FOCUSING IN BY-PRODUCT RECOVERY AND WASTE MINIMIZATION IN BATCH-PRODUCTION SCHEDULING

This paper deals with the potential by-product recovery and waste minimization that is present in the production scheduling problem of multipurpose batch processing networks. In batch processes the amount of waste generated depends mainly on the number of products and batches of each product that require frequent equipment cleaning. Thus, equipment cleaning and preparatory subtasks are essentially involved in waste minimization considerations. The work is based on an open modeling framework developed recently (Puigjaner et al., 1942), which makes it possible to focus on the detailed consequences of every subtask carried out in the different manufacturing steps in each product recipe. Reuse of raw materials and solvents recovery is considered. Consequently, the conventional recipe definition, i.e., the sequence of processing tasks which must be performed to manufacture a given product, is expanded in order to include the additionals tasks needed for waste treatment and materials recovery. So, product recipe tasks will be distinguished from recovery/reuse tasks according to whether they are indispensable for product manufacturing.