Investigation of the effects of different slags as accelerant on anaerobic digestion and methane yield

Abstract

In the anaerobic digestion (AD) system, different additives are used to accelerate microorganism activities and increase biogas and methane production. In this study, the effect of different types of slag that emerge in the iron and steel industry on biogas production and methane yield was investigated. Blast furnace slag (BFS), steelmaking converter slag (SCS), and steelmaking ladle slag (SLS) obtained from an integrated iron and steel plant were added to the reactors with cattle manure as substrate at different concentrations (1, 1.5, 2, 2.5, and 3%). In the fed-batch experiments, the highest cumulative biogas yield was 399.5 mL/gVS and the methane yield was 238.2 mL CH4/gVS in the reactor to which 1% BFS was added. The highest COD removal rates were observed at S1-1, S1-2, S1-5, and S2-2 by 65.36%, 63.88%, 54.08%, and 54.96%, respectively. The biogas production and methane yields were found to be higher in the slag added reactors than in the control reactor, which indicates that slag can be used as an additive in biogas production.