Seawater brine treatment optimization and mineral recovery

Qatar heavily depends on seawater desalination from the Arabian Gulf to fulfill its national potable water needs. A byproduct of this process is brine, which is often discharged back into the sea. However, this reject brine poses environmental risks due to its high levels of total dissolved solids (TDS), concentrated chemicals, temperature-resistant microorganisms, and potentially harmful toxins. For instance, our research indicates that brine produced through Multi-Effect Distillation (MED) contains a TDS of approximately 70 g/L. Globally, various brine management strategies, such as deep well injection and evaporation ponds, have been implemented to mitigate these risks. In Qatar, it is believed that brine undergoes some level of treatment before being discharged into the sea. Given that brine is rich in minerals and salts, it presents an opportunity for resource recovery to support local industry demands. For example, Qatar Vinyl Company (QVC) currently imports dry NaCl, which is a key raw material for producing caustic soda—a highly profitable product. Investigating methods to treat desalination brine and produce high-purity NaCl locally could provide a sustainable feedstock for caustic soda production. Additionally, the extraction of valuable minerals such as calcium (Ca), magnesium (Mg), and strontium (Sr) could enhance the economic viability of brine treatment, making the process more cost-effective and resource-efficient.

Hamad Bin Khalifa University (HBKU)