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邵宇婷等:Sludge characteristics, system performance and microbial kinetics of ultra-short-SRT activated sludge processes

发布时间:2020-06-09

ABSTRACT:

Activated sludge processes with an ultra-short sludge retention time (ultra-short-SRT) are considered to have potential for energy and resource recovery from wastewater. The present study focused on the sludge characteristics, system performance and microbial kinetics in ultra-short-SRT activated sludge (USSAS) processes using typical domestic wastewater (SRT = 0.5, 1, 2, 3 and 4 d). The results showed that compared with the sludge in conventional activated sludge (CAS) processes, the sludge structure in USSAS system was looser (fractal dimension, D2P, 1.19–1.33), the boundary was rougher (pore boundary fractal dimension, DB, 1.44–1.59), the sludge concentration was lower, and the sludge volume index (SVI) was higher; bacteria such as Thiothrix and Trichococcus that cause sludge bulking, which poses an operation risk, were extensively detected, especially at SRTs of 0.5 d and 1.0 d. The performance in terms of total chemical oxygen demand (tCOD) and phosphorus removal increased with increasing SRT, and the highest removal rate (approximately 85% for tCOD and 90% for phosphorus) was observed when the SRT was 4 d. Both bioconversion and biosorption were responsible for the C/P separation, and their roles were different for different types of organic matter and phosphorus under different SRT conditions. The proportion of phosphate-accumulating organisms (PAO) reached 2.4% when the SRT was 3 d, resulting in highly effective biological phosphorus removal. The values of microbial kinetic parameters such as YH and KdH in USSAS systems were higher than those in CAS systems, indicating faster microbial community renewal. This study was helpful for understanding the characteristics of USSAS process.

KEYWORDS: Ultra-short-SRT activated sludge process, Sludge characteristics, System performance, Removal of COD and phosphorus, Microbial kinetics

摘要:

具有超短污泥龄(SRT)的活性污泥工艺被认为具有回收废水中能源和资源潜力的工艺。本实验研究使用典型的生活污水运行的的超短SRTSRT = 0.51234d)活性污泥工艺系统(USSAS)的污泥特性,系统性能和微生物动力学。研究结果表明,与常规活性污泥工艺(CAS)相比,USSAS系统中的污泥:结构更疏松(分形维数D2P1.19–1.33),边界更粗糙(孔边界分形维数,DB1.44–1.59),污泥浓度较低,污泥体积指数(SVI)较高,可以检测到易引起污泥膨胀的细菌,如Thiothrix Trichococcus,这些细菌会造成操作风险,特别是在0.5d1.0dSRT条件下;随着SRT的增加,总化学需氧量(tCOD)和磷的去除性能有所提高,当SRT4d时,观察到最高去除率(tCOD约为85%,磷约为90%)。C/P分离是生物转化和生物吸附共同导致,在不同的SRT条件下,生物转化与吸附所导致C/P分离作用不同;当SRT3 d时,聚磷菌(PAO)的比例达到2.4%,从而实现了高效的生物除磷效应;USSAS系统中的微生物动力学参数(例如YHKdH)值高于CAS系统中的值,意味着更快的微生物群落更替。这项研究有助于理解USSAS系统的特征。

关键词: 超短泥龄活性污泥工艺,污泥特征,系统性能,碳磷分离性能,微生物动力学参数

原载于Environment International2020 Impact Factor = 7.577

原文链接:https://www.sciencedirect.com/science/article/pii/S0160412020319280