High-rate anaerobic reactors such as Upflow Anaerobic Sludge Blanket(UASB), Upflow Anaerobic Filter(UAF), and Upflow Anaerobic Sludge Bed Filter(UBF) reactors treating distillery wastewaters were operated at 35°C to find biomass holding capacity, maximum allowable loading rate and effect of temperature on operation efficiency.
The effluent SS concentration in UAF reactor was lower than in UASB and UBF reactors. In seven month operation, biomass was increased by 3.7, 3.3, 3.1 times of the initial seed sludge in UAF, UBF, and UASB reactors respectively. These results indicated that UAF reactor held the biomass well.
However, irrespective of biomass, the maximum loading rates were 45.2, 30.9, and 27.0 kg COD/㎥·d for UASB, UBF, and UAF reactors, respectively. Active biomass for decomposing organic matters and contact time were probably related to the loading rates. At the maximum loading rate, COD removal rates were 94% for UASB, 80% for UBF, 92% for UAF reactor while gas production rates were 18.3, 10.9, and 10.7 L/L·d with methane content of 52%, 52%, 53%, respectively.
The performance of three reactors was not much affected by increased temperatures. During when temperature was increased from 35°C to 45°C, there was not significant operational problems. However, when the temperature was increased from 45°C to 48°C, COD removal efficiency was dropped from 88%, 80%, 84% to 16%, 11%, 8% for UASB, UAF, and UBF reactors respectively.
