厌氧发酵中挥发酸含量与碳酸氢盐碱度的滴定法修正

Titration Method for Total Inorganic Carbon and Volatile Fatty Acids Determination in Anaerobic Digestion

摘要:

为探寻简单可行的厌氧发酵过程中挥发性脂肪酸(VFA)质量浓度与碳酸氢盐(TIC)碱度的测试方法，选用Nordmann滴定法与精密仪器法，在实验室条件下，对中温全混式鸡粪发酵液进行比较测定，并对该滴定法进行一定的修正。实验结果表明，修正前滴定法与精密仪器法测得的VFA质量浓度及TIC碱度存在极显著差异，均值相对误差均在50%以上，修正后差异性不显著，均值相对误差显著降低，且在有机负荷高于4.0g/(L·d)时，均值相对误差低于10%，可实现更为简便准确的VFA及TIC质量浓度测定；修正后滴定法测得的总VFA质量浓度与气相色谱法测得的乙酸质量浓度间存在良好的相关关系，可实现由滴定法估算实际厌氧发酵中的乙酸质量浓度；在对厌氧发酵系统的酸化预警作用中，相比于pH值，采用修正后滴定法测得的VFA与TIC质量浓度比更为及时有效。

Abstract:

In order to obtain a simple and reliable method for volatile fatty acid concentration and bicarbonate alkalinity, Nordmann titration method and instrument method were chosen in lab-scale CSTRs for chicken manure. The accuracy was compared and correction of titration method was made. The result showed that the Nordmann titration method and instrument method for VFA and TIC concentration determination were significant difference, and the mean relative error was more than 50%. After correction, the mean relative error was significantly reduced and lower than 10% when the organic load was higher than 4.0g/(L·d). It means that the modified titration method could achieve more simple and accurate determination of VFA and TIC concentration. Also, as the total VFA concentration measured by the modified titration method had a good correlation with the acetic acid concentration measured by gas chromatography, the modified titration method could estimate the acetic acid concentration. Compared to pH value, VFA/TIC ratio measured by modified titration method could realize early warning of acidification.