Weissbrodt David G, Lochmatter Samuel, Ebrahimi Sirous, Rossi Pierre, Maillard Julien, Holliger Christof
Laboratory for Environmental Biotechnology, School for Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne Lausanne, Switzerland.
Front Microbiol. 2012 Sep 13;3:332. doi: 10.3389/fmicb.2012.00332. eCollection 2012.
Aerobic granular sludge is attractive for high-rate biological wastewater treatment. Biomass wash-out conditions stimulate the formation of aerobic granules. Deteriorated performances in biomass settling and nutrient removal during start-up have however often been reported. The effect of wash-out dynamics was investigated on bacterial selection, biomass settling behavior, and metabolic activities during the formation of early-stage granules from activated sludge of two wastewater treatment plants (WWTP) over start-up periods of maximum 60 days. Five bubble-column sequencing batch reactors were operated with feast-famine regimes consisting of rapid pulse or slow anaerobic feeding followed by aerobic starvation. Slow-settling fluffy granules were formed when an insufficient superficial air velocity (SAV; 1.8 cm s(-1)) was applied, when the inoculation sludge was taken from a WWTP removing organic matter only, or when reactors were operated at 30°C. Fast-settling dense granules were obtained with 4.0 cm s(-1) SAV, or when the inoculation sludge was taken from a WWTP removing all nutrients biologically. However, only carbon was aerobically removed during start-up. Fluffy granules and dense granules were displaying distinct predominant phylotypes, namely filamentous Burkholderiales affiliates and Zoogloea relatives, respectively. The latter were predominant in dense granules independently from the feeding regime. A combination of insufficient solid retention time and of leakage of acetate into the aeration phase during intensive biomass wash-out was the cause for the proliferation of Zoogloea spp. in dense granules, and for the deterioration of BNR performances. It is however not certain that Zoogloea-like organisms are essential in granule formation. Optimal operation conditions should be elucidated for maintaining a balance between organisms with granulation propensity and nutrient removing organisms in order to form granules with BNR activities in short start-up periods.
好氧颗粒污泥对于高速生物废水处理具有吸引力。生物量洗出条件会刺激好氧颗粒的形成。然而，在启动过程中，生物量沉降和养分去除性能恶化的情况经常被报道。研究了在最多60天的启动期内，两个污水处理厂（WWTP）的活性污泥形成早期颗粒过程中，洗出动力学对细菌选择、生物量沉降行为和代谢活性的影响。五个气泡柱序批式反应器采用 feast-famine 模式运行，包括快速脉冲或缓慢厌氧进料，随后是好氧饥饿。当应用的表观气速（SAV；1.8 cm s(-1)）不足、接种污泥取自仅去除有机物的污水处理厂或反应器在30°C运行时，会形成沉降缓慢的蓬松颗粒。当SAV为4.0 cm s(-1)，或接种污泥取自生物去除所有养分的污水处理厂时，可获得沉降快速的密实颗粒。然而，在启动过程中仅好氧去除了碳。蓬松颗粒和密实颗粒分别显示出不同的优势系统发育型，即丝状伯克霍尔德氏菌属附属菌和动胶菌属相关菌。无论进料方式如何，后者在密实颗粒中占主导地位。在大量生物量洗出期间，固体停留时间不足和乙酸盐泄漏到曝气阶段的组合是动胶菌属在密实颗粒中增殖以及生物脱氮性能恶化的原因。然而，尚不确定类动胶菌属生物在颗粒形成中是否必不可少。应阐明最佳运行条件，以维持具有造粒倾向的生物体和养分去除生物体之间的平衡，以便在短启动期内形成具有生物脱氮活性的颗粒。
