The present disclosure is a method of removing contaminants from a feed stream comprising said contaminants and process liquid by bringing the feed stream into contact with a heated heating fluid in or in proximity to a separation vessel thereby causing process liquid to vaporise and flow out of the separation vessel as vapour, after which it can be recovered. Embodiments of the method may include using a heavy heating fluid whose density is higher than that of the feed stream and/or vigorously agitating the pool of heating fluid in the separation vessel.