Use of Red Mud to Removal Phosphorus from Biogas Slurry Implication for Practical Application

Abstract

This study investigated a novel approach by using red mud (RM), an industrial waste of alumina production, to remove phosphate from biogas slurry. First, the important parameters, which affect the removal efficiency of phosphate and final pH of solution (pHf), such as initial pH (pHi), RM dosage, reaction time and phosphate concentration of biogas slurry were explored. The results indicated that the phosphate removal efficiency decreased first, and then increased with the increase of pH. And the highest and the lowest phosphate removal efficiency were 89.6% and 47.2%, respectively, at pH 2.1 and pH 6.9 under given conditions. RM dosage and contact time had a positive effect, whereas initial phosphate concentration had a negative effect on phosphate removal and pHf. Overall, the results of this work demonstrated that RM can be proposed as a cost-effective absorbent for the effective removal of phosphate from biogas slurry.