Characterization and possible uses of ashes from wastewater treatment plants

This work, on the ashes from the wastewater treatment plant of Galindo (Vizcaya, Spain), has been outlined with the purpose of finding their physico-chemical properties and suggesting possible applications. Ashes contain important quantities of iron, calcium, silica, alumina and phosphates. X-Ray diffraction data make it possible to estimate the mineralogical compositions of the original ashes and also, after thermal treatment at 1200 and 1300 degrees C, the main reactions occurring in thermal treatment. Particle size analysis makes it possible to classify ashes as a very fine powdered material. The thermal treatment leads to a densification of the material and provokes losses of weight mainly due to the elimination of water, carbon dioxide and sulphur trioxide. Application tests show that ashes are not suitable for landfill and similar applications, because of their plastic properties. Testing for pozzolanic character, after the ashes had been heated at 1200 degrees C, did not lead to a strong material probably due to low contents in silica and alumina or to requiring a higher heating temperature. Thermal treatment leads to densification of the material with a considerable increase of compressive strength of the probes. The use of additives (clays and powdered glass) to improve ceramic properties of ashes will be the aim of a future work.     

Photostability of methidathion in wet soil amended with biosolid and a surfactant under solar irradiation

Photodegradation studies of the organophosphorous insecticide methidathion in thin layers of wet soil samples have been carried out under solar irradiation. Soil samples consisted of an agricultural soil added with two amendments: a municipal biosolid and the cationic surfactant TDTMA (tetradecyl trimethyl ammonium bromide). Dark controls of the different soil treatments were also considered. Soil and biosolid samples were previously autoclaved to eliminate biotic degradation. In this study we investigated the role of these amendments in methidathion photodegradation which is a rapid (<7 days) and indirect process. Although scarce differences were found between non-amended and amended samples, methidathion from soil exposed under sunlight is degraded more quickly than in dark conditions. Photodegradation products (methidathion oxon GS 13007 and GS 12956) were not detected.     

Monitoring morphological changes along the coast of Huelva (SW Spain) using soft-copy photogrammetry and GIS

This contribution deals with the use of different sources of data (field surveys with total station and GPS, air photographs and topographic maps) as well as their integrated digital treatment in a GIS context to quantify the morphological changes in a ridge of coastal dunes in the southwest of Spain. The results show very high and increm enting rates of foredune retreat significant losses of foredune surface and a clear negative sedimentary balance (lowering and inland migration) in its recent evolution (1979–1996). Two processes can explain this evolution: (1) marine erosion and (2) the reactivation of aeolian deflation. The combined use of GPS (code/phase) and soft-copy photogrammetry seem to provide the best for monitoring future changes.     

Aphid and episodic O3 injury in arugula plants (Eruca sativa Mill) grown in open-top field chambers

Aphid attacks and tropospheric ozone (O₃) cause stress and considerable damage in both wild and cultivated plants. Induced defense responses to aphid attacks and O₃ exposure share signaling pathways with common points. We investigated the plant–aphid interaction under O₃ exposure using open-top O₃ chambers. Ozone leaf injury was lower in aphid-infested plants than in aphid-free plants, although herbivore damage was not evident. Aphid population growth was strongly affected by previous exposure to O₃ but no direct effect of O₃ was observed. The possibility that during O₃ episodes, herbivores may reduce O₃ damage on host plants and that the offspring of the exposed aphids have lower population growth rates opens new and intriguing questions about potential effects of future increased tropospheric O₃ levels on plant–insect interactions.     

Construction and demolition waste as recycled aggregate for environmentally friendly concrete paving

Environmental Science and Pollution Research - Recycled aggregates (RA) from construction and demolition waste (CDW) instead of natural aggregates (NA) were analysed in the manufacture of new...     

Optimal conditions to produce extracts of compost and vermicompost from oil palm and coffee pulp wastes

Journal of Material Cycles and Waste Management - Compost and vermicompost extracts represent an alternative to synthetic fertilizers and pesticides because of their beneficial effects on plants....     

Cyanide treatment of mining tailings using suspended biomass and moving bed biomass reactors

Environmental Science and Pollution Research - Mexico is the top producer of silver and is on the eighth place from producing gold in the world. For instance, the hydrometallurgical extraction...