초록
According to our previous study, propionic acid-enriched volatile fatty acids (VFA), the preferred carbon source of biological wastewater nutrient removal, can be produced via the lactic acid pathway during the two-stage fermentation of organic wastes using Propionibacterium acidipropionici. In the current study a new strategy, based on lactic acid accumulation from sludge and food waste, was introduced to significantly increase the yield of propionic acid-enriched VFA. First, the effect of different temperature on the two-stage fermentation was fully discussed. Both advantages and disadvantages of the fermentation in different temperatures were elaborated. Furthermore, the proposed metabolic pathway at 35<SUP>o</SUP>C and 50<SUP>o</SUP>C was introduced. It was observed that by initially controlling temperature at 50<SUP>o</SUP>C for 4h and subsequently at 35<SUP>o</SUP>C for 2d, the steady and maximal accumulation of lactic acid was obtained in the first stage, which resulted in the yield of propionic acid-enriched VFA in the second stage being increased to 15.3g COD/L and the percentage of propionic acid in VFA reaching 69.9%.