pH值调控柠檬酸污泥厌氧发酵产酸及碳源潜力研究

以柠檬酸废水厌氧颗粒污泥为接种物,在不同pH值调控条件下开展柠檬酸生产废水剩余活性污泥厌氧发酵产酸研究。通过对发酵液挥发性脂肪酸(VFAs)、有机质、氮磷和污泥脱水性能的分析,探讨了柠檬酸污泥厌氧产酸机制。结果表明,pH³10的碱性条件更有利于有机质的溶出从而促进VFAs的产生。三维荧光光谱分析发现在恒定pH值下腐殖酸(HA)和富里酸(FA)会大量溶出降低VFAs的产量。初始pH=10是柠檬酸污泥厌氧产酸的最佳pH值,发酵4d的VFAs浓度最高达(6681.47±126.82)mg COD/L,是文献报道中市政污泥产酸量的近2倍,其中乙酸占比49.8%,发酵后产酸功能菌Chloroflexi、Bacteroidota的相对丰度分别由初始的9.52%、10.87%增至16.84%、14.39%,污泥归一化毛细吸水时间(n_CST)为(11.34±0.27)s×L/g,脱水性能良好,发酵液TP浓度为(20.45±0.33)mg/L。研究表明,利用柠檬酸剩余活性污泥碱性厌氧发酵产酸作为污水处理过程中的外加碳源具有较大潜力。

Effect of pH on acid production by anaerobic fermentation of citric acid sludge and carbon source potential of fermentation broth

The research of acid production by anaerobic fermentation with different pH control conditions was carried out for the treatment of waste activated sludge from citric acid wastewater, using anaerobic granular sludge of citric acid wastewater as inoculum. The mechanism of anaerobic acid production of citric acid sludge was evaluated by the analysis of volatile fatty acids (VFAs), organic matter, nitrogen and phosphorus contents and sludge dewatering performance. The results showed that the alkaline conditions with pH³10 were more conducive to the dissolution of organic matter to promote the production of VFAs. It was obvious that humic acid (HA) and fulvic acid (FA) at constant pH conditions would be dissolved in large quantities with Three-dimensional Excitation-Emission-Matrix Spectra analysis, thus reducing the yield of VFAs. The initial pH=10 was the optimum pH value for anaerobic acid production of citric acid sludge, and the VFAs concentration of (6681.47±126.82) mg COD/L for 4 days was the highest, which was nearly 2 times that of municipal sludge acid production reported in the literature, among which acetic acid was 49.8%. After fermentation, the relative abundances of acid-producing functional bacteria Chloroflexi and Bacteroidota increased from initial 9.52% and 10.87% to 16.84% and 14.39%, respectively. The normalized capillary suction time (n_CST) value of the final sludge was (11.34±0.27) s·L/g with good dewatering performance, and the TP concentration of fermentation broth was (20.45±0.33) mg/L. Studies have shown that the alkaline anaerobic fermentation of citric acid waste activated sludge to produce acid fermentation broth has a good development potential as an exogenous carbon source in the sewage treatment process.