Biogas production from brown grease using a pilot-scale high-rate anaerobic digester

Pengchong Zhang, Che-Jen Lin, James Liu, Pruek Pongprueksa, Simon A. Evers and Peter Hart

Renewable Energy, 2014, vol. 68, issue C, 304-313

Abstract: 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 m3). 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 m3-CH4@STP kg-VSremoved−1, higher than the typical range of other food wastes (0.11–0.42 m3-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.

Keywords: Brown grease; Biogas; Anaerobic digestion; Renewable energy (search for similar items in EconPapers)
Date: 2014
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Citations: View citations in EconPapers (1)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:68:y:2014:i:c:p:304-313

DOI: 10.1016/j.renene.2014.01.046

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