木薯燃料乙醇沼气双发酵耦联工艺中氨氮的调控

乙醇-沼气双发酵耦联工艺是将沼气发酵出水回用于乙醇发酵过程并不断循环的新型乙醇清洁生产工艺。实验发现,沼气发酵过程产生的氨会随着工艺循环而累积,在乙醇发酵时会和还原糖产生美拉德反应,导致乙醇产量下降。因此通过离心和通气等技术手段对耦联工艺中的氨进行了调控。实验分为对照组和调控组,分别考察了氨氮累积、氨氮调控效果、氨氮对工艺的影响等内容。实验结果显示,经过7批循环对照组中氨氮浓度累积至811 mg/L,氨氮浓度为550 mg/L时,乙醇发酵开始受到明显抑制,导致乙醇产量下降;调控工艺中氨氮浓度稳定在350 mg/L左右,乙醇产量无下降现象。氨氮累积间接造成对照组中碱度升高,其他沼气发酵指标稳定正常。调控工艺保证了乙醇产量和工艺稳定。

Regulation of Ammonia Nitrogen in a Cassava-based Ethanol-methane Coupled System

Cassava-based ethanol-methane coupled system is a novel cleaner ethanol production process in which the anaerobic digestion effluent is recycled to the next batch of ethanol fermentation process.However ammonia generated from the anaerobic digestion could be accumulated with the recycling and thus resulted in reduction of ethanol production due to Maillard reaction between ammonia and reducing sugar.Therefore the technology of centrifugation and ventilation were utilized to control the ammonia nitrogen.Control process and regulation process were designed to study accumulation and regulation of ammonia nitrogen and its influence on the process.Results showed that the ammonia nitrogen concentration increased to 811 mg/L after seven cycles of fermentation,and the ethanol fermentation was inhibited with obvious reduced ethanol production when the ammonia nitrogen concentration reached 550 mg/L in the control process.Such phenomenon did not occur in the process with ammonia nitrogen regulation,where the ammonia nitrogen concentration maintained at the level of approximately 350 mg/L.Ammonia nitrogen caused the accumulation of alkalinity in control process indirectly,but other parameters on methane fermentation were normal.Regulation process guaranteed the ethanol production and performance of the system.