Using sodium trithiocarbonate to precipitate heavy metals from industrial wastewater – from the laboratory to industrial scale

This paper presents the possibility of using sodium trithiocarbonate to remove heavy metals such as copper, nickel, and tin from industrial wastewater generated by the production of printed circuit boards (PCBs). Initial metal removal studies aimed at selecting an effective precipitant and optimizing the precipitation process were conducted on an laboratory scale. The smallest concentrations of copper, nickel, and tin in treated wastewater (Cu 0.09 mg/L, Ni 0.009 mg/L, Sn <0.005 mg/L) were obtained after using a stoichiometric sodium trithiocarbonate dose at pH 9.0-9.5. Optimizing the metal removal process was possible by using the surface response method to obtain a good adjustment of the experimental data to the data obtained from the model (R² = 0.9307, R² adj. = 0.8845). The results of laboratory and model studies were used during industrial-scale testing in a wastewater treatment plant located in a PCB manufacturing plant. Optimization the wastewater treatment process on an industrial scale allowed us to obtain treated wastewater with very low copper (<0.005-0.014 mg/L), nickel (<0.005-0.008 mg/L), and tin (<0.005 mg/L) concentrations.