In this study, the research protocol was designed to examine the effect of hydraulic retention time (HRT) on the efficiency of the production of biogas from sewage concentrates recovered from coagulation and adsorption process from Xiao Jiahe municipal wastewater treatment plant and to report on its overall performance. Three complete-mix, continuous stirred tank reactor (CSTR) with working volume of 900 mL were used. The digesters were operated at different HRT of 10 d, 20 d and 30 d. Biogas produced had methane composition of 60-70% and biogas production rates of 18 mL/d in reactor 1, 169 mL/d in reactor 2 and 114 mL/d in reactor 3. Reactor 3 showed stable performance with the highest methane yield of 166 mL/gCOD. Reactor 1 recorded lowest methane yield of 10 mL/ gCOD. Due to high organic loading rate (OLR) and shorter HRT, the VS degradation and biogas yield in reactor 1 decreased. Based on the data from this study, 30 d HRT and OLR of 0.6 gCOD/(L.d) was suggested as the designed criteria for ideal methane production from CSTR anaerobic digestion AD of sewage sludge recovered from coagulation and adsorption process.