Species-specific interaction of trihalomethane (THM) precursors in a scaled-up distribution network using response surface methodology (RSM). Issue 3 (1st February 2018)

• Record Type: Journal Article
• Authors: Rasheed, Sajida; Hashmi, Imran; Kim, Jong. K.; Zhou, Qizhi; Campos, Luiza C.
• Is Part Of: Environmental technology. Volume 39:Issue 3(2018)
• Page Start: 346
• Page End: 355
• Publication Date: 2018-02-01
• Subjects: Trihalomethanes -- distribution network -- precursors -- chlorine -- response surface methodology (RSM); Environmental engineering -- Periodicals; Environmental protection -- Periodicals; 628.05
• DOI: 10.1080/09593330.2017.1301564
• Languages: English
• ISSNs: 0959-3330

Abstract

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, R 2 = 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.