A potential biological approach for sustainable disposal of total dissolved solid of brine in civil infrastructure

• A sustainable method for the disposal of TDS in construction materials.
• Fly ash and microorganisms were used to stabilize TDS in the mortar.
• Microstructure analysis was performed to verify new mineral formation.

To meet growing water demand, more water is being harvested from nontraditional sources like brackish water from underground aquifers which contain total dissolved solids (TDS). Drinkable water is produced by separating TDS from water through desalination which typically produces 50–90% potable water and the remaining water (brine) is disposed in evaporation ponds or by injecting it below the ground surface, which is not sustainable. In this study, it was proposed to use TDS partially in place of sand to prepare mortar for possible application in highway infrastructure like fill material in vertical moisture barriers or embankments, etc. Since addition of TDS weakens the integrity of the cement matrix, fly ash and mutated aerobic bacteria were added to the cement matrix. Mortar specimens were subjected to strength and durability tests. Additionally, X-ray diffraction and scanning electron microscope tests were performed on mortar specimens. The preliminary test results indicated that fly ash and microorganism application not only improves the strength and durability, but these also stabilize TDS present in the mortar.