title: Species-specific interaction of trihalomethane (THM) precursors in a scaled-up distribution network using response surface methodology (RSM).
abstract: Response surface methodology (RSM) with central composite design (CCD) was used to monitor and optimize species-specific interaction of trihalomethane (THM) precursors in a scaled-up distribution network (DN). Independent variables such as applied chlorine (Cl2), contact time (t), humic acid (HA) and bromide ions (Br-) were analyzed using full factorial CCD. Analysis of variance revealed a good agreement between experimental data and proposed a two-factor interaction model (p = .04, R2= 0.7983). As a precursor, Cl-and Br-interaction with HA affected THMs' speciation. These precursor molecules were perceived least significant as discrete elements but HA: Br-and pH product significantly impacted total trihalomethane (TTHM) formation (r = 0.998, p = .007). This mutual interactive fraction was observed pH-dependent and influenced TTHM yield. Dibromochloromethane and bromoform formation was observed pH-dependent provided sufficient Br-in the system. Applied chlorine had significant (p = .01), while time had insignificant (p = .75) effect. Multiple response optimization suggested pH range between 6.0 and 7.6 and HA: Br-ratio between 1.3 and 5.9 were satisfactory for maintaining TTHM below ≤80 μg/L in DN with 0.88 desirability function (D). Their respective concentration may be minimized by changing precursor's individual concentration and possible combinations.
authors.affiliation: a Department of Civil, Environmental & Geomatic Engineering , University College London , London , UK.|b Institute of Environmental Sciences and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST) , Islamabad , Pakistan.
authors.forename: Sajida
authors.initials: S
authors.lastname: Rasheed
authors.affiliation: b Institute of Environmental Sciences and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST) , Islamabad , Pakistan.
authors.forename: Imran
authors.initials: I
authors.lastname: Hashmi
authors.affiliation: c Department of Civil Engineering , Kyungnam University , Changwon , South Korea.
authors.forename: Jong K
authors.initials: JK
authors.lastname: Kim
authors.affiliation: a Department of Civil, Environmental & Geomatic Engineering , University College London , London , UK.
authors.forename: Qizhi
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: a Department of Civil, Environmental & Geomatic Engineering , University College London , London , UK.
authors.forename: Luiza C
authors.initials: LC
authors.lastname: Campos
mesh_terms: D002712:Chlorides; D002713:Chlorine; D006812:Humic Substances; D008956:Models, Chemical; D022882:Trihalomethanes / Q000032:analysis / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D002712:Chlorides; D006812:Humic Substances; D022882:Trihalomethanes; D014874:Water Pollutants, Chemical; D002713:Chlorine; C015044:bromoform
keywords: Trihalomethanes; chlorine; distribution network; precursors; response surface methodology (RSM)