Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000, Gent, Belgium.
Department of Process Engineering, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Überlandstrasse 133, CH-8600, Dübendorf, Switzerland; Institute of Environmental Engineering, ETH Zürich, Stefano-Franscini-Platz 5, CH-8093, Zürich, Switzerland.
Water Res. 2019 Mar 1;150:349-357. doi: 10.1016/j.watres.2018.11.072. Epub 2018 Nov 30.
Ammonia recovery from urine avoids the need for nitrogen removal through nitrification/denitrification and re-synthesis of ammonia (NH) via the Haber-Bosch process. Previously, we coupled an alkalifying electrochemical cell to a stripping column, and achieved competitive nitrogen removal and energy efficiencies using only electricity as input, compared to other technologies such as conventional column stripping with air. Direct liquid-liquid extraction with a hydrophobic gas membrane could be an alternative to increase nitrogen recovery from urine into the absorbent while minimizing energy requirements, as well as ensuring microbial and micropollutant retention. Here we compared a column with a membrane stripping reactor, each coupled to an electrochemical cell, fed with source-separated urine and operated at 20 A m. Both systems achieved similar nitrogen removal rates, 0.34 ± 0.21 and 0.35 ± 0.08 mol N L d, and removal efficiencies, 45.1 ± 18.4 and 49.0 ± 9.3%, for the column and membrane reactor, respectively. The membrane reactor improved nitrogen recovery to 0.27 ± 0.09 mol N L d (38.7 ± 13.5%) while lowering the operational (electrochemical and pumping) energy to 6.5 kWh kg N recovered, compared to the column reactor, which reached 0.15 ± 0.06 mol N L d (17.2 ± 8.1%) at 13.8 kWh kg N. Increased cell concentrations of an autofluorescent E. coli MG1655 + prpsM spiked in the urine influent were observed in the absorbent of the column stripping reactor after 24 h, but not for the membrane stripping reactor. None of six selected micropollutants spiked in the urine were found in the absorbent of both technologies. Overall, the membrane stripping reactor is preferred as it improved nitrogen recovery with less energy input and generated an E. coli- and micropollutant-free product for potential safe reuse. Nitrogen removal rate and efficiency can be further optimized by increasing the NH vapor pressure gradient and/or membrane surface area.
从尿液中回收氨可避免通过硝化/反硝化和 Haber-Bosch 工艺重新合成氨（NH）来去除氮。以前，我们将一个碱化电化学电池与一个汽提塔耦合，与传统的空气汽提塔等其他技术相比，仅用电作为输入即可实现竞争性的氮去除和能源效率。使用疏水性气体膜进行直接液-液萃取可能是一种替代方法，可以在将氮最小化从尿液中回收进入吸收剂的同时最小化能量需求，同时确保微生物和微污染物的保留。在这里，我们比较了一个带有膜汽提反应器的柱子，每个柱子都与一个电化学电池耦合，用分离的尿液进料，并在 20 A m 下运行。两个系统都实现了类似的氮去除率，分别为 0.34 ± 0.21 和 0.35 ± 0.08 mol N L d，去除效率分别为 45.1 ± 18.4%和 49.0 ± 9.3%，对于柱子和膜反应器。膜反应器将氮回收提高到 0.27 ± 0.09 mol N L d（38.7 ± 13.5%），同时将操作（电化学和泵送）能量降低至 6.5 kWh kg N 恢复，与柱式反应器相比，柱式反应器的氮回收率为 0.15 ± 0.06 mol N L d（17.2 ± 8.1%），能耗为 13.8 kWh kg N。在尿液进料中添加了自荧光 E. coli MG1655 + prpsM 的浓度增加了 24 小时后在柱子汽提反应器的吸收剂中观察到，但在膜汽提反应器中没有观察到。在两种技术的吸收剂中均未发现六种选定的微污染物中的任何一种。总的来说，膜汽提反应器是首选的，因为它可以提高氮回收率，减少能源投入，并为潜在的安全再利用生成不含大肠杆菌和微污染物的产品。通过增加 NH 蒸汽压梯度和/或膜表面积，可以进一步优化氮去除率和效率。
