Suchergebnisse

Summarization: The agricultural residues of Crete are considered to be of premium importance for local energy production, substituting a large part of conventional fuels. Future co-firing applications of local lignite and agroresidues may create problems related to the disposal of ashes, which contain harmful constituents. In this regard, the mobility of trace elements from selected lignite and biomass ashes, as well as mixtures of them, was investigated through batch and sequential extraction procedures. In these tests, leaching conditions were aimed at a close approximation to field conditions. The concentrations of heavy metals released in local soil of acidic nature were determined by atomic absorption spectroscopy and were compared to those in the original samples. The results demonstrated that toxic metal ions were released in low quantities, below the legislative limit values, with the exception of Cr extracted from specific lignite/biomass mixtures. This leaching behavior was attributed to the incorporation of the trace elements in the crystal lattice of the soil minerals. A small portion was also captured by carbonates and/or iron oxides of the soil or the ash residue. Biomass ash addition to the lignites' ashes was beneficial, reducing the heavy metal contents of the soil leachates. ; Presented on: Energy and Fuels

Summarization: This study focused on the determination of the toxic metal content of Liquid Crystal Displays (LCDs) present in various Waste Electrical and Electronic Equipment (WEEE). The main objective was the identification and quantification of toxic metals detected in LCD panels. An experimental procedure which involved dismantling, shredding, pulverization, digestion and chemical analysis was followed for the sorting, separation and analysis of LCD monitors from various electronic devices that are currently on the market. Nine selected devices were examined, originated from four different types of e-waste (WEEE); TVs, computers, mobile phones and tablets. Eleven metals were measured in all examined samples. In addition, concentration values of chromium (Cr), cadmium (Cd), lead (Pb) and mercury (Hg) were compared with the respective limits set by the RoHS 2002/95/EC Directive that was recently renewed by the 2012/19/EU recast. The comparison revealed that the examined toxic metals on LCD panels did not exceed the limits set by the European Union (EU). Furthermore, when results were compared to the TTLC regulatory limits it was revealed that in three samples As concentrations were higher than the limit. Finally, when the TCLP test was implemented the aforementioned samples did not exhibit proportionally elevated values in their leachates. ; Presented on: Resources, Conservation and Recycling

Summarization: Considering the enormous production of waste personal computers nowadays, it is obvious that the study of their composition is necessary in order to regulate their management and prevent any environmental contamination caused by their inappropriate disposal. This study aimed at determining the toxic metals content of motherboards (printed circuit boards), monitor glass and monitor plastic housing of two Cathode Ray Tube (CRT) monitors, three Liquid Crystal Display (LCD) monitors, one LCD touch screen monitor and six motherboards, all of which were discarded. In addition, concentrations of chromium (Cr), cadmium (Cd), lead (Pb) and mercury (Hg) were compared with the respective limits set by the RoHS 2002/95/EC Directive, that was recently renewed by the 2012/19/EU recast, in order to verify manufacturers' compliance with the regulation. The research included disassembly, pulverization, digestion and chemical analyses of all the aforementioned devices. The toxic metals content of all samples was determined using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The results demonstrated that concentrations of Pb in motherboards and funnel glass of devices with release dates before 2006, that is when the RoHS Directive came into force, exceeded the permissible limit. In general, except from Pb, higher metal concentrations were detected in motherboards in comparison with plastic housing and glass samples. Finally, the results of this work were encouraging, since concentrations of metals referred in the RoHS Directive were found in lower levels than the legislative limits. ; Presented on: Waste Management