A low-cost method using steel-making slag to quench the residual phosphorus from wastewater effluent

This study demonstrates a novel application of steel-making slag for quenching residual phosphorus in wastewater effluent after chemical precipitation. The results showed that the phosphorus removal efficiency was low without the supernatant pH adjustment. Decreased pH of the supernatant resulted in increased removal efficiency. At the optimal conditions (i.e. pH 8.5 and steel-making slag dosage of 5 g/L), approximately 98 phosphorus removal could be achieved with the output level of less than 0.1 mg/L. The results also demonstrated that enhanced phosphorus removal by pH adjustment resulted from the involvement of adsorption in the removal process. This observation was evidenced via the compliance with Langmuir isotherm of the adsorption of phosphorus to steel-making slag at decreased pH. In addition, the results indicated that the presence of inorganic carbon in the supernatant could facilitate phosphorus removal via co-precipitation effects. © 2023 The Author(s)