Nanoferrosonication: A novel strategy for intensifying the methanogenic process in sewage sludge

In this work, the effect of coupling ultrasonic pretreatment with dosing of zero-valent iron nanoparticles (nanoferrosonication, NFS) to improve the anaerobic digestion of sewage sludge was studied. Biochemical methane potential tests were conducted at 15,000 and 25,000 kJ/kgTS and their combinations with 2 and 7 mgFe(0)/gVS. The biogas yield increased from 106 (control) to 143 (25,000 kJ/kgTS) and 308 mL/gVS with NFS (7 mgFe(0)/gVS + 15,000 kJ/kgTS). The methane content increased from 55.6 to 66%, and the maximum VS removal was 11.5% at 7 mgFe(0)/gVS+ 15,000 kJ/kgTS. The results demonstrated that NFS was effective in intensifying the process.