmol/(kg·d),粉煤灰与消化污泥以1∶1～1.5∶1混配后可满足填埋场对覆盖材料渗透系数和抗压强度的要求。

煤矸石中无机和有机氮的溶出规律研究

在我国生态脆弱煤矿区,地下采空区多以煤矸石为填充材料用于矿井水的临时储存和净化,然而,煤矸石中溶出的氮素对矿井水水质的影响研究报道却很少。文中以保德矿区采集的煤矸石为研究对象,在温度为25℃,达西流量0.25mL/min条件下通过柱模拟试验研究了地下采空区充填煤矸石无机和有机氮的溶出规律,这对于评价地下采空区预处理矿井水效果具有重要意义。研究结果表明:煤矸石溶出的氮素主要为氨氮,其次为有机氮。在整个实验过程中,煤矸石中氨氮、总氮(TN)及有机氮的溶出具有间歇性特点,这与所研究煤矸石的岩石成分、矿物成分和化学成分有关,且氨氮的间歇性溶出对淋出液中pH值的变化也有一定影响。淋出液中氨氮(NH+4-N)、硝态氮(NO-3-N)、亚硝态氮(NO-2-N)、总氮(TN)和溶解性总固体(TDS)浓度的最大值均出现在实验初始取样点18h;其中硝态氮、亚硝态氮和TDS均经过了快速下降、缓慢下降至稳定三个阶段。实验开始时淋出液中硝态氮浓度约为实验结束时的42倍左右,亚硝态氮浓度约为结束时的600倍左右。总体上,煤矸石中各类氮素在前期溶出速度较快,但溶出量随时间的推移而减小并趋于稳定。