城市污水处理厂活性污泥生物泡沫研究进展

Research progress towards biological foaming of activated sludge in municipal wastewater treatment plants

摘要:

城市污水处理厂运行过程中一旦发生活性污泥生物泡沫，就会影响污泥沉降和处理厂运行效能，对出水水质、作业安全和公共健康带来一系列挑战。生物泡沫是自活性污泥法诞生以来长期困扰污水处理厂运行的难题。生物泡沫的形成需要气泡、表面活性物质和疏水物质等3点基本的要素，在其中主要富集了诺卡氏型丝状细菌(Nocardioform filamentous bacteria)和微丝菌(Candidatus Microthrix parvicella)这两种类型微生物。多种环境和运行因素包括温度、溶解氧、pH、污泥龄、特别是营养物质种类和浓度等均会对这些丝状微生物的生长产生影响。抑制丝状细菌生长的常用控制策略包括选择器、生长动力学控制、投加化学药剂以及噬菌体等方法，通过降低两类丝状细菌在生化池中的浓度以期消除生物泡沫现象。本文总结了生物泡沫的类型、成因、表征生物泡沫程度的指标、影响生物泡沫的环境因素以及常用的调控策略的原理及优缺点等，尽可能全面地介绍活性污泥生物泡沫的研究现状，并探讨未来研究方向和控制策略，期望能够为今后研究活性污泥微生物和污水处理厂运行调控提供有价值的参考。

关键词:城市污水处理厂，活性污泥，生物泡沫，诺卡氏型丝状细菌，微丝菌

Abstract:

Biological foaming is one of the most significant problems influencing the activated sludge settlement which determines the long-term stability of waste water treatment plant (WWTP) operation. Biological foaming gives rise to challenges to effluent water quality, work safety and public health. The formation of biological foaming requires three basic elements: air bubbles, surfactants and hydrophobic substances. Usually, Norcardioform filamentous bacteria and Candidatus Microthrix parvicella are enriched in the foam. A variety of environmental factors, including temperature, dissolved oxygen, pH, sludge retention time and especially nutrients type and concentration, have impacts on the growth of these bacteria. According to it, the paper also introduces the current strategies for controlling the growth of the two types of filamentous bacteria, including selectors, kinetics-based growth control, chemical addition and ecological methods, such as, phages to reduce filamentous bacteria concentration in mixed liquid, in order to alleviate biological foaming. This paper discusses, in detail, the causes and types of biological foaming, indexes representing foaming severity, environmental factors affecting the foaming, and advantages and disadvantages of commonly used control strategies, so as to introduce biological foaming problem of activated sludge as comprehensively as possible and provide helpful information for future research.

Key words:Wastewater treatment plants, Activated sludge, Biological foaming, Nocardioform filamentous bacteria, Candidatus Microthrix parvicella