Wet oxidation of municipal bio-solids in New Zealand. An overview

Management and disposal of sludge generated in municipal waste water treatment plants constitute serious logistical and financial problems, in addition to stringent landfilling regulatory requirements. Wet oxidation, a technology invented in the 1950s, was considered as a solids deconstruction method.

The conventional approach of this technology is to target destruction of the organics to carbon dioxide and water. In contrast, this work utilised wet oxidation as a conversion technology, targeting deconstruction of municipal biosolids into valuable compounds such as acetic acid. Laboratory-scale (600 mL) reactor studies were utilised to determine the impact of different process conditions on deconstruction performance. The results obtained indicated that significant yield and purity of acetic acid could be achieved in hydrothermal processes for beneficial re-use. As a result, a joint project with Rotorua District Council to establish a pilot plant to conduct further studies for commercial plant scale design is currently underway.