title: Microbial community response to chlorine conversion in a chloraminated drinking water distribution system.
abstract: Temporary conversion to chlorine (i.e., "chlorine burn") is a common approach to controlling nitrification in chloraminated drinking water distribution systems, yet its effectiveness and mode(s) of action are not fully understood. This study characterized occurrence of nitrifying populations before, during and after a chlorine burn at 46 sites in a chloraminated distribution system with varying pipe materials and levels of observed nitrification. Quantitative polymerase chain reaction analysis of gene markers present in nitrifying populations indicated higher frequency of detection of ammonia oxidizing bacteria (AOB) (72% of samples) relative to ammonia oxidizing archaea (AOA) (28% of samples). Nitrospira nitrite oxidizing bacteria (NOB) were detected at 45% of samples, while presence of Nitrobacter NOB could not be confirmed at any of the samples. During the chlorine burn, the numbers of AOA, AOB, and Nitrospira greatly reduced (i.e., 0.8-2.4 log). However, rapid and continued regrowth of AOB and Nitrospira were observed along with nitrite production in the bulk water within four months after the chlorine burn, and nitrification outbreaks appeared to worsen 6-12 months later, even after adopting a twice annual burn program. Although high throughput sequencing of 16S rRNA genes revealed a distinct community shift and higher diversity index during the chlorine burn, it steadily returned towards a condition more similar to pre-burn than burn stage. Significant factors associated with nitrifier and microbial community composition included water age and sampling location type, but not pipe material. Overall, these results indicate that there is limited long-term effect of chlorine burns on nitrifying populations and the broader microbial community.
authors.affiliation: Via Department of Civil and Environmental Engineering, Virginia Tech , Blacksburg, Virginia 24061, United States.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Caitlin R
authors.initials: CR
authors.lastname: Proctor
authors.forename: Marc A
authors.initials: MA
authors.lastname: Edwards
authors.forename: Marsha
authors.initials: M
authors.lastname: Pryor
authors.forename: Jorge W
authors.initials: JW
authors.lastname: Santo Domingo
authors.forename: Hodon
authors.initials: H
authors.lastname: Ryu
authors.forename: Anne K
authors.initials: AK
authors.lastname: Camper
authors.forename: Andrew
authors.initials: A
authors.lastname: Olson
authors.forename: Amy
authors.initials: A
authors.lastname: Pruden
mesh_terms: D000641:Ammonia / Q000032:analysis; D001105:Archaea / Q000235:genetics; D020562:Betaproteobacteria / Q000235:genetics; D002700:Chloramines / Q000032:analysis / Q000737:chemistry*; D002713:Chlorine / Q000032:analysis / Q000737:chemistry*; D060766:Drinking Water / Q000382:microbiology* / Q000592:standards; D058465:Nitrification; D009573:Nitrites / Q000032:analysis; D009576:Nitrobacter / Q000235:genetics; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014871:Water Microbiology / Q000592:standards*; D014881:Water Supply / Q000592:standards
chemical_list: D002700:Chloramines; D060766:Drinking Water; D009573:Nitrites; D012336:RNA, Ribosomal, 16S; D002713:Chlorine; D000641:Ammonia