Bioparticulate solubilization and biodegradation in semi-continuous aerobic thermophilic digestion

The solubilization and biodegradation of microbial solids in aerobic thermophilic biotreatment system was investigated. The effects of cycle time, charge size and inorganic nitrogen availability on the process were studied using a semi-continuously operated 1.5 litre bioreactor operating at 60C. A fill and draw volume of 50 per cent gave a total solids removal of consistently more than 59 per cent of feed concentration. Degradation efficiencies were lower for the 25 per cent charge size and were affected by the presence of inorganic nitrogen in the feed. With a 50 per cent bioreactor volume charge size, under conditions of nitrogen excess, DOC concentration after 24 or 72 h was only slightly higher than influent DOC, whereas in the absence of added nitrogen there were much higher DOC concentrations.