Leachate treatment in Germany

Abstract

Landfill leachate is a problem that has to be dealt with not only today but also in the near and
distant future. Generally, leachate production takes place after the closure as well as during
the operation of a landfill. As previous studies show the process of leachate output continues
for decades if not centuries after the end of the landfill operation. Therefore the problem of
leachate output, and subsequently its treatment, remains after the closure. Another important
fact 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 leachate
treatment processes. Since no standard treatment system has been developed so far, a number
of different systems have been implemented.
In Germany about 150 leachate treatment plants were operated in full scale, in 1998. Mainly
three different systems are applied. The most common treatment system consists of a
combination of a biological stage and an activated carbon filtration. Another frequently used
system combines biology and reverse osmosis. Thirdly, the combination of biology and
chemical oxidation is used relatively often. Other feasible systems with different process
combinations are used in practice. In any case it is remarkable that nearly all systems include
a biological stage.
Although the described treatment systems are already in use for a number of years, many of
them still have serious operational problems. This results mainly from their complex technical
structure 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 with
high operational costs and maintenance expenditure will be operated over the leachate output
period. Further research should therefore concentrate on developing simple, reliable
techniques that can be operated without maintenance. Since all present treatment systems are
set up with biological stages it seems reasonable to examine whether biological processes can
be used individually for long-term leachate treatment. For this reason we are currently
investigating the performance of soil filters with regard to Ammonia removal from landfill
leachate at the University of Wuppertal.