Remediation of metal ore mine waste using combined chemical- and phytostabilisation

The combination of chemical stabilisation (using fly ash, lime and steel shots) and phytostabilisation (using grass mixture and two Sorghum species ) were applied to remediate a highly acidic metal ore mine waste in Gyöngyösoroszi, Hungary. The change in metal mobility was monitored by chemical, biological and ecotoxicological methods. Chemical stabilisation reduced the amount of Cd from 441 to 0.42 μ g l-1, Cu from 1510 to 11.7 μ g l-1 and Zn from 89079 to 48.8 μ g l-1 in drainage water and extractable As from 0.404 to 0.086 mg kg-1 in waste within two years. The high toxicity of the mine waste was reduced to non-toxic and healthy vegetation developed on the previously barren surface with metal content fulfilling animal fodder quality criteria. The technology reduced the risk on all possible pathways fulfilling all target criteria

SAPONIN ACTIVITY OF DIFFERENT PARTS OF ALFALFA SEEDLINGS

The saponin content of alfalfa of different age was investigated by thin-Iayer- chromatographic densitometric method and by a biological method, by the Trichoderma- bioassay. With the help of the Trichoderma-bioassay the highest level of saponin was determined in the cotyledons of the alfalfa seedlings, independently of the age of the seedlings. Comparing the results obtained by the two methods it was found that the fungistatic activity or toxicity of the saponins of the cotyledons are more intensive than that of the leaves of developed plants

Comparative evaluation of microbial and chemical methods for assessing 4-chlorophenol biodegradation in soil

Reliable methods for assessing soil microflora and it’s activity are a prerequisite for successful technology planning and sustainable bioremediation of contaminated sites. The main objectives were to evaluate several microbiological soil-testing methods for characterizing the 4-chlorophenol biodegradation in the soil microcosm and to find the most appropriate methodology for testing biodegradation potential. The activity of the soil microflora were characterized by contaminant degrading cell concentration, dehydrogenase enzyme activity, three types of soil respiration and substrate utilization of the microbial community. The contaminant concentrations were measured by exhaustive extraction and by non-exhaustive cyclodextrin extraction. Most of the applied biological methods were found to be reliable indicators of chlorophenol biodegradation in soil, and can be useful as a pre-implementation methodology to support technology selection and design. The microbial community analyses by BIOLOG EcoPlateTM provided very good results and can be suitable for use in biodegradation assessment and evaluation in soil

Hydrogen peroxide oxidation for in situ remediation of trichloroethylene – from the laboratory to the field

In this paper we present the remediation possibilities of a trichloroethylene contaminated site of a former metalworking plant in Hungary, where high TCE concentration (150 μg/L to 35.000 μg/L) was detected in the groundwater. Lab-scale experiments were performed to compare the potential bioremediation technology-alternatives eg.: enhanced biodegradation; pump & treat by UV irradiation (photodegradation); in situ chemical oxidation (ISCO) applying different oxidants (KMnO4, Na2S2O8 and H2O2). The lab-scale experiments showed in all cases reduction of the TCE-concentration of the water. Comparing the removal efficacy and concerning the time requirement ISCO was the most effective in laboratory studies

Assessing Toxicity of Organic Aquatic Micropollutants Based on the Total Chlorophyll Content of Lemna minor as a Sensitive Endpoint

The present study examined the chlorophyll content in a 7-day contact time experiment series. Lemna minor was exposed to caffeine, benzophenone, bisphenol A, 3,4-dichlorophenol, metamizole-Na, Na-diclofenac, acetochlor, atrazine, diuron, metazachlor and metolachlor to find a convenient sensitive response to the tested chemicals including some emerging micropollutants. The results demonstrated the differences in sensitivity to the tested micropollutants. As anticipated the industrial chemicals and the pesticides were the most toxic. The lowest observed effect concentration (LOEC) values determined for 3,4-dichlorophenol, acetochlor, diuron, metazachlor and metolachlor were 2.5 µg/L, 0.05 µg/L, 0.5 µg/L, 5 µg/L and 0.5 µg/L, respectively. These values were comparable with the environmental concentrations reported in literature. Our study provides valuable information on the feasibility of Lemna minor total chlorophyll method as a sensitive and reliable bioassay for testing toxicity at µg/L range and it may support risk assessment of organic micropollutants in freshwater ecosystems

Dispersal and attenuation of trace contaminants downstream of the Ajka bauxite residue (red mud) depository failure, Hungary

This paper identifies the spatial extent of bauxite processing residue (red mud)-derived contaminants and modes of transport within the Marcal and Raba river systems after the dike failure at Ajka, western Hungary. The geochemical signature of the red mud is apparent throughout the 3076 km(2) Marcal system principally with elevated Al, V, As, and Mo. Elevated concentrations of Cr, Ga, and Ni are also observed within 2 km of the source areas in aqueous and particulate phases where hyperalkalinity (pH < 13.1) is apparent. Although the concentrations of some trace elements exceed aquatic life standards in waters (e.g., V, As) and fluvial sediments (As, Cr, Ni, V), the spatial extent of these is limited to the Torna Creek and part of the upper Marcal. Source samples show a bimodal particle size distribution (peaks at 0.7 and 1.3 mu m) which lends the material to ready fluvial transport. Where elevated concentrations are found in fluvial sediments, sequential extraction suggests the bulk of the As, Cr, Ni, and V are associated with residual (aqua-regia/HF digest) phases and unlikely to be mobile in the environment. However, at some depositional hotspots, association of As, Cr, and V with weak acid-extractable phases is observed

The effects of leaching from alkaline red mud on soil biota: modelling the conditions after the Hungarian red mud disaster

A soil column experiment was set up to investigate the effect of red mud from Ajka (Hungary) on a typical soil profile from the concerned area. The chemical changes caused by the leachate of the red mud and the effects of these changes on living organisms were assessed. Ecotoxicological tests with Vibrio fischeri, Sinapis alba and Folsomia candida were performed and the number of aerobic heterotrophic microorganisms was determined. The total, plant available, exchangeable and water soluble fractions of Na, Mo, Cu, and Cr increased in the soil mostly due to their leaching from the red mud layer and partly to the increase of the pH and DOC concentration. The chemical changes had significant effects on the test organisms only in the 0 – 30 cm soil layer except for F. candida that had a lower survival rate also in the 30 – 50 cm soil layer. There were no severe toxic effects detected on the test organisms. Furthermore in case of the aerobic heterotrophic cell number and S. alba germination a stimulating effect was revealed. However, the red mud itself was toxic, therefore the performed ecotoxicology tests have justified the removal of red mud from the soil surface after the disaster