Abstract

ABASS, M. et al. Optimization of complex integrated water and membrane network systems. J. S. Afr. Inst. Min. Metall. [online]. 2015, vol.115, n.12, pp.1143-1158. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2015/v115n12a2.

Water and energy are key resources in the process and mining industries. Increasing environmental and social pressures have made it necessary to develop processes that minimize the consumption of both these resources. This work considers the synthesis and optimization of water networks through partial treatment of water (regeneration) before recycle/re-use. Two types of membrane regenerators are considered, namely electro-dialysis and reverse osmosis. For each of the membrane regenerators, a detailed design model is developed and incorporated into the water network model in order to minimize water and energy consumption, and operating and capital costs. This represents a rigorous design and accurate cost representation as compared to the 'black-box' approach. The presence of continuous and integer variables, as well as nonlinear constraints, renders the problem a mixed integer nonlinear programming (MINLP) problem. Four cases are presented. The first case looks at the incorporation of multiple electrodialysis regenerators with single contaminant streams within a water network (WN), while the second considers the multiple contaminant scenario. Case 3 examines the incorporation of a reverse osmosis network superstructure within a WN, and case 4 looks at both electrodialysis and reverse osmosis membranes. The developed models are applied to a pulp and paper and a petroleum case study to demonstrate their applicability, assuming both a single and multiple contaminant scenario. The model was solved in GAMS using BARON and DICOPT. The results indicate a wastewater reduction of up to 80% and savings of up to 44% in fresh water intake, 82% in energy, and 45% in the total annualized cost.

Keywords : sustainable; synthesis; optimization; reverse osmosis; electrodialysis.

        · text in English     · English ( pdf )