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

摘要： 大量氮磷营养物质排入海湾，引起了富营养化、赤潮等一系列海洋污染问题，污海水中氮磷处理技术研究已引起人们的重视。磷酸铵镁化学沉淀法具有可同时脱除氨氮和磷酸盐，但还未应用于低浓度氨氮废水的处理，尤其是污海水中氨氮的处理。本文采用磷酸铵镁（MAP）化学沉淀法对污海水中氨氮进行处理实验研究，利用污海水中大量存在的Mg2+，以Na2HPO4作为沉淀剂，探讨了初始反应体系pH值、PO43?/NH4+投配比、反应时间等因素对氨氮脱除效果的影响。结合沉淀结晶物XRD和SEM分析，确定了MAP沉淀法处理污海水中氨氮的最佳反应条件：初始反应体系pH值为9.5～10.5，PO43?/NH4+投配比为1.1/1，反应时间为40 min。实验结果表明，在最佳反应条件下，随着氨氮初始浓度的增大，氨氮去除率逐渐增大，当进水氨氮浓度为12 mg/L时，氨氮去除率达到42.80%。

关键词: 磷酸铵镁, 污海水, 低浓度氨氮, 去除效果, 沉淀结晶物