Direct electrical energization methods for removal of persistent substances from water are under investigation in the framework of the ytriD-project. The emphasis of the first stage of the project is the energy efficiency. A comparison is made between a batch reactor with a thin layer of water and an aerosol reactor. The method of energization is mainly the application of fast pulses. In case of the batch reactor it is compared with DC. The ozone concentration is determined as an indicator for the efficiency of the chemical reactions, the yield is 4 g/kWh for the DC batch reactor, 50 g/kWh for the pulsed batch reactor and 50-100 g/kWh for the aerosol reactor. For initial testing phenol degradation is determined. 50% of the initial 0.1 mM is...