Biotechnological Processes for Energy Production Unit-IMDEA Energy, 28935, Móstoles, Madrid, Spain.
Biofuels Unit-Research Center for Energy, Environment and Technology (CIEMAT), 28040, Madrid, Spain.
Environ Sci Pollut Res Int. 2018 May;25(14):14263-14270. doi: 10.1007/s11356-018-1643-9. Epub 2018 Mar 10.
During the last decade, a lot of research has been focused on identifying the methane yields achievable when using microalgae biomass (fresh and pretreated) as a substrate in anaerobic digestion. Encountered differences are frequently attributed to the different microalgae strains (cell walls and macromolecular profiles) or the different metabolic activities of anaerobic sludge used as inoculum. Nevertheless, under the hypothesis that the state of microalgae upon biomass storage may also play a significant role, this study was designed to evaluate the effect of biomass processing and storage on methane yields and hydrolysis kinetics in batch mode assays. Slight changes in the macromolecular profile distribution of the different tested biomass were observed. Regardless of the time that the biomass was stored, results revealed that frozen biomass doubled the hydrolysis constant and enhanced methane yield by 1.56-fold compared to fresh microalgae biomass (82.4 mL CH g COD in). Similar enhancement was obtained with the freeze-dried biomass, and slightly lower values were obtained (1.34-fold) for the biomass kept at 4 °C longer than a week. Likewise, the semi-continuously operated reactor fed with microalgae biomass stored for 28 days at 4 °C did not show any effect in terms of methane production, although nitrogen mineralization was higher than expected. Remarkably, the initial stage of the biomass should be carefully considered for comparison purposes with the available literature on batch mode assays. This study highlights the importance of considering how the biomass is stored before the anaerobic digestion process to avoid misleading conclusions.
在过去的十年中，大量的研究集中在确定使用微藻生物质（新鲜和预处理）作为厌氧消化的底物时可实现的甲烷产量。所遇到的差异通常归因于不同的微藻菌株（细胞壁和大分子谱）或用作接种物的厌氧污泥的不同代谢活性。然而，根据微藻生物质储存状态也可能起重要作用的假设，本研究旨在评估生物质处理和储存对分批模式试验中甲烷产量和水解动力学的影响。观察到不同测试生物质的大分子谱分布有轻微变化。无论生物质储存多长时间，结果都表明，与新鲜微藻生物质相比（82.4 mL CH g COD in），冷冻生物质将水解常数提高了一倍，并将甲烷产量提高了 1.56 倍。冻干生物质也获得了类似的增强效果，而对于在 4°C 下储存超过一周的生物质，获得的值略低（1.34 倍）。同样，以 4°C 储存 28 天的微藻生物质为进料的半连续操作反应器在甲烷生产方面没有显示出任何效果，尽管氮矿化率高于预期。值得注意的是，在与分批模式试验的现有文献进行比较时，应仔细考虑生物质的初始阶段。本研究强调了在进行厌氧消化之前考虑生物质储存方式的重要性，以避免产生误导性结论。
