A simple, practical process to reduce the high costs associated with the disposal of dirt in wool-scouring effluent is described. The process is based upon observation that the settling dirt is hindered by the presence of grease. Thus streams that are rich in dirt but low in grease (e.g. the nozzle discharge of the grease centrifuge, and the settling tank sediment) were selected for treatment in a decanter centrifuge. A large fraction of the dirt in a mixture of these streams (typically 60%) was recovered as a spadeable sludge (more than 50% total solids) suitable for disposal at most municipal or commercial tips. An economic analysis of the process by the discounted cash flowrate method shows that it generates a favourable internal rate of return on investment.