Enhanced volatile fatty acids accumulation in anaerobic digestion through arresting methanogenesis by using hydrogen peroxide
Yanran Xu, Zhen He
Abstract
Abstract Volatile fatty acids (VFAs) can be accumulated as a final product of anaerobic digestion via arresting methanogenesis. Herein, hydrogen peroxide (H 2 O 2 ) was studied to inhibit methanogenesis for enhancing VFA accumulation with glucose as a substrate. The addition of 0.06 wt.% H 2 O 2 significantly reduced methane production and led to a VFAs concentration of 1233.1 ± 55.9 mg L −1 , much higher than 429.3 ± 5.6 mg L −1 in the control that did not have H 2 O 2 addition. The dominated VFAs with H 2 O 2 were acetic acid and propionic acid. A low H 2 O 2 dosage of 0.03 wt.% produced 466.3 ± 3.9 mg L −1 more VFAs than that of O 2 addition at the similar (theoretical) dosage, but when the dosage was relatively higher, the VFA accumulation with O 2 addition became more than that with H 2 O 2 addition, likely because of stronger oxidation of VFAs by the overly added H 2 O 2 . A hypothetical mechanism for H 2 O 2 inhibition suggests that at a low H 2 O 2 concentration the inhibition is mainly toward methanogenesis to limit their consumption of VFAs and a high H 2 O 2 concentration starts to inhibit hydrolysis and acidogenesis and/or oxidize VFAs. Those results encourage further exploration of H 2 O 2 ‐based arresting methanogenesis for VFAs production.