Determination of the water quality correction factor alpha using a tracer gas method

The purpose of this work is to evaluate,. in a bubble column pilot using di fferent wastewaters, the water quality correction factor alpha, defined as the ratio between the volumetric mass transfer coefficient kla(O2) in the w astewater and kla(O2) in clean water. The characteristic of this paper is that the volumetric mass transfer coeff icient kla(O2) is determined using propane as a tracer gas as it is neither produced nor consumed in biological reactors. Three types of water were tested in a bubble column pilot: raw wastewater, the supernatant of mixed liquor from an aeration tank and treated water aft er the secondary settler. The first results show that the alpha factor depe nds on water quality and seems to be linked to organic carbon and surface t ension. The separation of the parameters kl and a allowed us to understand the vari ations of the alpha factor. (C) 1999 Elsevier Science Ltd. All rights reser ved.