The biological and abiotic effects of powdered activated carbon on the anaerobic digestion performance of cornstalk.

Abstract To comprehensively evaluate the biological and abiotic influence of powdered activated carbon (PAC) on the anaerobic digestion of cornstalk, mesophilic and thermophilic digestion were conducted. Adding PAC (10 g/L) under thermophilic system obtained the maximum cellulose degradation rate and methane yield (MY), which were 57.47% and 128.19 L/kg VS. However, adding same dose of PAC at mesophilic system decreased the MY by 8.16% while increased the cellulose degradation rate and methane production rate by 6.48% and 17.92%. Under mesophilic conditions, the enhancement of PAC was owing to the enrichment of cellulolytic microorganisms, improvement of the syntrophic process and direct interspecies electron transfer. The lower methane yield was attributed to the adsorption of carbon source by PAC and CH4 consumption by Norank_c_Bathyarchaeia. The good performance of thermophilic system was owing to the lower adsorption capability of PAC, absence of Norank_c_Bathyarchaeia, and concentrated carbon flow to methane.