BIOASSAY FOR FULL-SCALE UV DISINFECTION SYSTEMS

A new bioassay technique for ultraviolet (UV) disinfection is presented which permits application to full-scale systems. The technique involves comparison of batch dose-response behavior and full-scale, continuous-flow disinfection efficacy using indigenous indicator organisms present in secondary or tertiary wastewater effluent. This approach allows the bioassay to be applied to UV systems of all sizes, thereby eliminating the need for extrapolation of pilot-scale bioassays to full-scale systems. By comparing the results of the bioassay with dose estimates from numerical modelling, a semi-quantitative assessment of full-scale system hydrodynamic efficiency is developed relative to two idealized reactor models. This approach has merit in terms of evaluating full-scale disinfection system design and identification of hydrodynamic shortcomings.