Economic evaluation of reverse osmosis brine evaporation: Environmental management in Mexico

Abstract

Reverse osmosis desalination is one of the most widely used technologies to reduce global water shortages. However, it presents environmental impacts from brine effluents that do not receive prior treatment at their disposal. The objective of this study is to evaluate the evaporation of brine discharges from desalination processes in brackish water (26 816 mg/L total dissolved solids [TDS]) and seawater (55 648 mg / L TDS) using electrical and thermal energy as a source of heat. The system was optimal when it presented higher salt removal (97 %) and evaporation rate (3.373 L/d), as well as lower energy consumption (5.43 kWh) and operating cost ($8.54 MXN/d), with level of significance p = 0.05. The extension of the electrical system to a multi-stage flash distillation thermal system presents an investment of $703 016.00 MXN with a return of investment of 20%, recovery time of 10 years, and product water cost of $37.37 MXN/m3. Brine evaporation systems are socially efficient for reducing environmental and economic problems caused by the management of brine effluents.