Remediation of industrial brine using coal-combustion fly ash and Co2

• Remediation of waste brine by mineral carbonation of fly ash
• SO4, Na, NO3 and Pb among elements reduced with treatment
• Calcite and dolomite among minerals predicted to form

A protocol is proposed whereby waste fly ash and CO2 emissions from coal fired power plants are utilized in remediating brine waste. The solid residues generated may be used as mine backfill since they consist mainly of benign calcium carbonate. Following treatment with fly ash and CO2, over 99% removal of NO3− was achieved while B3 +, V2 +, MO2 + and Cl− concentrations increased. Major element removal from brine upon carbonation was as follows: Na+ (15–29%), Mg2 + (53–87%), K+ (70–88%), Ca2 + (40–73%) and SO42 − (12–36%). Speciation modeling of the major elements present in brine showed that Na+, K+ and Cl− exist mainly as free ions while Mg2 + and Ca2 + are associated with SO42 − as well as being in their free forms. SO42 − ions were present in its free form to a great extent as well as associated with Na+, Ca2 +, Mg2 + and K+ respectively, in a decreasing order. Co-treatment of brine using FA and CO2 may therefore be a potent brine remediation protocol which can be optimized for maximum removal of various elements.