Block copolymers derived from 2,2′-azobis(2-cyanopropanol). I. Synthesis of poly(urethane-block-methyl methacrylate) and poly(urethane-block-styrene)

Block copolymers with polyester-urethane and polymethyl methacrylate (PMMA) or polystyrene (PS) sequences were obtained by the use of polyester- or polyether-urethane macroazo initiators (PUMAI). PUMAI with a well-defined number of azo groups per chain were prepared via a two-stage reaction procedure using 2,2′-azobis(2-cyanopropanol) (ACP), 4,4′-methylene diphenyl diisocyanate (MDI) and α, ω-hydroxy polycaprolactone (PCL). The characteristics of the obtained block copolymers depend on the reaction conditions, and a yield of 98% was obtained for a P(U-b-MMA) synthesized with a ratio of macroazo initiator to monomer equal to 1/400. In similar conditions, copolymerization of styrene was more difficult, and the maximum block copolymer yield obtained in this work was only of 37% for a ratio of macroazo initiator to monomer equal to 1/150. Combination of different analyses Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (¹H-NMR), and size exclusion chromatography (SEC) carried out on both crude and fractionated copolymers showed this kind of synthesis yielding di- and triblock copolymers and only a little amount of PU homopolymer. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 613–627, 1998     

反应-共沸-分馏组合法处理醇酮装置酸性废水

探讨了环己醇和环己酮生产中酸性蒸发废水的处理途径,在实验的基础上,确定了反应-共沸-分馏组合法处理醇酮生产中酸性蒸发废水的适宜酯化反应试剂及处理过程的工艺条件。经本法处理后,该酸性蒸发废水的COD值由100000～160000mg／L降至300mg／L以下,COD去除率达到99％以上。采用反应-共沸-分馏组合法处理该酸性蒸发废水的同时,可获取相应的甲酸正丁酯（纯度为97％）或甲酸异戊酯（纯度为96％）。     

Colloidal organic matter from wastewater treatment plant effluents: Characterization and role in metal distribution

Colloidal organic matter from wastewater treatment plants was characterized and examined with respect to its role in metal distribution by using tangential flow ultrafiltration, liquid chromatography coupled with organic carbon and UV detectors, and an asymmetrical flow field-flow fractionation (AFlFFF) multidetection platform. Results revealed that a humic-like fraction of low aromaticity with an average molar mass ranging from 1600 to 2600 Da was the main colloidal component. High molar mass fractions (HMM), with molar mass ranges between 20 and 200 kDa, were present in lower proportions. Ag, Cd, Cu, Cr, Mn and Zn were found mainly in the dissolved phase (<0.45 μm) and their distribution between colloidal and truly dissolved fractions was strongly influenced by the distribution of dissolved organic carbon. AFlFFF coupled to ICP-MS showed that Ag, Cd, Cu, Cr, Mn and Zn associate to the low molar mass fraction of the colloidal pool, whereas Al, Fe and Pb were equally bound to low and high molar mass fractions.     

Size distribution of methylmercury associated with particulate and dissolved organic matter in freshwaters

Water samples were collected from 20 wetland, river and lake sites across Eastern Ontario and Western Quebec to investigate the distribution of methylmercury (MeHg) associated with various size fractions of dissolved organic matter (DOM). Tangential Flow UltraFiltration (TUF) was used to fractionate DOM by nominal molecular size (<0.2 μm, <300 kDa, <30 kDa, <5 kDa and <1 kDa). DOM fluorescence (DOM FL) and absorbance (DOC Abs) were used to quantify DOM photoreactivity and aromaticity in each sample. Significant differences in the size-associated distribution of MeHg, Dissolved Organic Carbon (DOC), DOM FL, and DOM Abs were observed between wetlands, rivers, and lakes. The low molecular weight (LMW) fraction (<5 kDa) in wetlands contained the majority of MeHg (70.0 ± 13.8%), DOC (56.1 ± 9.4%), and DOM FL (77.4 ± 7.5%). DOM FL was also high in the LMW fraction for rivers (60.6 ± 25%) and lakes (75.2 ± 16.9%). Mean MeHg concentrations in the LMW fraction of lakes (41 ± 26 pg L^− 1) and rivers (32 ± 19 pg L^− 1) were substantial but much lower than wetlands. Rivers had the highest percentage of methylmercury (38.0 ± 23.5%) in the particulate (>0.2 µm) fraction. This research highlights the importance of low molecular weight dissolved organic matter in methylmercury fate. For example, a large proportion of MeHg was found in the LMW weight fractions (mean = 47.3 ± 25.4%) of the wetlands, rivers, and lakes in this study.     

Long-term distribution, mobility and plant availability of compost-derived heavy metals in a landfill covering soil

The application of municipal waste compost (MWC) and other organic materials may serve to enhance soil fertility of earthen materials and mine spoils used in land reclamation activities, particularly in the recovery of degraded areas left by exhausted quarries, mines and landfill sites among others. The long-term distribution, mobility and phytoavailability of heavy metals in such anthropogenic soils were studied by collecting soil samples at different depths over a 10 y chronosequence subsequent to amendment of the top layer of a landfill covering soil with a single dose of mechanically-separated MWC. Amendment resulted in a significant enhancement of the metal loadings in the amended topsoils particularly for Cu, Zn and Pb, which were also the predominant metals in the compost utilised. Although metals were predominantly retained in the compost amended soil horizon, with time their vertical distribution resulted in a moderate enrichment of the underlying mineral horizons, not directly influenced by compost amendment. This enrichment generally resulted from the leaching of soluble organo-metal complexes and subsequent adsorption to mineral horizons. However, in the course of the 10-y experimental period, metal concentrations in the underlying horizons generally returned to background concentrations suggesting a potential loss of metals from the soil system. Analysis of the tissues of plants growing spontaneously on the landfill site suggests that metal phytoavailability was limited and generally species-dependent.     

Effective removal of effluent organic matter (EfOM) from bio-treated coking wastewater by a recyclable aminated hyper-cross-linked polymer

Effluent organic matter (EfOM) is a complex matrix of organic substance mainly from bio-treated sewage effluent and is considered as the main constraint to further advanced treatment. Here a recyclable aminated hyper-cross-linked polymeric adsorbent (NDA-802) featured with aminated functional groups, large specific surface area, and sufficient micropore region was synthesized for effective removal of EfOM from the bio-treated coking wastewater (BTCW), and its removal characteristics was investigated. It was found that hydrophobic fraction was the main constituent (64.8% of DOC) in EfOM of BTCW, and the hydrophobic-neutral fraction had the highest SUVA level (7.06 L mg^?1 m^?1), which were significantly different from that in the domestic wastewater. Column adsorption experiments showed that NDA-802 exhibited much higher removal efficiency of EfOM than other polymeric adsorbents D-301, XAD-4, and XAD-7, and the efficiency could be readily sustained according to continuous 28-cycle batch adsorption–regeneration experiments. Moreover, dissolved organic matter (DOM) fractionation and excitation-emission matrix (EEM) fluorescence spectroscopy study indicated that NDA-802 showed attractive adsorption preference as well as high removal efficiency of hydrophobic and aromatic compounds. Possibly ascribed to the presence of functional aminated groups, relatively large specific surface area and micropore region of the unique polymer, NDA-802 possesses high and sustained efficiency for the removal of EfOM, and provides a potential alternative for the advanced treatment.     

Solids accumulation in six full-scale subsurface flow constructed wetlands

In this study, we evaluated the amount of accumulated solids in six different horizontal subsurface flow constructed wetlands (SSF CWs). We also investigated the relationship between accumulated solids and, on one hand, the wastewater quality and load and, on the other hand, the hydraulic conductivity of the granular medium. Aerobic and anaerobic biodegradability tests were also conducted on the accumulated organic matter. Experiments were carried out on full scale wastewater treatment systems consisting of SSF CWs with stabilisation ponds, which are used for the sanitation of small towns in north-eastern Spain. There were more accumulated solids near the inlet of the SSF CWs (3-57 kg dry matter (DM)/m2) than near the outlet (2-12 kgm DM/m2). Annual solids accumulation rates ranged from 0.7 to 14.3 kg DM/m2 year, and a positive relationship was observed between accumulation rates and loading rates. Most of the accumulated solids had a low level of organic matter (<20%). The results of the aerobic and anaerobic tests indicated that the accumulated organic matter was very recalcitrant and difficult to biodegrade. The hydraulic conductivity values were significantly lower near the inlet zone (0-4 m/d) than in the outlet zone (12-200 m/d). Although hydraulic conductivity tended to decrease with increasing solids accumulation, the relationship was not direct. One major conclusion of this study is that the improvement of primary treatment is necessary to avoid rapid clogging of the granular media due to solids accumulation.     

Determination of estrogens and estrogenic activity in wastewater effluent by chemical analysis and the bioluminescent yeast assay

A scheme of bioassay-directed analysis has been developed which combines a yeast assay screening for estrogenic activity with a liquid chromatographic-mass spectrometric (LC-MS/MS) chemical analysis, chromatographic fractionation, solid phase extraction and freeze-drying. The test scheme was applied on effluent samples collected from a municipal sewage treatment plant. The aim was to determine the substances responsible for main portion of the estrogenic activity in the samples and to compare the efficiency of different procedures for isolation and concentration of estogenicity. LC-MS/MS analyses were used for the quantification of 17beta-estradiol, estrone, estriol and 17alpha-ethinylestradiol, and the measured concentrations compared with the activities found in the yeast assay. Following conversion of the concentrations measured by LC-MS/MS to 17beta-estradiol equivalents it was concluded that freeze-drying, solid phase extraction and the chemical analysis gave comparable activities. Since estrone was the major estrogen in the effluent, this estrogen was also the major contributor to the estrogenic activity in the effluent. The estrogenic activity was equivalent to 4-7 ng/L of 17beta-estradiol. The yeast assay results from the tests of the chromatographic fractions showed that the major activity resides in the fraction where estrone, 17beta-estradiol and 17alpha-ethinylestradiol eluted. The activity of this fraction was substantially higher than the activity of the original wastewater sample. The reason for this could in part be explained by an inhibition of activity occurring in the original water sample.     

Effects of soluble and particulate substrate on the carbon and energy footprint of wastewater treatment processes

Most wastewater treatment plants monitor routinely carbonaceous and nitrogenous load parameters in influent and effluent streams, and often in the intermediate steps. COD fractionation discriminates the selective removal of VSS components in different operations, allowing accurate quantification of the energy requirements and mass flows for secondary treatment, sludge digestion, and sedimentation. We analysed the different effects of COD fractions on carbon and energy footprint in a wastewater treatment plant with activated sludge in nutrient removal mode and anaerobic digestion of the sludge with biogas energy recovery. After presenting a simple rational procedure for COD and solids fractions quantification, we use our carbon and energy footprint models to quantify the effects of varying fractions on carbon equivalent flows, process energy demand and recovery. A full-scale real process was modelled with this procedure and the results are reported in terms of energy and carbon footprint. For a given process, the increase of the ratio sCOD/COD increases the energy demand on the aeration reactors, the associated CO₂ direct emission from respiration, and the indirect emission for power generation. Even though it appears as if enhanced primary sedimentation is a carbon and energy footprint mitigation practice, care must be used since the nutrient removal process downstream may suffer from an excessive bCOD removal and an increased mean cell retention time for nutrient removal may be required.     

气分脱丙烷塔的模型建立

以某石化企业12万吨,年气体分馏装置脱丙烷塔为研究对象,采用机理建模与数学验证相结合,根据热力学平衡方程建立模型,并通过Matlab仿真.实验证明,该模型有效地反应了脱丙烷塔的机理特性,可为该装置的进一步研究提供模型支持.