A MATHEMATICAL-MODEL FOR THE OPTIMAL-DESIGN AND OPERATION OF AN ANAEROBIC CO-DIGESTION PLANT

The anaerobic co-digestion of high strength industrial wastewaters in centralised plants receiving effluents from various local small scale industries is considered to be superior than individual small scale tr eatment plants. An approach is proposed to systematically tackle co-di gestion problems, with respect to both biological and engineering mode ls. In a steady-state mathematical model presented, the effect of comb ining wastewaters in mixtures, based on major component groups (i.e. l ipids, hydrocarbons and proteins), is systematically accounted for. Th e model is then solved via a non-linear optimisation program (NLP) whi ch results in the determination of an optimal design of the necessary reactors and their respective layout, by balancing the natural trade-o ffs between reactor and post-treatment costs (due to high pollutants e missions). The preparation of appropriate mixtures is the major parame ter controlled. The applicability and potential of the model are demon strated with a small example. Copyright (C) 1996 IAWQ.