ABSTRACT
Disinfection and removal of organic micropollutants are the two aspects of the production of drinking water from surface water that are currently of particular importance. They are important issues because conventional water treatment processes are not always able to cope with them. This was first realized when chlorine, a commonly used disinfectant, was found to result in the formation of trihalomethanes, and when various micropollutants were detected in drinking water at concentrations far exceeding acceptable levels. Thus, new, advanced water treatment processes are needed.
Amsterdam Water Supply (AWS) introduced two new integral concepts for the treatment of surface water. They include conventional pretreatment of Rhine River water by coagulation, sedimentation and rapid sand filtration, followed either by slow sand filtration and reverse osmosis or by ozonation, Granular Activated Carbon (GAC) filtration, slow sand filtration and reverse osmosis. The performances of these two concepts were tested and evaluated by AWS. The mechanisms playing a role were studied in the context of the research project conducted jointly by IHE, NORIT NV, Kiwa NV and AWS. In particular, attention was paid to the following aspects: removal of pesticides, metabolites and other organic micropollutants by combined ozonation and GAC filtration, and by reverse osmosis; disinfection by ozonation and by reverse osmosis; and control of the fouling and scaling of reverse osmosis membranes. The research presented in this thesis was conducted within the framework of this project. Its focus is on the removal of pesticides by Biological Activated Carbon filtration, which is a combination of ozonation and GAC filtration.
