The effects of the solid bed immersion in the anaerobic digestion of straw-cattle manure (SCM) were studied using two batch reactors of 2 m of solid height and 440 L of total volume. The reactors were operated in parallel with total (R1_100%) and partial solid height immersion (R2_74%) and no liquid recirculation. Recovered methane yield was 31.1% higher in R1 than in R2, 33.7 and 23 Nm³ CH₄ t⁻¹_SCM respectively. The volatile solids (VS) and fiber degradation was studied in layers distributed each 0.5 m of the initial solid bed height profile; VS removal was measured at 16% at 2 m height in contrast to 39.9% at the reactor bottom. VS removal was related with hemicellulose and cellulose biodegradation, maximal hemicellulose and cellulose degradation in the studied layers were 68.2 and 49.5% respectively. Physical and rheological changes of the solid phase were measured between the SCM and the digestate. Macropores volume was reduced from 30.4% to values between 0.82 and 5.57%, this decrease was related to the water content and the fiber degradation state in each layer. Similarly, yield stress values obtained with the slump test depends on total solids content and fiber degradation state, yield stress values ranged from 1.41 and 2.23 kPa for raw and digested SCM. Moreover, values of cohesion and the friction angle were between 1.5 and 2.8 kPa and 15.6 and 47.7° respectively. Physical and rheological properties of digested SCM depends on the solid degradation state and the water availability through the material’s height profile.

Graphic Abstract

中文翻译：

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440 L分批中试反应器浸入对稻草-牛粪厌氧降解及流变性质的影响

使用两个固体高度为2 m，总体积为440 L的间歇式反应器研究了固体床浸没在秸秆牛牛粪（SCM）厌氧消化中的影响。使反应器与全部（R1_100％）和部分固体高度浸入（R2_74％）平行运行，并且不进行液体再循环。R1中的回收甲烷产率比R2、33.7和23 Nm ³ CH ₄ t ^-1 _SCM高31.1％分别。在每个初始固体床高度分布为0.5 m的层中研究了挥发性固体（VS）和纤维降解。在2 m高度测得的VS去除率为16％，而在反应器底部的VS去除率为39.9％。VS去除与半纤维素和纤维素的生物降解有关，在研究的层中最大的半纤维素和纤维素降解分别为68.2和49.5％。测量了SCM和消化物之间固相的物理和流变学变化。大孔体积从30.4％减小到0.82至5.57％之间的值，该减小与每个层中的水含量和纤维降解状态有关。同样，通过坍落度测试获得的屈服应力值取决于总固体含量和纤维降解状态，屈服应力值的范围为1.41和2。原始和消化的SCM为23 kPa。此外，内聚力和摩擦角的值分别在1.5和2.8kPa之间以及15.6和47.7°之间。消化后的SCM的物理和流变特性取决于固体的降解状态和通过材料的高度分布获得的水分。

图形摘要