关键词: 磷酸铵镁, 污海水, 低浓度氨氮, 去除效果, 沉淀结晶物

Abstract: Nitrogen (N) and phosphorus (P) are continuously discharged into the ocean，causing serious marine pollution problems，such as eutrophication and red tide. Much attention has been paid to removal N and P from contaminated seawater. Magnesium ammonium phosphate (MAP) precipitation method has the advantages of removal ammonia nitrogen and phosphate simultaneously，but it has not been used in low concentrated ammonia nitrogen wastewater treatment，especially in contaminated seawater treatment. In this research，MAP precipitation method was used to removal ammonia nitrogen in contaminated seawater. Mg2+ ion in seawater and Na2HPO4 were utilized as the precipitants. The influencing factors on ammonia nitrogen removal efficiency，such as pH，molar ratio of PO43?/NH4+ and reaction time were investigated. Combined with XRD and SEM analysis of the deposit crystals，the optimal reaction conditions of ammonia nitrogen removal in contaminated seawater by MAP precipitation method were determined as the following：pH value，9.5—10.5；PO43?/NH4+ molar ratio，1.1/1；reaction time，40 min. The experimental results showed that under the optimal reaction conditions，increase of initial ammonia nitrogen concentration reduced ammonia nitrogen removal rate. The ammonia nitrogen removal rate was 42.80% when initial ammonia nitrogen concentration was 12 mg/L.

Key words: magnesium ammonium phosphate, contaminated seawater, low concentrated ammonia nitrogen, removal efficiency, deposit crystals