Abstract

Yu Menglin¹, Yin Danyang², Shi Jing^1*, Song Duanmei¹ and Xu Zhengwen²

DOI : http://dx.doi.org/10.13005/ojc/320125

In the experiment, the crystallization process was compared with the chemical precipitate process for phosphorus removal efficiency. Calcites were used as seeds to remove and recover phosphorus from synthetic phosphorite wastewater. The results indicated that under the same wastewater compositions, the crystallization process showed better phosphorus removal performance. At the initial stage, the corresponding removed Ca/P ratio (DCa/DP) was 1.43:1. When the phosphorus concentration was low, phosphorus could be removed further in the crystallization system, whereas the chemical precipitation stopped. During the reaction, calcium concentration firstly decreased because of precipitation or crystallization. Then it slightly increased, which possibly resulted from the transformation of HAP precursor or the dissolution of calcite seeds. The effects of pH, initial phosphorus concentration and Ca/P ratio were investigated. Phosphorus removal and recovery efficiency increased with the increment of the above three factors. In addition, the Response Surface Methodology was used to optimize the related factors. A significant quadratic model was obtained. From the optimization results, it could be found that when pH value was 9.0, molar ratio was 1.07 and reaction time was 36 h, the phosphorus removal rate could reach 96.1%.

calcite; hydroxyapatite; phosphorus recovery; phosphorus wastewater

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