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Abstract: Traditionally, the benefits of erosion control projects in Mediterranean watersheds were valued by the replacement cost method (RCM). Nowadays, however, environmental economics has provided alternative methods, such as contingent valuation (CV) and others based on stated preferences, the main strength of which is their capacity to capture non-use and future use values, which are essential for the monetary valuation of erosion. This study uses CV to estimate the externalities associated with watershed restoration and erosion control projects conducted in the Aljibe Basin (Almería, Spain). Comparison shows that CV estimates of net environmental benefits are almost double those obtained using standard methods. Thus, the project meets the profitability criteria in the former case but not in the latter. In concrete terms, the Internal Rates of Return are 5.23% versus 2.25%, respectively. The above shows CV to be a useful tool for estimating the social–environmental return on investment in this kind of project. However, as the experimental phase of this study shows, CV is not without certain issues and limitations, the majority of which derive from its hypothetical nature. Moreover, being preference-based, it may be more coherent with a cost–benefit analysis approach. The RCM, on the other hand, is highly detailed in technical terms and, by using physical data, produces more objective results. The two can therefore be considered complementary rather than competing methods, since they view the valuation from different perspectives. [Copyright &y& Elsevier]

Binderless activated carbon discs for methane adsorption have been prepared by impregnation of olive stones with solutions of ZnCl2, compacting under pressure at 150 and 300°C and heat treatment at 500°C under a flow of nitrogen. The porosity development along the activation process is expected for this precursor; activated carbons with a very small volume of meso- and macropores and a large volume of micropores are obtained when the impregnation ratio is intermediate, XZn=0.30g/g. Since compacting under pressure means a low interparticle space, the disc volume (above 1.2cm3/g) is almost equally distributed between micropores and the carbon skeleton. The methane capacity at 3.4MPa is in the range of 100V/V.Two discs were further activated by reaction under a flow of carbon dioxide. Although such activation implies a decrease in the bulk density because there is an increase in interparticle space (specially when the original disc is very dense), there is a net increase in the volume of micropores, the methane capacity increasing around 10%. [Copyright &y& Elsevier]

Phosphoric acid has been used as activating agent in the preparation of binderless activated carbon discs. The granular precursor was impregnated with different solutions of phosphoric acid, hot pressed in discs, heat treated under a flow of nitrogen and washed with distilled water to extract the excess acid. The role of the impregnation ratio and the temperature of conforming have been analysed. The discs have a bulk density higher than the granular activated carbon because there is a considerable reduction of the interparticle space, the contribution of non-microporous volume being small. The discs exhibit a high volume of microporosity accessible to both nitrogen and methane molecules. Best results (storage capacity of 131, v/v) were obtained when using an impregnation ratio XP=0.35 g phosphorous/g precursor (maximum micropore volume and minimum interparticle space) and conforming at 100 °C (higher temperatures reduce the volume of micropores). Some discs were additionally activated under a flow of carbon dioxide, the maximum methane storage capacity (near 150, v/v) being obtained when burn-off is in the 10–40% range. [Copyright &y& Elsevier]