Papers by Author: Sabine Willscher

Abstract: Large sites with a low contamination of metall(oid)s were in the past a problem for remediation measures – the “traditional” processes were too expensive for an application on such expanded areas. Phytoremediation can be an alternative for such low contamination problems. In Germany, a research project is performed on this subject, in cooperation of the University of Jena and the TU Dresden. The field site is a former U mining area. Until 1991, a low grade U ore dump for sulfuric acid leaching was located on this site. After the close-down of the U mining in East Germany in 1991, the dump material was removed. Now, a phytoremediation test field is constructed on top of this site for the capture of the remained contaminants coming up by capillary forces. The paper pictures the phytoremediation in general, the research project and gives some first preliminary results.

Abstract: Important groups of microbes were investigated in three hard coal mining dumps in Saxonia/ Germany. In the particular dumps, different chemophysical and geochemical conditions are existing, depending on the kind of remediation up to six decades ago. Thiobacillus denitrificans, iron and sulfate reducers, and general aerobic heterotrophs and fungi were counted by MPN and CFU methods. Samples were taken from drilling cores in different depths out of the dumps, from seepage-, surface- and ground waters and from sediments. Similarities and significant differences were found between the microbial populations of the three dumps, depending on the appropriate environmental conditions. As a result, enhanced counts of T. denitrificans were detected at all three sites, originating from fertilizers (agricul-ture, gardens) and atmospheric precipitations. Sulfate reducers and aerobic heterotrophic microorganisms are suited indicators for the ongoing biogeochemical processes in the dumps

Abstract: . The historical hard coal mining area of the districts of Zwickau and Lugau/ Oelsnitz in Saxonia (Germany) is a source of heavy metals and arsenic polluting the adjacent ground- and surface waters. Heavy metals and metalloids like Zn, Cd, Ni, Co, As and Mn are transported, partially as fine precipitates, to the adjacent river Zwickauer Mulde and with that to the river Elbe. Some of the dumps are partially older than 150 years, and some of them were remediated more than 50 years ago. Today we still can learn from the more or less successful remediation measures after some decades of application. In this paper, three different dumps are presented and differences between their remediation measures and the long-term success of it shall be pointed out. As a result, especially a sealing and covering of a dump turned out as very successful for the prevention of AMD generation. A further utilization of such a remediated and revegetated area is possible, or it can be “given back” to the nature. In contrast, a revegetation without covering results in a long-term AMD-generation of such a mining dump site.

Abstract: It was the aim of this work to investigate the sorption characteristics of the Biocer material that consists of cells of Bacillus sphaericus that are immobilised on a ceramic carrier material, performing column experiments with model waters and real mine drainage waters from a U remediation site in East Germany. In column experiments a nearly quantitative sorption of Cu2+ was performed from solutions of different Cu2+ concentrations and at different flow rates. The desorption of the Cu2+ in the columns was nearly quantitative in a very short time. The columns could be regenerated 16 times without a substantial loss of the sorption capacity of the material. In experiments with U using real drainage waters, a specific U sorption capacity of 2.34 mg/g was determined. By variation of the experimental parameters, the long-term stability and sorption properties of the Biocer columns can be substantially improved.

Abstract: An enhanced entry of heavy metals and metalloids into ground and surface water was observed in the historical hard coal mining areas of the districts of Zwickau and Lugau/ Oelsnitz in Saxonia, Germany. Heavy metals and metalloids like Mn, Co, Ni, Zn, As and Cd are enriched in the surface waters of the district. This environmental impact is observed even though a recultivation of some of the dumps occurred partially already 50 years ago. In this study, preliminary microbial and geochemical characterizations of samples from drilling cores in different depths of a dump site, of surface and ground water samples, and of sediments are described. Thiobacillus denitrificans appeared to be a dominating species in these moderately acidic environment especially where there is nitrate infiltration and inflow, respectively, due to agricultural use of the adjacent area. Some of the sediment samples also contained high counts of iron- and sulfate-reducing bacteria due to the organic detritus on the sediment surface.

Abstract: Electrical and electronic equipment (EEE), e.g. printed circuit boards, contain substantial amounts of metals, e.g. Cu, Pb and Sn. The objective of this work was to investigate the bioleaching of a material, originating from a technical waste processing facility, as one possible way of a complete separation of the metals from the polymer carrier. During the leaching experiments the mechanism of the leaching process was investigated, and biofilms and precipitates were analyzed by microscopical (SEM) and spectroscopical methods (EDX, XRF, XRD). The enhanced formation of exopolymer layers seems to promote the precipitation of secondary mineral particles beneath and the sorption of particles from the suspension on the layer surface.