Digestion Performance of Various Combinations of Thermophilic and Mesophilic Sludge Digestion Systems

Abstract

Various combinations of single and multi-stage anaerobic and aerobic/anaerobic digestion system were studied to evaluate their solids reduction potential along with capabilities to control sulfur based biosolids odor compounds. All the multi-staged digestion systems removed more volatile solids than the single stage anaerobic digestion systems even at the same overall detention time. However, digestion systems with mesophilic digestion as the final stage showed a much lower headspace organic sulfur contents in the dewatered biosolids than the systems with thermophilic digestion as the final stage. This observation leads to the conclusion that placing a mesophilic anaerobic digestion system at the end of multi-stage digestion systems will enable greater sulfur based odor reduction from dewatered biosolids along with greater solid reduction.