Abstract:

The digestate from anaerobic fermentation of food waste has high organic matter content and high potential for fertilization. Compared with traditional composting, using hydrothermal technology to convert organic waste into humic acids has many advantages such as high substrate adaptability and short reaction time, which is conducive to promote the use of digestate as fertilizer in the anaerobic fermentation project of food waste. The present study provided options for the resource utilization of food waste anaerobic digestate as well as a source of feedstock and better process conditions for the production of humic acid-like substances. In this study, the effects of hydrothermal reaction pH and temperature on the yield and characteristics of humic acid and fulvic acid were investigated using anaerobic digestate as feedstock. The highest humic acid yield of 43.31% was achieved at a neutral reaction pH and temperature of 200℃. The humic acid-like products generated were found to have typical humic acid structure by FTIR and 3D-EEM analysis. And the fulvic acid yield was also more than 8% at 180—200℃. Carbon and nitrogen flow analysis showed that the carbon efficiency increased to more than 40% when the reaction temperature reached 200℃, and hydrothermal humification could recover more than 25% of nitrogen through humic acid.

Key words: food waste digestate, hydrothermal humification, humic acid, fulvic acid, carbon-nitrogen flow

摘要：

厨余垃圾厌氧发酵沼渣有机质含量较高，仍具有较高的肥料化潜力。相比传统堆肥，利用水热技术将有机废弃物转化为腐殖酸类物质具有原料适应性强、时间短等优势，有利于解决厨余垃圾厌氧发酵工程中沼渣肥料化的问题。为此，本研究提供了厨余厌氧沼渣资源化利用的可选方法以及生产腐殖酸类物质的一种原料来源和较佳工艺条件。本文以厨余厌氧沼渣为原料，系统考察了pH和温度等不同水热反应条件对腐殖酸和富里酸等腐殖化产物产率和特性的影响。研究表明：反应pH为中性、温度为200℃条件下腐殖酸产率最高，可达43.31%。通过傅里叶红外变换光谱（FTIR）、三维激发发射矩阵（3D-EEM）分析发现生成的腐殖酸类产物具有典型的腐殖酸结构。而富里酸在180~200℃时产率较高，达到8%左右。碳氮流分析显示反应温度达到200℃时，碳效率增加至40%以上；而水热腐殖化可以通过腐殖酸回收25%以上的氮元素。

关键词: 厨余沼渣, 水热腐殖化, 腐殖酸, 富里酸, 碳氮流