Issue 1 [March]( Issue on Solid Waste Management )Editorial Investigating the properties of plastic resin pellets found in the coastal areas of Lesvos IslandKarapanagioti H.K. and Klontza I., Pages:71-76 DOI: https://doi.org/10.30955/gnj.000411Paper Topic: General Issue: Issue 1Get Full Paper AbstractPlastic pellets (small granules, 1-5 millimeters in diameter) are widely distributed in the ocean and coastal zones all over the world. They are an industrial raw material for the plastic industry and are unintentionally released to the environment both during manufacturing and transport. These pellets are highly persistent and because of their hydrophobic nature they have being identified as carriers of toxic chemicals in the marine environment. Several marine organisms accumulate plastic particles in their stomach. A positive correlation between the mass of ingested plastic and PCBs in fat tissues has been documented. Also, plastic pellets are proposed as indicators of organic pollution in the sea. However, the sorption mechanisms of organic contaminants onto plastic pellets are not yet well understood. For this reason we collected such pellets from various beaches in Lesvos island. Since this material is highly heterogeneous we also obtained, from plastic manufacturers, virgin pellets made from polyethylene and polypropylene. Phenanthrene was used as the model sorbate. It is a compound with high toxicity and abundance in the environment and relatively easy to use in the laboratory. Also, there are many publications dealing with phenanthrene sorption onto different materials and our results are easily compared with previous research. Batch experiments were performed to determine the sorption kinetics of the pellets. Factors under investigation included pellet material, degree of pellet erosion, and sorption kinetic behavior. All of the five beaches in Lesvos island investigated had plastic pellets on the sand surface. All of these plastic pellets were eroded and 2/3 of them had similar appearance to virgin polyethylene pellets obtained from plastic manufacturers. Pellet color is not indicative of erosion that will lead to varying sorption kinetic behavior. Pellet density could not be used to identify pellets sampled from the beach. Apparent sorption coefficient increases with time for all pellets investigated. Thus, sorption into plastic pellets is limited by diffusion in the polymer phase. 2/3 of the plastic eroded pellets demonstrate sorption kinetics similar to virgin polyethylene pellets after 38 days. Slag and ash chemistry after high-calcium lignite combustion in a pulverized coal-fired power plantPapastergios G., Fernandez –Turiel J.L., Georgakopoulos A. and Gimeno D., Pages:77-82 DOI: https://doi.org/10.30955/gnj.000358Paper Topic: General Issue: Issue 1Get Full Paper AbstractMore than 73% of the electrical power requirements of Greece are generated in lignite-fired power plants. Greece is the thirteenth largest coal and the fifth largest lignite producer in the world. The lack of domestic high-rank coals makes necessary to use low quality lignite for power generation in Greece. These lignites are characterized by a high water and ash content and a low calorific value. The low quality of such lignites generates important technical and environmental problems during combustion. Slagging and fouling are common inside the power units and affect with particular severity the power plants performance. Slagging deposits take place in the high temperature radiant sections of the boiler, and are usually associated with some degree of melting of the ash. Fouling deposits are produced in the lower temperature convective sections of the boiler, and are generally related to condensation on the low temperature tube surfaces. Problems in boilers associated with ash deposits include modification of the heat transfer in different sections of the furnace, physical distortion of metal pieces due to the weight of the deposit, clogging of burners, and corrosion and erosion of metal walls. Feed lignite always carries more than 20% of inorganic matter, and its mineralogy and chemistry are originally related to geological factors. Five representative samples were collected from the inner surfaces of Unit 1 of the Agios Dimitrios Power Plant, Northern Greece, reflecting the main types of ash deposits occurring in the combustion facility. The chemistry of these high-calcium ash deposits has been investigated. Moreover, a fly ash and a bottom ash samples were taken and analyzed in order to investigate their possible impact on the environment after land-filling. All samples were digested by using 2.5 ml HNO3, 5ml HF and 2.5 ml HClO4 (1:2:1). Sixty element concentrations were determined in all samples by inductively coupled plasma–mass spectrometry (ICP–MS) and inductively coupled plasma – optical emission spectrometry (ICP-OES). Calcium is the most abundant element in all samples due to the dominance of calcium phases. The chemical composition of the bottom ash, fly ash, slag and fouling deposits, is mainly influenced by the chemical composition of the feed lignite and the co-excavated sterile materials, which are marly limestones containing, on average, 93% of calcite. Pages« first ‹ previous 1 2
