Disruption of cell to cell communication in the aeration unit of a cannibal process: Sludge reduction efficiency and related mechanisms

Abstract The Cannibal process is a commercial method for excess sludge reduction in activated sludge plants with small sizes. However, the relatively low efficiency in sludge reduction (up to 50%) for some plants is the main impediment to its more widespread adoption. This study provides a biological method for upgrading Cannibal process. The suggested method includes disruption of cell to cell communication between bacterial communities in aerobic flocs in order to increase endogenous respiration. A quorum quenching (QQ) agent is applied in the aerobic tank in order to increase the free bacteria population, which leads to enhanced microbial predation and a decrease in extracellular polymeric substances. The sludge production yield (Y obs ) of three pilots including a control sequencing batch reactor (SBR), a Cannibal system, and a QQ-Cannibal system was 0.5, 0.38, and 0.29, respectively. The results of a respirometery study also indicated that enhanced endogenous respiration caused sludge reduction in the QQ-Cannibal pilot system.