A 25-liter, no-mix energy-efficient anaerobic digester was designed to act as liquid-solid separator for the production of a fertilizer concentrate and the reduction of pollutants in the effluent. The performance of the no-mix energy-efficient digester was compared to that of a continuous stirred tank reactor at a 20-day hydraulic retention time and six temperature levels within the mesophilic range (20-45°C). The no-mix energy-efficient digester had a higher biogas production rate (32-94%), higher COD reduction (38-63%), and higher solid reduction (64-98%). The sludge obtained from the bottom of the digester had high nitrogen and ash concentrations, while the effluent had no offensive odor.