The Determination of VFAs in Digestive Juice of Excess Active Sludge with Gas Chromatography

Anaerobic disgestion is a main treatment process of excess active sludge,which has been used widely.Lot's volatile fatty acids(VFAs) were produced during the course of digestion.The gas chromatography was used to determining some VFAs,which are acetic acid;propionic acid,i-butyric,butyric acid,i-valeric,valeric acid in digestive juice of excess actived sludge.The results showed that the time intervals of all kinds of VFAs were clear and sharply.Among the coefficients of variation of all VFAs in the repeated test,the coefficient of variation of i-valeric was 3.23% which was the biggest one.Results also indicated that the repeatability of determination methods was acceptable.The recovery rates of acetic acid;propionic acid,butyric,i-butyric acid,valeric,i-valeric acid in digestive juice were 105%,98%,99%,98%,105%,96%,respectively and met the requirements of stipulations in literature.