Effects of pH on phosphorus removal capacities of basic oxygen furnace slag

• Published in: Ecological engineering 2016-04, Vol.89, p.1-6
• Main Authors: Han, Chong, Wang, Zhen, Yang, Wangjin, Wu, Qianqian, Yang, He, Xue, Xiangxin
• Format: Article
• Language: English
• Subjects: Adsorption; Basic oxygen furnace slag; Phosphorus; Precipitation
• ISSN: 0925-8574; 1872-6992
• DOI: 10.1016/j.ecoleng.2016.01.004

•BOF-slag had high PRCs at acidic, neutral and alkaline pH.•Chemical extraction was used to analyze effects of pH on phosphorus removal paths.•Weak adsorption and Ca-P precipitates were main removal paths at alkaline pH.•Adsorption on Fe-oxys was main removal path at neutral and acidic pH. Phosphorus removal capacities (PRCs) of basic oxygen furnace slag (BOF-slag) in different pH ranges were investigated using batch experiments. The fractions of different phosphorus containing compounds in fresh and reacted BOF-slag were measured by chemical extraction methods. Fresh and reacted BOF-slag was characterized through combining several methods. The results show that BOF-slag had high PRCs (21–30mgP/g) and that the PRCs of BOF-slag at alkaline pH were comparable to the ones at neutral and acidic pH. At alkaline pH, phosphorus removal occurred via both the weak adsorption onto BOF-slag and the precipitation of calcium phosphates. At neutral and acidic pH, phosphorus removal was achieved through the chemical adsorption onto Fe containing minerals in BOF-slag. Influences of the pH on weakly bound phosphorus, Ca associated phosphorus, and Fe associated phosphorus in the reacted BOF-slag were also discussed in detail.