Study On Extraction Of Volatile Fatty Acids From Anaerobicly Acidified Broth Of Municipal Sludge

The components of anaerobicly acidified broth of sludge are unexpected due to the complexity of municipal sludge with toxic inorganic or organic substances. The separation of organic acids from anaerobicly acidified broth of sludge could avoid the product inhibition and improve the efficiency and rate of sludge conversion to organic acids. The study of the separation of organic acids is of significance. The supported liquid membrane combines the solvent extraction and membrane separation with many advantages, such as high separation efficiency, low energy consumption and concentration of organic acids. This main investigation of this thesis includes: the selections of the appropriately membrane modules, solvent and extractant etc.; the optimization of operating conditions of supported liquid membrane. The major results are summarized as follows:(1)The supported liquid membrane is composed of hydrophobic PP microfiltration, trialkyl phosphine oxide, sulfonated kerosene and NaHCO3.(2)The volatile fatty acids production was improved by a slight amount of sulfonated kerosene while the effect was not clear by lots of sulfonated kerosene. The production was improved by 20% with 1/32 sulfonated kerosene.(3)The optimal conditions of the extraction of organic acids were as follows: the concentration of organic acids in feed was 20 g/L, the concentration of extractant was 3 %, the ratio of length to diameter for membrane module was 10:1, the stripping phase pH was 9, the stripping agent was NaHCO3, its concentration was 30 g/L, the extraction temperature was 30℃, the extraction time was 360min, the concentrate efficiency was 2.0. The total extraction efficiency amounted to 85.0%.(4)The extraction efficiency of total acids and acetic acids were 69.0% and 65.0% respectively, while the concentrate efficiency was 1.3 and 1.4.