Bacterial removal performance and community changes during advanced treatment process: A case study at a full-scale water reclamation plant

Abstract

Advanced treatment is of great significance to water reclamation and reuse, which can improve water quality, control microbial risks and guarantee the safety of water reuse. This study evaluates the microbial quantity and bacterial community dynamics during advanced wastewater treatment and reuse processes (i.e. denitrification biofilter (DNBF), ultrafiltration (UF), ozonation, ultraviolet (UV) disinfection) at a large-scale water reclamation plant. It is found that different treatment processes had significant influence on the cultivability of total bacteria and the log reduction values of fecal coliform at DNBF, UF, ozonation and UV are calculated as 0.38, 2.46, 0.38 and 1.63 respectively. Moreover, the bacterial diversity in the treatment process showed apparent spatial differences, among which the effluent from ozonation process had the lowest bacterial diversity. Sequencing analysis indicated the existence of pathogenic bacterium such as Arcobacter, Bacteroides and Pseudomonas in the secondary effluent. Notably, Pseudomonas remained the most dominant species (relative abundance 41.9% in UV effluent) in reclaimed water after advanced treatment processes, which calls for high attention to sustainable water reuse. In order to inhibit bacterial regrowth in the storage tank, chlorine disinfection is recommended to improve the continuous disinfection capability of the system.