The Haber–Bosch (HB) process has provided most of commercial ammonia at the expense of high energy consumption and high CO2 emission. Nitrate electroreduction is showing great potential as an alternative route for the green and scale-up synthesis of ammonia at ambient conditions. However, the performance has lagged due to lack of efficient electrocatalysts. In this work, we present the facile synthesis of uniform Cu nanodisks with exposed (111) facets as highly active electrocatalyst for electrochemical ammonia synthesis, delivering a high ammonia yield of 2.16 mg mg–1 cat h–1 and a maximum Faradaic efficiency of 81.1% at −0.5 V versus a reversible hydrogen electrode (RHE). The remarkable activity is originated from the surface reconstructed triatomic Cu clusters due to the cathodic deoxygenation process. As a result, the reconstructed surface shows enhanced affinity to the adsorption of nitrate ions which undergo successive break of three N–O bonds, followed by subsequent formation of three N–H bonds to finally form NH3. The present study provides the feasible preparation of Cu based advanced catalysts and a unique insight into the mechanism of nitrate electroreduction.

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This paper investigates the comprehensive assessment of water quality, which is generally a multi-attribute assessment problem. In this context, the grey relational analysis is adopted to settle the no uniformity problem of water quality attributes. The principal component analysis is applied to calculate the weighting values corresponding to various attributes of water quality so that their relative importance can be properly and objectively described. Results of study reveal that grey relational analysis coupled with principal component analysis can effectively solve the multi-attribute water quality assessment. The method is universal and can be a useful tool to improve the comprehensive assessment of water quality.

Struvite (MgNH4PO4∙6H2O) is an insoluble double salt. It can precipitate in places such as pipes, aerators and pumps, which could lead to substantial problems influencing the normal operation of wastewater treatment equipments. At present, removal of ammonium nitrogen from various wastewaters by the formation of struvite has been widely investigated. This paper reviewed the research and application efforts concerning the treatment of ammonium nitrogen by struvite precipitation, which were obtained at home and abroad in recent years. The mechanism and influence factors of struvite precipitation for ammonium nitrogen removal were discussed. Additionally, the problems that still should be resolved and the research directions in future were pointed out.

BCM (Biology Cilium Magnetic) technology is a kind of municipal wastewater advanced treatment technology. By using high elastic cilia filler in the oxygen unit, the volume loading of oxygen unit has been greatly increased, and more solubility pollutants could be removed in the oxygen unit. The total phosphorus and suspended substance are deeply removed by magnetic separation coagulation system. The effect of BCM technology is that all pollutants indexes could reach to the first level A standard of GB18918-2002. BCM technology is suitable for AA/O, oxidation ditch and SBR process which needs to be upgraded from the first level B to the first level A standard. The high elastic cilia filler in oxygen unit doesn’t require extra land and extra air. The magnetic separation coagulation system only needs very small land. So BCM technology is suitable for municipal wastewater treatment in China.