EARTH

[31001-12-07] Struvite as platform of heterogeneous nucleation of heavy metal hydroxide: a novel method for simultaneous removal of heavy metals from different strength wastewaters

○Cong Peng^1,2 (1. The Nagoya University, 2. Central South University)

Chairman:JI Whan Ahn（KIGAM）, Richard Alorro (Curtin University)

Keywords:Heavy metals, Struvite, Heterogeneous nucleation, Crystal synthesis, Precipitation

Heavy metals existing in the water have brought much concern. The conventional hydroxide precipitation treatment is hard to achieve satisfactory removal efficiency, particularly for low-strength wastewater. The research has used the in-situ synthesized struvite crystals for the enhanced removal of heavy metals Cu, Ni, Pb, Zn, Mn and Cr from solution. The experiments have studied the removal efficiency under pH values from 6.0 to 10.0, including a series of struvite addition quantity. The research compared the performance of struvite treatment and mere hydroxide precipitation treatment as a control treatment. It was found that struvite treatment was far superior than the control treatment. For extremely low heavy metal concentration it achieved removal of 99.1%, 97.9%, 99.9%, 98.9%, 96.9% and 98.3%, which were much higher than that of control treatment, which were 10.5%, 8.7%, 13.2%, 14.1%, 6.7% and 10.5%. Through XPS and SEM analysis, it was found the heavy metal hydroxides were precipitated on the struvite surface. Moreover, based on TEM observations, it was found the heavy metal hydroxides had a nucleation and development on the struvite’s surface. The heterogeneous nucleation mechanism has been proposed for struvite treatment, which provides relationship of sorption, nucleation, and precipitation of heavy metal hydroxides on struvite surfaces and realize the quantification of the ability of struvite in enhancing heavy metal precipitate formation.