Sustainable and efficient removal of phosphorus from wastewater through red mud residue after deep dealkalization

Abstract

The increase phosphorus content in industrial wastewater can seriously deteriorate the water quality and correspondingly cause the eutrophication of rivers, lakes and underground water. The calcium silicate powder (CSP) was prepared from the red mud residue after deep dealkalization for phosphorus removal from wastewater, and the corresponding removal performance and adsorption mechanism were investigated in this work. Under the optimal conditions, a phosphorus removal efficiency of 96.32 % and a maximum immobilization capacity of 24.08 mg∙g−1 were achieved. The kinetic and isotherm data are well-fitted by the pseudo-second-order and Langmuir models, while the phosphorus is mainly removed by chemisorption, accompanied by the formation of a monolayer film on the heterogeneous surface. A novel Source-Parameters-Strategy-Demand architecture was proposed to evaluate the application potential of calcium silicate powder and environmental risk. The findings confirmed the validity of calcium silicate prepared from red mud residue for the phosphorus removal from wastewater, which has the unique advantages in simultaneously solving the industrial solid waste pollution and excessive phosphorus discharge.