Performance and microbial community analysis of a pilot-scale UASB for corn-ethanol wastewater treatment

The performance and microbial community structure of a pilot-scale upflow anaerobic sludge blanket (UASB) reactor inoculated with flocculent sludge were investigated over 52 days. The characteristics of corn-ethanol wastewater were as follows: COD_Cr, 1,050–4,970 mg l^?1; ammonia, 14–298 mg l^?1; and alkalinity, 332–2,867 mg l^?1. The UASB could start up smoothly with a hydraulic loading rate lower than 180 l h^?1 and a ratio of volatile fatty acid versus alkalinity between 0.04 and 0.48. The maximum gas production rate was 432 l h^?1 and the highest volumetric loading rate of 7.2 kg m^?3 day^?1 was obtained after 48 days. The 1 mm granules could form a complex network and were composed of many Methanosaeta. Aceticlastic methanogens served as a dominant methanogenic group, which accounted for the relatively high resistance to shock loading.