Start up of Thermophilic UASB (Upflow Anaerobic Sludge Blanket) Reactors Using Micro-Carrier and Mesophilic Granular Sludge

Two start-up methods of thermophilic UASB reactor were investigated for fast start-ups; one utilized micro-carrier as an initial support material and the other used intact mesophilic UASB granules as an initial seed. With both methods thermophilic granules having high activity were obtained in less than 3 months, even with acidified wastewater. Maximum sludge load for VFA substrate and sugar substrate were 3.2 and 0.9 kgCOD/kgVSS/day, respectively. Pre-acidogenesis was indispensable for high-performance treatment of sugar-containing substrate. It was proven that with a two-phase system sludge load could be raised to 3.0 kgCOD/kgVSS/day for sugar containing wastewaters. Some features of obtained sludge were examined, including maximum substrate utilizing activities, temperature dependence, pH dependence, and activity deterioration under lower loading conditions.