A synthesis approach for industrial city water reuse networks considering central and distributed treatment systems

This paper presents an optimization approach to the development of macroscopic networks for water integration within industrial cities. The methodology considers various strategies for industrial wastewater reuse amongst different processing facilities that operate within the city. Two different scenarios for the placement of intermediate water treatment interceptors are considered: (1) on-site ‘decentralized’ water treatment within each plant, and (2) off-site ‘centralized’ water treatment that can be shared amongst a cluster of existing industrial plants. The overall objective is to develop cost-efficient water networks that can attain effective interplant water integration scenarios, whilst considerably reducing freshwater consumption and wastewater discharge where appropriate. The optimization model has been formulated as a Mixed Integer Non-Linear Program (MINLP), and accounts for pressure drops associated with piping across all individual source-interceptor-sink allocations. Additionally, a representation that accounts for constrained water transport was adopted, in which designated corridor regions within an industrial city are utilized for the planning of economical pipeline networks that achieve desirable water allocation strategies. In doing so, shortest routing options were obtained between water sources, sinks, and treatment interceptors, according to a given industrial city layout. A case study that considers various different scenarios in terms of contaminant information and piping connectivity is presented to illustrate the proposed approach.