Effects of adding micro- and nano-sized biomass fly ash on two-stage biohythane production from the urban organic solid waste

In this work, the effect of ash particle size on the sequential production of bioH2 and bioCH4 for biohythane recovery from the organic fraction of municipal solid waste (OFMSW) was investigated for the first time using micro- and nano-sized biomass fly ash (FA). In the first hydrogenogenic stage, the highest bioH2 yield of 215 mL/g VSadded was noticed in the reactor added with micro-sized FA. On the contrary, in the second methanogenic stage, the maximum bioCH4 yield of 676 mL/g VSadded was witnessed in the reactor fed with acidogenic effluent containing nano-sized FA. In the integrated two-stage process, the addition of FA with nano-sized particles showed superiority over micro-sized FA supplementation and led to an increase of about 582 and 595% in organic matter conversion and energy yield, respectively, compared to the control test, as well as achieving biohythane with an optimal hydrogen content of 15% v/v. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.