Department of Civil, Environmental, and Architectural Engineering , University of Colorado Boulder , Boulder , Colorado 80303 , United States.
Department of Civil and Environmental Engineering , University of California , Los Angeles , California 90095 , United States.
Environ Sci Technol. 2018 Aug 7;52(15):8930-8938. doi: 10.1021/acs.est.8b01349. Epub 2018 Jul 10.
Wastewater contains significant amounts of nitrogen that can be recovered and valorized as fertilizers and chemicals. This study presents a new membrane electrode coupled with microbial electrolysis that demonstrates very efficient ammonia recovery from synthetic centrate. The process utilizes the electrical potential across electrodes to drive NH ions toward the hydrophilic nickel top layer on a gas-stripping membrane cathode, which takes advantage of surface pH increase to realize spontaneous NH production and separation. Compared with a control configuration with conventionally separated electrode and hydrophobic membrane, the integrated membrane electrode showed 40% higher NH-N recovery rate (36.2 ± 1.2 gNH-N/m/d) and 11% higher current density. The energy consumption was 1.61 ± 0.03 kWh/kgNH-N, which was 20% lower than the control and 70-90% more efficient than competing electrochemical nitrogen recovery processes (5-12 kWh/kgNH-N). Besides, the negative potential on membrane electrode repelled negatively charged organics and microbes thus reduced fouling. In addition to describing the system's performance, we explored the underlying mechanisms governing the reactions, which confirmed the viability of this process for efficient wastewater-ammonia recovery. Furthermore, the nickel-based membrane electrode showed excellent water entry pressure (∼41 kPa) without leakage, which was much higher than that of PTFE/PDMS-based cathodes (∼1.8 kPa). The membrane electrode also showed superb flexibility (180° bend) and can be easily fabricated at low cost (<20 $/m).
污水中含有大量的氮，可以回收并转化为肥料和化学品。本研究提出了一种新的膜电极与微生物电解相结合，可从合成浓缩物中非常有效地回收氨。该过程利用电极之间的电势将 NH 离子驱动到气体剥离膜阴极的亲水性镍顶层，利用表面 pH 值的增加实现自发的 NH 生产和分离。与传统分离电极和疏水性膜的对照配置相比，集成膜电极显示出 40%更高的 NH-N 回收率（36.2 ± 1.2 gNH-N/m/d）和 11%更高的电流密度。能量消耗为 1.61 ± 0.03 kWh/kgNH-N，比对照低 20%，比竞争电化学氮回收工艺（5-12 kWh/kgNH-N）效率高 70-90%。此外，膜电极上的负电势排斥带负电荷的有机物和微生物，从而减少了结垢。除了描述系统的性能外，我们还探讨了控制反应的基本机制，这证实了该过程在高效废水氨回收方面的可行性。此外，基于镍的膜电极表现出优异的水入口压力（约 41 kPa）而没有泄漏，比基于 PTFE/PDMS 的阴极（约 1.8 kPa）高得多。该膜电极还具有出色的柔韧性（180°弯曲），并且可以以低成本（<20 美元/米）轻松制造。
