Food wastes are typically disposed of in landfills for convenience and economic reasons. However, landfilling food wastes increases the organic content of leachate and the risk of soil contamination. A sound alternative for managing food wastes is anaerobic digestion, which reduces organic pollution and produces biogas for energy recovery. In this study, anaerobic digestion of a common food waste, brown grease, was investigated using a pilot-scale, high-rate, completely-mixed digester (5.8 m(3)). The digestibility, biogas production and the impact of blending of liquid waste streams from a nearby pulp and paper mill were assessed. The 343-day evaluation was divided into 5 intensive evaluation stages. The organic removal efficiency was found to be 58 +/- 9% in terms of COD and 55 +/- 8% in terms of VS at a hydraulic retention time (HRT) of 11.6 +/- 3.8 days. The removal was comparable to those found in organic solid digesters (45-60%), but at a much shorter HRT. Methane yield was estimated to be 0.40-0.77 m(-3)-CH4@STP kg-VSremoved-1, higher than the typical range of other food wastes (0.11-0.42 m(-3)-CH4@STP kg-VSremoved-1), with a mean methane content of 75% and <200 ppm of hydrogen sulfide in the biogas. The blending of selected liquid wastes from a paper mill at 10 vol% of brown grease slurry did not cause significant reduction in digester performance. Using a pseudo-first-order rate law, the observed degradation constant was estimated to be 0.10-0.19 d(-1) compared to 0.03-0.40 d(-1) for other organic solids. These results demonstrate that brown grease is a readily digestible substrate that has excellent potential for energy recovery through anaerobic digestion. (C) 2014 Elsevier Ltd. All rights reserved.