Enhancing Volatile Solids Reduction by Application of Sludge Ozonation using the Lyso™ Process to Aerobic Digesters

Ozonation of a recirculated stream from an aerobic digester has been employed to reduce volatile solids. The Praxair Lyso™ process, which utilizes plug flow principles for the ozone – sludge lysis reaction was used as the Ozone contactor. Sludge drawn from the aerobic digester is circulated through the Lyso™ where the sludge and ozone are contacted. Plug flow operations minimizes excessive ozone consumption by enhancing the selectivity of ozone for cell lysis rather than random COD oxidation. Sludge ozonation enabled up to 80% sludge reduction with less than 10 days of HRT in the digester, indicating significant enhancement of Volatile Solids Reduction (VSR). The specific ozone utilization values obtained during the tests ranged from 0.01-0.03 kg O3/kg SS removed. This specific ozone consumption value is about an order of magnitude lower than alternative sludge ozonation concepts.We develop a conceptual model of sludge ozonation process using the GPS-X™ process modeling software platform. A simplified metric for reporting ozone effectiveness rates in sludge ozonation processes is proposed.