title: Using coagulation to restrict microbial re-growth in tap water by phosphate limitation in water treatment.
abstract: Extensive microbial re-growth in a drinking water distribution system can deteriorate water quality. The limiting factor for microbial re-growth in a tap water produced by a conventional drinking water treatment plant in China was identified by determining the microbial re-growth potential (MRP) by adding different nutrients to stimulate growth of a natural microbial consortium as inoculum and flow-cytometric enumeration. No obvious change of MRP was found in tap water after addition of carbon, whereas, a 1- to 2-fold increase of MRP was observed after addition of phosphate (P). This clearly demonstrated that microbial re-growth in this tap water was limited by P. Most of the re-grown microbial flora (>85%) consisted of high nucleic acid content cells. A subsequent investigation of the MRP in the actual water treatment plant demonstrated that coagulation was the crucial step for decreasing MRP and producing P-limited water. Therefore, a comparison concerning the control of MRP by three different coagulants was conducted. It showed that all the three coagulants efficiently reduced the MRP and shifted the limitation regime from C to P, but the required dose was different. The study shows that it is feasible to restrict microbial re-growth by P limitation using coagulation in water treatment.
authors.affiliation: School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China.
authors.forename: Gang
authors.initials: G
authors.lastname: Wen
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China. Electronic address: majun@hit.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.affiliation: School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China.
authors.forename: Ting-Lin
authors.initials: TL
authors.lastname: Huang
authors.affiliation: Eawag, Swiss Federal Institute for Aquatic Science and Technology, Department of Environmental Microbiology, P.O. Box 611, Überlandstrasse 133, CH-8600 Dübendorf, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Egli
mesh_terms: D000534:Alum Compounds; D000536:Aluminum Hydroxide; D002712:Chlorides; D060766:Drinking Water / Q000382:microbiology*; D005290:Ferric Compounds; D005434:Flow Cytometry; D010710:Phosphates; D010758:Phosphorus / Q000032:analysis; D014871:Water Microbiology; D018508:Water Purification; D060753:Water Quality
chemical_list: D000534:Alum Compounds; D002712:Chlorides; D060766:Drinking Water; D005290:Ferric Compounds; D010710:Phosphates; C016213:aluminum oxychloride; D010758:Phosphorus; C041524:aluminum sulfate; D000536:Aluminum Hydroxide; C024555:ferric chloride
keywords: Coagulation; Flow cytometry; Microbial re-growth; Phosphate limitation