Kinetic Study and Scaleup of the Oxidation of Nanofiltration Retentates by O₃

This paper reports on the upscaling of an O₃ reactor for the oxidation of natural organic matter. Natural organic matter is responsible for fouling of nanofiltration membranes used for drinking water production. The proposed concept is to feed the retentate stream of a nanofiltration module (400 m³ h^–1) to an O₃ reactor (bubble column) and subsequently recycle it to a second nanofiltration module. The O₃ oxidation of the retentate stream in the bubble column is analyzed in terms of the two-film theory with mass transfer and chemical reaction. The kinetic regime of the ozonation process, i.e., the chemical reaction rate relative to the mass-transfer rate, is determined using data from laboratory-scale experiments. This information is used for the calculation of the reactor volume and the required O₃ dose on an industrial scale. An economic assessment of the integrated nanofiltration–O₃ oxidation process also is given