改性沸石吸附柱去除和回收脱磷尿液废水中氨氮试验研究

Removal and Recovery of Ammonium Nitrogen from Phosphorus-removed Human Urine by Modified Zeolite Column

经鸟粪石沉淀法回收尿液中磷后的废水中仍含有高浓度的氨氮,若直接排放,不仅会造成水体污染,也导致氮资源浪费。本文在5%HCl浸提,400℃焙烧,结合微波处理改性沸石以提高氨氮吸附能力的基础上,研究了改性沸石吸附柱高度(H)、吸附柱串联数量(N)以及水力停留时间(T)对脱磷尿液废水中氨氮去除效果的影响,评价了HCl溶液、NaCl溶液及其组合对吸附氨氮饱和的沸石的再生效果。结果表明:HCl-焙烧-微波改性沸石对氨氮的平衡吸附量为17.9 mg·g-1,是天然沸石对氨氮平衡吸附量(6.9 mg·g-1)的2.6倍。当柱高H=35 cm,水力停留时间T=2.0 h,吸附柱串联个数N=3时,改性沸石对脱磷尿液废水中氨氮的去除效果最佳。当吸附柱内氨氮负荷小于6370 mg时,吸附柱出水中氨氮浓度低于30 mg·L-1。10%HCl+5 g·L-1NaCl混合液作为沸石再生剂时,氨氮洗脱率达到88.3%,再生沸石的平衡吸附量可达16.4 mg·g-1,为改性沸石的91.6%。可见,改性沸石吸附柱可有效去除脱磷尿液废水中氨氮,同时10%HCl+5 g·L-1NaCl混合溶液能够有效实现沸石再生和氨氮回收。研究结果为脱磷尿液废水中氨氮处理与回收中试试验奠定了基础。

Struvite precipitation is an effective way to remove phosphorus （P） from human urine, but leaves most of nitrogen in the treated urine. Its direct discharge to the environment could lead to water nitrogen pollution and waste nitrogen resource. In this study, an adsorption column filled with zeolite modified by 5% HCl rinsing, calcination under 400℃ and subsequent treatment by microwave, was built to investigate the effects of column height（H）, column number（N） and hydraulic retention time（T） on the removal of ammonium nitrogen from phosphorus-removed human urine. Effects of eluting solvents（HCl, NaCl, HCI＋NaCl） on the desorption of ammonium nitrogen adsorbed on the column were also assessed. The adsorption capacity of this modified zeolite was 17.9 mg·g-1, 2.6 times that of natural zeolite（6.9 mg·g-1）. The optimal parameters of the modified zeolite column for removing ammonium nitrogen were 35 cm for H, 2 hours for T, and 3 for N. The concentration of ammonium nitrogen in the effluent was less than 30 mg·L-1 at up to 6370 mg of ammonium nitrogen load in adsorption column. Combination of 10% HC1＋5 g. L-1 NaCl released 88.3% of ammonium nitrogen adsorbed on the modified zeolite. The equilibrium adsorption capacity of the regenerated zeolite was 16.4 mg·g-1, or 91.6% of that of the original modified zeolite. Our results suggest that the modified zeolite could be used to effectively remove ammonium nitrogen from phosphorus-removed human urine and be reused via regenera- tion.