Chemical precipitation and biosorption treating landfill leachate to remove ammonium-nitrogen

Using chemical precipitation and biosorption to recovery the NH₄ ⁺-N from landfill leachate had been studied. Under optimum conditions of pH 10, contact time 30 min, Mg/N/P molar ratio 1:1:1 for chemical precipitation in which initial NH₄ ⁺-N concentration of 610–640 mg/L was achieved by NH₄ ⁺-N removals around 88 %. And using banana peels (BPs) and modified biosorbent (NMBPs) to further purify the water containing NH₄ ⁺-N was carried out. The experimental results showed that the NMBPs can greatly improve the sorption removal for NH₄ ⁺-N. The pH value was an important parameter in NH₄ ⁺-N removal. The residue NH₄ ⁺-N was 4.5–5.8 mg/L, which can meet the “standard for pollution control on the landfill site of municipal solid waste” (GB16889-2008). Based on X-ray diffraction analysis, chemical precipitation filter residue was compared with commercial MAP, which showed that the precipitate has the similar crystal structure with MAP. Fourier transform infrared absorption spectrum analysis of BPs, NMBPs before and after sorption revealed the active of hydroxyl groups at the surface of BPs have been strengthened after modified; and nitrogenous groups appeared after biosorpting the NH₄ ⁺-N.