Knežević Katarina, Reif Daniela, Harasek Michael, Krampe Jörg, Kreuzinger Norbert
Institute for Water Quality and Resource Management, TU Wien, 1040 Vienna, Austria.
Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, 1060 Vienna, Austria.
Membranes (Basel). 2022 Feb 18;12(2):241. doi: 10.3390/membranes12020241.
Electrodialysis (ED) is a promising technology suitable for nutrient recovery from a wide variety of liquid waste streams. For optimal operating conditions, the limiting current density (LCD) has to be determined separately for each treated feed and ED equipment. LCD is most frequently assessed in the NaCl solutions. In this paper, five graphical methods available in literature were reviewed for LCD determination in a series of five feed solutions with different levels of complexity in ion and matrix composition. Wastewater from microbial fermentation was included among the feed solutions, containing charged and uncharged particles. The experiments, running in the batch ED with an online conductivity, temperature, and pH monitoring, were conducted to obtain data for the comparison of various LCD determination methods. The results revealed complements and divergences between the applied LCD methods with increasing feed concentrations and composition complexity. The Cowan and Brown method had the most consistent results for all of the feed solutions. Online conductivity monitoring was linearly correlated with the decreasing ion concentration in the feed solution and corresponding LCD. Therefore, the results obtained in this study can be applied as a base for the automatized dynamic control of the operating current density-voltage in the batch ED. Conductivity alone should not be used for the ED control since LCD depends on the ion exchange membranes, feed flow, temperature and concentration, ionic species, their concentration ratios, and uncharged particles of the feed solution.
电渗析（ED）是一项很有前景的技术，适用于从各种液体废物流中回收养分。为了实现最佳运行条件，必须针对每种处理后的进料和ED设备分别确定极限电流密度（LCD）。LCD最常在NaCl溶液中进行评估。本文回顾了文献中可用的五种图形方法，用于在一系列五种离子和基质组成复杂性不同的进料溶液中测定LCD。进料溶液中包括来自微生物发酵的废水，其中含有带电和不带电的颗粒。实验在具有在线电导率、温度和pH监测功能的间歇式ED中进行，以获取数据用于比较各种LCD测定方法。结果表明，随着进料浓度和组成复杂性的增加，所应用的LCD方法之间存在互补性和差异。对于所有进料溶液，考恩和布朗方法的结果最为一致。在线电导率监测与进料溶液中离子浓度的降低以及相应的LCD呈线性相关。因此，本研究获得的结果可作为间歇式ED中运行电流密度-电压自动动态控制的基础。由于LCD取决于离子交换膜、进料流量、温度和浓度、离子种类、它们的浓度比以及进料溶液中的不带电颗粒，因此电导率不能单独用于ED控制。
