COD、pH值和运行周期对好氧瞬时补料工艺合成聚羟基脂肪酸酯的影响

Effects of COD concentration,pH and operation cycle in production of polyhydroxyalkanoates(PHA) by aerobic dynamic feeding(ADF)

聚羟基脂肪酸酯(PHA)是一种可生物降解塑料,具有良好的应用前景。混合菌种生产PHA是目前PHA生产的研究重点。以乙酸钠为碳源用好氧瞬时补料(ADF)工艺驯化出了生产聚羟基脂肪酸酯(PHA)的混合菌种。PHA含量在加入营养液后4和10 h达到最大值。研究了营养液COD、pH值和SBR运行周期对PHA生产的影响。COD=12 000 mg·L^(-1)和运行周期12 h均会引发污泥膨胀;COD=3 000 mg·L^(-1)和运行周期48 h会导致污泥流失。pH=7的中性环境下PHA生产菌不具备竞争优势;pH=10时微生物细胞活性受抑制。最适条件为COD=6 000 mg·L^(-1),pH=8.5,运行周期=24 h,此时得到PHA含量最大值31.1%。

Polyhydroxyalkanoates（ PHAs） are a type of biodegradable plastics and have good application prospects. Production of PHAs by mixed microbial cultures is a main direction of the PHA production research. In this study,mixed microbial cultures were enriched by aerobic dynamic feeding（ ADF） with sodium acetate.Maximal PHA content was achieved 4 and 10 h after the feeding. The effects of nutrition COD concentration,pH,and the sequencingbatch reactor（ SBR） operation cycle on PHA production were also studied. The results revealed that both the COD concentration of 12 000 mg·L^-1and the operation cycle for 12 h bead to sludge bulking. Sludge washout occurred at COD concentration of 3 000 mg ·L^-1or when the cycle was for 48 h. The PHA-producing bacteria did not demonstrate a competitive advantage at neutral pH（ 7. 0）. Microbial-cell activity was inhibited at pH 10. The optimal conditions for PHA production were the following： COD concentration of6 000 mg·L^-1,pH 8. 5,and the operation cycle for 24 h. The maximal PHA content（ 31. 1 %） of sludge dry weight was obtained under the optimal conditions.