Chala Bilhate, Oechsner Hans, Fritz Thomas, Latif Sajid, Müller Joachim
Institute of Agricultural Engineering Tropics and Subtropics Group (440e) Universität Hohenheim Stuttgart Germany.
State Institute of Agricultural Engineering and Bioenergy Universität Hohenheim Stuttgart Germany.
Eng Life Sci. 2018 Apr 6;18(8):551-561. doi: 10.1002/elsc.201700168. eCollection 2018 Aug.
In this study, the anaerobic performance and stability of coffee husk and pulp with and without trace element (TE) supplement was investigated, using 20 L mesophilic continuous stirred tank reactors for 140 days of experiment (DOE). The TE was cocktail of trace metals composed of Fe, Ni, Zn, Co, Mn, Mo, Se W and B. The organic loading rate (OLR) was increased stepwise from 2.5 (HRT = 40 d) to 6.0 kg VS m d(HRT = 16.7 d). The highest methane productivity from pulp with and without TE was 1.272 and 0.965 m m d at an OLR of 6.0 and 5.0 kg VS m d; while the husks performed 0.895 and 0.795 m m d respectively, both at an OLR of 6.0 kg VS m d. The specific methane yield (SMY) of pulp (at OLR = 5 kg VS m d) with and without TEs was 217.9 ± 4.7 and 193.1 ± 8.2 L kgVS; while husk yielded 149.2 ± 6.0 and 132.5 ± 4.9 L kgVS, respectively. The effect of TEs on SMY was statistically significant (p < 001) at higher OLRs (5.0 - 6.0 kg VS m d). The TEs improved the anaerobic stability through an optimum alkalinity ratio (VFA/TIC < 0.3) and suppressed the accumulation of volatile fatty acids. Mono digestion of husks and pulp are prone to lack Mo, Zn, Ni and Fe in long-term anaerobic fermentation. Further studies on co-digestion of husk/pulp with animal manure and dry fermentation helps to efficiently use this biomass resource.
在本研究中，使用20升中温连续搅拌釜式反应器进行了140天的实验（实验设计），研究了添加和不添加微量元素（TE）的咖啡果壳和果肉的厌氧性能及稳定性。TE是由铁、镍、锌、钴、锰、钼、硒、钨和硼组成的微量金属混合物。有机负荷率（OLR）从2.5（水力停留时间=40天）逐步提高到6.0千克挥发性固体/立方米·天（水力停留时间=16.7天）。在OLR为6.0和5.0千克挥发性固体/立方米·天时，添加和不添加TE的果肉的最高甲烷产率分别为1.272和0.965立方米/立方米·天；而在OLR为6.0千克挥发性固体/立方米·天时，果壳的甲烷产率分别为0.895和0.795立方米/立方米·天。在OLR为5千克挥发性固体/立方米·天时，添加和不添加TE的果肉的比甲烷产量（SMY）分别为217.9±4.7和193.1±8.2升/千克挥发性固体；而果壳的比甲烷产量分别为149.2±6.0和132.5±4.9升/千克挥发性固体。在较高的OLR（5.0 - 6.0千克挥发性固体/立方米·天）下，TE对SMY的影响具有统计学意义（p<0.01）。TE通过最佳碱度比（挥发性脂肪酸/总无机碳<0.3）提高了厌氧稳定性，并抑制了挥发性脂肪酸的积累。在长期厌氧发酵中，果壳和果肉的单一消化容易缺乏钼、锌、镍和铁。进一步研究果壳/果肉与动物粪便的共消化和干式发酵有助于有效利用这种生物质资源。
