Method for processing liquid waste containing arsenic into calcium-iron complexes

Abstract

The essence of the technical solution is the chemical removal of arsenic from liquid waste and its transformation into a thermodynamically stable and insoluble solid phase. The process uses the synergistic effect of a precipitation solution based on ferric chloride (FeCl3) or ferrous chloride (FeCl2) in combination with calcium chloride (CaCl2). In the reaction environment, amorphous iron hydroxides are formed and arsenic is subsequently fixed into complex calcium-ferric matrices with low leachability. The reaction takes place at a controlled pH in the range of 7.0 to 9.5. The technical solution enables effective processing of liquid waste even at high arsenic concentrations, while the residual arsenic concentration in the separated water falls below the limit values ​​for discharge to wastewater treatment plants.