Effect of organic compounds on dry anaerobic digestion of food and paper industry wastes

Abstract

Effects of antimicrobial compounds on dry anaerobic digestion (dry-AD) processes were investigated. Four compounds with known inhibition effects on traditional wet digestion, i.e. car-3-ene, hexanal, 1-octanol and phenol were selected and investigated at concentrations of 0.005%, 0.05% and 0.5%. Food waste (FW) and Paper waste (PW) were used as model substrates, all assays were running with the substrate to inoculum ratio of 1:1 (VS basis) corresponding to 15% TS in reactors. Generally, increasing concentrations of inhibitors resulted in decreasing methane yields with a few exceptions; in all these specific cases, long, lag phase periods (60 days) were observed. These adaptation periods made possible for the microbial systems to acclimatize to otherwise not preferred conditions leading to higher methane yields. Comparing the effects of the four different groups, phenols had the highest inhibitory effects, with no methane production at the highest amount added, while the lowest effects were obtained in cases of car-3-ene. Furthermore, the results showed that adding inhibitors up to a certain concentrations can repair the balance in AD process, slowing down the degradation steps, hence making it possible for the methanogens to produce a higher amount of methane. This phenomenon was not observed in case of PW, which is already a slow degradable substrate in its nature.

Integrating Torrefaction of Pulp Industry Sludge with Anaerobic Digestion to Produce Biomethane and Volatile Fatty Acids: An Example of Industrial Symbiosis for Circular Bioeconomy

“…However, a complete inhibition was observed when the concentration was further increased to 5600 mg/L. In another study, Jansson et al [30] observed that methane yield was reduced by 66% when phenol concentration increased from 0.005 to 0.05 (w/v %) during the anaerobic digestion of paper waste.…”

“…As discussed in Section 3.4.1, the concentration of inhibitory compounds at a certain level could be beneficial to the AD process. At the same time, the microbial community can also adapt to these inhibitory compounds up to a certain concentration [30]. However, the further rise in the same compounds could inhibit the process.…”

Apple orchard waste recycling and valorization of valuable product-A review

“…The highest methane production reached 0.34 L g −1 VS added , co-digest of apple pulp, cow slurry, and olive pomace have produced stable biogas of 400 L/kg volatile solids. Jansson et al [ 23 ] investigated CSTR for digestion of residue of vegetables, the digestion of sugar beet pulp and asparagus waste led to a methane generation of 0.263 and 0.230 l g −1 VS fed, respectively, and reduction in VS equal to 95.2% and 89.7%. In comparison to single-phase digestion, batch sequencing reactors are becoming more critical for anaerobic digestion, when it comes to enhancing solid retention and unsettlement.…”