The present invention relates to a substrate device provided for installation into a bioreactor which is suitable for the breakdown of pollutants in wastewater, wherein wastewater can pass through the substrate device, and the substrate device can be seeded with at least one microorganism. To optimize the throughflow of wastewater and provide sufficient space for the attachment of microorganisms, it is proposed according to the invention that the substrate device has a multiplicity of undulating plates arranged in parallel planes, wherein the peaks and troughs of adjacent undulating plates run in a non-parallel manner with respect to one another. The present invention furthermore relates to a bioreactor and to a vehicle washing installation having a substrate device of said type, and to a method for the biological treatment of wastewater by means of a substrate device according to the invention.
