Anaerobic digestion of crude glycerol from biodiesel manufacturing using a large-scale pilot plant: Methane production and application of digested sludge as fertilizer

• Published in: Bioresource technology 2013-07, Vol.140, p.342-348
• Main Authors: Baba, Yasunori, Tada, Chika, Watanabe, Ryoya, Fukuda, Yasuhiro, Chida, Nobuyoshi, Nakai, Yutaka
• Format: Article
• Language: English
• Subjects: Anaerobiosis; Applied sciences; Biodegradation, Environmental; Biofuel production; Biofuels; Biological and medical sciences; Biological treatment of sewage sludges and wastes; Biotechnology; Crude glycerol; Digested sludge; Energy; Energy balance; Environment and pollution; Equivalence; Exact sciences and technology; Fatty Acids, Volatile - metabolism; Fertilizers; Fertilizing; Fundamental and applied biological sciences. Psychology; Glycerol - chemistry; Glycerols; Grasses; Hydrogen-Ion Concentration; Industrial applications and implications. Economical aspects; Loading rate; Methane; Methane - biosynthesis; Methane production; Pilot plant; Pilot Projects; Plants (organisms); Poaceae - growth & development; Pollution; Sewage - chemistry; Sludge; Thermodynamics; Waste Disposal, Fluid - methods; Wastes
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2013.04.020

•Methane was produced from crude glycerol using a large-scale pilot plant.•Output energy exceeded input energy at a loading rate of 1ml glycerol/L-day.•It was possible to recover methane productivity after a power failure for 1month.•Grass yield increased 1.2 times by applying the digested sludge as liquid manure. This report is the first to consider methane production energy balance from crude glycerol at a practical rather than a laboratory scale. Crude glycerol was added to the plant progressively at between 5 and 75L glycerol/30m3-day for 1.5years, and the energy balance was positive at a loading rate of 30L glycerol/30m3-day (1ml/L-day). At this loading rate over one year, an energy output equivalent to 106% of the energy input was achieved. The surplus energy was equivalent to transport for 1200km, so the proper feedstock-transportation distance was within a 12.5-km radius of the biogas plant. In addition, the digested sludge contained fertilizer components (T-N: 0.11%, P2O5: 0.036%, K2O: 0.19%) that increased grass yield by 1.2 times when applied to grass fields. Thus, crude glycerol is an attractive bioresource that can be used as both a feedstock for methane production and a liquid fertilizer.