Biosolids Conditioning With Hydrodynamic Cavitation Part II: an Extended Pilot Scale Evaluation

Mechanical treatment of biosolids by Controlled Hydrodynamic cavitation (CHC) successfully resulted in cell lysis as evident by the increase on sCOD, ammonia, and phosphate. Passing the WAS through the CHC unit a minimum of 10 times resulted in an increase in these parameters from over 20% to greater 100% after 30 passes. Even though these parameters usually indicate that improvement in digester performance should be achieved, gas generation results were unexpected. Initial digester gas production increased with CHC treatment but subsequently decreased and became similar to the untreated digester. Therefore, the long term effect of the mechanical lysing (CHC) process and subsequent increase in soluble COD on bio-degradability of sludge was not conclusively determined during this evaluation. In order to understand and develop this technology further, additional research needs to be carried out on a bench-scale system.