Treatment of sewage sludge in a continuous-flow radiofrequency-oxidation system

ABSTRACT

This study explored the applicability of a pilot-scale continuous-flow radiofrequency (RF) heating system to treat sewage sludge by the RF-oxidation process (RF/H₂O₂). Depending on temperature and hydrogen peroxide dosage, high amounts of soluble chemical oxygen demand and volatile fatty acid were produced, and phosphates, nitrogen, and metals were solubilized. A high temperature and/or a higher H₂O₂ dosage implemented in this system yielded high solubilization of organic matters. Orthophosphate increased with an increase in treatment temperature up to 60°C, its concentration decreased as temperature further increased. There was little effect on orthophosphate release by varying H₂O₂ dosage. The efficiency of the RF/H₂O₂ process was comparable to the microwave (MW) enhanced advanced oxidation process (MW/H₂O₂-AOP), in terms of solids disintegration and nutrient release; however, the solubilization rate was lower for RF/H₂O₂ process. The overall energy consumed by the RF/H₂O₂ process was higher than the MW/H₂O₂-AOP.

KEYWORDS:

• Radiofrequency
• sludge
• solids disintegration
• nutrient release

Acknowledgements

The authors wish to acknowledge the technical assistance provided by Tim Ma and Paula Parkinson.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCiD

Kwang V. Lo http://orcid.org/0000-0003-1196-2160

Additional information

Funding

The research funding was supported by the Natural Science and Engineering Research Council (NSERC) of Canada and Growing Forward 2, BC Ministry of Agriculture.