An integrated approach to vivianite recovery from waste activated sludge
Zhetai Hu, Weiwei Li, Haoran Duan, Huang Xin, Jia Meng, Liangzhen Yang, Min Zheng
Abstract
The waste activated sludge (WAS) of wastewater treatment system is often rich in phosphorus (P), which is a basic element of human life and could use up in the near future. This study proposed an integrated approach to efficiently recover P as vivianite from WAS and simultaneously enhance the sludge dewaterability. The raw WAS was first acidified using FeCl3, which was then fed to anaerobic fermenter for Fe3+ reduction. After fermentation, a technology named acid-elutriation was introduced to convert Fe and P from solid phase to liquid phase and concomitantly enhance the liquor-solid separation. Finally, vivianite was obtained via sludge eluate neutralization. The enhanced sludge dewaterability not only increases the recovery efficiency of Fe and P but also decreases the cost of sludge disposal.