Sonolysis and ozonation as pretreatment for anaerobic digestion of solid organic waste.

This study aims to compare the efficiency of sonolysis and ozonation in improving anaerobic biodegradability of source sorted organic fraction of municipal solid waste, for the enhancing of biogas production and energy recovery as well. The methane yield of solid organic material anaerobic digestion is significantly affected by substrate availability, which can be favoured by pretreatments. In this investigation, both sonolysis and ozonation effects on substrate solubilisation and anaerobic biodegradability were evaluated under different treatment conditions. Results show that both pretreatments can significantly improve the solubilisation of organic solid waste. However, during ozonation experiments, no correlation was observed between increased solubilisation and biogas production: the application of higher ozone doses led to the formation of by-products less biodegradable than untreated substrate. This evidence makes the ultrasound process more efficient than ozonation and addresses further studies for sonolysis optimisation as pretreatment for solid waste anaerobic digestion.