Investigation on the Effect of Nickel and Cadmium on Struvite Crystallization in Landfill Leachate

Abstract

Struvite is an eco-friendly fertilizer that is widely produced from waste streams. Landfill leachate is rich in ammonium-nitrogen (NH4-N), which encourages its recovery in the form of struvite, however, the presence of heavy metals, especially Cd and Ni, could affect the purity of struvite crystals. This work aimed at studying the effect of Cd and Ni on the purity and morphology of struvite crystals obtained from synthetic solution (Phase 1) and synthetic landfill leachate (Phase 2). Batch experiments of struvite precipitation were implemented with different concentrations of Cd and Ni. The results of aqueous analysis showed minor reduction in NH4-N recovery in both phases when Cd or Ni existed. Moreover, XRD and SEM analyses of solid samples illustrated that all crystals were highly pure struvite. In addition, the effect of Cd and Ni in Phase 2 was slightly more significant than in Phase 1. The results suggested that struvite can be safely recovered from landfill leachate contaminated with Cd and Ni, however, more intense research should be conducted on actual landfill leachate to have deeper understanding of mutual and advanced effects of heavy metals.