Evaluation of low-rank coals as raw material for Fe and Ca organomineral fertilizer using a new EDXRF method

A rapid and reliable method for analyzing Fe and Ca in low-rank Greek coals was developed. The presence of Fe and Ca is of importance regarding the potential use of these coals as raw material for organomineral fertilizers. Samples were collected from the main Greek lignite deposits and standards were prepared using Atomic Absorption Spectroscopy (AAS), which were also employed in the Energy Dispersive X-ray Fluorescence (EDXRF) method. The new method offers the advantages of being timesaving, non-destructive and can be easily incorporated in a fertilizer production line. Analysis of low-rank Greek coals demonstrated a significant Fe and Ca content ranging from 0.15 to 1.97 wt.% for Fe and from 0.04 to 2.51 wt.% for Ca. When both EDXRF and AAS techniques were applied, the Fe and Ca concentration values differed less than 5%, demonstrating that both techniques are reliable for low-rank coals in the above concentration range. These EDXRF results may be used as a preliminary test regarding the application of Greek coals in organomineral fertilizer production, given that in these coals iron and calcium are the most abundant metals. © 2008 Elsevier B.V. All rights reserved

Innovative biocatalytic production of soil substrate from green waste compost as a sustainable peat substitute

In the present work, a new simple and quick eco-friendly method is discussed to handle effectively the green wastes and produce a sustainable peat substitute of high quality on the large scale. Principal physicochemical parameters, i.e., temperature, moisture, specific weight, pH, electrical conductivity and, also, microorganisms, organic matter, humic substances, total Kjeldahl nitrogen and total organic carbon, C/N ratio, ash, metal content and phytotoxicity, were monitored systematically. Humic substances content values were interrelated to both C/N ratio and pH values and, similarly, bulk density, TOC, TKN, C/N, GI, ash and organic matter were found interconnected to each other. A novel biocatalyst, extremely rich in soil microorganisms, prepared from compost extracts and peaty lignite, accelerated the biotransformation. Zeolite was also employed. The compost does not demonstrate any phytotoxicity throughout the entire biotransformation process and has increased humic substances content. Both humic substances content and germination index can be employed as maturation indices of the compost. Addition of compost, processed for 60 days only, in cultivations of grass plants led to a significant increase in the stem mass and root size, annotating the significant contribution of the compost to both growth and germination. The product obtained is comparable to peat humus, useful as peat substitute and can be classified as a first class soil conditioner suitable for organic farming. © 2016 Elsevier Lt

Design and Implementation of a Virtual Laboratory for Machine Dynamics

Laboratory experiments are considered to be a crucial component of engineering and science curricula by all stakeholders in the education process. In traditional laboratories, students develop practical skills and become effective professionals. However, the major drawbacks of traditional laboratories are their high demand on resources, significant maintenance costs and the inability to delivery the laboratory content in distance education. Virtual laboratory experiments represent a valuable option for educational laboratories, due to their advantages over traditional hands-on as well as remote experiments, including the ease of reconfiguring the experimental system, the high flexibility in the input specifications, the possibility of conducting experiments using devices otherwise infeasible and the option of re-running experiments multiple times. In response to the need for developing laboratory resources that provide a practical experience to online engineering students, this paper describes a simulation-based virtual laboratory, which is used at Stevens Institute of Technology (SIT) in a junior-level course on mechanisms and machine dynamics as a compliment to experimental work in the traditional hands-on laboratory. This virtual laboratory system alleviates the space, time and cost constraints associated with traditional laboratories and serves as an efficient teaching aid. It conveys to the students practical issues associated with actual experiments and provides learning outcomes that are comparable to those of traditional physical laboratories. The students have the opportunity to explore a wide range of experimental configurations and parameters. In addition, the system includes a realistic rendering of the experimental setup and its components, thus providing the students with a strong feeling of immersion, as if they were performing an experiment in a traditional laboratory

Dispersion and sorption of oil spills by emulsifier-modified expanded perlite

Three grain sizes of expanded perlite were modified with emulsifiers and their potential usefulness in combating oil spills was studied. The tests in the laboratory show that when this perlite is added to a water-oil mixture, the light perlite particles move on the surface spreading over it very quickly (in fractions of a second). It seems that the emulsifier disperses the oil, but at the same time it disperses the perlite particles. At the end there is an emulsion and also perlite particles saturated with it. The usefulness in combating oil spills at sea depends on the following characteristics: (a) With emulsifier-modified perlite some of the oil can be removed (in the form of emulsion), whereas with emulsifiers only this is not possible. Simultaneously the spill is dispersed quickly, before spreading. (b) The action is quick even with a calm sea. Self-mixing is inherent to the process. (c) The action is quick and limited to the surface, where the perlite particles float. There is little waste of the emulsifier in the bulk of the sea. © 2002 Elsevier Ltd. All rights reserved