利用矿化垃圾层预防和控制渗滤液导排系统堵塞

在卫生填埋场中,垃圾渗滤液导排系统堵塞普遍存在,悬浮固体形成的物理堵塞、有机物降解和金属离子沉淀导致的生物-化学堵塞是引起导排系统堵塞的关键因素.本文构建了"矿化垃圾+砾石层导排"的渗滤液下渗装置,通过矿化垃圾预处理渗滤液中悬浮固体和有机物以控制导排系统发生的物理和生物-化学堵塞.结果表明,在矿化垃圾层,渗滤液中化学需氧量(COD)和悬浮固体(SS)去除较多,去除率分别达到了85%和87%,并且Ca²⁺浓度也出现了波动较大的现象;然而,渗滤液在砾石层下渗过程中,其COD、SS和Ca²⁺浓度保持稳定.并且,砾石层可排水孔隙率在长期运行的过程中没有明显变化,表明渗滤液在砾石导排层没有形成明显的沉淀.与此同时,在没有添加矿化垃圾的对照组发现,砾石层可排水孔隙率减少最多的区段是渗滤液的进水点位(可排水孔隙率减少达到了53%),即渗滤液有机负荷最大处的饱和砾石层堵塞最为严重,其无机堵塞物主要是碳酸钙等.因此,在渗滤液流入砾石层前,采用矿化垃圾层部分饱和的方式对渗滤液中有机物和悬浮固体进行预处理,可以预防和控制渗滤液在砾石层形成沉淀堵塞.研究为填埋场的运行管理渗滤液导排系统堵塞提供了新的思路和方法.

Prevent and control the clogging of leachate drainage system by using the aged refuse layer

In sanitary landfill process,landfill leachate drainage system clogging is common,the physical clogging caused by suspended solids,biological and chemical clogging caused by organic degradation and metal ion precipitation are the key factors that lead to the clog of the leachate drainage system.In this paper,the leachate infiltration device of"aged refuse+gravel layer"was constructed,which pretreatment of suspended solids and organic matter in leachate by aged refuse to control physical and bio-chemical clogging in the drainage system.The results showed that,in the aged refuse layer,the key factors for the formation of biological and physical precipitation of leachate:chemical oxygen demand(COD)and suspended solids(SS)of leachate were removed more,the removal rates of COD and SS reached 85%and 87%,respectively,and the Ca²⁺concentration also fluctuated greatly;however,during leachate infiltration into the gravel layer,COD,SS and Ca²⁺concentration remained basically stable thereafter.Moreover,the drainage porosity of the gravel layer did not change significantly during long-term operation,indicating that the leachate did not form significant precipitation in the gravel drainage layer.At the same time,in the control group without adding aged refuse,the area with the most serious clogging and the greatest reduction of drainage porosity was near the influent point of leachate(the drainage porosity was reduced by 53%),that is,the saturated gravel layer with the greatest organic load of the leachate had the most serious clogging,and the inorganic clogging material was mainly calcium carbonate.Therefore,before the leachate flows into the gravel layer,organic matter and suspended solids in the leachate are pretreated by partially saturated aged refuse layer,which can prevent and control the leachate from forming a precipitation clog in the gravel layer.The study provides a new idea and method for landfill operation management of leachate drainage system clogging.