While provision of safe drinking water is considered a basic human right, there are major challenges in the developing world for its provision. The ability to deliver safe water using a cost-appropriate technology is a major aspect of the problem. One of the technologies that has the potential to contribute significantly is the ceramic water filter (CWF); however, as shown herein, there are significant differences between performance of CWFs in the laboratory and in field applications. The CWFs employed in this study (field and laboratory) have a pore fraction of 21.0 -22.4% and an average maximum pore diameter of 5.7 -15.2 μm. Field studies were completed in Longhai City, China, a rural community in southeastern China with red earth, high precipitation and intensive human/ domestic activities. During field trials, CWFs demonstrated an average removal efficiency of 94.7%, with values ranging from 75 -100%, whereas in laboratory studies, average removal efficiency was determined to be 99.5%, with values ranging from 97.7 -99.9%. Differences between the lab and field removal efficiencies are attributed to contamination of the filter element and receptacle by villagers during field utilization and cleaning. Effective technology transfer to the end-user is required to achieve the bacterial removal efficiency attainable by the technology itself.

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It is known that cell potential increases while anode resistance decreases during the start-up of microbial fuel cells (MFCs). Biological capacitance, defined as the apparent capacitance attributed to biological activity including biofilm production, plays a role in this phenomenon. In this research, electrochemical impedance spectroscopy was employed to study anode capacitance and resistance during the start-up period of MFCs so that the role of biological capacitance was revealed in electricity generation by MFCs. It was observed that the anode capacitance ranged from 3.29 to 120 mF which increased by 16.8% to 18-20 times over 10-12 days. Notably, lowering the temperature and arresting biological activity via fixation by 4% para formaldehyde resulted in the decrease of biological capacitance by 16.9 and 62.6%, indicating a negative correlation between anode capacitance and anode resistance of MFCs. Thus, biological capacitance of anode should play an important role in power generation by MFCs. We suggest that MFCs are not only biological reactors and/or electrochemical cells, but also biological capacitors, extending the vision on mechanism exploration of electron transfer, reactor structure design and electrode materials development of MFCs.

The electrocatalytic activities of a series of copper alloys, Cu/Ni/Zn (Cu60Ni15Zn25) and Cu/Zn (Cu62Zn38), toward the reduction of nitrate were investigated, in comparison with that of pure copper. Electrochemical analysis showed that the copper alloy electrode exhibited higher electrochemical reduction rate of nitrate. The extreme difference (R) between the orthogonal experiments revealed that the NO3--N concentration was the main determinant of the removal percentage, followed by the current density and electrolyte concentration, while the impact of the initial pH was minimal. The conditions of the electrolysis experiments with Cu/Ni/Zn and Cu/Zn cathodes were optimized as follows: a current density of 8 mA/cm2, a NaCl concentration of 2.0 g/L, and an initial pH of 3.0. The nitrate reduction reaction process with copper alloy cathodes was confirmed by electrochemical analysis and electrolysis experiments. Therefore, copper alloyed with Zn and Ni is a feasible option for practical application to the electrocatalytic reduction of nitrate. Practitioner points Alloy of Cu, Zn, and Ni improved electrochemical nitrate reduction reaction. Electrochemical reduction of nitrate was confirmed in the presence of NaCl. The optimized current density with copper alloy cathodes was 6 mA/cm2. A feasible strategy was provided for the improving nitrate removal and minimizing by‐products.

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