Map precipitation from landfill leachate and seawater bittern waste

Abstract

The leachates generated at Hong Kong landfill sites contain high strength of ammonium-nitrogen (NK??-N) over 3,000 mg 1?? and are generally inhibitive to most biological treatment processes. To remove the NK??-N from the landfill leachates and also recover the nitrogen as a struvite fertilizer, a lab-scale study was performed to investigate the feasibility of NH??-N removal and struvite crystallization using different magnesium sources. Three combinations of chemicals, MgCl?¡P6H?O+Na?HPO?¡P12H?O, MgO+H?PO?and MgSO?¡P7H?O+Ca(H?PO?)¡PH?O, were first used at different molar ratios to precipitate NH??-N from the leachate. The experimental results indicated that NH??-N was removed by 92%, 36% and 70% respectively at pH 9.0 and a molar ratio of Mg:N:P = 1:1:1. Two synthetic se