Characterization of the temperature-phased biofilter-ASBR process at rich organic loads

The temperature phased anaerobic biofilter-ASBR process is a new system that employs a thermophilic biofilter (> 40 degrees C) followed by a mesophilic anaerobic sequencing batch reactor (ASBR -35 degrees C). The uniqueness of this system is that it takes advantage of the fast reaction rates at thermophilic temperatures as well as the high organic removal. efficiency associated with mesophilic temperatures. One of the purposes of this study was to show the compensating effect of the second stage mesophilic system. To accomplish this a high organic load was applied to the system at a low hydraulic retention time(HRT). Using non-fat dry milk (NFDM) as a substrate, loads up to 26.8 g COD/L/day were applied to the system at HRTs of 16 and 14 hours. As the organic load was increased, effluent quality from the first stage biofilter decreased. Despite the increased organic load to the second stage, organic removals remained high due to the compensating effect of the second stage ASBR. The reactors achieved total and soluble chemical oxygen demand (GOD) removals in excess of 91% and 96%, respectively, for the duration of the study.