for producing a water phase substantially free of liquid hydrocarbon product a liquid hydrocarbon product comprising some water and a sludge phase comprising suspended ash and or char particles the water phase is fed to the recovery unit 14 the liquid hydrocarbon product is fed to the second centrifuge 13 for further separation of water and ash and or char preferably the liquid hydrocarbon product after said first centrifuge is being divided prior to entering said second centrifuge 13 preferably a fraction of said liquid hydrocarbon product produced is recycled to said pretreatment step 1 the second centrifuge 13 is preferably a high speed disc bowl centrifuge designed as an oil purifier i e suitable for producing a liquid hydrocarbon product substantially free of water water from the second centrifuge 13 is preferably mixed with water from the first centrifuge 12 and fed to the recovery unit 14 similarly ash and or char from the second centrifuge 13 is mixed with ash and or char from the first centrifugation 12 dried not shown and send to storage for effective separation the centrifuges 12 13 according to an embodiment of the present invention is preferably operated at a temperature in the range 50 to 200 u00b0 c such as a temperature in the range 70 to 150 u00b0 c the pressure during said separation by centrifugation is maintained at a pressure sufficiently high to avoid boiling at the prevailing temperature e g a pressure of up to 15 bar preferably a pressure up to 10 bar more preferred a pressure up to 5 bar the water phases from the gas separating means 11 centrifuges 12 and 13 are fed to a recovery device 14 where liquid organic compounds and.