Modeling and kinetic characterization of wastewater disinfection using chlorine and UV irradiation

Abstract

Sewage disinfection has the primary objective of inactivating pathogenic organisms to prevent the dissemination of waterborne diseases. This study analyzed individual disinfection, with chlorine alone, ultraviolet radiation alone, and a combined disinfection process (chlorine-UV radiation). Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC 11229, Salmonella typhi ATCC 14028, and Clostridium perfringens were selected to evaluate the efficiency of different disinfection processes. The aim of the present study was to characterize the kinetics of chlorine (as NaHOCl) consumption, to evaluate responses of these bacterial species to the chlorination, the ultraviolet (UV) radiation, and the chlorine/UV disinfection processes in secondary wastewater using a batch laboratory reactor. Another target of this work was to study the modeling of the kinetic of water disinfection by chlorination and/or UV irradiation. Two kinetic models (Chick-Watson and Hom) were tested as to ability to scale disinfection of these bacterial species by different ultraviolet and/or chlorine doses. The results of the kinetics of chlorine consumption showed that monochloramines and trichloramines were the most important forms of residual chlorine as compared to free chlorine and dichloramines. The kinetics of inactivation of all examined bacterial strains showed that the application of the model of Hom in its original form was not representative of this kinetics of inactivation. Modification of this model, considering an initial decline of bacteria during the contact of water with chlorine, improved the results of the model. By the same, results revealed that the involved processes of UV irradiation were too complex to be approached by a simplified formulation, even in the case of specific strains of microorganisms and the use of nearly constant UV radiation intensity. In fact, the results have pointed out that the application of the Chick-Watson law is known to be inadequate to describe microbial inactivation with tailing or shoulder behavior. However, the UV kinetic studies also revealed that the first instants of exposure (2 to 10 s) to a UV intensity of 5 to 8 mW.cm-2 appeared as the deciding factors in disinfection with UV irradiation. It was shown that the combination of chlorine with UV yielded additive effects on the inactivation of bacterial strains and spectacular disinfection efficiency at a short contact time and less dose. In contrast to most studies, UV irradiation alone and chlorine alone exhibited low disinfection efficiency in inactivation of tested bacterial strains.

Chlorine Tolerance and Inactivation of Escherichia coli recovered from Wastewater Treatment Plants in the Eastern Cape, South Africa

“…Values obtained for disinfection exponent n ranged between 1.57 and 22.43 while time exponent m had values of −0.23-0.17. For inactivation reactions with coefficient n greater than 1, the chlorine dose has a greater influence on bacterial inactivation than contact time [60]. These results suggest a greater impact of chlorine dose of 1.5 mg/L on bacterial inactivation than the effect of exposure time.…”

Ultraviolet Disinfection Pilot Study at the Fargo Wastewater Treatment Plant

“…As mentioned in Chapter 2, first-order models have been widely used in previous studies to describe microbial response to UV light (Mounaouer & Abdennaceur, 2016;Jolis et al, 2001;Severin et al, 1984).…”

Modeling the dynamic kinetics of microbial disinfection with dissipating chemical agents—a theoretical investigation

“…The most commonly employed models have been the original and variants of the Chick-Watson and Hom’s model (Chick 1908 ; Watson 1908 ; Hom 1972 ). These models’ mathematical properties and application to disinfectants, such as chlorine, chlorine dioxide, ozone, hydrogen peroxide, paracetic acid, copper, and ethanol, have been described and discussed in numerous publications, e.g., Armstrong et al ( 2017 ), Chang et al ( 2018 ), Chong et al ( 2011 ), Falsanisi et al ( 2006 ), Ganguly et al ( 2018 ), Gyurek and Finch ( 1998 ), Haas and Joffe ( 1994 ), Haas and Kara ( 1984 ), Ibarguen-Mondragon et al ( 2020 ), Jessen et al ( 2008 ), John et al ( 2005 ), Kampf ( 2018 ), Lambert and Johnston ( 2000 ), Luukkonen et al ( 2015 ), Mounaouer and Abdennaceur ( 2016 ), Rattanakul et al ( 2015 ), Rossi et al ( 2007 ), and Schijven et al ( 2019 ).…”