Effects of ozone treatment on the soil organic matter on contaminated sites

In recent years, the ozone treatment technique has been discussed for remediation of contaminated sites. In this paper, data on the effects of ozonation of soil organic matter in ground and pore waters are presented. An aqueous soil extract was ozonated in a stirred tank reactor and characterized by size-exclusion chromatography with online UV and dissolved organic carbon detection. Additionally, degradation experiments were carried out with these extracts in a bacteria regrowth measurement system. After ozonation, a decrease of the humic acid fraction and a reduction of its average molecular size could be recognized. In contrast to this, there was an increase of the building block fraction and the low molecular acid fraction. These two fractions were readily degradable by microorganisms. Therefore, the bacteria regrowth increased with ozonation time. As a result of this, a fast and high regrowth of bacteria can be expected after the ozone remediation technique has been applied. The UV absorbance of extracts at a wavelength of 254 nm showed no significant changes before and after biological degradation. It can be supposed that the microorganisms were not able to degrade chromophoric groups absorbing at a wavelength of 254 nm.