Stability of ex situ biological methanation of H/CO with a mixed microbial culture in a pilot scale bubble column reactor.

Biological methanation is a promising technology for gas and carbon valorisation. Therefore, process stability is required to allow its scale up and development. A pilot scale bubble column reactor was used for ex situ biological methanation with Mixed Microbial Culture (MMC).

An improved hydrodynamic model for percolation and drainage dynamics for household and agricultural waste beds.

This study focuses on the hydrodynamic modelling of percolation and drainage cycles in the context of solid-state anaerobic digestion and fermentation (VFA platform) of household solid wastes (HSW) in leach bed reactors. Attention was given to the characterization of the water distribution and hydrodynamic properties of the beds. The experimental procedure enabled the measurement of water content in waste beds at different states of compaction during injection and drainage, and this for two types of HSW and for two other type of wastes.

Screening of Phytophagous and Xylophagous Insects Guts Microbiota Abilities to Degrade Lignocellulose in Bioreactor.

Microbial consortia producing specific enzymatic cocktails are present in the gut of phytophagous and xylophagous insects; they are known to be the most efficient ecosystems to degrade lignocellulose. Here, the ability of these consortia to degrade lignocellulosic biomass in anaerobic bioreactors was characterized in term of bioprocess performances, enzymatic activities and bacterial community structure. In a preliminary screening, guts of (beetle), (chafer), (cockroach), (locust), and (cricket) were inoculated in anaerobic batch reactors, in presence of grounded wheat straw at neutral pH.

Composition, texture and methane potential of cellulosic residues from Lewis acids organosolv pulping of wheat straw.

Cellulosic pulps have been successfully isolated from wheat straw through a Lewis acids organosolv treatment. The use of Lewis acids with different hardness produced pulps with different delignification degrees. The cellulosic residue was characterised by chemical composition, X-ray diffraction, FT-IR spectroscopy, N2 physisorption, scanning electron microscopy and potential for anaerobic digestibility.

Total solid content drives hydrogen production through microbial selection during thermophilic fermentation.

In this study, the effect of total solid content (TS) on thermophilic hydrogen production from wheat straw was investigated. Six TS contents ranging from wet to dry conditions (10-34%TS) were tested in batch tests. A decrease of H₂ yields was observed and three statistical groups were distinguished according to the TS content: wet conditions (10% and 14%TS) with 15.

Total solids content: a key parameter of metabolic pathways in dry anaerobic digestion.

Background: In solid-state anaerobic digestion (AD) bioprocesses, hydrolytic and acidogenic microbial metabolisms have not yet been clarified. Since these stages are particularly important for the establishment of the biological reaction, better knowledge could optimize the process performances by process parameters adjustment.

Results: This study demonstrated the effect of total solids (TS) content on microbial fermentation of wheat straw with six different TS contents ranging from wet to dry conditions (10 to 33% TS).

Microbial community signature of high-solid content methanogenic ecosystems.

In this study, changes in bacterial and archaeal communities involved in anaerobic digestion processes operated with high solid contents were investigated. Batch tests were performed within a range of total solids (TS) of 10-35%. Between 10% and 25% TS, high methanogenic activity was observed and no overall specific structure of active bacterial communities was found.

Total solids content drives high solid anaerobic digestion via mass transfer limitation.

The role of the total solids (TS) content on anaerobic digestion was investigated in batch reactors. A range of TS contents from 10% to 35% was evaluated, four replicates were performed. The total methane production slightly decreased with TS concentrations increasing from 10% to 25% TS.

Application of electro-active biofilms.

The concept of an electro-active biofilm (EAB) has recently emerged from a few studies that discovered that certain bacteria which form biofilms on conductive materials can achieve a direct electrochemical connection with the electrode surface using it as electron exchanger, without the aid of mediators. This electro-catalytic property of biofilms has been clearly related to the presence of some specific strains that are able to exchange electrons with solid substrata (eg Geobacter sulfurreducens and Rhodoferax ferrireducens). EABs can be obtained principally from natural sites such as soils or seawater and freshwater sediments or from samples collected from a wide range of different microbially rich environments (sewage sludge, activated sludge, or industrial and domestic effluents).

Checking graphite and stainless anodes with an experimental model of marine microbial fuel cell.

A procedure was proposed to mimic marine microbial fuel cell (MFC) in liquid phase. A graphite anode and a stainless steel cathode which have been proven, separately, to be efficient in MFC were investigated. A closed anodic compartment was inoculated with sediments, filled with deoxygenated seawater and fed with milk to recover the sediment's sulphide concentration.