Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, China 210098 and College of Environment, Hohai University, Nanjing, China 210098 E-mail:
Water Sci Technol. 2014;69(4):825-32. doi: 10.2166/wst.2013.785.
Flume experiments were conducted to investigate the distribution and composition of extracellular polymeric substances (EPS) in biofilms and the detachment mechanism of biofilms grown under different flow velocity conditions. The results of biofilm growth kinetics showed that the growth trends were coincident with the logistic growth model. The growth kinetics parameters reached their maximum under intermediate velocity (IV) condition. Biofilms exhibited different profiles of EPS composition and distribution, depending on the flow conditions in which the biofilms were grown. The amounts of total polysaccharide and total protein in the thin biofilm (high velocity condition 2 - HV2) were both generally greater than those in the thick biofilm (IV). As compared to the heterogeneous distribution of EPS in the thick biofilms (IV), the EPS in the thin biofilms (HV2) exhibited more homogeneous distribution, and the bound EPS in the thin biofilms (HV2) were much greater than those in the thick biofilms (IV). From the detachment tests, an inverse relationship was observed between the proportion of detached biomass and the value of flow velocity during growth. Biofilms grown under higher velocities showed stronger cohesion than those grown under lower velocities. Therefore, water velocity during biofilm growth conditioned the distribution and composition of EPS, as well as its detachment characteristics under higher shear stress.
采用流动腔实验研究了不同流速条件下生物膜中细胞外聚合物（EPS）的分布和组成以及生物膜的脱落机制。生物膜生长动力学的结果表明，生长趋势与逻辑斯谛增长模型一致。在中等流速（IV）条件下，生长动力学参数达到最大值。生物膜的 EPS 组成和分布呈现不同的特征，这取决于生物膜生长的流动条件。在薄生物膜（高速条件 2-HV2）中，总多糖和总蛋白的量通常都大于厚生物膜（IV）中的量。与厚生物膜（IV）中 EPS 的不均匀分布相比，薄生物膜（HV2）中的 EPS 分布更加均匀，并且薄生物膜（HV2）中的结合态 EPS 比厚生物膜（IV）中的多得多。从脱落试验中可以看出，脱落生物量的比例与生长过程中的流速值呈反比关系。在较高流速下生长的生物膜比在较低流速下生长的生物膜具有更强的内聚力。因此，生物膜生长过程中的水流速度影响了 EPS 的分布和组成，以及在较高剪切力下的脱落特性。
