Enhanced methane production through bioaugmentation of butyrate‐oxidizing hydrogen‐producing acetogens in anaerobic wastewater treatment

Abstract

A feasible and readily available source of hydrogenproducing acetogens (HPAs) was developed by obtaining microflora D83 dominated by butyrate-oxidizing HPAs through enrichment and subculture of anaerobic sludge with the use of butyric acid. The effect of bioaugmentation of D83 both on methane production through glucose fermentation and molasses wastewater treatment was evaluated. At a bacterial number-to-activated sludge ratio of 1:9, inoculation of microflora D83 could enhance methane yield and production rate from glucose by a factor of 2.1 and 2.0, respectively. In treatment of normal molasses wastewater, chemical oxygen demand (COD) removal efficiency improved from 75.6% to 88.2%, and the accumulated methane yield and methane yield obtained through COD removal increased by a factor of 2.3 and 2.0, respectively. Hydrogen-producing acetogenesis is apparently a rate-limiting step in methanogenesis because bioaugmentation of HPAs during methane production improved not only hydrogen-producing acetogenesis but also hydrolysis/acidogenesis and methanogenesis.

Effect of bioaugmentation on digestate metal concentrations in anaerobic digestion of sewage sludge

“…Bioaugmentation of methane fermentation with hydrogen-producing acetogens (HPAs) obtained through enrichment and subculturing of anaerobic sludge with the use of butyric acid improved not only hydrogen-producing acetogenesis but also hydrolysis/acidogenesis and methanogenesis. At a bacterial number-to-activated sludge ratio of 1:9, inoculation with HPAs improved the yield and rate of methane production by a factor of 2.1 and 2.0, respectively [52]. In our study, bioaugmentation favored growth of Pseudomonas sp.…”

Bioaugmentation with Mixed Hydrogen-Producing Acetogen Cultures Enhances Methane Production in Molasses Wastewater Treatment

“…The original anaerobic activated sludge used to screen for HPA-dominated cultures was collected from an anaerobic baffled reactor [ 28 ]. The enrichment medium, micronutrient solution, and vitamin solution were prepared as described by Liu et al [ 13 ] and Wang et al [ 14 ]. 10 mL of anaerobic sludge sampled and inoculated to 300 mL serum bottles, and each bottle contained 100 mL propionic acid or butyric acid enrichment medium.…”

“…Only when the consumption of propionic acid or butyric acid was up to 85% that 10 mL of bacterial suspension was extracted and injected as inocula for the subsequent batch cultures. The successful enrichment of HPA-dominated cultures (Z08 for HPA-dominated culture that oxidized propionic acid; Z12 for HPA-dominated culture that oxidized butyric acid) depended on the rate of CH4 production from propionic acid and butyric acid [ 13 , 14 ].…”

“…The growth rate of HPA is as typically as slow as that of MB [ 12 , 13 ]. HPA, however, requires more rigorous living conditions than MB [ 14 ]. Thus, HPA could potentially become the rate-limiting factor in anaerobic wastewater treatment under certain conditions.…”

“…Bioaugmentation accelerates the start-up and maintains the stability of bioreactors and enhances the conversion rate of complex substrates. The methane production increased at least 38% [ 26 , 27 ] and has increased total biogas and CH 4 yields through COD removal [ 13 , 14 ]. In addition, the ability of propionate-oxidizing and butyrate-oxidizing HPA to enhance CH 4 production has been investigated.…”