The use of different organic carbon sources in the denitrification of wastewater containing 2500 mg nitrates/L in a SBR was studied. Three alternative sources of carbon were tested: wastewater from a sweet factory, a residue from a soft drinks factory and a residue from a dairy plant. The first two are sugar rich, whereas the third presents a high content in lactic acid. Maximum specific denitrification rates of between 42 and 48 mg NO 3 -N/g VSS·h were obtained. The effluents were nitrate free and very low COD concentrations were obtained in 4-6 hours reaction time, especially with the sugar-rich carbon sources. The values of the denitrifier net yield coefficient were higher than when using methanol (0.93-1.75 g VSS formed /g NOx-N reduced ). The lowest value was obtained using the lactic acid-rich residue. The optimum COD/N ratios varied between 4.6 for the lactic acid-rich carbon source and 5.5 -6.5 for the sugar-rich carbon sources.

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This paper analyses six strategies for managing the MSW generated in Asturias (Spain) in terms of their environmental impacts applying the Life Cycle Analysis methodology.To this end, the effect of these strategies on Human Health, Ecosystem Quality, GlobalWarming and Resource Depletion is studied. The analysed management options include direct landfill with recovery of biogas (S-0), direct incineration with energy recovery (S-1), biomethanization of the source-separated organic fraction with direct incineration of the mixed fraction (S-2), biomethanization of the source-separated organic fraction, sorting of the mixed fraction and incineration of the rejected fraction (S-3), biomethanization of the source-separated organic fraction, sorting of the mixed fraction and incineration of the rejected fraction following aerobic stabilization of the organic fraction (S-4 ) and biomethanization of the source-separated organic fraction, sorting of the mixed fraction and landfill of the rejected following aerobic stabilization of the organic fraction (S-5). The Consortium for Waste Management (COGERSA) provide data regarding on transport and collection of waste and consumption of energy, water, oil and reagents at each processes. The results obtained suggest that Scenario S-3 has the least impact on the analysed damage categories while the scenarios including landfilling produces the greatest impact in all the categories analysed. Regarding involved processes in studied scenarios, the transport produces a significant impact in the environment, biomethanization contributes to reducing the impact in all the damage categories and incineration adversely affects the categories of Human Health and Climate Change, but helps to reduce damage in the Resources category. M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT NUMBER OF WORDS INCLUDING REFERENCES,

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