Discussion of Zero Liquid Discharge as a solution for desalination brine management - A case study at Desolenator’s project in Dubai

Abstract

Desalination is forecasted to have a key role in narrowing the worldwide water demand-supply gap. However, the negative environmental impact of desalination due to brine discharge is a major drawback. The recycling of brine following the Zero Liquid Discharge (ZLD) approach has been recently proposed as a sustainable brine management solution. The extraction of water and resources from the brine while producing valuable solids is considered to be an essential strategy to fulfil the water-supply and resource gap. A broader application of these ZLD technologies is currently limited because the technologies are still associated with very high capital and operation costs, custom-design on a case-to-case basis, and difficulties to deal with complex streams. This report detailly summarizes conventional and emerging ZLD and resource recovery technologies to provide guidance for brine management aiming to decrease the environmental impact of desalination. Limited information concerning the actual economic data (capital and operation cost) of ZLD technologies have been identified. Thus, a market survey is conducted to assess the techno-economic data of commercially available ZLD technologies. The gained knowledge is applied to design and assess the best fitting ZLD chain for Desolenator’s project in Dubai, the United Arab Emirates, using real-life feedwater data. Three different ZLD treatment chains have been designed considering the water composition, process performances, and market availability. The conducted multi-criteria analysis which includes environmental, social, economic, and technical dimensions, showed that the proposed traditional thermal ZLD chain is expected to have the least impact at Desolenator’s project site. The subsequent techno-economic analysis concluded that the proposed treatment chain is just economically feasible if additional revenue via salt recovery is achieved. Knowing the technical, environmental, social, and economic data of conventional and emerging ZLD technologies and systems is essential. Further research in the field to assess such data in combination with the development of less technically complex and cost intensive ZLD technologies is needed for a broader application of ZLD as a brine management solution worldwide. This is a worthwhile task for the future to decrease the environmental impact of desalination and lead to an increased contribution against the growing water scarcity.