Lab of Environmental Engineering, Department of Chemistry, University of Science & Technology of China, Hefei 230026, China.
Water Res. 2010 Jul;44(13):3787-96. doi: 10.1016/j.watres.2010.04.035. Epub 2010 May 4.
Activated sludge in a sequencing batch reactor (SBR) is subjected to alternating feast-and-famine conditions, which may result in the enhanced production of microbial products: extracellular polymeric substances (EPS), soluble microbial products (SMP), and internal storage products (X(STO)). In this work, the long-term formation of these three microbial products by activated sludge in an SBR is investigated using an expanded unified model with a parallel experimental study. We also use the model to compare the impacts in an SBR to those in a continuous-flow activated sludge system. The model captures all experimental trends for all components with solids retention time (SRT) for global steady state and within a cycle. At an SRT of 20 days, the active microorganisms constitute about 28% of the mixed liquor volatile suspended solids (MLVSS); the remaining biomass is comprised of residual inert biomass (X(I)) of 40%, EPS of 31%, and X(STO) of approximately 1%. The active biomass becomes a smaller fraction with the increasing SRT, while the inert biomass becomes increasingly dominant. For soluble components, effluent chemical oxygen demand (COD) is dominated by SMP, which varies to some degree in a cycle, peaking as external substrate becomes depleted. Within the SBR cycle, external substrate (S) declines strongly in the first part of the cycle, and SMP shows a small peak at the time of S depletion. X(STO) is the only biomass component that varies significantly during the cycle. It peaks at the time that the input substrate (S) is depleted. Simulation for a continuous-flow activated sludge system and comparison with an SBR reveals that the constant "famine" conditions of the continuous system lead to lower EPS and X(STO), but higher MLVSS and X(I).
在序批式反应器（SBR）中，活性污泥会经历交替的丰食-饥饿条件，这可能导致微生物产物（胞外聚合物物质（EPS）、可溶性微生物产物（SMP）和内部储存产物（X（STO））的产量增加。在这项工作中，使用扩展的统一模型和并行实验研究，研究了活性污泥在 SBR 中的这些三种微生物产物的长期形成情况。我们还使用该模型比较了 SBR 和连续流活性污泥系统中的影响。该模型以固体停留时间（SRT）为全局稳态和周期内的所有组件捕获所有实验趋势。在 SRT 为 20 天时，活性微生物约占混合液挥发性悬浮固体（MLVSS）的 28%；其余生物量由 40%的剩余惰性生物质（X（I））、31%的 EPS 和大约 1%的 X（STO）组成。随着 SRT 的增加，活性生物质的比例变小，而惰性生物质变得越来越占主导地位。对于可溶性成分，出水化学需氧量（COD）主要由 SMP 组成，SMP 在周期内会有一定程度的变化，在外源底物耗尽时达到峰值。在 SBR 周期内，外部底物（S）在周期的前半部分急剧下降，而在 S 耗尽时 SMP 出现小峰值。X（STO）是周期内唯一变化显著的生物质成分。它在输入底物（S）耗尽时达到峰值。对连续流活性污泥系统的模拟以及与 SBR 的比较表明，连续系统恒定的“饥饿”条件导致 EPS 和 X（STO）降低，但 MLVSS 和 X（I）升高。
