碱性条件促进纺织印染污泥厌氧发酵产挥发性脂肪酸

系统研究了酸性（pH值5、pH值6）、中性（pH值7）和碱性（pH值8～10）条件下，纺织印染污泥厌氧发酵产挥发性脂肪酸（VFA）的发酵类型，比较了总酸及主要酸的最高发酵浓度及分布、总酸及乙酸的产率和生产速率，并揭示了碱性条件有利于有机酸发酵的机制。研究结果表明，不同pH值条件下，乙酸型均为主要发酵类型，但较低的pH值利于丁酸累积。总酸及乙酸的浓度随着pH值的升高而增加，且碱性条件能够促进纺织印染污泥发酵产酸，原因为高pH值能促进有机物的降解并提高转化效率，同时较高的pH值抑制了有机酸的降解。pH值为10是厌氧发酵产酸并累积乙酸的最佳pH值。该条件下，乙酸和总酸的质量浓度达最高，为8.21 g/L和14.08 g/L；乙酸和总酸产率也达最高，为34.97%和75.72%；同时乙酸和总酸的生产速率达最高值，为2.41 g/(L·d)和3.48 g/(L·d)。pH值为6比较适合丁酸发酵，丁酸的最高浓度为1.89 g/L。

Alkalinity improved production of volatile fatty acid from anaerobic fermentation of textile dyeing sludge

The study of acidity (pH 5, pH 6), neutrality (pH 7) and alkalinity (pH 8—10) conditions on the type of fermentation, maximum concentration of total VFA and major acids, VFA distribution，yields and the production rates of total VFA and acetic acid from the textile dyeing sludge by anaerobic fermentation were investigated, and the mechanisms of the alkalinity condition beneficial to producing the organic acids were revealed. The results showed that acetic acid-type fermentation was the main type at different pH, but a lower pH was in favor of the accumulation of butyric acid. The concentrations of total VFA and acetic acid increased with increasing pH. The alkalinity condition could promote production of VFA because a high pH could promote the degradation of organic matter, improve conversion efficiency and inhibit the degradation of organic acids. pH at 10 was the optimum value to reach the best total VFA and acetic acid production from the sludge. At that pH value, the concentrations of acetic acid and total VFA were 8.21 g/L and 14.08 g/L respectively. The yields of acetic acid and total VFA could reach 34.97% and 75.72% respectively. In addition, the rate of acetic acid and total VFA production could reach 2.41g/(L·d) and 3.48 g/(L·d), respectively; Meanwhile, when the pH was 6, butyric acid could reach the highest concentration of 1.89g/L, suggesting that the pH value at 6 is suitable for the butyric acid-type fermentation.