Increasingly strict environment regulations stimulate the adoption of clean technologies and materials recycling in the process industry. The emphasis is now on improving process efficiency, minimising effluents and optimising waste treatment and disposal practices to ensure compliance with discharge and disposal legislation. Some of the waste is consequence of process inefficiency, as occurs with part of the product changeover waste. This paper refers to the product changeover waste which is processing-sequence dependent. A procedure for reducing the amount of this waste is proposed. It is based on the generation of non permutation schedules, where the order in which the products are processed may be different in all the recipe stages, and passing of products between stages is allowed.