Center for Microbial Ecology and Technology (CMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Gent, Belgium.
Department d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain.
Environ Sci Technol. 2020 Mar 17;54(6):3618-3627. doi: 10.1021/acs.est.9b06804. Epub 2020 Feb 27.
Source separation of urine can enable nutrient recycling, facilitate wastewater management, and conserve water. Without stabilization of the urine, urea is quickly hydrolyzed into ammonia and (bi)carbonate, causing nutrient loss, clogging of collection systems, ammonia volatilization, and odor nuisance. In this study, electrochemically induced precipitation and stabilization of fresh urine was successfully demonstrated. By recirculating the urine over the cathodic compartment of an electrochemical cell, the pH was increased due to the production of hydroxyl ions at the cathode. The pH increased to 11-12, decreasing calcium and magnesium concentrations by >80%, and minimizing scaling and clogging during downstream processing. At pH 11, urine could be stabilized for one week, while an increase to pH 12 allowed urine storage without urea hydrolysis for >18 months. By a smart selection of membranes [anion exchange membrane (AEM) with a cation exchange membrane (CEM) or a bipolar membrane (BPM)], no chemical input was required in the electrochemical cell and an acidic stream was produced that can be used to periodically rinse the electrochemical cell and toilet. On-site electrochemical treatment, close to the toilet, is a promising new concept to minimize clogging in collection systems by forcing controlled precipitation and to inhibit urea hydrolysis during storage until further treatment in more centralized nutrient recovery plants.
尿液的源头分离可以实现养分的回收、便于废水管理和节约用水。如果尿液未经稳定化处理，尿素会迅速水解为氨和（重）碳酸盐，造成养分流失、收集系统堵塞、氨挥发和异味问题。在这项研究中，成功地展示了电化学诱导沉淀和新鲜尿液的稳定化。通过将尿液在电化学电池的阴极室中循环，阴极产生的氢氧根离子导致 pH 值升高。pH 值增加到 11-12，使钙和镁浓度降低超过 80%，并最大限度地减少了下游处理过程中的结垢和堵塞。在 pH 值为 11 时，尿液可以稳定保存一周，而将 pH 值增加到 12 可以使尿液在无尿素水解的情况下储存超过 18 个月。通过智能选择膜（阴离子交换膜 (AEM) 与阳离子交换膜 (CEM) 或双极膜 (BPM)），电化学电池中无需添加任何化学物质，同时产生酸性流，可以定期冲洗电化学电池和厕所。在厕所附近进行现场电化学处理是一种很有前景的新概念，可以通过强制控制沉淀来最大限度地减少收集系统中的堵塞，并抑制储存过程中的尿素水解，直到在更集中的养分回收厂进行进一步处理。
