回流比对剩余污泥厌氧发酵产酸的影响

挥发性脂肪酸（VFAs）是强化生物除磷过程中易于利用的碳源。在影响剩余污泥厌氧发酵的因素中，回流搅拌是影响因素之一。因此，确定最适SRT为10 d后，通过采用控制回流比的方法，研究了剩余污泥在不同回流比条件下厌氧发酵的情况。结果表明：回流比的增大能够促进污泥水解过程中SCOD和STOC的溶出；回流比为300%时VFAs浓度最高，可以达到284.64 mg·L-1，约为不回流情况下（146.82 mg·L-1）的2倍；回流比为300%时产酸率也要大于不回流搅拌和回流比为500%的情况，最高可达到0.58 g·g-1（以VS计），在VFAs中以乙酸和丙酸的含量占主导。

Effect of reflux ratio on anaerobic fermentation and acidogenesis of excess sludge

Volatile fatty acids (VFAs) are recognized as the carbon sources suitable for enhanced biological phosphorus removal processes. Reflux stirring is one of the factors affecting anaerobic fermentation of excess sludge. After confirming an optimal solids retention time of 10 d, the effect of different reflux ratios on the anaerobic fermentation of excess sludge was investigated. The results show that an increase in reflux ratio promoted the release of SCOD and STOC during the hydrolysis of the excess sludge. When the reflux ratio was 300%, the concentration of VFAs reached a maximum value of 284.64 mg·L-1, which is almost 2 times higher than it was without reflux (146.82 mg·L-1). In addition, the acid-producing rate was also higher than it was without reflux or with a reflux ratio of 500%, reaching a maximum value of 0.58 g·g-1 (by VS calculate). Moreover, acetic acid and propionic acid were identified as the main VFAs.