Reduction of water usage in industry by using the MINLP coordinates technique

•Reuse of the wastewater can be optimised by using the MINLP coordinates technique.•This technique can be expanded regarding the usages of wastewater for utilities and raw materials.•Distribution from the main reservoir could be used for the parallel or sequentially split parts.•The parallel or sequential split parts including different alternatives for usages of wastewater.

Natural resources are limited, so we need to handle them carefully. Wastewater also belongs as a significant natural resource. The re-usage of wastewater is to save fresh water and for the preparation of raw materials or/and utilities. The wastewater re-usage distribution can be optimised using mixed-integer nonlinear programming (MINLP), as a tool in combinations using the coordinates technique. The main goal of this MINLP coordinates technique was: i) wastewater and condensate, as produced during different industrial processes, could be collected for: utilities for steam-generation, and the preparations of raw materials; ii) wastewater and condensate could be collected within the main reservoir; iii) distributions from the main reservoir could be used with including different alternatives, which can reduce pollution, based on the re-usage of wastewater. Alternatives included in the optimization model represent potential solutions, which need to be evaluated on appropriate way.The MINLP coordinates technique for wastewater re-usage distribution was tested on existing formalin and methanol industrial processes, thus allowing the saving of water and generated by 280 kEUR/a profit.