Series‐Event Kinetic Model for Chemical Disinfection

Severin, Blaine F.; Suidan, Makram T.; Engelbrecht, Richard S.

doi:10.1061/(asce)0733-9372(1984)110:2(430)

Cited by 42 publications

(33 citation statements)

References 3 publications

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“…There is a substantial literature base establishing the delayed Chick-Watson model as an appropriate model for disinfection data with an apparent lag phase (e.g., see references 8, 11, 24, 40-42, and 47). Other disinfection models account for lag (e.g., the Hom-Hass model [13][14][15] and the series-event model [44]), but selection of the delayed Chick-Watson model allowed the initial lag phase to be accounted for with a lag coefficient (b) that is consistent with the concentration-time (Ct) concept of disinfection, providing a physical meaning for b (i.e., the Ct required to overcome the initial lag phase during disinfection). In addition, the Ct concept is used by the USEPA to regulate water disinfection (10); therefore, in this research, it was desired to use a model consistent with the Ct concept.…”

Section: Resultsmentioning

confidence: 99%

Monochloramine Disinfection Kinetics of Nitrosomonas europaea by Propidium Monoazide Quantitative PCR and Live/Dead BacLight Methods

Wahman

Wulfeck-Kleier

Pressman

2009

Appl Environ Microbiol

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Monochloramine disinfection kinetics were determined for the pure-culture ammonia-oxidizing bacterium Nitrosomonas europaea (ATCC 19718) by two culture-independent methods, namely, Live/Dead BacLight (LD) and propidium monoazide quantitative PCR (PMA-qPCR). Both methods were first verified with mixtures of heat-killed (nonviable) and non-heat-killed (viable) cells before a series of batch disinfection experiments with stationary-phase cultures (batch grown for 7 days) at pH 8.0, 25°C, and 5, 10, and 20 mg Cl 2 /liter monochloramine. Two data sets were generated based on the viability method used, either (i) LD or (ii) PMA-qPCR. These two data sets were used to estimate kinetic parameters for the delayed Chick-Watson disinfection model through a Bayesian analysis implemented in WinBUGS. This analysis provided parameter estimates of 490 mg Cl 2 -min/liter for the lag coefficient (b) and 1.6 ؋ 10 ؊3 to 4.0 ؋ 10 ؊3 liter/mg Cl 2 -min for the Chick-Watson disinfection rate constant (k). While estimates of b were similar for both data sets, the LD data set resulted in a greater k estimate than that obtained with the PMA-qPCR data set, implying that the PMA-qPCR viability measure was more conservative than LD. For N. europaea, the lag phase was not previously reported for culture-independent methods and may have implications for nitrification in drinking water distribution systems. This is the first published application of a PMA-qPCR method for disinfection kinetic model parameter estimation as well as its application to N. europaea or monochloramine. Ultimately, this PMA-qPCR method will allow evaluation of monochloramine disinfection kinetics for mixed-culture bacteria in drinking water distribution systems.As a result of stage 1 and stage 2 disinfectant and disinfection by-product rules, chloramination for secondary disinfection in the United States is predicted to increase to 57% of all surface and 7% of all groundwater treatment systems (49). A recent survey reported that 30% of the respondents currently chloraminate to maintain distribution system residual, and other recent surveys suggest that between 8 and 12% of drinking water utilities are contemplating a future switch to chloramination (3, 43).Although chloramines are considered weaker disinfectants than chlorine for suspended bacteria, chloramines are perceived as more effective disinfectants for a biofilm (25, 53). As a result of their lower reactivity, chloramines are believed to penetrate a biofilm further and thereby to more effectively disinfect biofilm bacteria with depth than chlorine (53).Chloramination comes with the risk of distribution system nitrification (2, 21, 22). Based on utility surveys, 30 to 63% of utilities practicing chloramination for secondary disinfection experience nitrification episodes (3,21,43,54). Nitrification in drinking water distribution systems is undesirable and may result in water quality degradation (e.g., disinfectant depletion, coliform occurrences, or nitrite/nitrate formation) and subsequent noncompliance with exis...

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Section: Resultsmentioning

confidence: 99%

Monochloramine Disinfection Kinetics of Nitrosomonas europaea by Propidium Monoazide Quantitative PCR and Live/Dead BacLight Methods

Wahman

Wulfeck-Kleier

Pressman

2009

Appl Environ Microbiol

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“…In the first phase of this treatment a delay in the inactivation of E. coli was observed. This kinetic phase is known as shoulder and can be attributed to the need of bacteria to absorb a threshold UV dose to begin producing severe damages that cause its inactivation (Severin et al, 1984). The shoulder and the lower inactivation rate may be due to the decrease in the transmittance of light in water with high salt concentration.…”

Section: E Coli Inactivation In Artificial Seawatermentioning

confidence: 99%

Comparative effect of simulated solar light, UV, UV/H2O2 and photo-Fenton treatment (UV–Vis/H2O2/Fe2+,3+) in the Escherichia coli inactivation in artificial seawater

et al. 2013

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Fe 2þ and 10 mg L À1 of H 2 O 2 , led to the fastest bacterial inactivation kinetics. Using H 2 O 2 / UV 254 high disinfection rates were obtained similar to those obtained with photo-Fenton under UV 254 light. In Milli-Q water, the rate of inactivation for Escherichia coli was higher than in Leman Lake water and seawater due to the lack of inorganic ions affecting negatively bacteria inactivation. The presence of bicarbonate showed scavenging of the OH radicals generated in the treatment of photo-Fenton and H 2 O 2 /UV 254 . Despite the negative effect of inorganic ions, especially HCO 3 -, the disinfection treatments with AOPs in lake water and seawater improved significantly the disinfection compared to light alone (simulated sunlight and UV 254 ). In the treatment of photo-Fenton with simulated sunlight, dissolved organic matter had a beneficial effect by increasing the rate of inactivation. This is associated with the formation of Fe 3þ -organo photosensitive complexes leading to the formation of ROS able to inactivate bacteria. This effect was not observed in the photo-

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“…Fitting an RTD model to the data rather than calculating the mean and variance from the raw data is done for two reasons. The first is so that a variable from the RTD model can be applied to another model, for example, in the case of the TISM, the number of tanks that characterize the RTD can be applied to the disinfection model by Severin et al [20]. The second is that the long 'tails' on observed distributions make it difficult to calculate a meaningful value of the variance [12].…”

Section: Resultsmentioning

confidence: 99%

“…This confirms that experimental RTDs were recorded for a sufficient period of time in order to determine the appropriate parameters. Referring to Egarr et al [1] where the disinfection model by Severin et al [20] utilizes the number of tanks from the TISM, this article highlights that there may be a desire to develop the existing disinfection model for improved disinfection predictions using the ADM rather than the TISM. A possible improvement to the disinfection model could simply be a substitution of the inverse of the normalized variance, from equation (8), for the number of tanks, predicted using the ADM model.…”

Section: Discussionmentioning

confidence: 99%

Assessment of residence time in a hydrodynamic vortex separator by applying distribution models

O'Doherty

Egarr

Faram³

et al. 2009

Proceedings of the Institution of Mechanical Engineers, Part E:

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A number of models exist to simulate the residence time distribution (RTD) of a system or process. Four of these models known as the tanks in series model, axial dispersion model (ADM), aggregated dead zone model, and the advection dispersion equation, have been used to assess which is most suitable for representing the RTD of a hydrodynamic vortex separator (HDVS) when compared to RTD measurements taken under laboratory conditions on a full-scale 3.4 m diameter unit. Computational fluid dynamics (CFD) is also used to model the HDVS and compare with the RTD models and experimental measurements. It has been shown that the fit by each of the RTD models to observed RTDs vary quite considerably, with the ADM being the most appropriate for the HDVS studied, based on having the highest R 2 t value. Given the number of model variables that influence CFD predictions, the outputs from the CFD models appear to be reasonable.

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Series‐Event Kinetic Model for Chemical Disinfection

Cited by 42 publications

References 3 publications

Monochloramine Disinfection Kinetics of Nitrosomonas europaea by Propidium Monoazide Quantitative PCR and Live/Dead BacLight Methods

Monochloramine Disinfection Kinetics of Nitrosomonas europaea by Propidium Monoazide Quantitative PCR and Live/Dead BacLight Methods

Comparative effect of simulated solar light, UV, UV/H2O2 and photo-Fenton treatment (UV–Vis/H2O2/Fe2+,3+) in the Escherichia coli inactivation in artificial seawater

Assessment of residence time in a hydrodynamic vortex separator by applying distribution models

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