Electro-assisted CNTs/ceramic flat sheet ultrafiltration membrane for enhanced antifouling and separation performance

• A stable and electroconductive CNTs/ceramic membrane was fabricated. • The membrane with the electro-assistance exhibited optimal fouling mitigation. • The removal efficiency was improved by the -2.0 V electro-assistance. • Electro-assisted filtration is energy-saving than that of commercial membrane. Ultrafiltration is employed as an important process for water treatment and reuse, which is of great significance to alleviate the shortage of water resources. However, it suffers from severe membrane fouling and the trade-off between selectivity and permeability. In this work, a CNTs/ceramic flat sheet ultrafiltration membrane coupled with electro-assistance was developed for improving the antifouling and separation performance. The CNTs/ceramic flat sheet membrane was fabricated by coating cross-linked CNTs on ceramic membrane, featuring a good electroconductivity of 764.75 S/m. In the filtration of natural water, the permeate flux of the membrane with the cell voltage of -2.0 V was 1.8 times higher than that of the membrane without electro-assistance and 5.7-fold greater than that of the PVDF commercial membrane. Benefiting from the electro-assistance, the removal efficiency of the typical antibiotics was improved by 50%. Furthermore, the electro-assisted membrane filtration process showed 70% reduction in energy consumption compared with the filtration process of the commercial membrane. This work offers a feasible approach for membrane fouling mitigation and effluent quality improvement and suggests that the electro-assisted CNTs/ceramic membrane filtration process has great potential in the application of water treatment.     

Removal of tetrachlorobisphenol A and the effects on bacterial communities in a hybrid sequencing biofilm batch reactor-constructed wetland system

SBBR-CW system was proposed to effectively treat wastewater containing TCBPA. CW unit contributed more than SBBR to the removal of TCBPA. TCBPA changed the composition and structure of bacterial community in the system. GAOs massively grew in SBBR, but did not deteriorate TP removal efficiency. Tetrachlorobisphenol A (TCBPA) released into the sewage may cause environmental pollution and health risk to human beings. The objective of this study was to investigate the removal of TCBPA and bacterial community structures in a laboratory-scale hybrid sequencing biofilm batch reactor (SBBR)-constructed wetland (CW) system. The results showed that the removal efficiency of chemical oxidation demand (COD), ammonia, total nitrogen and total phosphorus in the SBBR-CW system was 96.7%, 97.3%, 94.4%, and 88.6%, respectively. At the stable operation stage, the system obtained a 71.7%±1.8% of TCBPA removal efficiency with the influent concentration at 200 mg/L. Illumina MiSeq sequencing of 16S rRNA gene revealed that the presence of TCBPA not only reduced the bacterial diversity in the SBBR-CW system, but also altered the composition and structure of bacterial community. After the addition of TCBPA, Proteobacteria increased from 31.3% to 38.7%, while Acidobacteria and Parcubacteria decreased greatly in the SBBR. In contrast, Acidobacteria replaced Proteobacteria as the dominant phylum in the upper soils of CW. The results indicated that TCBPA stimulated the growth of GAOs in the SBBR without deteriorating the phosphorus removal due to the presence of sufficient carbon sources. The ammonia oxidizing bacteria, Nitrosomonas, and denitrification bacteria, Hyphomicrobium and Pseudomonas, were inhibited by TCBPA, resulting in a decreasing the removal efficiency of TN and ammonia.     

Historical changes in the major and trace elements in the sedimentary records of Lake Qinghai,Qinghai–Tibet Plateau: implications for anthropogenic activities

Environmental Geochemistry and Health - Sediment sequences in Lake Qinghai spanning the past 100 years were explored to assess the effects of changes in local land desertification, dust...     

蟛蜞菊水提液对水华蓝藻——卵孢金孢藻的化感作用研究

为探究陆生植物对水华蓝藻的化感作用,本文采用不同浓度的蟛蜞菊(Wedelia chinensis)水提液对卵孢金孢藻(Chrysosporum ovalisporum)进行了为期6 d的室内培养试验,结果发现:蟛蜞菊水提液对卵孢金孢藻的化感作用总体上呈"低促高抑";当蟛蜞菊水提液浓度大于6 g·L~(-1)时,将显著降低卵孢金孢藻光合作用有效量子效率(YⅡ)、最大量子产量(Fv/Fm)、叶绿素a(Chla)含量和藻细胞生物量(P0.01);当浓度大于8 g·L~(-1)时,单位藻细胞内的超氧化物歧化酶(SOD)、谷胱甘肽-S-转移酶(GST)活性显著高于对照组(P0.05),表明蓝藻细胞受到较强的胁迫作用;透射电镜观察结果表明:高浓度蟛蜞菊水提液会破坏细胞膜,导致藻细胞内的类囊体、羧基体、气囊等超微结构受损,并最终导致藻细胞溶解、藻丝断裂和死亡。此外,本文利用Logisitic模型研究了蟛蜞菊水提液对卵孢金孢藻的半效应浓度(EC50),其24 h、48 h、72 h和144 h的EC50分别为:3.78 g·L~(-1)、4.47 g·L~(-1)、4.72 g·L~(-1)和6.55 g·L~(-1)。本研究为中国湖泊蓝藻水华的防治增添了基础数据和新的技术思路。     

静电除尘器粉尘运动轨迹的数值模拟与分析

为了分析线-管式静电除尘器的流动特性以及粉尘收集过程,建立流场、电场和颗粒动力场的数学模型,利用fluent软件对其进行数值模拟。结果表明:逃逸粉尘平均粒径随工作电压增高呈非线性递减关系,但随入口流速增大基本呈线性递增关系;而粉尘向收尘板偏移趋势随工作电压增高而增强,但随入口流速增大而减弱。     

球团生产及其废气污染控制

球团矿具有良好的冶金性能,与高碱度烧结矿搭配入炉,可改善高炉各项操作指标。近年来,我国钢铁企业对球团矿的需求日益增加,球团建设和产能快速增长,其中以链箅机-回转窑工艺为主,随之带来对环境的污染问题,尤其是对空气污染。介绍球团生产发展状况和其废气污染控制措施。     

山西农田土壤交换性镁含量、分布特征及其与土壤化学性质的关系

采用田间调查与室内分析相结合的方法,研究了山西省农田土壤交换性镁(Mg)含量、分布特征及其与土壤主要化学性质的关系。结果表明,山西省主要农田土壤(0~20 cm)交换性镁含量平均为255.1 mg/kg,变幅为78.1~641.8 mg/kg,其中85%的土壤交换性镁含量在100~400 mg/kg之间,随地区不同而异。土壤剖面(0~100 cm)交换性镁含量为78.1~717 mg/kg,其含量随土壤层次加深呈现出增加的趋势。不同类型土壤交换性镁含量高低依次为潮土>褐土>栗褐土>石灰性褐土>黄绵土>褐土性土。土壤交换性镁含量与土壤pH值、EC值、有机质含量和碱解氮含量呈显著线性正相关,与K/Mg呈显著线性负相关,与全磷含量、速效磷含量、速效钾含量和Ca/Mg呈显著的曲线关系。     

Influence of aeration intensity on the performance of A/O-type sequencing batch MBR system treating azo dye wastewater

Among the numerous parameters affecting the membrane bioreactor (MBR) performance, the aeration intensity is one of the most important factors. In the present investigation, an anoxic/aerobic-type (A/O-type) sequencing batch MBR system, added anoxic process as a pretreatment to improve the biodegradability of azo dye wastewater, was investigated under different aeration intensities and the impact of the aeration intensity on effluent quantity, sludge properties, extracellular polymeric substances (EPS) amount generated as well as the change of permeation flux were examined. Neither lower nor higher aeration intensities could improve A/O-type sequencing batch MBR performances. The results showed 0.15 m³·h^-1 aeration intensity was promising for treatment of azo dye wastewater under the conditions examined. Under this aeration intensity, chemical oxygen demand (COD), ammonium nitrogen and color removal as well as membrane flux amounted to 97.8%, 96.5%, 98.7% and 6.21 L·m^-2·h^-1, respectively. The effluent quality, with 25.0 mg·L^-1COD, 0.84 mg·L^-1 ammonium nitrogen and 8 chroma, could directly meet the reuse standard in China. In the meantime, the sludge relative hydrophobicity, the bound EPS, soluble EPS and EPS amounts contained in the membrane fouling layer were 70.3%, 52.0 mg·g^-1VSS, 38.8 mg·g^-1VSS and 90.8 mg·g^-1VSS, respectively, which showed close relationships to both pollutant removals and membrane flux.     

Integrating Stressor and Response Monitoring into a Resource-Based Water-Quality Assessment Framework

Following a global trend, the new policy goals emphasize the need to protect rather than to use the ability of ecosystems to recover from disturbances. This necessitates the adoption of response measurements to quantify ecological condition and monitor ecological change. Response monitoring focuses on properties that are essential to the sustainability of the ecosystem. These monitoring tools can be used to establish natural ranges of ecological change within ecosystems, as well as to quantify conceptually acceptable and unacceptable ranges of change. Through a framework of biological criteria and biological impairment standards, the results of response monitoring can become an integral part of future water resource management strategies in South Africa.     

防治油气集输过程中烃类污染的主要途径

烃类是油气田主要的大气污染物,主要来源于油气集输过程中的烃类损耗。降低烃类损耗,回收挥发气体,是减少大气污染的重要途径。孤东油田应用大罐抽气、原油稳定、轻烃回收等工艺对烃类进行回收治理,文章介绍了使用的工艺系统,分析了治理技术的经济效益,得出结论：采用大罐抽气、原油稳定和轻烃回收技术防治油气田烃类污染是可行的,技术成熟,工艺较简单,投资少,见效快,效益明显。在油气田全面推广应用,可以大大降低油气田的烃类污染负荷