进水底物浓度对蔗糖废水产酸合成PHA影响研究

混合菌群合成生物可降解塑料(PHA)成为目前研究的热点,三段式PHA合成工艺(水解产酸、产PHA菌富集、PHA合成)被广泛应用.在三段式工艺中,产PHA菌的富集非常关键,只有稳定产生PHA菌才能保障PHA合成的产量.针对产PHA菌富集系统容易出现污泥膨胀的问题,本研究考察了进水底物浓度对产PHA菌富集效率及运行稳定性的影响.在560mg·L-1、1 120 mg·L-1、1 680 mg·L-1这3组不同进水底物浓度的对比实验中,证实了COD 1 120 mg·L-1条件下富集反应器能够在较短污泥龄下稳定富集具有较高污泥浓度的高效产PHA菌,且不会发生污泥膨胀.在94 d的富集期后其批次实验最大PHA含量、PHA转化率(COD/COD)及PHA比合成速率能分别达到50%、0.714 5及0.191 2 mg·(mg·h)-1.研究还同时证实细胞内糖原水平高低与其PHA合成能力密切相关,可采用其作为富集效果的重要检测指标之一.

Influence of Substrate Concentration on PHA Production Using Fermented Sugar Cane as Substrate

PHA was a kind of biodegradable polymer produced by mixed microorganisms. In recent years, 3-stage PHA synthesis process (including substrate hydrolysis, culture selection, and PHA synthesis) was commonly used for PHA production. In this kind of process, culture selection is the key stage, which directly affects the PHA production efficiency. In order to deal with sludge bulking occurred in the culture selection system, this paper analyzes the influence of substrate concentration on culture selection efficiency as well as operation stability. Under different influent substrate concentrations of 560 mg·L^-1, 1120 mg·L^-1 and 1680 mg·L^-1, we confirmed that influent substrate concentration(COD) of 1120 mg·L^-1 is the most suitable parameter for the bacteria enriching process after a long period of time under short SRT. After 94 days of cultivation, we achieved 50% of PHA content, 0.7145 COD/COD of PHA conversion rate and 0.1912 mg·(mg·h)^-1 of specific PHA storage rate at the end of batch tests with nutrient starvation. The study also confirmed that glycogen level in cells has a close relationship with its PHA synthesis ability, which shows its potential to predict the enrichment efficiency.