Improving hydrogen production from the anaerobic digestion of waste activated sludge: Effects of cobalt and iron zero valent nanoparticles

Recently, different metallic additives have been studied to improve biohydrogen production, such as salts or oxides with iron and nickel. The results have been positive in simple systems, but there are very few studies of the use of nanoparticles of iron and cobalt in systems that use complex substrates such as sludge. In the present study, the effects on hydrogen production from anaerobic digestion of waste activated sludge by zero valent iron nanoparticles (NZVI) and cobalt (CoNP) dosage were investigated. The maximum hydrogen yields were reached with 7 mg/gVS for both additives, 5.74 and 5.40 mLH(2)/gVS(added), for NZVI and CoNP, respectively. In contrast, a low yield was observed in the control reactor (1.79 mLH(2)/gVS(added)), representing increases of over 200%. The dosage of CoNP and NZVI decreased the redox potential and increased the volatile fatty acid concentration, mainly acetic acid. The results indicate that NZVI and CoNP stimulate the early stages of anaerobic digestion of sludge. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.