吸收液对中空纤维膜接触器回收尿液中氨氮的影响

采用中空纤维膜接触器（Hollow Fiber Membrane Contactor， HFMC）回收尿液中的氨氮，系统研究了吸收液类型（H₃PO₄、H₂SO₄和HNO₃）对氨回收效能、水蒸气的跨膜通量和所获液体肥料的影响.结果表明，使用H₂SO₄作为吸收液时氨氮回收效能最优，其次是H₃PO₄和HNO₃.当采用H₂SO₄为吸收液时，氨氮回收率、氨跨膜通量和传质系数分别为84.49%±0.01%、22.92 g·m^-2·h^-1和2.37×10^-6 m·s^-1.HNO₃的挥发性使其从吸收液侧反向跨膜至料液侧，导致氨跨膜传质驱动力变小；此外，NH₃和HNO₃会在膜孔中反应并生成NH₄NO₃气溶胶，增加氨在膜孔中的传质阻力，导致氨氮的回收效能降低.对采用不同吸收液时膜两侧的水的活度差和理论水通量进行了计算，结果表明，随着氨氮的不断跨膜吸收，膜两侧的活度差和水通量逐渐增大，实验结束时水通量分别为7.44×10^-2 kg·m^-2·h^-1（H₃PO₄）、9.06×10^-2 kg·m^-2·h^-1（H₂SO₄）和2.00×10^-2 kg·m^-2·h^-1（HNO₃）.肥料组分分析表明，以H₂SO₄和HNO₃为吸收液可以获得仅含N素的单一液体肥料，以H₃PO₄作吸收液可获得N-P复合肥，（NH₄）₂HPO₄和NH₄H₂PO₄所占的比例分别为88.33%和11.67%.

Effect of stripping solution on the recovery of ammonium nitrogen from human urine by hollow fiber membrane contactor

A hollow fiber membrane contactor (HFMC) was used to recover ammonium nitrogen from human urine. The effect of stripping solution on the ammonia recovery efficiency, water vapor transmembrane flux and the obtained liquid fertilizer quality were investigated. The results showed that the best performance of ammonia capture was obtained when using H₂SO₄ as the stripping solution, followed by H₃PO₄ and HNO₃. The ammonia recovery efficiency, transmembrane flux and mass transfer coefficient were 84.49%±0.01%, 22.92 g·m^-2·h^-1 and 2.37×10^-6 m·s^-1, respectively, when using H₂SO₄ as the stripping solution. The reverse mass transfer from the stripping solution side to the feed solution side was observed due to the volatility of HNO₃ with reduced transmembrane driving force of ammonia transfer. In addition, NH₄NO₃ aerosol could be generated by HNO₃ and NH₃ reactions in the membrane pores, increasing the mass transfer resistance and decreasing the ammonium nitrogen capture efficiency. The water activity difference and water vapor transmembrane flux were calculated for different acids as stripping solutions. The results showed that the water activity difference and transmembrane flux gradually increased as ammonia was continuously captured by the stripping solutions with the water fluxes of H₃PO₄, H₂SO₄ and HNO₃ of 7.44×10^-2 kg·m^-2·h^-1, 9.06×10^-2 kg·m^-2·h^-1 and 2.00×10^-2 kg·m^-2·h^-1, respectively at the end of experiments. Liquid single N fertilizer was directly obtained using HNO₃ or H₂SO₄ as stripping solutions, while liquid N-P fertilizer was obtained using H₃PO₄ as the stripping solution with the proportions of (NH₄)₂HPO₄ and NH₄H₂PO₄ were 88.33% and 11.67%, respectively.