Comparison of methanogenic potential of wood vinegar with gradient loads in batch and continuous anaerobic digestion and microbial community analysis

Dongliang Hua^a,b, Qingwen Fan^a, Yuxiao Zhao^a,b, Haipeng Xu^a,b, Lei Chen^a,b, Yan Li^a,b,c

Energy Research Institute, Qilu University of Technology (Shandong Academy of Sciences), Shandong Provincial Key Laboratory of Biomass Gasification Technology, Jinan 250014, China.

Abstract

Anaerobic digestion (AD) of wood vinegar wastewater (WVWW) has considerable potential in energy recovery and sustainable development. WVWW contains abundant acetic acid and some refractory organics. Therefore, the batch and continuous AD of WVWW were investigated. The threshold value of the inhibitory concentration was obtained at a chemical oxygen demand (COD) of 4 g/L in batch AD. Three-dimensional electrolysis was adopted to improve the biodegradability of WVWW, and a reduction in the inhibitory rate from 38.2% to 4.9% and an increase in methane production by 53.8% were observed. The up-flow anaerobic sludge blanket reactor achieved an efficient conversion of methane at an organic loading rate (OLR) of <8.58 g COD/L·d. However, the OLR of 10.01 g COD/L·d decreased the methane production from 350.6 to 42.5 mL CH₄/g COD_fed. Aminicenantales, Acetobacterium, Anaerolineae, and SBR1031 were the dominant bacterial genera in continuous AD. Fewer genera with similar classifications were detected in the batch AD. In the archaea community, acetotrophic methanogens (Methanosaeta) dominated and increased continuously with increasing OLR. Microbial analysis revealed that toxic substances affected bacterial diversity and promoted the enrichment of Intestinimonas, Syntropobacter, and Propionicimonas at high OLRs. The continuous AD was most suitable for the energy recovery from WVWW.

Graphical abstract

Keywords: Methanogenesis, Microbial community, Up-flow anaerobic sludge blanket reactor, Wood vinegar wastewater.