Co-digestion of hog manure with glycerol to boost biogas and methane production

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Wohlgemut, Oswald
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The use of off-farm materials as amendments in anaerobic digestion of manure is an interesting option due to the benefits of boosting biogas production, and making the process more economical for the farmer. The addition of varying amounts of glycerol, which is a by-product of biodiesel production, was used as an amendment to anaerobic digestion of hog manure in lab-scale tests. The use of 2% glycerol produced the greatest amount of methane and biogas, however stabilization time was high, and the digestion of nutrients in the manure decreased. The addition of 4% glycerol resulted in an overloading of COD and digester failure. The addition of 1% glycerol resulted in a doubling of the methane and biogas production and the acclimation period was quite short, while the effluent quality remained good. There were no detrimental effects of using crude glycerol observed compared to using pure glcyerol. Batch tests also showed that smaller additions of glycerol (0.5%, 1%) produced the highest methane yields and were recommended as good co-substrates for anaerobic digestion with hog manure.
anaerobic, digestion, glycerol, methane