垃圾填埋场渗滤液回流处理技术研究进展

垃圾渗滤液回流处理后，CODcr去除率最高达95％，在半好氧状态下NH3-N质量浓度降低至10mg/L几以下，渗滤液水质得到改善；渗滤液回流增加了湿度，使有机物的降解速率加快；渗滤液同流处产甲烷速率是不回流处产甲烷速率的2倍多：渗滤液回流处的总沉降幅度可达填埋场深度的20％，而不回流处仅为8％。回流处理技术分为直接回流至垃圾层、表面喷灌或浇灌至填埋场表面、地表下回流或内层回流技术。在填埋场处于产酸阶段早期，回流的渗滤液量宜少不宜多：在产气阶段则可逐渐增加。应将稳定化程度高的垃圾层区(产甲烷区)排出的渗滤液回流至新填人的垃圾层(产酸区)，将新垃圾层所产生的渗滤液回流至老的稳定化区。通过控制垃圾的组成、回流的时间、渗滤液的pH值等手段可改善回流处理效果。

Recirculation technology of leachate in municipal solid waste landfill

The character and quantity of landfill leachate varied greatly, and the concentrations of NH3-N and organic pollutants in leachate are high. Biological treatment, land treatment and physical-chemistry treatment are the main treatment methods recently. Landfill leachate recirculation technology can improve the leachate quality, i.e., the removing rate of CODcr is 95% and the NH3-N concentration is lower than 10mg/L; accelerate the speed of waste disposing, i.e., leachate recirculation increases the humidity in waste pile, so the disposing speed of organic matter is increased and the total sedimentation rate in recirculation field is 20% but only 8% in non-recirculation field; increase CH4 producing rate, i.e., the producing rate in recirculation field is 2 times more than that in non-recriculation field; decrease the maintenance expense of landfill field. Recirculating leachate into waste directly, spraying on waste surface and recycling under the waste are the primary treatment means. The recirculating effect can be improved through controlling the waste component, the date of recirculating and the pH of leachate. Though the landfill leachate recirculation technology is more appropriate than traditional methods, the malodor produced in recirculating process should be noticed.