pH值对苦荞渣厌氧发酵性能的影响

Effect of pH Value on Anaerobic Fermentation Performance of Tartary Buckwheat Residue

以苦荞渣为原料,设置不同总固体(TS)质量分数的发酵液进行厌氧发酵,探究TS质量分数对发酵产气量及发酵液酸化的影响。并通过对发酵液添加缓冲溶液探究整个厌氧发酵过程中挥发性脂肪酸的变化情况。结果表明:当TS质量分数为4%时,产气情况良好;当TS质量分数超过4%时,系统就会发生酸化,酸化的原因是由于过量的丁酸积累所导致。通过使用缓冲溶液(30%NaOH溶液)调节pH值进行联合产氢产甲烷联合发酵,可促进丁酸向乙酸的转化,有效解决酸积累问题并提高能源转化效率。相同TS质量分数下,产氢产甲烷联合组(4#和5#)的能源转化效率分别是未处理组(2#和3#)的10.8倍和12.8倍。酸化后使用缓冲溶液调节pH值不仅可以快速恢复产气,恢复产气率也相比其他恢复方式的产气率更高,TS产气率达到1267 mL/g。使用Modified Gompertz方程进行拟合发现,相关系数(R)均在0.99以上,拟合结果较好。

Tartary buckwheat residue was used as raw material,and the fermentation broth with different total solid(TS)mass fraction was used to investigate the acidification experiment.After obtaining the mass fraction of acidified TS,it was readded with buffer solution for anaerobic fermentation.The changes of volatile fatty acids in the whole process of anaerobic fermentation were monitored.The results showed that when the mass fraction of TS was 4%,the gas production was good.When the mass fraction of TS exceeded 4%,acidification occurred in the system,which was caused by excessive accumulation of butyric acid.The conversion of butyric acid to acetic acid could be promoted by using buffer solution(30%NaOH solution)to adjust pH value for combined hydrogen and methane production fermentation,which could effectively solve the problem of acid accumulation and improve energy conversion efficiency.Under the same TS mass fraction,the energy conversion efficiency of the combined hydrogen and methane production group(4#and 5#)were 10.8 times and 12.8 times of those of the untreated group(2#and 3#),respectively.Adjusting pH value with buffer solution after acidification not only could quickly restore gas production,but also had a higher gas production rate than other recovery methods,and the gas production rate of TS could reach 1267 mL/g.Modified Gompertz equation was used for fitting,and it was found that the correlation coefficients R were all above 0.99,and the fitting results were good.