A Hybrid Approach for Increasing Baffling Factors in Contact Tanks

Kattnig, Justin J.; Venayagamoorthy, Subhas K.

doi:10.5942/jawwa.2015.107.0164

Cited by 7 publications

(3 citation statements)

References 18 publications

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“…Although segregated flows are expected to achieve more disinfection than mixed flows, it is not readily apparent how traditional baffling or inlet/outlet modifications could encourage flow segregation. Random packing has recently been proposed as a method to reduce dispersion in water treatment reactors (Barnett, Kattnig, Venayagamoorthy, & Whittaker, ; Kattnig & Venayagamoorthy, ). A similar concept could be applied using structured, tubular packing.…”

Section: Resultsmentioning

confidence: 99%

Assessing flow segregation and mixing by modeling residual disinfectant conversion

2019

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Microbial inactivation and chemical conversion in water treatment reactors depend on the degree of flow segregation and earliness of mixing (i.e., micromixing).However, little is known about micromixing in full-scale water treatment reactors. This study used the seasonal conversion of residual disinfectant between chloramines and free chlorine as reactive tracers to evaluate micromixing in full-scale baffled and unbaffled clearwells. Effluent tracer concentrations were modeled using segregated flow (SF), maximum mixedness (MM), tanks-in-series (TIS), and reactor network (RN) models. Breakpoint reactions were most accurately predicted by the TIS model for both clearwells. The MM model was only accurate in the unbaffled clearwell under steady flow conditions. Segregated flows with different residence times (e.g., SF, some RNs) poorly represented observations. Micromixing was significant in the full-scale reactors studied, and the TIS model most accurately represented observed micromixing. When modeling multiple reactions or nonfirst-order reactions, reactor models should incorporate micromixing.

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Section: Resultsmentioning

confidence: 99%

Assessing flow segregation and mixing by modeling residual disinfectant conversion

2019

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“…In another laboratory-scale study by Kattnig and Venayagamoorthy (2015), RPM was used to create "porous walls" located at the inlet and turns in a baffled tank. Results of this study indicated a 35%-62% improvement in the hydraulic disinfection efficiency in terms of BF (Kattnig, 2014).…”

Section: Introductionmentioning

confidence: 99%

Random packing material in disinfection contactors: Effects on baffling and energy loss

2021

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This study investigates the potential improvement in the hydraulic disinfection efficiency and the possible energy loss as a result of the presence of random packing material (RPM) in a laboratory-scale chlorine contactor. Tracer tests were conducted on a 55-gal drum tank filled with RPM in varying amounts in different configurations to measure the efficiency of each setup in terms of baffling factor (BF). The bulk pressure drop was measured to determine the energy loss for each configuration. The results of this study show that securing RPM near the inlet, in any amount, improves the BF by 300% to more than 900%. The amount of RPM begins to have an impact at or above an inlet jet Reynolds number of $27,700. Also, changes in head loss due to the presence of RPM (in any amount, configuration, and/or flow rate) were generally considered to be negligible.

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“…Computational fluid dynamic (CFD) modeling can be used to simulate clearwell performance during design and has been shown to match tracer studies in some studies (Kattnig & Venayagamoorthy, 2015). CFD modeling can be used as a design tool to predict BE.…”

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confidence: 99%

Baffling efficiency insights gained from tracer studies at 32 Washington treatment plants

et al. 2018

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This article summarizes tracer studies performed at 32 water treatment plants in Washington State ranging from 5 to 5,400 gpm, with contact basins from 200 gal to 1.5 mil gal. Multiple tracer studies were performed at each plant. The goal of the tracer studies was to determine the baffling efficiency (BE) of each basin by determining T10/T, where T10 is the time at which 10% of a tracer is measured at the outlet of a basin, and T is the hydraulic residence time. The tracer studies indicated that most facilities historically used BE values higher than what the tracer studies indicated for calculating compliance with disinfection regulations. The majority of the basins were rectangular, baffled basins. The tracer studies indicated that standard design parameters, such as length‐to‐width ratio, were not as accurate in predicting basin performance compared with calculating baffled channel cross‐sectional velocity. This effect was pronounced where cross‐sectional flow velocity was below the Reynolds laminar flow threshold. For circular, baffled basins, a relationship between cross‐sectional velocity and BE was also evident. The study also identified issues with plants having parallel, chlorine contact basins where uneven flow splitting between basins created an overall system BE less than the BE of individual basins.

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A Hybrid Approach for Increasing Baffling Factors in Contact Tanks

Cited by 7 publications

References 18 publications

Assessing flow segregation and mixing by modeling residual disinfectant conversion

Assessing flow segregation and mixing by modeling residual disinfectant conversion

Random packing material in disinfection contactors: Effects on baffling and energy loss

Baffling efficiency insights gained from tracer studies at 32 Washington treatment plants

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