Integrating dissolved and particulate matter into a prediction tool for ozonation of organic micropollutants in wastewater

Ozonation is an established technique used to reduce the discharge of organic micropollutants into the aquatic environment, but the possibility of predicting the ozone demand for different wastewater matrices is still limited, especially in the presence of suspended solids (SS). A new tool for the prediction of the removal of organic micropollutants with ozone, based on dissolved and particulate matter in activated sludge effluents, was therefore developed. The removal of 25 organic micropollutants was determined on laboratory scale in the presence and absence of suspended solids. The linear trajectories of the dose–response curves enabled the determination of a new set of removal constants, based on dissolved chemical oxygen demand (COD) and SS. The presence of SS had a more negative effect on the removal of slow-reacting micropollutants (removal constant <3.5 mg COD_Cr,diss·mg O₃⁻¹) with ozone than on the fast-reacting micropollutants (removal constant >3.5 mg COD_Cr,diss·mg O₃⁻¹). However, the decreased removal of the organic micropollutants was generally small, <10%, at typical SS concentrations, <25 mg SS·L⁻¹. Integration of the new removal constants based on COD and SS enabled the removal in an ozone pilot plant to be modelled with an average deviation of <10% for several organic micropollutants. The use of the frequently measured parameters, COD and SS, as input parameters could facilitate the future use of the tool to predict the removal of micropollutants during ozonation.