: This paper presents fundamental and theoretical aspects of biological waste gas treatment technologies as well as examples of applications to di †erent compounds. The three most widely used technologies are described, namely bioÐltration, bioscrubbing and trickling bioÐltration, focusing more extensively on bioÐltration which is the most studied and most extensively used process. A description of the di †erent technologies from technological and economic points of view, including an analysis of models used in waste gas biotreatment is given. Results presented in the literature concerning the removal of aliphatic, aromatic and mixtures of contaminants are reviewed. Carrier materials, inocula selected and alternatives proposed for regulating moisture content, pH values or for controlling pressure drop are considered. New technologies and reactor design studied at laboratory-scale are mentioned.1998 SCI (

No abstract

This paper presents fundamental and theoretical aspects of biological waste gas treatment technologies as well as examples of applications to di †erent compounds. The three most widely used technologies are described, namely bio-Ðltration, bioscrubbing and trickling bioÐltration, focusing more extensively on bioÐltration which is the most studied and most extensively used process. A description of the di †erent technologies from technological and economic points of view, including an analysis of models used in waste gas biotreatment is given. Results presented in the literature concerning the removal of aliphatic, aromatic and mixtures of contaminants are reviewed. Carrier materials, inocula selected and alternatives proposed for regulating moisture content, pH values or for controlling pressure drop are considered. New technologies and reactor design studied at laboratory-scale are mentioned.1998 SCI (

Betaine, also known as N,N,N-trimethyl glycine, is a soluble nitrogenous compound present at signi®cant concentrations in sugar-beet molasses. Molasses is used as substrate in a wide range of industrial fermentations, for example, alcohol, acid and yeast cell production. Betaine is not consumed to any signi®cant extent during these fermentations and appears to largely pass through the subsequent processing stages, becoming an important constituent of the wastewater produced by these industries. The present study con®rmed that betaine is present in large amounts in sugar-beet molasses (up to 6% w/w) and in the ef¯uent of processes using sugar-beet molasses as substrate (up to 4.5 g dm ). Betaine appeared to be almost completely degraded in the two full-scale anaerobic treatment plants sampled. This was con®rmed by anaerobic activity tests performed with both acclimated and unacclimated anaerobic sludge. The results obtained suggest the possible involvement of a multistep degradation process, with the likelihood of a nitrogen-containing intermediate. Finally, although not totally discountable, betaine degradation does not appear to be coupled to sulfate reduction during treatment of high-sulfate wastewaters.

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An open dynamic chamber for the continuous monitoring of diffusive and ebullitive fluxes of methane (CH4) in aquatic ecosystems was designed and developed. This method is based on a standard floating chamber in which a well-defined carrier gas flows. The concentration of CH4 is measured continuously at the outlet of the chamber, and the flux is determined from a mass balance equation. The method was carefully tested in a laboratory and was subsequently applied to two lakes, in Mexico, with contrasting trophic states. We show here that the method allows for the continuous quantification of CH4 diffusive flux higher than 25 × 10–6 g m–2 h–1, the determination of ebullitive flux, and the individual characterization of bubbles larger than 1.50–1.72 mm in diameter. The method was also applied to determine carbon dioxide emissions (CO2). In that case, the method was less sensitive but allowed for the characterization of diffusive fluxes higher than 10 mg CO2 m–2 h–1 and of bubbles larger than 5.3–8.4 mm in diameter. This high-throughput method can be adapted to any gas detector at low cost, making it a convenient tool to better constrain greenhouse gas emission from freshwater ecosystems.

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High latitudes are experiencing intense ecosystem changes with climate warming. The underlying methane (CH4) cycling dynamics remain unresolved, despite its crucial climatic feedback. Atmospheric CH4 emissions are heterogeneous, resulting from local geochemical drivers, global climatic factors, and microbial production/consumption balance. Holistic studies are mandatory to capture CH4 cycling complexity. Here, we report a large set of integrated microbial and biogeochemical data from 387 samples, using a concerted sampling strategy and experimental protocols. The study followed international standards to ensure inter-comparisons of data amongst three high-latitude regions: Alaska, Siberia, and Patagonia. The dataset encompasses different representative environmental features (e.g. lake, wetland, tundra, forest soil) of these high-latitude sites and their respective heterogeneity (e.g. characteristic microtopographic patterns). The data included physicochemical parameters, greenhouse gas concentrations and emissions, organic matter characterization, trace elements and nutrients, isotopes, microbial quantification and composition. This dataset addresses the need for a robust physicochemical framework to conduct and contextualize future research on the interactions between climate change, biogeochemical cycles and microbial communities at high-latitudes.