USE OF A ROTARY DRUM REACTOR WITH GRINDING BEADS FOR MICROBIAL SOIL REMEDIATION

The microbial degradation of hydrocarbon contaminants in soil is often limited by a lack of oxygen and poor bioavailability of contaminants. An approach to solve these problems is treating the soil in a rotary drum reactor with grinding beads. The treatment can be performed perio dically or continuously and results in mixing of the soil and, thus, s ufficient aeration. The grinding beads prevent ail agglomeration of th e moist soil, if the moisture content is kept slightly above the plast ic limit, which corresponds to the moisture content of maximum microbi al activity. Furthermore, the grinding beads cause a mechanical stress to the soil, leading to a release of organic compounds to the soil wa ter and an opening of pores which were previously inaccessible to micr oorganisms. Thus, the mechanical stress leads to an increased microbia l activity of limited duration but exceeding the stress duration itsel f. In order to reach a high microbial activity lasting for a longer ti me, periodical mechanical stress is suitable to prevent simultaneous c onsolidation of the soil which results in a decreased aeration and, th erefore, a lower microbial activity. In summary, a faster degradation of contaminants in soil can be achieved by treatment in a rotary drum reactor with grinding beads.