Leachate treatment in Germany

Abstract

Landfill leachate is a problem that has to be dealt with not only today but also in the near anddistant future. Generally, leachate production takes place after the closure as well as duringthe operation of a landfill. As previous studies show the process of leachate output continuesfor decades if not centuries after the end of the landfill operation. Therefore the problem ofleachate output, and subsequently its treatment, remains after the closure. Another importantfact is that leachate characteristics vary within a wide range over time in quantity and quality.A lot of research has been done in order to investigate the efficiency of different leachatetreatment processes. Since no standard treatment system has been developed so far, a numberof different systems have been implemented.In Germany about 150 leachate treatment plants were operated in full scale, in 1998. Mainlythree different systems are applied. The most common treatment system consists of acombination of a biological stage and an activated carbon filtration. Another frequently usedsystem combines biology and reverse osmosis. Thirdly, the combination of biology andchemical oxidation is used relatively often. Other feasible systems with different processcombinations are used in practice. In any case it is remarkable that nearly all systems includea biological stage.Although the described treatment systems are already in use for a number of years, many ofthem still have serious operational problems. This results mainly from their complex technicalstructure which makes it difficult to solve the problems. An additional obstacle is the longterm operation of such systems. It is unlikely that today's high-tech treatment systems withhigh operational costs and maintenance expenditure will be operated over the leachate outputperiod. Further research should therefore concentrate on developing simple, reliabletechniques that can be operated without maintenance. Since all present treatment systems areset up with biological stages it seems reasonable to examine whether biological processes canbe used individually for long-term leachate treatment. For this reason we are currentlyinvestigating the performance of soil filters with regard to Ammonia removal from landfillleachate at the University of Wuppertal.