Section Twenty-One
LANDFILL LEACHATE AND MINE DRAINAGE
90    TWO-STAGE BIOLOGICAL/CHEMICAL TREATMENT OF
HAZARDOUS WASTE LANDFILL LEACHATE
Henning Albers, Research Engineer
Rolf Kayser, Professor
Technical University of Braunschweig
D-3300 Braunschweig, West Germany
INTRODUCTION
Since the 1972 Waste Disposal Act the number of landfills in West-Germany has decreased from
about 50,000 to 3,118 in 1984.' Among these are 385 sanitary landfills and nearly 100 sites for
industrial or 'special' wastes. The Waste Disposal Act distinguishes between household wastes and
household-similar industrial wastes which may be disposed of at controlled sanitary landfills and
"special" wastes which have to be removed in disposal facilities with stricter requirements. One part of
the latter category are the so-called "hazardous" wastes. According to common German terminology
the expression special waste, not hazardous waste, is used in the following text.
Both types of landfills have to be equipped with a bottom liner and a leachate collection system is
recommended. The leachates are to be treated before discharge to receiving waters. The standards
which have to be met after treatment will be raised from 1987 on. Because of the large variety of
pollutants present in leachates from special waste landfills, meeting the new standards is a problem
especially with these waters. To achieve this, new ways and combinations of treatment processes must
be developed.
COMPOSITION AND TREATMENT OF GERMAN *SPECIAL' WASTE LEACHATES
In 1986 Weitzel2 summarized data from 41 German special waste landfill leachates. Ranges, median
and mean values are given in Table I.
Table I contains 'conventional' parameters which are commonly determined in these waters. There
still remains a great lack of data for hazardous organic pollutants. The relatively new parameter AOX
(i.e. Adsorbable Halogenated Hydrocarbons) cannot compensate this lack for all purposes.
For all parameters very broad ranges of concentrations have been found. This fact indicates that
also in Germany no typical special waste landfill leachate can be defined: the variety of the landfilled
wastes is too large. This corresponds to findings by Shuckrow et o/.3 for American hazardous landfill
leachates.
Nevertheless, a close look at the median and mean values shows, that many leachates are characterized by a high content of organic matter (COD, also BOD5), high values for ammonia, salts and
halogenated hydrocarbons (AOX), but fairly moderate levels of heavy metals. Nowadays the trend is
to keep away special wastes with organic contents and highly watersoluble constituents from above-
ground landfills in order to minimize problems with leachate generation and treatment. This should
lead to more "inorganic" leachates arising from future special waste landfills. At present time,
common practice is the combined treatment of these leachates together with other wastewaters in
biological sewage plants. Often, high costs for transportation to these plants have to be accepted.
Additionally in some cases a pre-treatment step (oil-separation, flocculation, chemical oxidation) is
required before discharge to the sewage plant.
On the other hand, in some particular cases very expensive technical solutions are applied for the
separate treatment of special waste landfill leachates. Examples are the evaporation in a coal-fired
power plant or a separate evaporator.4 In those cases, treatment costs reach up to DM 120 ($ 60) per
cubic meter.
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