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Municipal (urban) wastewater treatment creates environmental problems, especially in urban areas where urban waste water and industrial waste water have a common treatment system. The present paper aims at describing a method which facilitates the mixing of resulting sludge with metallurgical coke in the process of iron agglomeration due to the heat input brought about by the combustibles in their composition. This method may be applied to reduce the huge quantities of sewage sludge which results from urban wastewater treatment. Since our work is focused only on sewage sludge use, the first stage of our research included a series of tests which were made on sewage sludge collected from the wastewater treatment plant (WWTP) of Galati to determine their elemental composition in relation to calorific values. As regards the second stage, a series of measurements were made to determine the calorific values of sewage sludge and mixtures of sewage sludge with coke in order to find the optimal proportion to be used in the metallurgical process. On the basis of the results obtained, we suggested two possible situations in which sewage sludge and coke mixtures could be used in the metallurgical process: 1) using sewage sludge in the process of cast iron extraction in the blast furnace and 2) using sewage sludge as raw matter in the process of cast iron production in the blast furnace.The purpose of this study is twofold: 1) to find an alternative for using the sludge resulting from the process of urbanwastewater treatment and 2) to reduce the consumption of coking coal in metallurgical processes. [ABSTRACT FROM AUTHOR]

The aim of this paper is an extended study over 12 months, concerning the nature of sludge obtained from a treatment plant and the possibility of its treatment by combustion. The analysis of structural and morphological characteristics of sewage sludge was performed, by SEM and EDAX techniques. Thermal analyses were performed on sludge samples by DSC and bomb calorimeter techniques. Thermal analyzes were performed both on sludge samples with unmodified composition and sludge samples mixed with metallurgical coke in order to determine the optimal concentration of sludge in coke to be sold as fuel. The concentrations of sludge in the coke ranged from 0.5 to 10 percent. Experimental determination of the calorific content was compared with the calculated value. The incineration method of sewage sludge is possible, but only at lower concentration values than 2% wt. At this concentration, some certain deviations already appear in terms of a complete combustion of organic substances under these circumstances. The calorific content was determined using the bomb calorimeter. [ABSTRACT FROM AUTHOR]

Generally, the polymer materials and the unsaturated polyester resin as a particularization are nonconductive materials considering their thermal properties. In order to improve the thermal properties of polymer materials, they are added with good heating conductive particles. The aim of this paper is to study the influence of a special type of carbon nanotubes, at different concentrations (0,10%; 0,15%; 0,20%), on the thermal properties improving process of a polymer/MWCNT nanocomposite material. In this way, the studies on the influence of an oscillating magnetic field introduction in the obtaining technology of polymer/MWCNT nanocomposite materials are realized. The final target in the technological chain is an improved dispersion of MWCNTs in polymer matrix. In accordance with percolation theory, it was analyzed the contribution of both carbon nanotubes concentration and their dispersion technology to a new nanocomposite material obtaining with improved thermal properties. SEM analysis demonstrates the dispersion of polymer/MWCNT precursor systems correlated with thermal conductivity analysis. Both SEM and thermal conductivity analysis confirms MWCNT optimum concentration in polymer matrix. [ABSTRACT FROM AUTHOR]

Commonly, the polymers are dielectric materials. A method to improve the polymer materials electric properties is the addition of the particles with superior electric parameters into the unsaturated matrix. In this way, multiwall carbon nanotubes (MWCNT) were used, as pristine material. A new dispersion technology of the pristine MWCNT was experimented. In order to relieve physical and chemical processes that induce the improved electrical properties to polymer/MWCNT nanocomposite material, the results obtained for different MWCNT concentrations (0,10%; 0,15%; 0,20%) are comparative presented. MWCNTs optimum dispersion concentration was assessed by a rheological analysis measuring the viscosity of polymer/MWCNT nanocomposite precursor system. The nanoscale effect appeared at carbon nanotubes proximity with concentration increasing and also the technological process contribution is demonstrated by precursor viscosity variation. In this paper, a comparative study of precursor systems viscosity variation at three different concentrations and nanocomposite materials electrical conductivity is presented. The critical analysis of the obtained results demonstrates MWCNT optimum concentration of 0,175%. [ABSTRACT FROM AUTHOR]

Commonly, the polymers are dielectric materials. A method to improve the polymer materials electric properties is the addition of the particles with superior electric parameters into the unsaturated matrix. In this way, multiwall carbon nanotubes (MWCNT) were used, as pristine material. A new dispersion technology of the pristine MWCNT was experimented. In order to relieve physical and chemical processes that induce the improved electrical properties to polymer/MWCNT nanocomposite material, the results obtained for different MWCNT concentrations (0,10%; 0,15%; 0,20%) are comparative presented. MWCNTs optimum dispersion concentration was assessed by a rheological analysis measuring the viscosity of polymer/MWCNT nanocomposite precursor system. The nanoscale effect appeared at carbon nanotubes proximity with concentration increasing and also the technological process contribution is demonstrated by precursor viscosity variation. In this paper, a comparative study of precursor systems viscosity variation at three different concentrations and nanocomposite materials electrical conductivity is presented. The critical analysis of the obtained results demonstrates MWCNT optimum concentration of 0,175%. [ABSTRACT FROM AUTHOR]

A new strategy for nanoparticles dispersion into polymer matrix is described in this work. In order to improve the properties of the polyester composites, multiwall carbon nanotubes were chemically coated by a molecular layer of iron (III) oxide. Following a two phases method that includes energy supply into polymer, an optimum ratio between enthalpy and entropy was obtained. Considering physical-chemical interaction inside the dispersed system, during its evolution from raw material to nanocomposite, different types of energy, harmless for the system but acting in the proper direction for an effective dispersion, were applied. XRF, FTIR and SEM analysis were used to emphasis the effect of oscillating magnetic field on nanoparticles dispersion. Also, the influence of dispersion method on composite properties was discussed. [ABSTRACT FROM AUTHOR]