Abstract: The biological washing reactor and the wet electrofilter are located in a common container. This container ends at the bottom at a biotank. A droplets remover is located at the purified gas outlet. The exhaust gas which is to be purified and which contains impurities in form of aerosols, dust and organic gases flows through the exhaust gas inlet into the container and flows firstly through the preliminary separator and thereafter through a biological washing reactor and the wet electrofilter. The process water for the continuous sprinkling of the preliminary separator and of the biological washing reactor, and for the intermittent cleaning of the wet electrofilter and of the droplets remover is circulated in a closed loop via the biotank. The circulated process water is regenerated in the biotank.