title: Endotoxin contamination and control in surface water sources and a drinking water treatment plant in Beijing, China.
abstract: In this paper, endotoxin contamination was determined in treated water following each unit of a drinking water treatment plant (WTP) in Beijing, China and its source water (SW) from a long water diversion channel (Shijiazhuang-Beijing) originating from four reservoirs in Hebei province, China. The total-endotoxin activities in SW ranged from 21 to 41 EU/ml at five selected cross sections of the diversion channel. The total-endotoxin in raw water of the WTP ranged from 11 to 16 EU/ml due to dilution and pretreatment during water transportation from Tuancheng Lake to the WTP, and finished water of the WTP ranged from 4 to 10 EU/ml, showing a 49% decrease following the full-scale treatment process at the WTP. Compared with the 31% removal of free-endotoxin, the WTP removed up to 71% of bound-endotoxin in raw water. The traditional treatment processes (coagulation, sedimentation and filtration) in the WTP removed substantial amounts of total-endotoxin (up to 63%), while endotoxin activities increased after granular activated carbon (GAC) adsorption and chlorination. The total-endotoxin in the actual water was composed of free-endotoxin and bound-endotoxin (endotoxin aggregates, bacteria-bound endotoxins and particle-attached endotoxins). The endotoxin aggregates, bacteria-bound endotoxins and particle-attached endotoxins co-exist as suspended particles in water, and only the bacteria-bound endotoxins were correlated with bacterial cells suspended in water. The particle distribution of endotoxin aggregates in ultrapure water was also tested and the results showed that the majority (64-89%) of endotoxin aggregates had diameters <2 μm. The endotoxin contamination and control in treated water following each unit of the WTP processes and its SW from reservoirs are discussed and compared with regard to bacterial cell counts and particle characteristics, which were dependent, to a certain extent, on different flow rates and turbulence of the water environments.
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China. zhangcancqu@163.com
authors.forename: Zhang
authors.initials: Z
authors.lastname: Can
authors.forename: Liu
authors.initials: L
authors.lastname: Wenjun
authors.forename: Sun
authors.initials: S
authors.lastname: Wen
authors.forename: Zhang
authors.initials: Z
authors.lastname: Minglu
authors.forename: Qian
authors.initials: Q
authors.lastname: Lingjia
authors.forename: Li
authors.initials: L
authors.lastname: Cuiping
authors.forename: Tian
authors.initials: T
authors.lastname: Fang
mesh_terms: D000327:Adsorption; D002681:China; D060766:Drinking Water / Q000032:analysis / Q000737:chemistry* / Q000382:microbiology; D004731:Endotoxins / Q000032:analysis*; D005374:Filtration; D005618:Fresh Water / Q000737:chemistry / Q000382:microbiology*; D014876:Water Pollution / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D060766:Drinking Water; D004731:Endotoxins