Development of an innovative soil remediation: "Cyclodextrin-enhanced combined technology".

This paper introduces an in situ "Cyclodextrin-enhanced soil bioremediation technology" which is a combination of 1. in situ bioventilation for biodegradation in the unsaturated soil zone; 2. physico-chemical treatment of the pumped ground water; 3. impulsive flushing for the three-phase soil. For enhancement of biodegradation and solubilization randomly methylated beta-cyclodextrin (RAMEB) was used. An additional aim of this study was to prove the importance of the technology monitoring which was used for characterisation of the soil processes by an integrated methodology. It consists of physico-chemical, biological and ecotoxicological methods specific for the contaminants. For technology monitoring the mobile soil phases--soil gas and ground water--were analysed. Sampling of the whole soil was carried out at the start and end of the technology application. RAMEB resulted in the enhanced removal of pollutants both from the saturated and unsaturated soil zones. Moreover, the biodegradation was more effective than the pump and treat technology, proved by the establishment of the carbon material balance in all soil phases.

Comparison of bioassays by testing whole soil and their water extract from contaminated sites.

The harmful effects of contaminants on the ecosystems and humans are characterised by their environmental toxicity. The aim of this study was to assess applicability and reliability of several environmental toxicity tests, comparing the result of the whole soils and their water extracts. In the study real contaminated soils were applied from three different inherited contaminated sites of organic and inorganic pollutants. The measured endpoints were the bioluminescence inhibition of Vibrio fischeri (bacterium), the dehydrogenase activity inhibition of Azomonas agilis (bacterium), the reproduction inhibition of Tetrahymena pyriformis (protozoon), and Panagrellus redivivus (nematode), the mortality of Folsomia candida (springtail), the root and shoot elongation inhibition of Sinapis alba (plant: white mustard) and the nitrification activity inhibition of an uncontaminated garden soil used as "test organism". Besides the standardised or widely used methods some new, direct contact ecotoxicity tests have been developed and introduced, which are useful for characterisation of the risk of contaminated soils due to their interactive nature. Soil no. 1 derived from a site polluted with transformer oil (PCB-free); Soil no. 2 originated from a site contaminated with mazout; Soil no. 3 was contaminated with toxic metals (Zn, Cd, Cu, Pb, As). In most cases, the interactive ecotoxicity tests indicated more harmful effect of the contaminated soil than the tests using soil extracts. The direct contact environmental toxicity tests are able to meet the requirements of environmental toxicology: reliability, sensibility, reproducibility, rapidity and low cost.

Enhanced biodegradation of transformer oil in soils with cyclodextrin--from the laboratory to the field.

The use cyclodextrins for the intensification of bioremediation by improving the mobility and bioavailability of contaminants has recently been studied. In this work, the role of randomly methylated beta-cyclodextrin in the bioremediation of soils contaminated with transformer oil was studied both in bench scale bioreactors and through field experiments. The aims of this research were to (a) establish the scientific background of a cyclodextrin-based soil bioremediation technology, (b) demonstrate its feasibility and effectiveness in the field, and (c) develop an integrated methodology, consisting of a combination of physical, chemical, biological and ecotoxicological analytical methods, for efficiently monitoring the technology performances. The stepwise increasing scale of the experiments and the application of the integrated analytical methodology supported the development of a scientifically established new technology and the identification of the advantages and the limitations of its application in the field. At each phase of the study, randomly methylated beta-cyclodextrin was found to significantly enhance the bioremediation and detoxification of the transformer oil-contaminated soils employed by increasing the bioavailability of the pollutants and the activity of indigenous microorganisms.