This research is on a two-phase anaerobic digestion system adapting advanced reactors such as UASB and AF for high rate treatment of distillery wastewater with high solid concentration. The phase separation was controlled by kinetic and environmental control.
When SS concentration was 4.1 g/L, the first phase UASB reactor was effectively operated up to the loading rate of 16.5 kg COD/m3. day, producing 3.9 g HAc/day per liter of reactor volume.
The operational results of the two methanogenic reactors (UASB and AF) indicated that they performed similarly during the start-up, when the loading rate increased to 12 kg COD/m3. day. But, after an initial shock load at operation day 90, the performance of UASB was more stable than that of AF. This difference is probably due to a less active biomass content of the AF compared with the UASB.
In the methanogenic UASB reactor, loading rate of 44 kg COD /m3. day was applied with an average COD removal of 80% and a specific gas production of 16.5 L/L.day, with a methane content of more than 65%.
Without addition of alkaline chemicals, it seemed possible to maintain the appropriate pH in the first phase by recirculating the effluent from methanogenic phase.
