Study on the effect of potassium on struvite precipitation in synthetic landfill leachate

Abstract

Struvite precipitation (MAP, MgNH4PO4.6H2O) is a common method for the treatment of ammonium-nitrogen (NH4-N) in wastewater. Landfill leachate, one of the most hazardous waste streams, contains different pollutants (e.g. potassium (K)) that could affect the process of MAP recovery. This study investigated the effect of K on NH4-N recovery by struvite precipitation from landfill leachate. Bench-scale experiments were carried out using synthetic landfill leachate, by varying N:K molar ratio from 0.0 to 1.0, in which the results illustrated that increasing the molar ratio of K:N from 0.0 to 1.0 lowered the recovery of NH4-N from 88% to 77%. Additionally, the precipitation of K compounds was confirmed by Scanning Electron Microscope/Energy Dispersive X-ray analysis (SEM-EDX). Finally, this study concluded that only high concentrations of K could affect the purity of struvite recovered from landfill leachate.