Simultaneous Recovery of Sulfate and Ammonia from Treated Brine: A Comprehensive Approach Utilizing Chemical Precipitation and Electrocoagulation

Soda ash Na
2
CO
3
) is conventionally manufactured through the Solvay process, which involves the reaction of CO2 with highly saline water in the presence of ammonia (NH
3
). This results in the formation of insoluble sodium bicarbonate (NaHCO
3
) and soluble ammonium chloride (NH
4
Cl. In the present study, an innovative approach has been devised to efficiently address the removal of ammonia and sulfate from the effluent of the Solvay process. This novel method utilizes electrochemical coagulation, incorporating calcium oxide (CaO) as a buffering reagent, to achieve high levels of ammonia and sulfate recovery. The reclaimed ammonia can be recycled and reintroduced into the initial stage of the Solvay process. Furthermore, sulfate ions are recuperated in the form of calcium sulfate, a value-added product with diverse industrial applications. To determine the influence of critical operational parameters, such as calcium oxide concentration (ranging from 2 to 3 g/100 ml), current density (10-20 mA/cm
²
, temperature (20- 30°C, and mixing rate (1–2 R/S), on ammonia and sulfate removal in the combined approach, Response Surface Methodology (RSM) analysis was employed. The findings revealed that under optimal conditions, with a calcium oxide concentration of 3.5 g/100 mL, a current density of 19.95 mA/cm2, a temperature of 35°, and a mixing rate of 0.76 R/s, the combined approach achieved a remarkable 99.50% removal of ammonia and 96.03% removal of sulfate.