Predicting the disinfection efficiency range in chlorine contact tanks through a CFD-based approach

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Computational Fluid Dynamics

Background:

• Current disinfection contact tank (CT) performance assessment relies on Hydraulic Efficiency Indicators (HEIs) from Residence Time Distribution (RTD) curves.
• While CFD models aid RTD prediction for CT assessment, they don't directly optimize disinfection biochemistry.
• Existing methods lack direct integration of disinfection kinetics into the CT design process.

Purpose of the Study:

• To refine modeling practices for simulating disinfection processes within CTs.
• To integrate kinetic models with CFD to optimize CT design beyond HEIs.
• To address uneven contact time by simulating reactive processes and hydrodynamic conditions.

Main Methods:

• Developed three-dimensional computational fluid dynamics (CFD) models with kinetic models.
• Simulated chlorine decay, pathogen inactivation, and by-product formation in CTs.
• Analyzed seven CT design variations using experimental and computational data, then tested with numerical modeling.

Main Results:

• Optimized hydrodynamic conditions led to more uniform disinfectant contact times.
• Improved pathogen inactivation was observed with optimized designs.
• Controlled accumulation of potentially carcinogenic by-products was achieved.

Conclusions:

• Integrating CFD with kinetic models offers a superior approach to CT design.
• Optimizing hydrodynamics is crucial for enhancing disinfection efficiency and safety.
• Advanced modeling can lead to better water treatment outcomes by considering disinfection biochemistry directly.