Resolving UV Hydraulic Issues During Facility Start-Up

Hydraulics are a key factor in the design and performance of UV disinfection systems. While hydraulic issues are best resolved during design, UV disinfection system hydraulics problems often become apparent during facility start-up. This paper discusses two case studies of UV disinfection system start-up hydraulic issues, how the issues were identified, and how they were resolved. Case Study 1 focuses on system inlet hydraulics, specifically hydraulic short-circuiting caused by 90-degree bends immediately prior to the UV reactors. A three-dimensional flow diffuser was developed which resulted in substantial improvement in inlet hydraulics, which was not achieved using baffle plates commonly used for flow conditioning. Case Study 2 focuses on system outlet hydraulics, specifically short-circuiting due to uneven flow split between channels. Improvements in weir gate controls were implemented to improve flow split between channels, while the limitations of such improvements were also apparent.