磷酸铵镁沉淀与沸石吸附组合工艺处理海水中的氨氮

大量陆源营养物质的输入是导致我国近岸海域富营养化问题的主要原因, 传统生化法对海水中氮磷处理能力有限, 天然沸石凭借较强的选择性离子交换性能已成为一种较为经济和高效的水处理材料。本研究通过穿透实验考察了天然沸石对海水中氨氮的动态吸附性能, 采用磷酸铵镁(MAP)沉淀和沸石吸附组合工艺对海水中氨氮进行处理。实验结果表明, 天然沸石吸附氨氮达平衡时间随过滤速度的增大而减小, 随滤层高度的增加而增大, Logistic模型能较好反映天然沸石对海水中氨氮的动态吸附过程。MAP沉淀法与沸石吸附法联用可以将海水中氨氮含量降低至较低水平, 适宜的滤柱过滤条件为:滤速20L/h, 滤层高度100cm。通过焙烧或NaCl浸洗处理能够恢复天然沸石对海水中氨氮的吸附能力, 300℃焙烧2h和1.5mol/L NaCl溶液浸洗24h条件下的再生率分别为99.38%和122.22%。

Ammonia nitrogen removal from seawater by magnesium ammonium phosphate(MAP) precipitation combined with zeolite adsorption

The nutrients delivery from land usage and anthropogenic emissions in quantity is the main reason for euthrophication of coastal seawater in China. Nitrogen(N) and phosphorus(P) in seawater are hard to remove by conventional biological treatments. Due to its high ion exchange capacity and selectivity, natural zeolite has been one of the most efficient and economical water treatment materials. This paper studied the dynamic adsorption behavior of ammonium nitrogen from seawater, expressed as breakthrough curve, using natural zeolite bed filter. The magnesium ammonium phosphate(MAP) precipitation and zeolite adsorption combined process was performed to remove ammonia nitrogen from seawater. Experimental results showed that the adsorption reached equilibrium in a shorter period of time at higher flow rate lower and filter column height. It is indicated that the dynamic adsorption of ammonia nitrogen from seawater on zeolite filter was best represented by the Logistic model. The concentration of ammonium nitrogen in seawater dropped to a low level when treated with MAP precipitation combined with zeolite adsorption. The suitable filtration conditions of natural zeolite bed filter were as the following:The filter speed was 20L/h, and the filter column height was 100cm. The ammonia adsorption capacity of natural zeolite could be restored by using calcination or NaCl immersion. After treated by calcination at 300℃for 2h and immersed in 1.5mol/L NaCl solutions for 24h, the regeneration rate of natural zeolite was 99.38% and 122.22% respectively.