Abstract
A mesophilic （35℃） UASB reactor treating synthetic wastewater containing methanol as sole carbon source was continuously operated for over 430 days by changing the volume loading rate from 2.5 to 120 kg-CODCr・m−3・d−1. The microbial community structure of the granules was analyzed with the molecular tools and its metabolic characteristics were evaluated using specific methanogenic activity test. The process was successfully operated with over 95％ soluble CODCr removal efficiency at VLR 30 kg-CODCr・m−3・d−1 for approximately 300 days, and granulation satisfactory proceeded. Granules of 0.1 to 2 mm in diameter mainly consist of aggregated coccoid cells. Specific methanogenic activity tests indicate that the methanol-methane pathway and the methanol-H2/CO2-methane pathway are predominant in the methane fermentation of the methanol. The results of cloning and fluorescence in situ hybridization analysis suggests that Methanomethylovorans hollandica were predominant in the reactor, and formed a large cluster as a granule, which is different from the Methanosarcina-dominant community previously considered in the researches on anaerobic methanol treatment.
