Effects of several different flux enhancing chemicals on filterability and fouling reduction of membrane bioreactor (MBR) mixed liquors

The main objective of this work was to determine the effectiveness of various chemicals on filterability and fouling reduction in MBR mixed liquors. Different lab-scale experiments were conducted with a total of 7 different additives (3 cationic polymers (MPL30, MPE50, KD452), a biopolymer (Chit), a starch (Sta), and 2 metal salts (FeCl₃, PACl)). Initially, batch shaker tests were performed for each additive to determine the optimum dosages in terms of soluble microbial products (SMP) removal. Then, short-term filtration trials and critical flux tests were performed. All tested additives were able to remove SMP, but at different extent; 33, 45, 51, 36, 38, 54, and 56% for MPL30, MPE50, KD452, FeCl₃, PACl, Chit, and Sta, respectively. The cationic polymer KD452 exhibited the best performance in terms of the extent of SMP removal and the required dosage. All tested cationic polymers, starch and chitosan significantly reduced fouling rates and increased permeability values. At their optimum dosages, the cationic polymers MPE50, MPL30 and KD452 provided 96, 80 and 74% reductions in fouling rates, respectively. The enhancements in critical flux achieved by MPL30, MPE50, KD452, FeCl₃, PACl, Chit, and Sta were 38, 46, 38, 14, 14, 0, and 22% in comparison with raw mixed liquor. Cationic polymers increased critical flux values to levels above 50 L m⁻² h⁻¹. SMP removal from MBR mixed liquors and further improvement in filtration performance and fouling control did not always correlate. Overall, based on the lab-scale tests conducted, cationic polymeric additives were found to be favorable over the other additives due to their steady and successful performance in fouling control. The performance of cationic polymers was independent of small variations in dosing, while for other additives over- or under-dosing showed detrimental effects on filterability.     

全氟和多氟化合物环境问题研究

全氟和多氟化合物（PFASs）是一类具有重要应用价值的含氟有机化合物,许多全氟和多氟化合物难以光解、水解和被生物降解,因此具有环境持久性,并可沿食物链累积放大。2009年5月9日,全氟辛烷磺酸（PFOS）及其盐和全氟辛烷磺酰氟被正式列入持久性有机污染物（POPs）名单,由此全氟和多氟化合物成为近年最受关注的新型污染物,其环境问题研究进入到了新的广度和深度。本文将就其分析方法、环境存在、生物累积放大效应、人体暴露和健康效应、新型全氟和多氟化合物等方面的研究,特别是2009年PFOS等被纳入POPs公约以来取得的研究新进展,进行较为全面的综述,并在此基础上对有关发展趋势进行展望。     

生物基化工与材料产业技术的开发与探索

本文阐述了中国石油化工集团公司(中国石化)在生物基化工与材料领域的探索路径和发展战略,介绍了中国石化近年来在生物基单体、生物基材料与可降解材料等领域开展的创新实践及取得的阶段性成果,主要包括乳酸—聚乳酸、丁二酸/二元醇—生物可降解材料、长链二元酸—生物基尼龙以及生物质芳烃—聚对苯二甲酸乙二酯(PET)等技术领域.提出了建立生物基化工与材料科学技术平台、突破关键技术、发展新兴产业等建议.     

An improved method for the simultaneous analysis of phenolic and steroidal estrogens in water and sediment

This paper describes an improved method for the extraction and analysis of seven endocrine disrupting chemicals with wide-ranging polarities from water and sediments using gas chromatography-tandem mass spectrometry (GC-MS/MS). The analytes were 4-tert-octylphenol, 4-nonylphenol, bisphenol A, estrone, 17β-estradiol, 17α-ethynylestradiol and 16α-hydroxyestrone. The optimised GC-MS/MS method produces increased selectivity and sensitivity compared to GC-MS, with limit of detection ranging from 0.01 to 0.49 ng L⁻¹ in water and from 0.05 to 0.14 ng g⁻¹ in sediment. Extraction from aqueous samples was performed by solid-phase extraction (SPE) and from sediment samples by microwave-assisted extraction (MAE). The improved method for the clean-up of sediment extracts carried out by SPE enhanced EDC recovery (86-102%) while reducing matrix interference and sample drying time. Derivatisation of final sample extracts was achieved using N,O-bis(trimethylsilyl)trifluoroacetamide and pyridine, and their stability was enhanced by reconstituting the derivatised extracts with hexane. The method was validated by spiking experiments which showed good recovery and reproducibility. The method was applied to samples taken from the Medway estuary in Kent, UK, where non-conservative behaviour of EDCs was demonstrated.     

A comparison of three analytical techniques for the measurement of steroidal estrogens in environmental water samples

Research into the analysis and monitoring of steroidal estrogens has grown significantly over the last decade, resulting in the emergence of a range of applicable techniques. In this study, three popular techniques, gas chromatography-mass spectrometry (GC-MS), gas chromatography-tandem mass spectrometry (GC-MS-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS) for the analysis of three highly potent steroidal estrogens in the aquatic environment have been compared. It has been observed that overall, the three techniques appear comparable in generating similar estrogen concentrations for river and effluent samples. Of the three techniques, the GC-MS technique is the simplest to operate, but fails to detect the estrogens at the lower-end of environmentally relevant concentrations. The tandem MS techniques are more selective than MS, and therefore able to detect lower concentration levels of the three steroidal estrogens of interest. However, the LC-MS-MS technique is more susceptible to matrix interferences for the analysis of samples, resulting in a reduction of the signal-to-noise ratio and a subsequent reduction in reliability and stability compared to GC-MS-MS. With the GC-MS-MS technique offering increased selectivity, the lowest limits of detection, and no false positive identification, it is recommended to be the preferred analytical technique for routine analysis of estrogens in environmental water samples.     

Comparison of total fluorine, extractable organic fluorine and perfluorinated compounds in the blood of wild and pefluorooctanoate (PFOA)-exposed rats: Evidence for the presence of other organofluorine compounds

The widespread occurrence and environmental persistence of perfluorinated compounds (PFCs) received worldwide attention recently. Exhaustive analysis of all fluorinated compounds in an environmental sample can be daunting because of the constraints in the availability of analytical standards and extraction methods. Combustion ion chromatographic technique for trace fluorine analysis was used to assess the concentrations of known PFCs (e.g., PFOS, PFOA) and total fluorine (TF) in the blood of wild rats collected from Japan. The technique was further validated using tissues from PFOA-exposed rats. Six PFCs (PFOS, PFOSA, PFUnDA, PFDA, PFNA, and PFOA) were detected in all of the wild rat blood samples. Concentrations of extractable organic fluorine (EOF) in fraction 1 (Fr1; MTBE extraction) of wild rats ranged 60.9-134 ng F mL⁻¹, while those in fraction 2 (Fr2; hexane) were below LOQ (32 ng F mL⁻¹); TF concentrations in the blood of wild rats ranged from 59.9-192 ng F mL⁻¹. The contribution of known PFCs in EOF-Fr1 (MTBE) varied from 9% to 89% (56% on average), and known PFC concentrations in TF content were less than 25%. In contrast, TF concentrations in the blood of PFOA-exposed rats ranged from 46900 to 111000 ng F mL⁻¹, with PFOA contributing over 90% of TF. A comparison of results from the samples analyzed in this study and the literature revealed three distinct groups with PFOA/known PFC and TF levels (i.e., wild rats and general population, occupationally exposed workers, and PFOA-exposed laboratory rats). The mass balance analysis of the different forms of fluorine in blood suggested the presence of other forms of organic fluorine in addition to known PFCs.     

Removal of 17β-estradiol by powdered activated carbon—Microfiltraion hybrid process: The effect of PAC deposition on membrane surface

The removal of 17β-estradiol (E2) was investigated in a powdered activated carbon-submerged microfiltration (PAC-MF) hybrid system to better understand the effect on the system performance of PAC deposition on the membrane. A series of experiments were carried out under various operating conditions. Although the rejection or adsorption of E2 by MF membrane itself was almost negligible, the concentration of E2 in the permeate was always lower than it was in the reactor. This is because E2 was further removed as it passed through the PAC layer deposited on the membrane. As the E2 removal efficiency by the deposited PAC was lower than that by the PAC in the bulk phase, the overall E2 removal was largely dependent on the fraction of the deposited PAC on the membrane which were influenced by operating parameters such as permeate flux, hydraulic retention time (HRT) and mixing intensity in a PAC-MF system. The effect of these parameters on the overall E2 removal rate were also determined quantitatively using model equations developed in this study.     

光驱动C1转换到高附加值化学品的研究进展

阐述了光驱动C1化学的最新研究进展,分别对光驱动费托合成、水煤气变换、二氧化碳加氢、甲烷重整和甲醇重整制氢的研究进行了综述,提出了当前研究存在的问题及发展方向.