Improved organic matter biodegradation through pulsed H injections during in situ biomethanation.

During in situ biomethanation, microbial communities can convert complex Organic Matter (OM) and H into CH. OM biodegradation was compared between Anaerobic Digestion (AD) and in situ biomethanation, in semi-continuous processes, using two inocula from the digester (D) and the post-digester (PoD) of an AD plant. The impact of H on OM degradation was assessed using a fractionation method.

Archaeal community composition as key driver of H2 consumption rates at the start-up of the biomethanation process.

The performance of hydrogen consumption by various inocula derived from mesophilic anaerobic digestion plants was evaluated under ex situ biomethanation. A panel of 11 mesophilic inocula was operated at a concentration of 15 g.L at a temperature of 35 °C in batch system with two successive injections of H:CO (4:1 mol:mol).

Microbial community redundance in biomethanation systems lead to faster recovery of methane production rates after starvation.

The Power-to-Gas concept corresponds to the use of the electric energy surplus to produce H by water electrolysis, that can be further converted to methane by biomethanation. However, the fluctuant production of renewable energy sources can lead to discontinuous H injections into the reactors, that may interfere with the adaptation of the microbial community to high H partial pressures. In this study, the response of the microbial community to H and organic feed starvation was evaluated in in-situ and ex-situ biomethanation.

Temperature and Inoculum Origin Influence the Performance of Ex-Situ Biological Hydrogen Methanation.

The conversion of H into methane can be carried out by microorganisms in a process so-called biomethanation. In ex-situ biomethanation H and CO gas are exogenous to the system. One of the main limitations of the biomethanation process is the low gas-liquid transfer rate and solubility of H which are strongly influenced by the temperature.

Biomethanation processes: new insights on the effect of a high H partial pressure on microbial communities.

Background: Biomethanation is a promising solution to upgrade the CH content in biogas. This process consists in the injection of H into an anaerobic digester, using the capacity of indigenous hydrogenotrophic methanogens for converting the injected H and the CO generated from the anaerobic digestion process into CH. However, the injection of H could cause process disturbances by impacting the microbial communities of the anaerobic digester.

Soft Microwave Pretreatment to Extract -Hydroxycinnamic Acids from Grass Stalks.

The aim of this article is to provide an analysis of microwave effects on ferulic and coumaric acids (FA and CA, respectively) extraction from grass biomass (corn stalks and miscanthus). Microwave pretreatment using various solvents was first compared to conventional heating on corn stalks. Then, microwave operational conditions were extended in terms of incident power and treatment duration.

Methanosarcina plays a main role during methanogenesis of high-solids food waste and cardboard.

Anaerobic digestion of food waste is a complex process often hindered by high concentrations of volatile fatty acids and ammonia. Methanogenic archaea are more sensitive to these inhibitors than bacteria and thus the structure of their community is critical to avoid reactor acidification. In this study, the performances of three different inocula were compared using batch digestion tests of food waste and cardboard mixtures.

Addition of granular activated carbon and trace elements to favor volatile fatty acid consumption during anaerobic digestion of food waste.

The effect of supplementing granular activated carbon and trace elements on the anaerobic digestion performance of consecutive batch reactors treating food waste was investigated. The results from the first batch suggest that addition of activated carbon favored biomass acclimation, improving acetic acid consumption and enhancing methane production. Adding trace elements allowed a faster consumption of propionic acid.

Accumulation of propionic acid during consecutive batch anaerobic digestion of commercial food waste.

The objective of this study was to test three different alternatives to mitigate the destabilizing effect of accumulation of ammonia and volatile fatty acids during food waste anaerobic digestion. The three options tested (low temperature, co-digestion with paper waste and trace elements addition) were compared using consecutive batch reactors. Although methane was produced efficiently (∼500ml CHgVS; 16l CHlreactor), the concentrations of propionic acid increased gradually (up to 21.

Kinetic study of dry anaerobic co-digestion of food waste and cardboard for methane production.

Dry anaerobic digestion is a promising option for food waste treatment and valorization. However, accumulation of ammonia and volatile fatty acids often occurs, leading to inefficient processes and digestion failure. Co-digestion with cardboard may be a solution to overcome this problem.

Cardboard proportions and total solids contents as driving factors in dry co-fermentation of food waste.

This study evaluated the influence of the co-substrate proportions (0-60% of cardboard in dry basis) and the initial total solid contents (20-40%) on the batch fermentation performance. Maximum hydrogen yields were obtained when mono-fermenting food waste at high solids contents (89mlH·gVS). The hydrogen yields were lower when increasing the proportions of cardboard.

Dry anaerobic digestion of food waste and cardboard at different substrate loads, solid contents and co-digestion proportions.

The increasing food waste production calls for developing efficient technologies for its treatment. Anaerobic processes provide an effective waste valorization. The influence of the initial substrate load on the performance of batch dry anaerobic co-digestion reactors treating food waste and cardboard was investigated.

Dynamic observation of the biodegradation of lignocellulosic tissue under solid-state anaerobic conditions.

The solid-state anaerobic digestion (SS-AD) of wheat straw was characterized under low inoculated batch tests during 244 days. High levels of degradation of the cellulose (52%±1) and hemicelluloses (55%±2) were observed at the final stages and associated to a methane yield of 204±16 NmL gTS(-1). Ultrastructural observations, using transmission electronic microscopy, indicated that microorganisms degraded wheat straw from the central to the outer tissue (i.

Substrate milling pretreatment as a key parameter for Solid-State Anaerobic Digestion optimization.

The effect of milling pretreatment on performances of Solid-State Anaerobic Digestion (SS-AD) of raw lignocellulosic residue is still controverted. Three batch reactors treating different straw particle sizes (milled 0.25 mm, 1 mm and 10 mm) were followed during 62 days (6 sampling dates).

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.

Single-phase and two-phase anaerobic digestion of fruit and vegetable waste: comparison of start-up, reactor stability and process performance.

Single-phase and two-phase digestion of fruit and vegetable waste were studied to compare reactor start-up, reactor stability and performance (methane yield, volatile solids reduction and energy yield). The single-phase reactor (SPR) was a conventional reactor operated at a low loading rate (maximum of 3.5 kgVS/m3 d), while the two-phase system consisted of an acidification reactor (TPAR) and a methanogenic reactor (TPMR).

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).

French Brittany macroalgae screening: composition and methane potential for potential alternative sources of energy and products.

Macroalgae are biomass resources that represent a valuable feedstock to be used entirely for human consumption or for food additives after some extractions (mainly colloids) and/or for energy production. In order to better develop the algal sector, it is important to determine the capacity of macroalgae to produce these added-values molecules for food and/or for energy industries on the basis of their biochemical characteristics. In this study, ten macroalgae obtained from French Brittany coasts (France) were selected.

Dynamic effect of total solid content, low substrate/inoculum ratio and particle size on solid-state anaerobic digestion.

Among all the process parameters of solid-state anaerobic digestion (SS-AD), total solid content (TS), inoculation (S/X ratio) and size of the organic solid particles can be optimized to improve methane yield and process stability. To evaluate the effects of each parameter and their interactions on methane production, a three level Box-Behnken experimental design was implemented in SS-AD batch tests degrading wheat straw by adjusting: TS content from 15% to 25%, S/X ratio (in volatile solids) between 28 and 47 and particle size with a mean diameter ranging from 0.1 to 1.

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.

Anaerobic co-digestion of solid waste: Effect of increasing organic loading rates and characterization of the solubilised organic matter.

The impact of stepwise increase in OLR (up to 7.5kgVS/m(3)d) on methane production, reactor performance and solubilised organic matter production in a high-loading reactor were investigated. A reference reactor operated at low OLR (<2.

Chemical and toxicological assessment of a full-scale biosolid compost.

The impact of a full-scale biosolid composting plant on the fate of a broad range of priority organic pollutants was investigated. Chemical analysis was performed at different steps of the process during two seasons. Simultaneously, the toxicological quality was assessed using estrogen α-, dioxin-, and pregnane X-receptor reporter cell lines.

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.

Control of start-up and operation of anaerobic biofilm reactors: an overview of 15 years of research.

Anaerobic biofilm reactors have to be operated in a way that optimizes on one hand the start-up period by a quick growth of an active biofilm, on the other hand the regular operation by an active control of the biofilm to avoid diffusion limitations and clogging. This article is an overview of the research carried out at INRA-LBE for the last 15 years. The start-up of anaerobic biofilm reactors may be considerably shortened by applying a short inoculation period (i.

Pretreatment methods to improve sludge anaerobic degradability: a review.

This paper presents a review of the main sludge treatment techniques used as a pretreatment to anaerobic digestion. These processes include biological (largely thermal phased anaerobic), thermal hydrolysis, mechanical (such as ultrasound, high pressure and lysis), chemical with oxidation (mainly ozonation), and alkali treatments. The first three are the most widespread.