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

Yuting Shao; Guo-Hua Liu; Yue Wang; Yuankai Zhang; Hongchen Wang; Lu Qi; Xianglong Xu; Jian Wang; Yuanpu He; Qinyu Li; Haitao Fan; Jingbing Zhang

doi:10.1016/j.envint.2020.105973

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

Environ Int. 2020 Oct:143:105973. doi: 10.1016/j.envint.2020.105973. Epub 2020 Jul 29.

Authors

Yuting Shao¹, Guo-Hua Liu², Yue Wang¹, Yuankai Zhang¹, Hongchen Wang³, Lu Qi¹, Xianglong Xu¹, Jian Wang¹, Yuanpu He¹, Qinyu Li¹, Haitao Fan¹, Jingbing Zhang¹

Affiliations

¹ Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing 100872, China.
² Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing 100872, China. Electronic address: lgh@ruc.edu.cn.
³ Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing 100872, China. Electronic address: whc@ruc.edu.cn.

PMID: 32738765
DOI: 10.1016/j.envint.2020.105973

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

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bioreactors
Kinetics
Phosphorus
Sewage*
Waste Disposal, Fluid*

Substances

Sewage
Phosphorus