Performance evaluation of a novel anaerobic digestion operation process for treating high-solids content chicken manure: Effect of reduction of the hydraulic retention time at a constant organic loading rate

Abstract

A novel feeding strategy was adopted in this study and the effect of reduction in hydraulic retention time (HRT) on the anaerobic digestion of chicken manure (CM) with a constant organic loading rate of 6.0gVS/L/d was investigated. The lab-scale CSTR was operated at 38°C and HRT_CM was reduced from 52days to 5days. At HRT_CM of 20-45days, the reactor was relatively stable in terms of the volumetric biogas production rates and specific biogas production (SBP), which were 2.2-2.4L/L/d and 338.3-418.7mL/gVS_added, respectively. However, process instability and VFA accumulation occurred when the HRT_CM was reduced to 10days due to excess microbes washout. The reduction in HRT_CM to 5days caused SBP to decrease to 198.7mL/gVS_added and the acetic acid content to exceed 6000mg/L. The biomass balance model showed that the biomass concentration at HRT_CM of 20-52days (0.473-0.615gVSS/L) was notably higher than that at HRT_CM of 5-10days (0.173gVSS/L).

Keywords: Ammonia inhibition; Anaerobic digestion; Biomass yield; Chicken manure; Hydraulic retention time; Kinetics.