Life cycle sustainability assessment of brine valorisation technology systems

Abstract

New valorisation technology systems can potentially solve the growing industrial challenge of managing increasing quantities of brine effluents, through the recovery of salts, minerals and water. Life Cycle Sustainability Assessment (LCSA) can aid the technology development by evaluating the sustainability implications between increased treatment and resource recovery and reuse. This study applies LCSA to four case studies involving innovative brine treatment and recovery systems: a demineralised water plant, a coal mine, textile plant and a silica plant. The results demonstrate potentially significant environmental and economic benefits of the Zero Brine systems compared to the reference systems. Climate change is lower for the Zero Brine systems in 3 of the 4 cases, reducing from: 3.0 to 2.5 CO₂ eq/m³ for the demineralised water plant, 18.6 to 10.7 CO₂ eq/m³ for the coal mine and 0.29 to −4.7 CO₂ eq/m³ for the silica plant (the negative value representing a credit due to recovered materials replacing virgin ones). This represents reductions in climate change of between 13 % to 1690 %. Other impacts of the Zero Brine systems were lower for the coal mine and silica plant, but higher for the DWP and textile plant (apart from resource depletion). Life Cycle Costing shows an increase of 45 % and 352 % in costs for the silica and demineralised water plant plants respectively, but a decrease of 14 % and 93 % in costs for the coal mine and textile plant respectively. The main social benefit is shown to be reductions in water use, which was reduced by up to 90 % in the silica plant case study. Other social indicators indicate minimal change, as many consumables in both systems are derived from European production. The study demonstrates that the benefits of Zero Brine systems depend on the recoverable sustainability “value” of the brine's constituents and whether they offset the increased consumption of energy and chemicals. The utilised LCSA approach of minimising the number of indicators and avoiding aggregation, helps to maintain transparency and interpretability, whilst streamlining the process and aiding communication and visibility. Further study should investigate the marketability of the recovered products, associated processing and distribution impacts, and verify the impacts of full-scale plants.