Abstract: The invention is in the field of biogas production. In particular the invention is directed to a process and apparatus for the conversion of carbon and hydrogen containing materials into biogas (viz. a gas stream comprising CH4) containing material and subsequent purification of the resulting gas. According to the invention biogas is produced from carbon and hydrogen containing starting material. The unpurified biogas is subsequently purified by subjecting it to a filtration step, which comprises feeding said biogas to at least one cyclone providing cyclone action, at least one water filter where said biogas is washed with water and at least one dry filter where said biogas is dry-filtered, thus producing a purified biogas, followed by subjecting said purified biogas to compression, preferably using a water ring compressor, followed by feeding the compressed gas to a water-gas separator.