A method of treating household refuse wherein selection, communication, etc., the fraction of the total refuse containing biodegradable organic dry matter is delivered to an anaerobic fermentation process. Anaerobic fermentation is carried out until all the dry matter is exhausted, degradation rates of the biodegradable organic dry matter (OTS.sub.biol) of 70% and more being attained. The resultant fermentation residue is subjected to a drying process in which the dry matter portion is increased to at least 90%. The resultant dry material no longer exhibits any biological activity. The exhaustive anaerobic fermentation process enables a maximum amount of biogas to be produced, its energy content being sufficient to supply the drying process. A further aspect of the reduction of the problematic refuse portion is the separation out of a fine-grained fraction (particle size >15 to 14 mm) which is purified wherein adherent material, particularly organic dry matter is removed, by counterflow washing in a washing unit so that inert material having an organic dry matter portion of at most 5% is produced. Washing may be carried out using process condensate such that a closed water circuit results.