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BACKGROUND: Bio‐hydrogen production from organic residues is an attractive process that combines energy generation with waste treatment. This work describes hydrogen production from molasses and cheese whey by biofilm and suspended‐cells of four hyperthermophilic Thermotoga spp. For the best performing strain, a preliminary process optimization was performed.RESULTS: In experiments with glucose‐fed T. neapolitana, HEPES was the best‐performing buffer, whereas the highest H2 rate was obtained with the biofilm support exposing the highest specific surface. All the Thermotoga strains tested (T. neapolitana, T. maritima, T. naphtophila, T. petrophila) were able to produce H2 from glucose, molasses and cheese whey under both suspended‐ and attached‐cell conditions. T. neapolitana was the best H2 producer with all three substrates. The best H2 production rate was higher on molasses (1.7 mmolH2 L$_{\rm {medium}}^{-1}$ h−1) than on cheese whey (0.94 mmolH2 L$_{\rm {medium}}^{-1}$ h−1), whereas the highest H2/substrate yields were similar for the two substrates (2.95 molH2 mol$_{\rm {monosaccharide consumed}}^{-1}$ on molasses and 2.50 molH2 mol$_{\rm {monosaccharide consumed}}^{-1}$ on cheese whey). With both wastes, the progressive growth medium simplification allowed a drastic reduction of medium cost, without significant losses of process performance.CONCLUSION: Both molasses and cheese whey are suitable substrates for H2 production by suspended‐ and attached‐cells of Thermotoga species. Copyright © 2012 Society of Chemical Industry

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A procedure for the design of an aerobic cometabolic process for the on-site degradation of chlorinated solvents in a packed bed reactor was developed using groundwater from an aquifer contaminated by trichloroethylene (TCE) and 1,1,2,2-tetrachloroethane (TeCA). The work led to the selection of butane among five tested growth substrates, and to the development and characterization from the site's indigenous biomass of a suspended-cell consortium capable to degrade TCE (first order constant: 96 L gprotein(-1) day(-1) at 30 °C and 4.3 L gprotein(-1) day(-1) at 15 °C) with a 90 % mineralization of the organic chlorine. The consortium immobilization had strong effects on the butane and TCE degradation rates. The microbial community structure was slightly changed by a temperature shift from 30 to 15 °C, but remarkably affected by biomass adhesion. Given the higher TCE normalized degradation rate (0.59 day(-1) at 15 °C) and attached biomass concentration (0.13 gprotein Lbioreactor(-1) at 15 °C) attained, the porous ceramic carrier Biomax was selected as the best option for the packed bed reactor process. The low TeCA degradation rate exhibited by the developed consortium suggested the inclusion of a chemical pre-treatment based on the TeCA to TCE conversion via β-elimination, a very fast reaction at alkaline pH. To the best of the authors' knowledge, this represents the first attempt to develop a procedure for the development of a packed bed reactor process for the aerobic cometabolism of chlorinated solvents.

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