盐度对模拟餐厨垃圾发酵液产聚羟基脂肪酸酯工艺的影响

利用餐厨垃圾发酵液生产聚羟基脂肪酸酯(PHA)可以在废物处理的同时实现有价资源回收。为探究发酵液中盐分对产PHA菌群富集过程的影响，以模拟餐厨垃圾发酵液为底物，研究了盐度存在下污泥理化性质、富集过程主要指标及菌群PHA合成能力等变化。结果表明，未经盐度富集的菌群易受到盐度抑制，在15 g·L⁻¹的盐度条件下，污泥PHA最大合成量可降至39.9%。富集过程中盐度的增加有利于污泥沉降性的提升，低盐度(5 g·L⁻¹)下菌群分泌胞外聚合物量最多，达49.8 mg·g⁻¹(以VSS计)，对菌群保护能力最强。不同盐度条件下的富集系统皆能保持较好的生态选择压力，但盐度对微生物生长的抑制随着浓度的增大而增强。经过盐度存在下长期富集后的污泥，在高盐度(10、15 g·L⁻¹)底物条件下，仍能获得较高的PHA最大合成能力，但其较低的生长活性不利于最终PHA产量的提升，短期富集下，高盐度会抑制PHA的合成；而低盐度(5 g·L⁻¹)有助于提高PHA合成能力，最高达50.5%。

Influence of salinity on polyhydroxyalkanoate production using simulated food waste fermentation liquid

Polyhydroxyalkanoate (PHA) production using food waste fermentation liquid could recover the valuable resource during the waste treatment. To explore the influence of salinity on PHA-accumulating bacteria enrichment process, simulated food waste fermentation liquid was used as substrate to investigate the changes in physiochemical properties of sludge, main process parameters and PHA storage ability when exposed to salinity. Results showed that the bacterial flora without salinity acclimation was inhibited by salinity and the maximum PHA content of sludge could decrease to 39.9% at salinity of 15 g·L−1. In enrichment process, the increase of salinity improved the sludge settleability, and the extracellular polymeric substance content reached the highest (49.8 mg·g−1 by VSS) at low salinity of 5 g·L-1, which could provide the strongest protection for bacteria. Robust ecological selective pressure could be maintained regardless of salinity gradients, but the inhibition on the growth of bacteria was enhanced with the increase of salinity. A good PHA storage ability could obtained with the substrates at high salinities of 10, 15 g·L−1 for the enriched bacteria after long-term enrichment at high salinity concentrations, but its low growth activity was not conducive to the improvement of final PHA production. Under short-term enrichment, the PHA production could be inhibited at high salinity concentrations while stimulated at low concentration (5 g·L−1), its highest production could reach 50.5%.