Experimental studies of microbial acclimation to condition of geological disposal system

not registered; not registered

TRU waste is disposed of deep underground by packed in cement compounds as engineering barrier material. One of negative effects to this disposal system is supposed to be ability of microbial degradation of organic compounds. This disposal system might be exposed to high alkali condition by cement compounds. For estimating the quantity of degradation of organic compounds under high alkali conditions, asphalt (blown asphalt) that is the major ingredient of TRU waste was used for the microbial acclimation test to high alkali condition and degradation test. After microbial were collected as water samples from three different conditions, those were cultured with asphalt as carbon source for acclimation under high alkali conditions. These acclimated microbial were used for vial and plate test measuring degradation rate of asphalt at high alkali condition. Estimation items were ICs, TOCs, groups and cell count of microbial from vial test, and also, quantity of asphalt degradation and cell count of microbial from plate test. Furthermore, the genetic information of microbial was analyzed with the DGGE method and those sequencing data. The result shows that microbial might degrade asphalt under high alkali condition like pH 12.5, and it was less asphalt degradation rate in anaerobic than in aerobic condition.