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, D_2P, 1.19–1.33), the boundary was rougher (pore boundary fractal dimension, D_B, 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 Y_H and K_dH 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SRT（SRT = 0.5、1、2、3和4d）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D_2P，1.19–1.33），边界更粗糙（孔边界分形维数，D_B，1.44–1.59），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 和Trichococcus，这些细菌会造成操作风险，特别是在0.5d和1.0d的SRT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SRT为4d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SRT为3 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Y_H和K_dH）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 International（2020 Impact Factor = 7.577）

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