Assessing flow segregation and mixing by modeling residual disinfectant conversion
Abstract
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 01, 2019
- Source ID
- 10.1002/aws2.1154
Entities
People
- Alexander S. Gorzalski
- Gregory W Harrington
- Orlando Coronell
Organizations
- United States Army Corps of Engineers
- United States Department of Defense
- University of North Carolina at Chapel Hill
- University of Wisconsin–Madison