An ozone/hydrogen peroxide/microwave-enhanced advanced oxidation process for sewage sludge treatment

Abstract

Solids destruction and nutrients release from sewage sludge were investigated using thermal destruction and/or oxidation processes. Hydrogen peroxide (H2O2), ozone (O3) and a combination of both were used for the oxidation processes performed at ambient temperature. Thermal destruction using microwave (MW) alone without an oxidant was also conducted. Microwave enhanced advanced oxidation processes (MW-AOP), such as MW/O3, MW/H2O2 and MW/H2O2/O3, were conducted at 100°C. In terms of nutrients release and solids reduction, the MW/H2O2/O3-AOP yielded the best result; an addition of ozone improved the MW-AOP process. More than 30% of TP and 20% of TKN were released into the solution. About 37% of total COD was also solubilized from sludge mass. Both the conventional oxidation processes and the MW-AOP processes could be used to release nutrients and to reduce solids from sewage sludge; however, the MW-AOP processes were superior in performance. Microwave heating alone also resulted in a substantial amount of ortho-phosphate into the solution.