Removal of organic micropollutantns from wastewater in a Swedish context
Abstract: Due to their potential environmental risk, the abatement of organic micropollutants from wastewater has gained increasing attention in recent years. This thesis evaluates the use of ozone in Swedish wastewater treatment plants (WWTPs) and the incentives for full-scale implementation of organic micropollutant removal.This work is divided into two sections: the first segment comprises quantitative research of the removal of organic micropollutants using ozone, and the second discusses a qualitative study on the drivers of full-scale implementation of quaternary treatment in Swedish WWTPs.Ozone oxidation of organic micropollutants was examined in Sweden, taking country-specific conditions into consideration. This technology was implemented on a pilot scale on site at a total of 14 WWTPs, and its influence on the removal rates of organic micropollutants was determined by ozone dose, hydraulic retention time (HRT), water temperature, pH, concentration of organic matter, and prior treatment level (high- or low-loaded activated sludge and post-precipitation).The results from the first section demonstrate that ozonation is a suitable technology for Swedish conditions. In general, a slightly higher ozone dose was needed, compared with reported values, and a shorter HRT (7 min) can be applied without altering the removal efficiency. Nitrogen removal was not a prerequisite for efficient removal of organic micropollutants, and the evaluation of ozone dose was similar, whether based on dissolved organic carbon (DOC) or chemical oxygen demand (COD).The second section indicates that two of the most prominent drivers were proactivity with regard to possible treatment requirements and the desire to protect receiving waters. There were also aspirations to increase general knowledge of organic micropollutants and the role of WWTPs in the release of these into the environment.
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