Ammonia recovery from landfill leachate using hydrophobic membrane contactors

Abstract

This article aims to evaluate membrane contactors capability to remove and recover ammonia from landfill leachate (LFL). A hydrophobic hollow fiber membrane module was used to achieve such purpose. A sulfuric acid diluted solution was used as extraction solution to speed up ammonia content removal. Several factors that have influence on ammonia removal and recovery capability such as ammonia solution pH, concentration of sulfuric acid solutions and flow rate of liquid phases have been examined. Microfiltration was the method used as pretreatment. The results have shown that membrane contactor operated with LFL (pH 10), 0.1 M acid solution and liquid flow rate up to 0.5 L min^-1 achieved 99.9% of ammonia removal, which corresponds to 79.1% of ammonia recovery from the extraction solution, and it is capable to produce highly purified ammonium sulfate solutions (41.2%, wt wt^-1) to be used as fertilizer. The concentration of total ammonia nitrogen (TAN) in the residual LFL complies with Brazilian law requirements of 20.0 mg L^-1 of TAN, regarding the disposal of effluents.