Magnesium Salt Recovery from Concentrate and Use in Treatment of Saline Water

Abstract

Magnesium salt was recovered from artificial concentrate and used in the removal of contaminants (PO4, Turbidity and NO3) from saline water that has high initial magnesium concentration (artificial brackish and sea water) at pH 11. Solar panels were used to enhance and expedite the precipitation process. PO4 removal efficiency increased as Recovered Magnesium Salt (RMS) increased, with the highest removal reaching 99.7% at a dose of 200 mg/l (RMS), initial PO4–P concentration of 20 mg/l, and water salinity of 40,000 mg/l. Removal efficiency of PO4 increased as the salinity of water increased. However, beyond 10,000 mg/l salinity, the improvement was practically non-existent. Removal efficiency for turbidity and NO3 also improved as the dose of RMS increased. There was no correlation between TDS concentration and turbidity or NO3 removal efficiency. Turbidity removal efficiencies reached a value of 90% at a dose of 200 mg/l RMS for initial turbidity value of 50 NTU, and water salinity of 40,000 mg/l. NO3 removal efficiency ranged from 38.4% to 99.2%. The study also evaluated the effect of anti-scalant use on the removal efficiency of PO4, turbidity, and NO3 using RMS. Results have shown, using 2 anti-scalants (Phosphonic acid and a proprietary anti-scalant (AS-4100)), that the negative effect disappears after two hours of anti-scalant addition.