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

[Display omitted] •A novel feeding strategy, keeping constant OLR but reducing HRTCM was adopted.•The effect of reducing HRTCM on CH4 fermentation of chicken manure was studied.•High content of ammonia was the main inhibition factor at HRTCM of 52days.•Reduce in HRTCM relaxed the inhibition of high ammonia at OLR of 6.0gVS/L/d.•The performance deterioration occurred as HRTCM decreased to 10days. 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 HRTCM was reduced from 52days to 5days. At HRTCM 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/gVSadded, respectively. However, process instability and VFA accumulation occurred when the HRTCM was reduced to 10days due to excess microbes washout. The reduction in HRTCM to 5days caused SBP to decrease to 198.7mL/gVSadded and the acetic acid content to exceed 6000mg/L. The biomass balance model showed that the biomass concentration at HRTCM of 20–52days (0.473–0.615gVSS/L) was notably higher than that at HRTCM of 5–10days (0.173gVSS/L).