Advanced Thermal Hydrolysis of secondary sewage sludge: A novel process combining thermal hydrolysis and hydrogen peroxide addition

The production of secondary sewage sludge at urban wastewater treatment plants (WWTPs) is increasing and this, in turn, leads to significantly higher wastewater treatment costs. Thermal Hydrolysis (TH) and Advanced Oxidation Processes (AOPs), such as Wet Air Oxidation (WAO) or Fenton's peroxidation, have been widely studied in an effort to manage this type of waste. In this work, a new process named Advanced Thermal Hydrolysis (ATH) is introduced for the pre-treatment and/or treatment of secondary sewage sludge and the advantages in terms of performance and improvements have been evaluated. The ATH process employs the synergistic effect of peroxidation plus direct steam injection and it operates under mild conditions and without the addition of a catalyst. The dewaterability and solubilization of sludge processed by ATH were monitored and the results were compared with those obtained by TH. The organic matter elimination was also assessed, with satisfactory results obtained in most cases. A concise economic viability discussion is included in this paper and it was concluded that ATH is a promising technology.