Yin Qidong, Sun Yuepeng, Li Bo, Feng Zhaolu, Wu Guangxue
College of Science and Engineering, National University of Ireland, Galway, Galway H91 TK33, Ireland; Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, Guangdong, China.
Department of Civil and Environmental Engineering, Virginia Tech, Ashburn, VA 20147, United States.
Sci Total Environ. 2022 Jun 10;824:153836. doi: 10.1016/j.scitotenv.2022.153836. Epub 2022 Feb 14.
Understanding the characteristics of functional organisms is the key to managing and updating biological processes for wastewater treatment. This review, for the first time, systematically characterized two typical types of strategists in wastewater treatment ecosystems via the r/K selection theory and provided novel strategies for selectively enriching microbial community. Functional organisms involved in nitrification (e.g., Nitrosomonas and Nitrosococcus), anammox (Candidatus Brocadia), and methanogenesis (Methanosarcinaceae) are identified as r-strategists with fast growth capacities and low substrate affinities. These r-strategists can achieve high pollutant removal loading rates. On the other hand, other organisms such as Nitrosospira spp., Candidatus Kuenenia, and Methanosaetaceae, are characterized as K-strategists with slow growth rates but high substrate affinities, which can decrease the pollutant concentration to low levels. More importantly, K-strategists may play crucial roles in the biodegradation of recalcitrant organic pollutants. The food-to-microorganism ratio, mass transfer, cell size, and biomass morphology are the key factors determining the selection of r-/K-strategists. These factors can be related with operating parameters (e.g., solids and hydraulic retention time), biomass morphology (biofilm or granules), and operating modes (continuous-flow or sequencing batch), etc., to achieve the efficient acclimation of targeted r-/K-strategists. For practical applications, the concept of substrate flux was put forward to further benefit the selective enrichment of r-/K-strategists, fulfilling effective management and improvement of engineered pollution control bioprocesses. Finally, the future perspectives regarding the development of the r/K selection theory in wastewater treatment processes were discussed.
了解功能微生物的特性是管理和更新污水处理生物过程的关键。本综述首次通过r/K选择理论系统地描述了污水处理生态系统中两种典型类型的策略者，并提供了选择性富集微生物群落的新策略。参与硝化作用（如亚硝化单胞菌属和亚硝化球菌属）、厌氧氨氧化（“Candidatus Brocadia”）和产甲烷作用（甲烷八叠球菌科）的功能微生物被鉴定为具有快速生长能力和低底物亲和力的r策略者。这些r策略者能够实现高污染物去除负荷率。另一方面，其他微生物如亚硝化螺菌属、“Candidatus Kuenenia”和甲烷鬃菌科则被描述为具有缓慢生长速率但高底物亲和力的K策略者，它们能够将污染物浓度降低到低水平。更重要的是，K策略者可能在难降解有机污染物的生物降解中发挥关键作用。食物与微生物比、传质、细胞大小和生物质形态是决定r/K策略者选择的关键因素。这些因素可与操作参数（如固体和水力停留时间）、生物质形态（生物膜或颗粒）和操作模式（连续流或序批式）等相关联，以实现目标r/K策略者的高效驯化。对于实际应用，提出了底物通量的概念，以进一步促进r/K策略者的选择性富集，实现对工程污染控制生物过程的有效管理和改进。最后，讨论了r/K选择理论在污水处理过程中发展的未来前景。
