• Retrofitting from CAS to MBR increased effluent quality and environmental benefits.• Retrofitting from CAS to MBR increased energy consumption but not operating cost.• Retrofitting from CAS to MBR increased the net profit and cost efficiency.• The advantage of MBR is related to the adopted effluent standard.• The techno-economy of MBR improves with stricter effluent standards. While a growing number of wastewater treatment plants (WWTPs) are being retrofitted from the conventional activated sludge (CAS) process to the membrane bioreactor (MBR) process, the debate on the techno-economy of MBR vs. CAS has continued and calls for a thorough assessment based on techno-economic valuation. In this study, we analyzed the operating data of 20 large-scale WWTPs (capacity≥10000 m3/d) and compared their techno-economy before and after the retrofitting from CAS to MBR. Through cost-benefit analysis, we evaluated the net profit by subtracting the operating cost from the environmental benefit (estimated by the shadow price of pollutant removal and water reclamation). After the retrofitting, the removal rate of pollutants increased (e.g., from 89.0% to 93.3% on average for NH3-N), the average energy consumption increased from 0.40 to 0.57 kWh/m3, but the operating cost did not increase significantly. The average marginal environmental benefit increased remarkably (from 0.47 to 0.66 CNY/g for NH3-N removal), leading to an increase in the average net profit from 19.4 to 24.4 CNY/m3. We further scored the technical efficiencies via data envelopment analysis based on non-radial directional distance functions. After the retrofitting, the relative cost efficiency increased from 0.70 to 0.73 (the theoretical maximum is 1), while the relative energy efficiency did not change significantly. The techno-economy is closely related to the effluent standard adopted, particularly when truncating the extra benefit of pollutant removal beyond the standard in economic modeling. The modeling results suggested that MBR is more profitable than CAS given stricter effluent standards. 相似文献
When I read the paper"Electrolytes enriched by potassium perfluorinated sulfonates for lithium metal batteries"from Prof. Jianmin Ma's group, which was published in Science Bulletin (doi.org/10.1016/j.scib.2020.09.018), I felt excited as presented a multi-factor principle for applying potassium perfluorinated sulfonates to suppress the dendrite growth and protect the cathode from the viewpoint of electrolyte additives. The effects of these additives are revealed through experimental results, molecular dynamics simulations and first-principle calculations. Specifically, it involves the influence of additives on Li+ solvation structure, solid electrolyte interphase (SEI), Li growth and nucleation. Following the guidance of the multi-factor principle, every part of the additive molecule should be utilized to regulate electrolytes. This multi-factor principle for electrolyte additive molecule design (EAMD) offers a unique insight on understanding the electrochemical behavior of ion-type electrolyte additives on both the Li metal anode and high-voltage cathode. In these regards, I would be delighted to write a highlight for this innovative work and, hopefully, it may raise more interest in the areas of electrolyte additives. 相似文献
Heteroatom-doped meso/micro-porous carbon materials are conventionally produced by harsh carbonization under an inert atmosphere involving specific precursors, hard/soft templates, and heteroatom-containing agents. Herein, we report a facile synthesis of N and O co-doped meso/micro-porous carbon (NOMC) by template-free carbonization of a small-molecule precursor in a semi-closed system. The semi-closed carbonizaiton process yields hydrophilic NOMCs with large surface area in a high yield. The porous structure as well as the elemental composition of NOMCs can be modulated by changing the holding time at a particular temperature. NOMCs as metal-free heterogeneous catalysts can selectively oxidize benzyl alcohol and its derivatives into aldehydes/ketones with>85%conversion in aqueous solution, which is much higher than that of the control sample obtained in tube furnace (21%conversion), mainly due to their high N content, high percentage of pyridinic N, and large surface area. The presence of O-containing moieties also helps to improve the hydrophilicity and dispersion ability of catalysts and thus facilitates the mass transfer process during aqueous oxidation. The NOMC catalysts also dispayed excellent activity for a wide range of substrates with a selectivity of>99%. 相似文献
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Environmental Science and Pollution Research - The present study, with the aid of GIS, utilizes high-density groundwater (GW) sampling data (1398 samples) to analyze the spatial variation... 相似文献
Environmental Science and Pollution Research - Rapid social development in China has resulted in severe air pollution and adverse impacts on people’s health. Although studies have been... 相似文献
Investors and other stakeholders are starting to pay attention to firms’ carbon emissions and carbon disclosure. This study investigated the effects of voluntary carbon disclosure information and carbon emissions on firm value from listed companies in the Shanghai and Shenzhen 300 (CSI 300) Index. We also apply the Probit model to predict the probability of voluntary carbon disclosure information. The results indicate that the increase in carbon emissions has a negative impact on firm value. The action that companies select to disclose carbon emissions has a positive impact on firm value. The effect of leverage ratio on VCDI is increasing year by year. What is more, the probability of the average size firm carbon disclosure was 30.73% in 2020. Company management needs to pay attention to the risks caused by carbon emissions and ensure the quality of carbon disclosure information, especially the authenticity and reliability of the information.