Abstract: A method is disclosed for treating sewage in which the combustible components of the sewage are separated from the sewage and utilized as a primary fuel. Scum is collected, preferably by skimming, from screened sewage. This scum comprises oils, greases, fats, water and intermixed solid material. The collected scum is then transferred to a separation tank. The scum is maintained within the tank in a quiescent and substantially nonagitated state for at least twelve hours, during which the combustible oils, greases, fats and the like are rendered separable from the other components of the scum. The scum is then conveyed from the tank to a processing unit where the fats, oils, greases and the like are separated from the water and solid material remaining in the scum. The resulting product is a combustible product and can be used as a primary fuel.