Evolution of Bacterial Community in a Full-scale Biotrickling Filter by Fluorescence in Situ Hybridization (FISH)

Direct inoculation of a biotrickling filter for hydrogenotrophic methanogenesis

Hydrogenotrophic biomethanation in a biotrickling filter has been reported to be a proven technology for biological biogas upgrading in recent studies. However, the preparation of enriched hydrogenotrophic methanogens in a separate reactor prior to biomethanation in a trickled bed is a lengthy procedure and therefore hard to apply on an industrial scale. This study explored the direct inoculation of anaerobic biogas digestate for simultaneous enrichment of hydrogenotrophic methanogens and biofilm immobilisation in a trickled bed system. The direct inoculation and formation of hydrogenotrophic biofilm was successful and resulted in a stable H₂ loading rate of 11  [Formula: see text] , with the highest specific methane productivity recorded at 3.03 Nm³m_R^-3d^-1 and a purity of 98% CH₄ in thermophilic conditions. The DNA analysis confirmed that hydrogenotrophic methanogens dominated the archaeal consortia.

Removal of acetone from air emissions by biotrickling filters: providing solutions from laboratory to full-scale

A full-scale biotrickling filter (BTF) treating acetone air emissions of wood-coating activities showed difficulties to achieve outlet concentrations lower than 125 mg C m^-3, especially for high inlet concentrations and oscillating emissions. To solve this problem, a laboratory investigation on acetone removal was carried out simulating typical industrial conditions: discontinuous and variable inlet concentrations and intermittent spraying. The results were evaluated in terms of removal efficiency and outlet gas emission pattern. Industrial emissions and operational protocols were simulated: inlet load up to 70 g C m^-3 h^-1 during 2 cycles of 4 h per day and intermittent trickling of 15 min per hour. The outlet gas stream of the pollutant was affected by intermittent spraying, causing a fugitive emission of pollutant. Complete removal efficiency was obtained during non-spraying. Average removal efficiencies higher than 85% were obtained, showing the feasibility of BTF to treat acetone. The outlet gas stream showed a clear dependence on the pH of the trickling liquid, decreasing the removal at pH < 5.5. Thus, a proper control of alkalinity, with regular NaHCO₃ addition, was required for successful operation. The laboratory findings were fruitfully transferred to the industry, and the removal of acetone by full-scale BTF was improved.