Process Comparisons of PhaSE Separation in Anaerobic Digestion of Complex Organic Substrates

两相厌氧消化被认为是提高甲烷生产效率的有利工艺。有机物各组分的厌氧消化机理有待进一步研究。例如，预计碳水化合物、蛋白质和脂类在厌氧降解过程中应该存在一些差异。用两种不同的底物脱脂奶和婴儿奶来分析这些影响。脱脂奶的主要成分是碳水化合物和蛋白质，占总量的87.4%，而婴儿奶的93.7%是碳水化合物和脂类。由于碳水化合物很容易生物降解，这项研究将比较蛋白质和脂质存在的影响。基材差异在工艺变化的模式上有差异，但在整体效率上的变化较小。婴儿奶中挥发性酸含量较少的原因是婴儿奶中只有47%的易生物降解的碳水化合物和蛋白质。相分离效应对碳水化合物没有明显的优点，对蛋白质有一点优势（Hanaki, 1986），但水解脂质并分解成长链脂肪酸会抑制产甲烷生物的活性（Tanaka, 1985）。因此，通过对单相操作和两相操作的比较，可以清楚地了解两相操作对脱脂奶的影响很小，并且通过避免这种抑制而使婴儿奶更稳定的原因。一般来说，建议对所有类型的底物进行两相操作，但特别强烈建议对含有高脂质的婴儿牛奶等底物进行两相操作。

The Two phase anaerobic digestion has been considered to be an advantageous process to improve the methane production efficiency. It remains still to be investigated for the anaerobic digestion mechanisms of each compornent of organic materials. For instance, it is expected that there should be some differences in the anaerobic degradation processes among carbohydrates, proteins and lipids.Two different substrates skimmed milk and baby milk were used to analyse these effects. The major components of skimmed milk are carbohydrates and proteins which makes up 87.4% of it whereas 93.7% of baby milk is carbohydrates and lipids. As carbohydrates are easily biodegradable the study will compare the effects of presence of proteins and lipids. Substrate differences have differences in the pattern of changes in the process, but less variations in the overall efficiencies. The reason for less percentages of volatile acids in the case baby milk can be found as baby milk has only 47% of easily biodegradable carbohydrates and proteins.Phase separation effects for carborhydrates has no clear merits and a little advantage for protein (Hanaki, 1986) but hydrolysing lipids and breaking into long-chain fatty acids inhibits methanogenous organisms activity (Tanaka, 1985). Therefore comparing the single phase and two phase operations the reasons for little different in skimmed milk and better stabilization for baby milk by two phase operation by avoiding this inhibition are clearly understood. Generally speaking two phase operations are reccommended for all the type of substrates, but especially highly reccommended for substrates like baby milk with high contents of lipids.