Treatment of radioactively-contaminated and metal-laden mine
waters and of seepage from tailings ponds and waste rock piles is among the key issues facing
WISMUT GmbH in their task to remediate the legacy of uranium mining and processing in the Free
States of Saxony and Thuringia, Federal Republic of Germany. Generally, contaminant loads of feed
waters will diminish over time. At a certain level of costs for the removal of one contaminant
unit, continued operation of conventional water treatment plants can hardly be justified any
longer. As treatment is still required for water protection, there is an urgent need for the
development and implementation of more cost efficient technologies. WISMUT GmbH and BioPlanta
GmbH have studied the suitability of helophyte species for contaminant removal from mine waters.
In a first step, original waters were used for an in vitro bioassay. The test results allowed for
the determination of the effects of biotic and abiotic factors on helophytes' tolerance range,
growth, and uptake capability of radionuclides and metals. Test series were carried out using
Phragmites australis, Carex disticha, Typha latifolia, and Juncus effusus. Relevant contaminant
components of the mine waters under investigation included uranium iron, arsenic, manganese,
nickel, and copper. Investigations led to a number of recommendations concerning plant selection
for specific water treatment needs. In a second step, based on these results, a constructed
wetland was built in 1998 as a pilot plant for the treatment of flood waters from the Pohla-
Tellerhauser mine and went on-line. Relevant constituents of the neutral flood waters include
radium, iron, and arsenic. This wetland specifically uses both physico-chernical and
microbiological processes as well as contaminant accumulation by helophytes to achieve the
treatment objectives. With the pilot plant in operation for three years now, average removal
rates achieved are 95 % for iron, 86 % for arsenic, and 75 % for radium. WISMUT GmbH intends to
put a number of other projects of passive/biological mine water treatment into operation before
the end of 2001.