Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ electrochemical impedance spectroscopy

• RED performance and stack resistance were studied by EIS and LSV. • Interface resistance were discriminated from Ohmic resistance by EIS. • Impacts of spacer shadow effect and concentration polarization were analyzed. • Ionic short current reduced the power density for more cell pairs. • The results enabled to predict RED performance with different configurations. Reverse electrodialysis (RED) is an emerging membrane-based technology for the production of renewable energy from mixing waters with different salinities. Herein, the impact of the stack configuration on the Ohmic and non-Ohmic resistances as well as the performance of RED were systematically studied by using in situ electrochemical impedance spectroscopy (EIS). Three different parameters (membrane type, number of cell pairs and spacer design) were controlled. The Ohmic and non-Ohmic resistances were evaluated for RED stacks equipped with two types of commercial membranes (Type I and Type II) supplied by Fujifilm Manufacturing Europe B.V: Type I Fuji membranes displayed higher Ohmic and non-Ohmic resistances than Type II membranes, which was mainly attributed to the difference in fixed charge density. The output power of the stack was observed to decrease with the increasing number of cell pairs mainly due to the increase in ionic shortcut currents. With the reduction in spacer thickness from 750 to 200 µm, the permselectivity of membranes in the stack decreased from 0.86 to 0.79 whereas the energy efficiency losses increased from 31% to 49%. Overall, the output of the present study provides a basis for understanding the impact of stack design on internal losses during the scaling-up of RED.     

Improvement of aquaculture water quality by mixed Bacillus and its effects on microbial community structure

Microbial remediation, especially the application of probiotics, has recently gained popularity in improving water quality and maintaining aquatic animal health. The efficacy and mechanism of mixed Bacillus for improvement of water quality and its effects on aquatic microbial community structure remain unknown. To elucidate these issues, we applied two groups of mixed Bacillus (Bacillus megaterium and Bacillus subtilis (A0?+?BS) and Bacillus megaterium and Bacillus coagulans (A0?+?BC)) to the aquaculture system of Crucian carp. Our results showed that the improvement effect of mixed Bacillus A0?+?BS on water quality was better than that of A0?+?BC, and the NH₄⁺-N, NO₂^?-N, NO₃^?-N, and total phosphorus (TP) concentrations were reduced by 46.3%, 76.3%, 35.6%, and 80.3%, respectively. In addition, both groups of mixed Bacillus increased the diversity of the bacterial community and decreased the diversity of the fungal community. Microbial community analysis showed that mixed Bacillus A0?+?BS increased the relative abundance of bacteria related with nitrogen and phosphorus removal, such as Proteobacteria, Actinobacteria, Comamonas, and Stenotrophomonas, but decreased the relative abundance of pathogenic bacteria (Acinetobacter and Pseudomonas) and fungi (Epicoccum and Fusarium). Redundancy analysis showed that NH₄⁺-N, NO₂^?-N, and TP were the primary environmental factors affecting the microbial community in aquaculture water. PICRUST analysis indicated that all functional pathways in the A0?+?BS group were richer than those in other groups. These results indicated that mixed Bacillus A0?+?BS addition produced good results in reducing nitrogenous and phosphorus compounds and shaped a favorable microbial community structure to further improve water quality.

Graphical abstract

     

省级政府环境治理绩效的组态生成机制研究——基于多重制度逻辑的动态FSQCA分析

省级政府承担着改善地区环境质量,守护一方绿水青山的重任。探究不同制度条件下地方政府环境治理绩效的组态生成机制,对加强生态文明建设,促进人与自然和谐共生的中国式现代化具有重要意义。基于多重制度逻辑理论,本文对30个省级行政区2017—2019年的数据进行了动态的汇总型FSQCA分析。研究发现：单一条件不能构成省级政府环境治理高绩效的必要生成条件;生成省级政府环境治理高绩效的组态机制共有四种,分别为：数据赋能单向机制、市场—法治协同机制、市场—公众协同机制以及政治—数据协同机制。进一步分析表明,在我国不同地区,生成省级政府环境治理高绩效的组态机制具有差异性。     

主余震作用下典型六层RC框架结构易损性分析∗

为研究 RC 框架结构在主余震作用下的易损性，以一典型六层 RC 框架结构为例，基于增量动力分析法和易损性分析，进行不同主余震作用下 RC 框架结构不同性能状态下超越概率的对比分析。选取 10 条满足场地条件的地震记录作为输入，分别以反应谱加速度为强度指标（IM）、最大层间位移角为损伤指标（DM），对 IDA 曲线簇进行分位分析。依据地震强度指标建立概率地震需求模型，并根据已定义的结构性能水准对框架结构进行易损性分析。 结果表明：双向地震和主余震作用相对于单向主震作用都会增加结构的易损性指数；结构在遭遇地震强度 S_a（ T₁， 5%）=0.5g 时，余震造成易损性指数的上限值、平均值和下限值分别增幅 6.3%、8.5%、11.5%；双向地震相对于单向地震造成易损性指数的上限值、平均值和下限值分别增幅 15.5%、20.1%、32.5%。     

Removal of SO2 from flue gas using blast furnace dust as an adsorbent

Environmental Science and Pollution Research - To control the SO2 emission and achieve the target of “waste controlled by waste”, a novel desulfurization method with blast furnace dust...