Wastewater Digester Enhancement and Sludge Volume Reduction Through Cell Lysis with Controlled Hydrodynamic Cavitation

The conditioning of biosolids is a growing issue due to extremely large increases in production of this waste, escalating disposal costs and inefficient use of produced methane. One approach to improve biosolids utilization is treating waste activated sludge (WAS) before anaerobic digestion to enhance digestion, increase methane production and lower biosolids production. Cavitation is the dynamic process of the formation, growth, and collapse of micro-sized bubbles in a fluid. During bubble collapse, extremely high temperature and intensive pressure waves are generated around the bubbles. Controlled hydrodynamic cavitation (CHC) is a process that seeks to optimally produce cavitation and harness the kinetic energy that is imparted to the fluid. These extreme physical conditions in CHC provide the primary mechanism for the lysing of bacteria cells. Preliminary studies show that by lysing the cells, methane generation can be increased along with reduction in biosolids production. This paper will describe the technology behind CHC and demonstrate its effect on WAS during a pilot study. The data will show improved dewatering, an increase in soluble COD, and reductions in TSS, VSS, SVI and particle size.