UV Irradiation in Turbid Starch Slurries

Ultraviolet light disinfection can be an effective means of controlling microorganisms due to its ease of use, lack of chemical carryover, and decreased chemical hazard concerns. However, particles in industrial process waters can shield microorganisms and reduce the effectiveness of UV treatment. In this study, a modified mixing regime is investigated for its influence on UV disinfection effectiveness in turbid slurries. A new baffle design provides beneficial UV exposure in slurries of high starch solids. The mixing and pulse-like action increase initial disinfection rates. It also inactivates residual bacteria that unmodified treatment does not, in moderate starch loads up to 10% by weight. In all tested cases (up to 20% solids as starch), the static pulse mixer induces one to two log inactivation more than unmodified UV.