BIOASSAY COMPARISON OF SIMILAR PILOT- AND FULL-SCALE UV DISINFECTION SYSTEMS

The NWRI/AWWARF Guidelines describe bioassay validation of equipment at a pilot scale (i.e., reactor making use of fewer lamps than applied at the field scale) with maintenance of velocity profiles between the pilot reactor and full-scale reactor being sufficient to allow for the assumption that the full-scale reactor provides an equivalent reduction equivalent dose (RED) to that observed during pilot-validation. In lieu of measuring velocity profiles, the City of Lincoln conducted MS2 bacteriophage bioassays of the full-scale reactor. The purpose of conducting full-scale bioassays were (1) to offer an alternative bioassay-based testing program to the conduct of velocity profiles to allow for scale-up between pilot and full-scale performance, (2) to document compliance of the City of Lincoln UV disinfection system with Criterion (a)(2) of CCR Title 22 §60301.230, and (3) to provide experimental evidence that could either support or counter the suggestions offered by the NWRI/AWWARF Guidelines for scaling from pilot-scale data to full-scale facility design. Testing was conducted on a single channel comprised of five banks making use of WEDECO TAK55HP equipment. Three flowrates were tested at two different wastewater transmittance conditions, corresponding with the treatment capacity associated with operating two, three, and four banks of lamps at a time. For all flowrates and both wastewater transmittance conditions investigated, the full-scale dose always exceeded that predicted from the pilot-scale derived design curve.