Ozone Oxidation of Biological Sludge: Effects on Disintegration, Anaerobic Biodegradability, and Filterability

This study deals with pretreatment of biological sludge by ozone oxidation for the purpose of biological sludge disintegration. Different ozone dose ranged between 0.005 and 0.25 gO(3)/g DS were used for the process optimization. The potential for improving anaerobic digestion through ozone oxidation was also investigated. In addition, the effect of ozone oxidation on filterability characteristics of sludge was evaluated using lab-scale experiments. The results showed that ozone effectively disintegrates the sludge. The highest disintegration degree (51.1%) was achieved when 0.1gO(3)/g DS was used. Biochemical methane potential (BMP) results suggest that ozone oxidation significantly enhanced the biodegradability of biological sludge. For 0.1 gO(3)/g DS, 25% higher methane production was achieved compared with raw sludge. The supernatant characteristics of the sludge were also affected by ozone oxidation. For 0.1 gO(3)/g DS, the soluble chemical oxygen demand (SCOD), dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) increased by 300%, 94.2%, 225%, and 200%, respectively. Finally, using ozone oxidation for the purpose of floc disintegration (0.1 gO(3)/g DS) had no negative effect on sludge filterability in terms of CST results. But at higher doses than 0.1 gO(3)/g DS, ozone oxidation reduced the filterability of sludge. (C) 2010 American Institute of Chemical Engineers Environ Prog, 30: 377-383, 2011