Removal of Phosphate from Wastewater Using Steel Slag Modified by High Temperature Activation

The phosphate removal potential of steel slag modified by high temperature activation has been investigated. The effects of adsorbent dose, pH, contact time and initial phosphate concentration on the phosphate adsorption by modified steel slag have been studied. Phosphate removal was seen to increase with increasing adsorbent dose, contact time and decreased with increasing initial phosphate, while reached the maximum at pH 8.0. Adsorption of phosphate followed first-order rate kinetics. Langmuir isotherms equation gave a better fit than the Freundlich equation. According to the coefficients of Langmuir isotherm the maximum adsorption capacity of modified steel slag was 11.12 mg P/g. The effects of both TP and DP removal of wastewater in tailings reservoir by infiltration column were stable during the 30 days of continuous operation, and the average removal rates of TP and DP were 88.87% and 92.22%, respectively. The modified steel slag as an adsorbent for phosphate could have extensive application prospect due to its abundant supply, low cost and high adsorption capacity.