Enhanced volatile fatty acids accumulation in anaerobic digestion through arresting methanogenesis by using hydrogen peroxide.

Abstract

Volatile fatty acids (VFAs) can be accumulated as a final product of anaerobic digestion via arresting methanogenesis. Herein, hydrogen peroxide (H2 O2 ) was studied to inhibit methanogenesis for enhancing VFA accumulation with glucose as a substrate. The addition of 0.06 wt.% H2 O2 significantly reduced methane production and led to a VFAs concentration of 1233.1±55.9mgL-1 , much higher than 429.3±5.6mgL-1 in the control that did not have H2 O2 addition. The dominated VFAs with H2 O2 were acetic acid and propionic acid. A low H2 O2 dosage of 0.03 wt.% produced 466.3±3.9mgL-1 more VFAs than that of O2 addition at the similar (theoretical) dosage, but when the dosage was relatively higher, the VFA accumulation with O2 addition became more than that with H2 O2 addition, likely because of stronger oxidation of VFAs by the overly added H2 O2 . A hypothetical mechanism for H2 O2 inhibition suggests that at a low H2 O2 concentration the inhibition is mainly toward methanogenesis to limit their consumption of VFAs and a high H2 O2 concentration starts to inhibit hydrolysis and acidogenesis and/or oxidize VFAs. Those results encourage further exploration of H2 O2 -based arresting methanogenesis for VFAs production.