生物反应器填埋场初期的重金属释放行为

Release of heavy metals during the initial stage of the bioreactor landfill

以库容10万m3的生物反应器填埋单元1.5年的渗滤液水质监测结果为依据,研究了该填埋单元初期的重金属释放行为.结果表明,渗滤液低pH值和高溶解性有机物(DOM)含量使渗滤液中的重金属浓度超过标准限值;但随着填埋层进入稳定产甲烷化阶段,重金属浓度显著下降,渗滤液中的腐殖质是影响此阶段重金属迁移的重要媒介.渗滤液中悬浮性固体、DOM分子量分级测试和VisualMinteq模型模拟计算结果表明,渗滤液中的重金属主要以与有机物,特别是以与腐殖质结合的形态存在.预测填埋单元内重金属的溶出过程可持续数百年.

The migration of heavy metals in the landfill was studied based on a field-scale bioreactor landfill with the capacity of 100 thousand m^3 and 1.5 years＇ monitoring of landfill leachate characteristics. In the initial landfill stage, high concentration of heavy metals in leachate was caused by the fast waste degradation and the low pH of the leachate. When the landfill was in the stabilized methanogenic stage, the concentration of heavy metals greatly decreased, and the migration of the heavy metals was affecting by the binding with humic substances in the leachate. The size distribution of heavy metals and the modeling results calculated by Visual Minteq show that the heavy metals was mainly bind to the organic matters, specially to the humic substances in the landfill leachate. The result of the mass balance calculation of heavy metals in the landfills indicated that the migration process of heavy metals in the landfill could last for hundreds of years.