Effect of TiO2 nanoparticles on anaerobic co-digestion of hybrid Pennisetum and sludge

Abstract

The effects of titanium dioxide (TiO₂) nanoparticles with different diameters (40 nm and 70.31 ± 10.07 nm) on the anaerobic co-digestion of hybrid Pennisetum and sludge were investigated through a 36-day fermentation experiment. The results showed that biogas production in a wet AD process improved when the diameter of the TiO₂ nanoparticles increased. Digesting using TiO₂ nanoparticles with a diameter of (70.31 ± 10.07) nm (T2 system) demonstrated a 162.6% higher biogas production compared to digestion with the 40 nm TiO₂ nanoparticle system. Moreover, the impact of the TiO₂ concentration on anaerobic digestion (AD) was also investigated. The T2 system biogas production was increased by 76.95%, 49.80%, 45.45%, and 5.88% in a wet AD process. Moreover, although the addition of T₂ did not shorten the lag phase of the process, it significantly affected the microbial community of the AD system. 16S RNA amplicon sequencing data demonstrated that hydrogenotrophic methanogens, such as Methanobacterium sp. and Methanobrevibacter sp., played a key role in methane production of the system. The addition of T₂ increased the microbial community diversity and richness.