Techno-Economic analysis of Membrane Distillation for High-salinity Wastewater Desalination

Membrane distillation is a separation method based on heat transfer due to vapour pressure gradient between the two sides of a microporous hydrophobic membrane. Owing to advantages such as low operating temperature and pressure, and insensitivity to the concentration of influent pollutants, it is considered as an appropriate membrane-based separation process to be integrated with other separation processes and has shown good performance on the desalination of brine. In this paper, the performance of direct contact membrane distillation for desalting produced water with a salinity of 100000 mg/L has been studied by adopting heat transfer model based on the Nusselt number and mass transfer model based on the Dusty gas model. The results indicate that increasing salinity from 35000 mg/L to 10000 mg/L reduces the volume of the product by only 10%, which is retrievable through increasing the feed temperature, raising the flow rate of the feed and permeate, and reducing the temperature of permeate.
The amount of error occurred in this model in comparison with the reported experimental data was lower than 14%, and economic projections made for a unit with the capacity of 11000 barrels of produced water per day indicate that the levelized cost of producing retreated water in this method is 1.95 $/m3, which is a reasonable number for hypersaline produced water.