Biochar addition with Fe impregnation to reduce HS production from anaerobic digestion.

Corn stover biochar (CSB) and maple biochar (MB) were added into anaerobic digesters and evaluated for hydrogen sulfide (HS) reductions. This was the first study to show Fe-impregnated biochar can eliminate HS production. The novel study evaluated biochar addition on HS reduction and nutrient concentrations using three experiments to test the effect of: 1) biochar concentration, 2) biochar particle size, and 3) Fe-impregnated biochar using triplicate lab-scale reactors. At the highest biochar dose (1.82 g biochar/g manure TS), HS production was 90.5% less than the control treatment (351 mL HS/kg VS). Biochar particle size did not significantly affect HS concentration. The Fe-impregnated biochar (0.5 g biochar/g manure TS) reactors had no HS detected in the CSB-Fe system. Methane (CH) in the biochar and control treatments were not significantly different in all three experiments. The results show that biochar added to digesters can significantly reduce HS production without affecting CH production.