Clean treatment of rejected brine by zero liquid discharge thermal desalination in Persian Gulf countries

In this study, four zero liquid discharge thermal desalination processes were technoeconomically investigated to select the most efficient and economic process for the treatment of the brine rejected from desalination units. These processes were (1) evaporation/crystallization, (2) evaporation/spray drying, (3) membrane distillation/crystallization, and (4) membrane distillation/spray drying. To harmonize the economic assessment conditions in this technoeconomic study, the feed concentration and feed flow rate of all processes were considered to be 80,000 ppm and 1500 m(3)/day, respectively. The results showed that the specific water production costs for Processes 1-4 were 8.1, 22.1, 8.4, and 20.7 $/m(3), respectively. Therefore, the produced water from Processes 1 and 3 had the lowest specific production cost. In addition, these processes had the lowest total fixed capital investment. On the other hand, although the specific production cost and the equivalent thermal gained output ratio of Processes 1 and 3 were almost the same, Process 1 can produce demineralized water. Therefore, Process 1 was considered as the most economic option due to the high economic value of demineralized water. [GRAPHICS] .

Automated summary

Through a technoeconomic investigation, the study found that evaporation/crystallization and membrane distillation/crystallization processes had the lowest production costs and total fixed capital investments for treating brine rejected from desalination units. While the cost and output ratio of evaporation/crystallization and membrane distillation/crystallization were similar, the former was able to produce demineralized water which gave it an edge in economic value.