title: Electrochemical disinfection of Escherichia coli in the presence and absence of primary sludge particulates.
abstract: Electrochemical (EC) residual disinfection of Escherichia coli (E. coli) in the presence and absence of primary sludge particulates (PSPs) was studied. The kinetics followed a first-order rate law. When PSPs were absent, the EC residual disinfection rate coefficient (k) increased linearly with EC pretreatment energy (EC, 0-0.63 kWh/m(3)). However, with 143 mg PSPs/L, k first increased linearly with EC (0-0.28 kWh/m(3)) and then decreased linearly with EC (0.28-0.42 kWh/m(3)). H2O2 was detected during EC pretreatment in PSPs-free samples and the H2O2 concentration (CH) increased with EC (0-0.83 kWh/m(3)) linearly. Chloride was detected in PSPs aqueous samples (143 mg PSPs/L) and its concentration (CC) changed during EC pretreatment: initially, a decrease of CC was observed when EC increased from 0 to 0.28 kWh/m(3), followed by an increase of CC when EC increased 0.28-0.42 kWh/m(3). In both cases, k correlated to the initial post-EC chloride concentration (CCI) in an inverse linear relationship. This two-stage change of CC and k was caused by a combination of two reactions: anodic oxidation of chloride and the reaction of chloramines with excess chlorine. This paper explains the mechanisms underlying EC residual disinfection in the presence and absence of PSPs, and proposes a feasible strategy for EC disinfection when PSPs are present, an approach that could be useful in the treatment of combined sewage overflow (CSO).
authors.affiliation: Department of Civil and Environmental Engineering, Southern Methodist University, Room 203, 3101 Dyer Street, Dallas, TX 75205, USA.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Cui
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Quicksall
authors.forename: Allison B
authors.initials: AB
authors.lastname: Blake
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Talley
mesh_terms: D002712:Chlorides / Q000032:analysis; D004203:Disinfection / Q000379:methods*; D004563:Electrochemistry / Q000379:methods*; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification*; D006861:Hydrogen Peroxide / Q000032:analysis; D007700:Kinetics; D052638:Particulate Matter / Q000494:pharmacology*; D012722:Sewage / Q000382:microbiology*; D013997:Time Factors; D018508:Water Purification
chemical_list: D002712:Chlorides; D052638:Particulate Matter; D012722:Sewage; D006861:Hydrogen Peroxide
keywords: Combined sewage overflow (CSO); Electrochemical residual disinfection; Primary sludge particulates (PSPs)