JOURNAL OF ENVIRONMENTAL ENGINEERING, vol.143, no.9, 2017 (SCI-Expanded)
In potable water treatment, the commonly used disinfectants are chlorine and ozone. Recently, the use of ozone has gained more acceptance due to its effective disinfectant properties. However, water treatment with ozone is more expensive because ozone production is an energy-intensive processes. Thus the mechanical mixing efficiency (passive mixing) of the contact system used in this process is critical to reduce the amount of disinfectant used to treat a fixed volume of water. Traditional contact tank designs suffer from poor mixing, short-circuiting, and high energy requirements to drive the flow through the contactor. This study introduces a patented novel baffle design to improve the efficiency of contact tanks. Computational fluid dynamics (CFD)-based analysis indicates that the proposed baffle design improves the mechanical mixing efficiency by 51% and reduces the energy required to drive the flow through the system and short-circuiting by 51 and 57%, respectively. Calculations indicate that the savings offered by this design will be on the order of several hundred thousand dollars per year for medium-sized water treatment plants. The proposed design is simple to implement without expensive infrastructure modifications, and can be used for both chlorine and ozone treatment. (C) 2017 American Society of Civil Engineers.