TORREFIED BIOMASS AS A BIOFILM SUPPORT FOR ANAEROBIC DIGESTION

The use of torrefied biomass chips as a biofilm support in a 50 liter mesophilic up flow anaerobic filter bioreactor (AFBR) for the treatment of dairy wastes is described and the results of testing are reported. Biofilms were characterized by Scanning Electron Microscopy of chip samples produced before and after torrefaction and also during culture in an anaerobic digester and additionally by determination of total ATP obtained from torrefied chip biofilms. Microorganism density, as determined by ATP concentration, was up to 9 times greater in the anaerobic filter than in the digester effluent, the average hydraulic retention time was less than 5 days and COD was consistently reduced by more than 70%. The results show that torrefied biomass chips can be used in an anaerobic filter to pre-treat dilute dairy industry waste streams before discharge to a municipal wastewater treatment plant and that the method offers the important advantages of no electrical energy input, biogas production, partial removal of the water insoluble fraction and a low hydraulic retention time.