电化学和Bioelectrochemically诱导铵恢复
Summary
We demonstrate the extraction of ammonium from an ammonium-rich stream using an electrochemical and a bioelectrochemical system. The reactor setup, operation and data analysis are discussed.
Abstract
Streams such as urine and manure can contain high levels of ammonium, which could be recovered for reuse in agriculture or chemistry. The extraction of ammonium from an ammonium-rich stream is demonstrated using an electrochemical and a bioelectrochemical system. Both systems are controlled by a potentiostat to either fix the current (for the electrochemical cell) or fix the potential of the working electrode (for the bioelectrochemical cell). In the bioelectrochemical cell, electroactive bacteria catalyze the anodic reaction, whereas in the electrochemical cell the potentiostat applies a higher voltage to produce a current. The current and consequent restoration of the charge balance across the cell allow the transport of cations, such as ammonium, across a cation exchange membrane from the anolyte to the catholyte. The high pH of the catholyte leads to formation of ammonia, which can be stripped from the medium and captured in an acid solution, thus enabling the recovery of a valuable nutrient. The flux of ammonium across the membrane is characterized at different anolyte ammonium concentrations and currents for both the abiotic and biotic reactor systems. Both systems are compared based on current and removal efficiencies for ammonium, as well as the energy input required to drive ammonium transfer across the cation exchange membrane. Finally, a comparative analysis considering key aspects such as reliability, electrode cost, and rate is made.
This video article and protocol provide the necessary information to conduct electrochemical and bioelectrochemical ammonia recovery experiments. The reactor setup for the two cases is explained, as well as the reactor operation. We elaborate on data analysis for both reactor types and on the advantages and disadvantages of bioelectrochemical and electrochemical systems.
Introduction
回收的废水收益的重要性有价值的产品作为宝贵的资源变得稀缺和治疗没有恢复只占成本。废水中含有既节能又可以恢复营养物，和营养恢复可以帮助以关闭生产循环1。恢复通过厌氧消化的能量是一个成熟的过程中，而营养物的回收是不常见的。回收从液体废物流如尿液和粪便的营养物质已被广泛地研究， 例如 ，通过生产鸟粪石和氨2,3的直接汽提的。但是，需要进行化学加成是这些过程4的缺点。这里，我们提出了一种用于阳离子营养素从废物流，包括钾和铵的回收。这些营养成分的阳离子形式允许恢复使用离子选择性膜在电化学系统中。在这种情况下，electrochemic人系统由一个阳极室（其中，氧化发生）的，一个阴极室（其中，减少发生）和离子选择性膜分离的隔室中。一电压跨细胞施加以产生电流从阳极到阴极。该电压可以通过外部电源来驱动水氧化和还原反应来产生。可选择地，阳极氧化， 例如 ，有机物，可以通过电细菌，需要较少的功率催化。以闭合电路并保持电荷平衡，带电物质，必须在电极之间迁移产生的每个电子。从阳极室到跨阳离子交换膜（CEM）阴极室铵传输因此可补偿电子4,5的通量。
这里提出的技术不仅能消除从废物流铵，而且还可以复苏。总氨氮（TAN）中都存在，阿蒙的平衡鎓（NH + 4）和氨（NH 3），并且是依赖于pH和温度6。 NH 4 +是丰富地，由于高TAN浓度及近中性的pH值，在阳极室与该带正电荷的物质可以因此通过在CEM当前被驱入阴极室提供。电流驱动的水在阴极处还原，导致生产氢氧离子和氢气。的TAN平衡转移至接近100％的NH 3，由于高PH值，在阴极室（> 10.0）。 NH 3是可以经由空气流通很容易地传送从汽提单元到吸收塔那里被捕获并集中在酸溶液中的气体。
这种技术具有的N-富状粪便流厌氧消化过程中减少铵毒性的潜力，从而增加从这些废物流能量回收，同时恢复营养素4。铵电化学和生物电化学提取，也可作为具有高TAN含量废物流的营养恢复技术应用，如尿液，从而避免对营养物的去除费用在污水处理厂7。
这里介绍的协议可以作为许多不同的电化学和生物电化学实验的基础，因为我们使用了模块化反应器中。不同类型的电极，膜和框架的厚度可以组合为在下面的协议说明。该协议的主要目的是提供一种用于电化学铵回收和生物电化学铵回收使用的电解池比较的装置。该系统中的提取效率，电源输入和再现性方面进行了评价。
Protocol
Representative Results
Discussion
这份手稿提供了必要的工具，以建立一个生物电化学和回收硫酸铵电化学电池。在结果部分提出了计算系统性能的评价提供参数。生物和电化学系统在设置和功能相似。两个系统之间的主要区别是一个固定的电流，电化学电池相对于一个固定的阳极电势的生物电化学设置的选择。固定电流对非生物的设置是必要的，以驱动电极反应，并允许还允许在本体阶段的处理的调节，从而导致稳态条件。为?…
Divulgazioni
The authors have nothing to disclose.
Acknowledgements
This work was supported by the BOF grant for SG from Ghent University. AL is supported by the Rutgers University NSF Fuels-IGERT. SA is supported by the European Union Framework Programme 7 project “ProEthanol 2G.” SA and KR are supported by Ghent University Multidisciplinary Research Partnership (MRP)—Biotechnology for a sustainable economy (01 MRA 510W). JD is supported by an IOF Advanced grant (F2012/IOF-Advanced/094). KR is supported by by the ERC Starter Grant “Electrotalk”. The authors thank Tim Lacoere for designing the TOC art figure, Robin Declerck for building the strip and absorption columns and Kun Guo for providing the inoculum source.
Materials
| Name of Material/ Equipment | Company | Catalog Number | Comments/Description |
| Carbon Felt 3.18 mm Thick | Alfa Aesar | ALFA43199 | Used as bioanode, 110 mm x 110 mm |
| Ti electrode coated with Ir MMO | Magneto Special Anodes (The Netherlands) | Used as stable anode for electrochemical tests | |
| Stainless steel mesh | Solana (Belgium) | RVS 554/64: material AISI 316L, mesh width: 564 micron, wire thickness: 140 micron, mesh number: 36,6 | Used as cathode, 110 mm x 110 mm |
| Stainless steel plate | Solana (Belgium) | inox 304 sheet, thickness: 0,5mm | Used as current collector for the bioanode |
| Ag/AgCl Reference Electrode | Bio-Logic (France) | A-012167 RE-1B | |
| Potentiostat (VSP Multipotentiostat) | Bio-Logic (France) | ||
| EC Lab | Bio-Logic (France) | software for performing electrochemistry measurements | |
| Cation Exchange Membrane | Membranes International (USA) | Ultrex CMI-7000 | Pretreated according to the manufacturers' instructions |
| Turbulence Promotor mesh | ElectroCell Europe A/S (Tarm, Denmark) | EPC20432-PP-2 | spacer material, 110 mm x 110 mm |
| Connectors | Serto | 1,281,161,120 | Other sizes possible, dependant on tubing type and size of holes in frames |
| Strip and absorption column | In house design | ||
| Tubing | Masterflex | HV-06404-16 | |
| Gas bag | Keika Ventures | Kynar gas bag with Roberts valve | |
| Rashig Rings | Glasatelier Saillart (Belgium) | Raschig rings 4 x 4 mm | Put inside the strip and absorption column to improve the air/liquid contact. Available with many suppliers |
| Rubber sheet | Cut to fit on the perspex frames | ||
| Perspex reactor frames | Vlaeminck, Beernem | In-house design, see tab "reactor frames" in this file |
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