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Published on: May 19, 2019
Low temperature calcium hydroxide treatment enhances anaerobic methane production from (extruded) biomass
Way Cern Khor1, Korneel Rabaey2, Han Vervaeren3
1Ghent University Campus Kortrijk, Department of Industrial Biological Science, Graaf K. de Goedelaan 5, 8500 Kortrijk, Belgium; Ghent University, Department of Biochemical and Microbial Technology, Laboratory of Microbial Ecology and Technology (LabMET), Coupure Links 653, 9000 Gent, Belgium.
Abstract:
Ca(OH)2 treatment was applied to enhance methane yield. Different alkali concentration, incubation temperature and duration were evaluated for their effect on methane production and COD conversion efficiency from (non-)extruded biomass during mesophilic anaerobic digestion at lab-scale. An optimum Ca(OH)2 pretreatment for grass is found at 7.5% lime loading at 10°C for 20h (37.3% surplus), while mild (50°C) and high temperatures perform sub-optimal. Ca(OH)2 post-treatment after fast extrusion gives an additional surplus compared to extruded material of 15.2% (grass), 11.2% (maize straw) and 8.2% (sprout stem) regarding methane production. COD conversion improves accordingly, with additional improvements of 10.3% (grass), 9.0% (maize straw) and 6.8% (sprout stem) by Ca(OH)2 post-treatment. Therefore, Ca(OH)2 pretreatment and post-treatment at low temperature generate an additional effect regarding methane production and COD conversion efficiency. Fast extrusion gives a higher energy efficiency ratio compared to slow extrusion.
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