电刺激对厨余垃圾厌氧发酵产脂肪酸的影响

The influence of electrical stimulation on fatty acids productionby anaerobic fermentation of food waste

电发酵是在厌氧发酵的基础上向反应体系增加微电压(一般<1.0 V)以提供电刺激,从而优化传厌氧发酵的方法。每年大量产生的厨余垃圾是有机固体废弃物减量化的瓶颈,更是实现“无废城市”和“碳达峰、碳中和”目标的梗阻。通过对比传统厌氧发酵和电发酵处理厨余垃圾产脂肪酸的能力,探究电刺激对此过程的促进作用。结果表明:增加电刺激后,C_(2)-C_(6)多种脂肪酸产量均有不同程度提升,正丁酸甚至由0.38 g/L提升至7.69 g/L,为传统厌氧发酵的20倍;作为最短的中链脂肪酸,正己酸仅在增加电刺激后生成;脂肪酸组分结构有所优化,C_(4)超越C_(2)成为主要产物,C_(4)和C_(6)在电发酵中的最大占比分别为73%和5%。反应进程大幅加快,脂肪酸提前9 d达到总浓度峰值;电发酵体系的pH下降速度快于传统厌氧发酵,顶空气体中二氧化碳和甲烷等副产物气体的含量也有所下降,其碳回收率远高于传统厌氧发酵。

Electric fermentation is a method of optimizing anaerobic fermentation by adding micro voltage(generally<1.0 V)to the reaction system on the basis of anaerobic fermentation to provide electrical stimulation.A large amount of food waste generated every year is not only the bottleneck of the reduction of organic solid waste,but also an obstacle to build a"waste free city"and achieve"carbon peak and carbon neutralization".The promoting effect of electric stimulation on fatty acids production was studied by comparing the fatty acids production abilities of traditional anaerobic fermentation and electric fermentation of food waste.The results showed that after exerting electrical stimulation,the production of fatty acids including C_(2)-C_(6) increased with varying degrees,and n-butyric acid increased from 0.38 g/L to 7.69 g/L,which was 20 times as much as that of traditional anaerobic fermentation.As the shortest medium chain fatty acid,n-hexanoic acid was generated only after exerting electrical stimulation.The composition of fatty acids was optimized.C_(4) had surpassed C_(2)and became the main product.The maximum proportion of C_(4) and C_(6) in electric fermentation reached 73%and 5%,respectively.The reaction process was significantly accelerated,and the concentration of total fatty acids reached the peak value 9 days in advance.The pH of the electric fermentation decreased faster than that of the traditional anaerobic fermentation.The content of carbon dioxide,methane and other by-products in the headspace gas also decreased.The carbon recovery rate of the electric fermentation was much higher than that of the traditional anaerobic fermentation.