Silicon and aluminum in Bulgarian coals

The presence and distribution of Si and Al in 19 Bulgarian coal basins and deposits, belonging to 8 coal provinces, were studied. Coals are of different rank (lignite to anthracite) and age (Late Carboniferous to Pliocene). The presence of both studied major elements depends strongly on: i) their concentration within the basin’s provenance; ii) the extent of terrigenous supply; iii) environmental acidity during peat formation; and iv) the presence and composition of epigenetic mineralization within the coal seams. Because of the presumed abundant terrigenous supply, the concentrations of both Si and Al are higher than the world average for most of the studied coals. Exceptions are the Maritsa-West, Burgas, Staniantsi, Oranovo, Chukurovo and Pernik Basins, for which reduced terrigenous supply can be suggested. For most of the basins, both Si and Al demonstrate good positive correlation with the ash yields, thus arguing for predominant inorganic affinity. Relatively low Si/Al ratios (typically <2) and good positive correlation between Si and Al (ro>0.6) imply the predominant role of the clay mineral assemblages as the main source of the elements in coal. Quartz is presumed to have dominant role only in Maritsa-West Basin. Poorer or negative correlations with the ash yields in part of the studied basins (i.e. Svoge, Maritsa-West, Sofia, Burgas and Dobrudzha Basins) suggest either mixed or predominantly organic affinity of the elements. Release of Si and Al from the clay minerals during the peat formation/diagenesis and subsequent formation of organo-metallic complexes is considered to responsible for such affinity.

Some aspects of the navigation period extension in the North-West Basin of inland waterways of the Russian Federation

The Russian Federation has a developed system of inland waterways (IWW) [1]. This system consists of 15 basins. Winter conditions are very harsh in some basins. Such basins, for example, include the Lena Basin. But in some basins, even in winter, conditions that block navigation do not form. These basins include the Volga-Baltic. However, during the extension of the navigation period in such basins, it should be borne in mind that the navigation safety system will have to be upgraded. This paper discusses some aspects, the introduction of which forms the prerequisites for extension of the navigation period on the waterways of the North-Western region of the Russian Federation. In addition, specific recommendations are provided for the implementation of the necessary automated systems to ensure a sufficient level of navigation in winter conditions on the IWW. These recommendations were obtained within the framework of the international project INFUTURE.

Advanced processed wastewater for different uses: constellations favouring future implementation of a multimodal water reuse concept

Advanced wastewater treatment is often used to produce one single water quality. In recent years, technologies have been developed that allow the production of different qualities that are fit for their purpose. These technology bundles are still not being marketed, and market requirements are unclear. Two constellations in West Basin, California and in Oman were analysed to shed light on the different constellations of actors, resource situations and institutions. The first led to the industrial reuse of several water qualities, while the second produced an application in holiday resorts, leisure and food production. A hypothetical solution was contrasted with an historical case. The analysis of the constellations showed that multi-sectoral investments and dependencies require strong cooperation arrangements and long-term agreements. Governmental institutions were revealed to be suitable for coordinating the process, especially during the initial phase, but also in view of security of supply. A (comparative) examination allows an initial, still provisional systematic overview of other constellations that favour systems with recycled water of different qualities. Further research is required to understand the welfare and distribution effects of multimodal water pricing policies and the feasibility of co-financing of agricultural irrigation and opportunities for more sustainable water reuse.