Influent and effluent quality of municipal wastewater treatment plants play significant roles in selecting the appropriate treatment technologies and influencing the ecology of receiving water bodies. The quality of reclaimed water sources for water reuse can also be determined based on the influent wastewater and treated effluent information. Comprehensive analyses based on statistical data collected from 3340 Chinese municipal wastewater treatment plants were performed so as to better understand the effects of influent and effluent wastewater quality on the treatment performance, environmental concerns and resources utilization. Provincial characteristics of wastewater quality both in quantity and quality were identified, providing valuable information for the proposal of targeted management strategies in pollution control, water reuse and resources recovery. The influents of municipal wastewater treatment plants in north China had high wastewater pollutant loadings, but the effluent was of high quality due to the wide implementation of water reuse strategies in northern water scarcity regions. The potentials for organic and nutrient recovery from the influents were brought forward based on the mass balance. The importance of wastewater as a resource, and the adoption of advanced treatment and resources utilization in the long-term should be highlighted for sustainable water management.
Controlling the duration that information lasts on paper so that it disappears as desired is crucial for information security. However, this area is rarely studied. Here, we report [TEMA]2SbCl5 (1, TEMA+ = methyltriethylammonium), [TEA]2SbCl5 (2, TEA+ = tetraethylammonium), [TEBA]2SbCl5 (3, TEBA+ = benzyltriethylammonium), and [Ph4P]2SbCl5 (4, Ph4P+ = tetraphenylphosphonium) with structure-dependent reversible photoluminescent switching induced by the absorption and thermal release of small guest molecules including H2O, methanol, and ethylene glycol. Comparing the structural disorder levels, bond lengths, and luminescent Stokes shifts of the compounds aided in understanding their selective absorption behavior. Our results indicated that the information duration on the rewritable paper coated with the title compounds is easily tuned by changing the cation of the compounds, the type of guest molecules, and laser heating power. Our study opens previously unidentified avenues for information security and extends the potential applications of rewritable paper.
Industrial production, environmental monitoring, and clinical medicine put forward urgent demands for high-performance gas sensors. Twodimensional (2D) materials are regarded as promising gas-sensing materials owing to their large surface-to-volume ratio, high surface activity, and abundant surfaceactive sites. However, it is still challenging to achieve facilely prepared materials with high sensitivity, fast response, full recovery, and robustness in harsh environments for gas sensing. Here, a combination of experiments and density functional theory (DFT) calculations is performed to explore the application of tellurene in gas sensors. The prepared tellurene nanoflakes via facile liquid-phase exfoliation show an excellent response to NO 2 (25 ppb, 201.8% and 150 ppb, 264.3%) and an ultralow theory detection limit (DL) of 0.214 ppb at room temperature, which is excellent compared to that of most reported 2D materials. Furthermore, tellurene sensors present a fast response (25 ppb, 83 s and 100 ppb, 26 s) and recovery (25 ppb, 458 s and 100 ppb, 290 s). The DFT calculations further clarify the reasons for enhanced electrical conductivity after NO 2 adsorption because of the interfacial electron transfer from tellurene to NO 2 , revealing an underlying explanation for tellurene-based gas sensors. These results indicate that tellurene is eminently promising for detecting NO 2 with superior sensitivity, favorable selectivity, an ultralow DL, fast response-recovery, and high stability.
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