PELLETIZATION OF BIOMASS IN A HYBRID ANAEROBIC BAFFLED REACTOR (HABR) TREATING ACIDIFIED WASTE-WATER

Pelletization of biomass was observed in a hybrid anaerobic baffled reactor treating molasses waste-water. The use of highly acidic molasses wastewater as substrate resulted in pelletization of the sludge within 30 days of operation. Change of substrate from acidified molasses to protein-rich molasses did not affect the process of pelletization. The biological pellets were able to grow and maintain their sludge settling-characteristics. The pellets were formed in all the three chambers of the reactor. The predominant methanogenic bacteria observed were Methanosarcina sp. in the first chamber and Methanothrix sp. in the rest of the reactor. Other bacteria morphologically similar to Methano-brevibacter, Methanococcus and Desulfovibrio were also observed. The reactor was able to remove 73% of soluble COD (Chemical Oxygen Demand) at the loading rate of 20 kg COD/m2 day. Methane production rates exceeded five volumes per day per unit volume of the reactor.