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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 β-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.

The limiting factor of soil remediation is often the low accessibility of the pollutants.Laboratory experiments have been carried out to investigate the effect of the randomlymethylated cyclodextrin (RAMEB) on bioremediation of various types of soils spikedwith Diesel and transformer oil and also on actual site soils contaminated with poorlydegradable mazout. The contaminated soil in the aerobic solid phase microcosm-experiments was amended with nutrients and supplemented with different amounts of RAMEB. An integrated chemical-biological-ecotoxicological methodology was applied to follow the bioremediation. The laboratory study proved the bioremediation enhancing effect of RAMEB both on artificially contaminated soils and on actual site mazout contaminated soils. RAMEB activated soil microbes by improving the bioavailability of the contaminants and accelerating biodegradation. Efficacy of RAMEB was influenced both by contaminantand environment related factors, such as the type and concentration of the pollutinghydrocarbons and characteristics of the soil.

The aim of the current research is to establish a suitable Environmental Risk Assessment (ERA) scheme for Danube sediments in Hungary by determining contaminants' concentrations by chemical analysis and by assessing their ecotoxicological effects. Seventeen sedimentation sites were identified, mainly upstream of Budapest, between river kilometres 1811 and 1586. The heavy metal contents and basic properties of sediments were determined. Excess heavy metal content was used to characterize the extent of heavy metal contamination. Direct contact biotests were developed for testing the toxic effect of contaminated sediments. Ecotoxicological effects were measured by three bacterial tests and one plant bioassay. Effect Concentrations were determined by the inhibition of the bioluminescence of Photobacterium phosphoreum. The resultant inhibition of different partial toxic effects was characterized by Cu equivalent. Chemical and ecotoxicological results were studied together, making it possible to characterize the extent of the pollution and its biological effects at the same time. It was concluded that combined chemical and ecotoxicological characterization of contaminated sediments may serve as a strong basis for assessing the site-specific risk of heavy metal pollution.