Effect of seed coat fragments on cotton yarn structure: impact of fragment size,attached fibres and position within yarn core

Seed coat fragments are a major source of cotton yarn imperfections. This article discusses the factors influencing the disruption caused by seed coat fragments in ring-spun yarn structure with a focus on three characteristics: the fragment's size, the amount of fibres attached to it and its position relative to the yarn core. The three characteristics were investigated through two experiments involving various types of yarn defects and a range of ring-spun yarn counts. Results presented in this article indicate that the three factors considered have a significant influence on the intensity of the disruption the seed coat fragment causes in the yarn structure, and are determinant of the type of defect that this disruption engenders (short/long defect).     

多杂质用水网络设计方法的改进与比较

通过引入分配因子和最小限制流量对多杂质用水网络超结构模型进行改进,使模型更简捷高效;在逐步线性规划法中引入改进的超结构模型,提供了用水过程的排序依据,可代替枚举法直接排序,提高了求解效率。通过实例比较了改进前后的两种设计方法,找出了它们之间的优势和劣势,结果表明,本文的改进策略可以快速和准确地解决多杂质用水网络设计问题。     

Contaminant transport with adsorption and their inverse problems

In Constales et al. (water Resources Res. 39(30), 1303, 2003) dual-well tests are used to reconstruct the flow and dispersion parameters in contaminant transport. A tracer is introduced by the injection well, which is considered to be in steady-state regime with the extraction well. Then, from measurements of the time evolution of the extracted tracer (breakthrough curve) the required model data has been recovered. In Constales et al. (water Resources Res. 39(30), 1303, 2003), a very precise numerical method has been developed for the solution of the direct problem. In Kačur et al. (Comput. Meth. Appl. Mech. Engo. 194(2–5), 479–489, 2005); Remešiková (J. Comp. Appl. Math. 169(1), 101–116, 2004) an extension has been discussed which adds adsorption terms to the model. The inverse problem of determination of sorption isotherms in nonequilibrium mode was solved by a Levenberg–Marquardt iteration method. In the present paper we develop the adjoint system to evaluate the sensitivity of the solution (via the breakthrough curve) on the sorption parameters in equilibrium and nonequilibrium modes. Possible use of the adjoint system in determining the several parameters occuring in the model is a crucial point for iteration methods. The obtained model parameters then can be used in a 3D flow and transport model with adsorption. The numerical experiments we present, justify the used method.     

Effect of Sediment on the Biodegradation of Petroleum Contaminants in Natural Water

Biodegradation of petroleum contaminants in natural water was studied within an Asian river context where high-suspended sediment content exists. Petroleum contaminant is one of the main pollutants in the Yellow River; at the same time, there is a high sediment content in the river system. This research highlighted the effect of sediment on the biodegradation of petroleum contaminants, as well as the related mechanisms regarding the effect. Biodegradation of petroleum contaminants was studied under different sediment contents. The distribution of petroleum contaminants in water and sediment phases as well as the relevant biodegradation kinetics were also investigated. The results showed that in water system with the sediment content of 0.5 g/L, about 84% of petroleum contaminants with the initial concentration of 11.64 mg/L could be degraded after incubation for 63 days at 20°C. It was also indicated that the presence of sediment exerted significant influences on the biodegradation of petroleum contaminants in water system, and the influences were different from one cultivation stage to another. In the first stage, the biodegradation rate was higher in the water system with sediment than in that without sediment. In the second stage, the biodegradation rate was lower in the former than in the latter. In the last stage, the biodegradation rate was higher in the water system with sediment than in that without sediment. The presence of sediment could stimulate the growth of petroleum contaminant-degrading bacteria. Moreover, about 90% of the contaminants and bacteria were attached on the sediment. The sorbed contaminants on sediment could also be biodegraded by bacteria. The biodegradation of contaminants in water and sediment phases all fit well with the first-order kinetics, and the biodegradation rate constant in water phase was higher than that in sediment phase. However, as the contaminant concentration at the sediment phase was much higher than that in water phase, the biodegradation of petroleum contaminants mainly occurred at the sediment phase.     

Phytoremediation: the state of rhizosphere ‘engineering’ for accelerated rhizodegradation of xenobiotic contaminants

Phytoremediation has emerged as the method of choice for cleaning up a broad range of environmental contaminants. One process through which plants render some xenobiotic organic contaminants innocuous in soil involves plant–microbe interactions in which root exudates stimulate entire microbial communities, or induce specific enzymes in competent individuals to cause enhanced rhizodegradation. For some contaminants these inherent processes can be slow; however, potentials exist for their improvement through rhizosphere manipulations. Although this requires a greater understanding than currently exists with respect to plant and microbe components and interactions involved in the biodegradation of xenobiotic contaminants, improved understanding is being achieved by advances in biochemical and molecular characterization, and visualization of rhizosphere phenomena. In combination with earlier knowledge of naturally‐occurring plant–microbe interactions such as the opine concept, this new knowledge considerably improves the opportunities for manipulating rhizosphere interactions to greatly accelerate rhizodegradation for routine practical implementation in the field. Copyright © 2007 Society of Chemical Industry     

Removal of contaminants from recirculated white water by ultrafiltration and/or biological treatment

This study investigated the potential of ultrafiltration technology and/or biological treatment to remove contaminants such as total dissolved solids (TDS), chemical oxygen demand (COD), total organic carbon (TOC), and resin and fatty acids (RFAs) from recirculated white water. Batch ultrafiltration experiments indicated that TDS, soluble COD, and TOC removal efficiencies were affected by membrane molecular weight (molar mass) cut-off, but were independent of the operating temperature, in the 20 to 60°C range. Except for fatty acids, where average removals exceeded 90%, the separation efficiency of the process for all other parameters (TDS, soluble COD, TOC, and resin acids) was moderate, ranging from 10 to 41%. Biological treatment using a sequencing batch reactor (SBR) unit was very effective in removing RFAs, TOC, total and soluble COD. Furthermore, ultrafiltration of the biologically treated process water resulted in significant additional TDS, soluble COD, and TOC removal.     

氢基质生物膜反应器在饮用水处理中的研究进展

该文对氢基质生物膜反应器(MBf R)的作用机理、特性以及对饮用水中氧化性污染物的去除可行性进行了论述,并对国内外利用该技术去除饮用水中常见氧化性污染物(如:重金属离子:重铬酸盐、砷酸盐、硒酸盐等;无机阴离子:硝酸盐、溴酸盐、高氯酸盐;卤代有机化合物:对氯硝基苯、三氯乙烷、三氯乙烯、氯仿)的研究现状进行了总结。最后指出了MBf R研究中存在的问题以及在工程应用上的现状和发展前景。     

The Impact of PAHs Contamination on the Physicochemical Properties and Microbiological Activity of Industrial Soils

The aim of this article is the study of the potential relationships between PAHs contamination, physicochemical parameters, and microbial activity in industrial soils. The research was based on two series of measurements. The first was conducted in June 2013 and the second in November 2013. Samples used in study were collected from the area of fuel handling and a loading station, located in the Silesia region of Poland. All collected samples were characterized by the following analytical procedures: PAHs content analysis, the basic physical and chemical parameters determinations (pH, CEC, humic acids content, TC, TN, TP) and microbial activity analysis. The obtained results were also subjected to statistical analysis, based on the Pearson's correlation coefficient calculations.

Results collected during described above procedure show that: the PAHs content was highly positively correlated with C and N contents (p < 0.001) and moderately correlated with humic acids and P contents (p < 0.01). This phenomenon confirms the thesis that the increase of soil organic matter content promotes accumulation of hydrophobic organic compounds such as PAHs. Microbiological analysis shows that bacteria from the mesophilic group are most resistant to PAHs contamination. This information indicates that the organisms belonging to this group should be considered as potentially useful in the soil bioremediation processes.