Integrated methodology to evaluate bioremediation potential of creosote-contaminated soils

Integrated methodology including chemical analyses as well as biological and ecotoxicological testing of soil was used to evaluate bioremediation potential of an aged, highly contaminated soil from a wood preservation plant. The soils contaminated with coal tar creosote originated from two sites (Site I: 8000 mg/kg and Site II: 133,800 mg/kg). A toxicity test-battery able to detect different effects using a variety of endpoints was developed and applied for the ecotoxicological assessment of creosote in soils: Azotobacter agile and Pseudomonas fluorescens dehydrogenase enzyme activity test, Vibrio fischeri bioluminescence test, Sinapis alba root and shoot elongation test and Folsomia candida mortality test. The biodegradation and its enhancement were investigated in small-scale bioreactors in short-term laboratory experiments. The joint evaluation of chemical, biological and ecotoxicological results made possible to compare different technologies, and investigate their applicability for remediation of soils contaminated with coal tar. The most sensitive direct contact tests that also correlated well with the creosote-reduction were Vibrio fischeri bioluminescence test, followed by Folsomia candida mortality test and Sinapis alba shoot elongation test

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

The Effect of TiO2 Nanoparticles on the Aquatic Ecosystem: A Comparative Ecotoxicity Study with Test Organisms of Different Trophic Levels

A comprehensive ecotoxicological assessment was carried out with Degussa VP nano TiO2 suspension applying a bioluminescent bacterium (Aliivibrio fischeri), algae (Pseudokirchneriella subcapitata, Scenedesmus subspicatus and Chlorella vulgaris), a protozoon (Tetrahymena pyriformis), the water flea (Daphnia magna) and an aquatic macrophyte, Lemna minor. TiO2 nanoparticles were toxic in the set of the conducted tests, but the toxicity level varied with the organisms and endpoints. According to our results the concentrations, the duration and the mechanisms of exposure are contributing factors to the toxicity of nanoparticles. The Tetrahymena phagocytic activity, the Daphnia heartbeat rate and the Lemna total chlorophyll content as ecotoxicity endpoints showed outstanding sensitivity. These organisms showed significant behavioural and physiological changes when exposed to low TiO2 nanoparticle concentrations (0.1 and 0.05 µg/L) considered to be lower than the predicted environmental concentration in surface waters. These results reveal the importance of behavioural and physiological assays in assessing the impact of nanoparticles and indicate that nanosized TiO2 may pose risks to the aquatic ecosystem

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

Environmental Toxicity Assessment of the Spilled Ajka Red Mud in Soil Microcosms for Its Potential Utilisation as Soil Ameliorant

After the red mud spill in Hungary one of the risk reduction measures was to remove the deposits from the soil surface. The residual thin red mud layer was ploughed into the soil. The aim of the present 8-month-long lab-scale microcosm experiment was to estimate the red mud amount with no adverse effects on the soil as natural habitat and to assess the mid-term environmental risk of red mud mixed into the soil. The red mud ratio mixed into the soil ranged between 0–40 %. The experiments were monitored by physico-chemical, biological and ecotoxicological methods. Mixing of 5 % red mud into the soil significantly increased the total As, Cr, Ni, Pb and Na content of the soil, but it did not exceed the Hungarian soil quality criteria. The microcosms containing 5 % red mud did not show any adverse effects on the testorganisms. Overall, 5 % red mud could be mixed into the soil without any mid-term adverse effects

Screening and Ranking Methodology Applied to Biochars Aimed at Acidic and Calcareous Sandy Soil Improvement

The application of biochar (the by-product of biomass pyrolysis), as a soil amendment has been accepted as a sustainable solution to improve soil quality. The current study aims to establish a decision support tool for characterizing, ranking, and selecting biochars of different origins for soil improvement, thereby contributing to the development of a systematic approach, which lacks in the existing literature.The development of a Multi-Criteria Decision Support Approach applying a banded and weighted rating and scoring system allowed the selection and ranking of various biochars suitable for improving sandy soils before application. First, 14 selected, different biochar products (produced from industrial by-products, herbaceous, wood-based and manure-based feedstocks) were characterized with several physicochemical, biological and ecotoxicological methods taking into account both the technological and the environmental efficiency aspects of biochar utilization. Then, a system for the assessment and ranking of biochars for acidic, and calcareous neutral sandy soil improvement was developed, which could be flexibly adapted to different soil problems as well. Based on their performance in the tests, scores from (−5) to (+5) were assigned to each biochar. As a result, the grain husks and paper fiber sludge biochar was ranked as the most suitable for both acidic and neutral calcareous sandy soil improvement, with 55 and 43 scores, respectively (from the maximum 100). The applicability of this innovative multicriteria scoring-ranking system, as a tool for potential biochar users, was verified in microcosms and field-scale experiments, demonstrating the positive influence of this biochar on the acidic sandy soil

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

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