Guo Jianhua, Peng Yongzhen, Yang Xiong, Wang Zhongwei, Zhu Ao
Key Laboratory of Beijing for Water Quality Science and Water Environmental Recovery Engineering, Beijing Engineering Research Center of Biological Nutrient Removal and Process Control, Beijing University of Technology, Beijing, 100124, China.
Appl Microbiol Biotechnol. 2014 Sep;98(17):7633-44. doi: 10.1007/s00253-014-5805-5. Epub 2014 May 21.
Filamentous bulking is a complicated problem in wastewater treatment plants treating various wastewaters, leading to the deterioration of the settling properties and the effluent quality. This study systematically investigated long-term effects of various carbon sources and feeding patterns on the growth of filamentous bacteria, in order to reveal the mechanism of filamentous bulking. Sludge volume index (SVI), microscopic observations, staining (Gram and Neisser staining), scan electron microscopic, and fluorescent in situ hybridization (FISH) were used to monitor the bulking and track the changes of microbial morphology and community structure of activated sludge in six lab-scale sequencing batch reactors (SBRs) fed with different carbon sources. Filamentous bulking was not observed in all SBRs under anoxic feeding pattern with a short fill time, in which SVI remained below 150 mL/g. In contrast, serious bulking (SVI > 500 mL/g) occurred under aerobic feeding pattern when fed with ethanol, propionate, acetate, and glucose, in which Thiothrix and Sphaerotilus natans proliferated as dominant filaments. Compared to glucose-fed reactor, relatively light bulking was caused in starch-fed reactor with the growth of Nostocoida limicola II. In addition, flocs in starch-fed reactor were more open and fluffy than flocs formed on readily biodegradable substrates. Finally, a framework integrating kinetic selection, diffusion selection, storage selection, and protozoa capture mechanism was proposed to explain filamentous bulking.
丝状膨胀是污水处理厂处理各类废水时面临的一个复杂问题，会导致沉降性能和出水水质恶化。本研究系统地调查了各种碳源和进料方式对丝状菌生长的长期影响，以揭示丝状膨胀的机制。采用污泥体积指数（SVI）、显微镜观察、染色（革兰氏和奈瑟氏染色）、扫描电子显微镜和荧光原位杂交（FISH）等方法，对六个以不同碳源进料的实验室规模序批式反应器（SBR）中活性污泥的膨胀情况进行监测，并追踪微生物形态和群落结构的变化。在填充时间较短的缺氧进料模式下，所有SBR中均未观察到丝状膨胀，此时SVI保持在150 mL/g以下。相比之下，在有氧进料模式下，当以乙醇、丙酸盐、乙酸盐和葡萄糖进料时，会发生严重膨胀（SVI > 500 mL/g），其中硫丝菌属和浮游球衣菌作为优势丝状菌大量繁殖。与以葡萄糖为进料的反应器相比，以淀粉为进料的反应器中，随着纤细颤蚓II型的生长，出现了相对较轻的膨胀。此外，以淀粉为进料的反应器中的絮体比在易生物降解底物上形成的絮体更松散、更蓬松。最后，提出了一个整合动力学选择、扩散选择、储存选择和原生动物捕获机制的框架来解释丝状膨胀。
