Suchergebnisse

Summarization: Chromium is a controversial element, since it has been classified as essential trace element, to chemically and biologically inert compound, to potent intoxicator. Concerns have been risen for chromium effects on human and aquatic life because chromium has been accused for genotoxicity and carcinogenesis. Metals and their ions or complexes (and thus chromium substances) are included in the indicative list of main pollutants (Annex VIII of the Water Framework Directive (2000/60/EC)). Biological effects of chromium are strongly depended on chromium speciation. No universal CrIII or CrVI discharge limits to the aquatic environment have been suggested by the EU. International bodies within the EU, such as the Helsinki Commission and the Oslo-Paris Convention, have issued recommendations on chromium discharge levels. National CrVI and CrIII discharge limits vary in each EU Member State with respect to the receiving water body (marine water, lake, river, sewer system). The maximum discharge limit to the aquatic environment in EU is 1 and 5 mg L−1 for CrVI and Crtotal, respectively. The present work summarizes EU legislation, with respect to the discharge limits to the aquatic environment for CrVI and CrIII. EU national limits that are currently effective are presented and compared to the limits in other parts of the world, such as Australia, Asia, USA, Latin America and South Africa. It is wise that future perspective of chromium policy should differentiate between CrIII and CrVI discharge limits to the aquatic environment, as analytical techniques become more sensitive and chromium speciation specific, and environmental awareness rises. ; Presented on:

Summarization: The Greek regions of Crete and of the Aegean Islands are of the southernmost river basin districts (RBDs) of the European Union. They both have limited water resources, and water demand often surpasses water availability. The geographical fractionation, particularly for the region of the Aegean Islands, is a major constrain for the implementation of an integrated water management plan. This article aims at presenting the current status of water resources in the above regions, and the existing water management plans. The article summarizes the pressures on the water resources of the above geographical regions, and investigates the possibility for utilization of nonconventional water resources, like desalinated seawater, reclaimed wastewater and brackish water. One of the conclusions among others is that the development of novel processes on water resources management should be one of the primary aims of any integrated water management plan. ; Παρουσιάστηκε στο: Desalination

Summarization: Landfill Gas (LFG) is a renewable energy resource. LFG quality and production rate are determined factors for the selection of the optimal technology for electric energy production. Environmental legislation, flue gas emissions, carbon footprint and maturity of technology should also be considered. The most common process for electric energy production from LFG is by Internal Combustion Engines (ICEs), which require approximately 40% minimum methane concentration. Microturbines have been also employed for electric energy production from LFG, requiring minimum methane concentration of approximately 35%. On the other hand, a relatively novel process, Gradual Oxidation (GO), can produce electric energy from LFG at methane concentrations as low as 1.5%. The present study examines the applicability of the above technologies for electric energy production from LFG, from various cells, at the landfill of Heraklion, Crete, Greece, from an economic point of view. The LandGEM (EPA) simulation model has been modified to account for the long them reduction of methane concentration in LFG, and has been adjusted, based on field measurements. The Net Present Values (NPVs) (for 15-years and 25-years from installation) for three distinct scenarios, with total electric energy production capacity of 800 kW, per scenario (using just ICEs, combination of ICE and GO or just microturbines), were calculated. The results indicated that the most profitable scenario (among the ones studied) was the one with the use of two microturbines with capacity 400 kW, each, yielding 15-years and 25-yeasr NPVs of 2.68 and 3.69 M€, respectively, for initial capital investment of 2.24 M€. ; Presented on: Chemosphere