Impact of Nanoparticle Addition and Ozone Pre-Treatment on Mesophilic Methanogenesis in Temperature-Phased Anaerobic Digestion

Abstract

Biodegradable organic waste offers significant opportunities for resource recovery withinthe frame of the circular economy. In this work, the effects of carbon-encapsulated iron nanoparticlesand ozone pre-treatments in the mesophilic methanogenic stage of a temperature-phased an-aerobicdigestion have been studied using biochemical methanogenic potential (BMP) tests and modelingsimulation. To do that, digestates from a pre-treated thermophilic acidogenic reactor that co-digestedsludge and wine vinasse were used. The addition of nanoparticles favored the removal of particulatematter, which increased by 9% and 6% in terms of total solids and volatile solids, respectively. Whencombined with ozone pre-treatment, these increases were 27% and 24%, respectively, demonstratingenhanced AD efficiency. The dose of iron nanoparticles encapsulated in carbon did not result ina statistically significant increase in methane production when sludge and vinasse were used asfeedstock. The combination of nanoparticles with the ozone pre-treatment significantly improvedthe methanogenic phase of the second stage, increasing the methane production yield by 22% andreducing the lag phase from 10 days to 3 days, according to the modified Gompertz model.