Impact of water quality and reactor hydrodynamics on wastewater disinfection by UV, use of CFD modeling for performance optimization

In order to ensure reliable operating conditions for adequate wastewater di sinfection in a UV reactor, two aspects were investigated as having a criti cal impact on the disinfection performances: water quality and hydrodynamic s of the water flow through the system. Tests performed with a collimator o n several wastewater effluents enabled us to relate the UV inactivation to the total suspended solids content of the water to be treated, the influenc e being decisive under 5 mg/l TSS. On the other hand, a CFD (Computational Fluid Dynamics) numerical tool was used to provide an accurate characteriza tion of the flow pattern within a vertical flow reactor. On the basis of su ch modeling, modifications in the geometry of the reactor could be proposed aiming at reducing zones of low dose and therefore improving disinfection performances. Side-by-side experimental comparisons between modified and un modified pilots enabled us to validate that approach. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.