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Climate warming is expected to drive an upward altitudinal shift of species distributions in mountain areas. In this study, we consider how environmental variables constrain the distribution of freshwater mollusks across elevations based on an extensive survey of the entire Pyrenean range. Results show that several altitude-related variables are significantly relevant for the distribution of all mollusks (i.e., temperature, sediment organic content). Others respond more precisely to some variables: fine substrate proportion increases the probability of finding Pisidium sensu lato (mostly Euglesa species), and the latter, the macrophyte presence, and Ampullaceana balthica. Despite the low acid-neutralizing capacity in many of the lakes, only the distribution of A. balthica was significantly constrained by this factor, independent from elevation. The results confirm a likely altitudinal expansion of the distributions of all species, particularly toward lakes with a summer surface temperature increasing above 12 °C. The pace of change is expected to differ among species according to different nonlinear thresholds in thermal response, which temperature value increases from Pisidium s.l. to Ampullaceana to Ancylus, and the taxon-specific sensitivity to substrates and chemical conditions.

Biogas generated in waste (water) treatment facilities is increasingly regarded as an important source of renewable energy. However, generally, the CH4 content in biogas ranges between 55-70%, depending waste(water) composition, and cannot be applied directly for high grade applications such as gas grid injection or vehicle fuel. Conventional biogas upgrading technologies are only cost-efficient when treating biogas flows exceeding 100 Nm3/h. Therefore, cost-effective external biogas upgrading, to remove H2O, CO2, H2S and other trace impurities, was assumed to pose a major challenge for the further dissemination of small-scale decentralized anaerobic digestion technology. Consequently, an integrated CO2-scrubbing mechanism, denominated as Autogenerative High Pressure Digestion (AHPD) was introduced. Previous work already showed that working pressures up to 90 bar and >95% CH4-content of the biogas are feasible. This work explores the future potential of AHPD by discussing constraints on the requirement of Acid Neutralizing Capacity (ANC), and the role of mineral addition. Although not the main focus of this work, insights on kinetics and population dynamics are used to support the findings. The fact that a continuous AHPD 1.5 m3 reactor is currently in operation brings the technology very close to practice., Water Management, Civil Engineering and Geosciences

Biogas generated in waste (water) treatment facilities is increasingly regarded as an important source of renewable energy. However, generally, the CH4 content in biogas ranges between 55-70%, depending waste(water) composition, and cannot be applied directly for high grade applications such as gas grid injection or vehicle fuel. Conventional biogas upgrading technologies are only cost-efficient when treating biogas flows exceeding 100 Nm3/h. Therefore, cost-effective external biogas upgrading, to remove H2O, CO2, H2S and other trace impurities, was assumed to pose a major challenge for the further dissemination of small-scale decentralized anaerobic digestion technology. Consequently, an integrated CO2-scrubbing mechanism, denominated as Autogenerative High Pressure Digestion (AHPD) was introduced. Previous work already showed that working pressures up to 90 bar and >95% CH4-content of the biogas are feasible. This work explores the future potential of AHPD by discussing constraints on the requirement of Acid Neutralizing Capacity (ANC), and the role of mineral addition. Although not the main focus of this work, insights on kinetics and population dynamics are used to support the findings. The fact that a continuous AHPD 1.5 m3 reactor is currently in operation brings the technology very close to practice., Water Management, Civil Engineering and Geosciences