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首页> 外文期刊>Journal of Environmental Engineering >Biogeochemical evaluation of mechanisms controlling CaCO3(s) precipitation in landfill leachate-collection systems
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Biogeochemical evaluation of mechanisms controlling CaCO3(s) precipitation in landfill leachate-collection systems

机译：控制垃圾渗滤液收集系统中CaCO3沉淀的机理的生物地球化学评估

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A common failure mode for landfills is clogging of the leachate-collection system. The reduction in hydraulic conductivity associated with clogging causes a buildup of leachate head on the underlying liner, potentially increasing advective contaminant transport from the landfill and contaminating adjacent groundwater. In this paper, the biogeochemical model CCBATCH is used to link a primary cause of leachate collection system failure-CaCO3(s) precipitation-to anaerobic degradation of volatile fatty acids (VFAs) in column reactors used to study the clogging phenomena. One key to applying CCBATCH correctly was dividing the VFA conversion into two steps: conversion of propionate to acetate, carbonic acid, and methane; and acetate conversion to methane and carbonic acid. The primary driver for CaCO3(s) precipitation in the columns was acetate fermentation to CH4 and H2CO3, which increased the total carbonate concentration in the leachate and shifted the acid/base control to a weaker acid system, which caused an increase in solution pH. A second key to proper modeling was adding CO2(g) gas transfer to CCBATCH. The modeling results indicate that the kinetics Of CO2(g) gas transfer was a key control over leachate chemistry once acetate fermentation was nearly complete. These results suggest that the best approach for the long-term control of CaCO3(s) clogging may be to enhance CO2(g) gas transfer from the leachate while buffering the leachate pH to near neutral. Taken together, these actions should decrease the yield of CaCO3(s) precipitated per mass of acetate removed. [References: 23]
机译：垃圾填埋场的常见故障模式是渗滤液收集系统堵塞。与堵塞相关的水力传导率的降低会导致渗滤液在下层衬砌上堆积，可能增加对流污染物从垃圾填埋场的迁移，并污染附近的地下水。本文使用生物地球化学模型CCBATCH将渗滤液收集系统故障的主要原因-CaCO3沉淀与用于研究堵塞现象的柱式反应器中的挥发性脂肪酸（VFA）的厌氧降解联系起来。正确应用CCBATCH的一个关键是将VFA转化分为两个步骤：丙酸酯转化为乙酸盐，碳酸和甲烷;乙酸盐转化为甲烷和碳酸。色谱柱中CaCO3沉淀的主要驱动因素是乙酸盐发酵生成CH4和H2CO3，这增加了渗滤液中碳酸盐的总浓度，并使酸/碱控制系统转向弱酸系统，从而导致溶液pH值增加。正确建模的第二个关键是将CO2（g）气体转移添加到CCBATCH。建模结果表明，一旦乙酸发酵接近完成，CO 2（g）气体转移的动力学是控制渗滤液化学的关键。这些结果表明，长期控制CaCO3堵塞的最佳方法可能是增强渗滤液中的CO2（g）气体转移，同时将渗滤液的pH缓冲至接近中性。总之，这些作用应降低每去除的乙酸盐质量沉淀出的CaCO3的收率。 [参考：23]

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