Study on removal of phosphorus as struvite from synthetic wastewater using a pilot-scale electrodialysis system with magnesium anode

Yuyan Cai; Zhiying Han; Xiaochang Lin; Yalin Duan; Jianghui Du; Zhangying Ye; Jun Zhu

doi:10.1016/j.scitotenv.2020.138221

Study on removal of phosphorus as struvite from synthetic wastewater using a pilot-scale electrodialysis system with magnesium anode

Sci Total Environ. 2020 Jul 15:726:138221. doi: 10.1016/j.scitotenv.2020.138221. Epub 2020 Mar 26.

Authors

Yuyan Cai¹, Zhiying Han², Xiaochang Lin¹, Yalin Duan¹, Jianghui Du¹, Zhangying Ye¹, Jun Zhu³

Affiliations

¹ College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
² College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China. Electronic address: hanzhiying@zju.edu.cn.
³ Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, USA.

PMID: 32320868
DOI: 10.1016/j.scitotenv.2020.138221

Abstract

Struvite precipitation may become ineffective in removing phosphorus due to the low concentration of phosphate in the liquid. In this study, electrolysis with a magnesium anode was applied to recovering phosphorus and ammonia as struvite from wastewater. A novel electrodialysis process (ED) with a magnesium anode was developed, and its feasibility to treat synthetic wastewater with low phosphate concentration was demonstrated in a pilot-scale experimental system. To achieve high phosphate removal efficiency in the product stream, the optimal initial pH and flow rate were found to be 8.8 and 200 L h^-1, respectively, for the ED system at a constant current of 0.1 A. The pilot-scale ED system under the consecutive batch mode removed 65% phosphate from the synthetic wastewater containning 10 mg L^-1P, and the phosphate concentration in the product stream was kept at 30 mg L^-1 after 280 min. The running cost of the ED system was estimated to be $31.27 kg^-1 P for synthetic wastewater with 10 mg L^-1 P, mainly resulting from the cost of the loss of the magnesium anode. The precipitates generated from the product stream were confirmed as struvite by XRD analysis.

Keywords: Electrodialysis; Magnesium anode; Phosphate; Struvite; Wastewater.