Première injection de lixiviat dans un digesteur anaérobique suivi par méthode géophysique.

3rd International Workshop on Geoelectrical MonitoringGELMON 2015, Vienna, AUT, 24-/11/2015 - 26/11/2015International audienceAnaerobic digestion (AD) has a high growing potential worldwide due to its combined environmental benefits such as reducing greenhouse gas, producing renewable energy, organic amendment and fertilizer. In France, 400 plants were recorded in 2015 which mainly handle agricultural residues using both liquid and solid state processes. The successful and efficient degradation of organic matter in AD needs balanced physical-chemical conditions for microbial development. Moisture content in the media, particularly, was found to be of great importance. Nevertheless, no information is available on the hydrodynamics of the circulation of the leachate through cattle manure or other agricultural residues. Moreover, agricultural residues and mixtures are particularly porous and heterogeneous and no data was found on the efficiency of those systems to humidify homogeneously such a substrate. The hydrodynamic flow characteristics and transfer time of the leachate are essential to design the optimal liquid injection system that will permit to reach uniform moisture content. Already applied in landfills for in-situ characterization of leachates flow through municipal solid waste (MSW), ERT was proven to give reliable results. The results led to the enhancement of the leachate injection system design and enriched the knowledge of MSW behavior. The non-intrusive, non-destructive and 3 dimensional response of the ERT method seems adapted to the study of the leachate infiltration through agricultural effluents in a SSAD plant. We present the first results of the use of 3D time-lapse electrical resistivity tomography performed during a leachate injection in a waste deposit cell in France (20 m3 of leachate was injected during 10 h). 72 electrodes and a Syscal PRO resistivity meter was used. For the inversion, the apparent resistivity have been interpreted taking into account (i) the boundary condition of the waste deposit cell (insulating boundary around the waste deposit cell) and (ii) the effects of temperature (indeed between the surface and the bottom of the waste deposit cell , we measured the variation of temperature in the range of +/-25 °C). The result highlighted the conductive character of this porous media with a resistivity included between 0.5 ohm.m and 10 ohm.m depending on the saturation state; we will show that the infiltration is clearly located by electrical resistivity tomography and that this media is very heterogeneous with complex infiltration shape. The first results suggest the interest of the 3D electrical resistivity tomography to study injection leachate injection in a SSAD plant

Dynamic effect of leachate recirculation on batch mode solid state anaerobic digestion: Influence of recirculated volume, leachate to substrate ratio and recirculation periodicity

International audiencePerformances of batch mode solid state anaerobic digestion (SSAD) were investigated through several leachate recirculation strategies. Three parameters were shown to particularly influence methane production rates (MPR) and methane yields: the length of the interval between two recirculation events, the leachate to substrate (L:S) ratio and the volume of leachate recirculated. A central composite factor design was used to determine the influence of each parameter on methane production. Results showed that lengthening the interval between two recirculation events reduced methane yield. This effect can be counteracted by recirculating a large volume of leachate at a low L:S ratio. Steady methane production can be obtained by recirculating small amounts of leachate, and by lengthening the interval between two recirculations, regardless of the L:S ratio. However, several combinations of these parameters led to similar performances meaning that leachate recirculation practices can be modified as required by the specific constraints SSAD plants configurations. © 2016 Elsevier Ltd

Fumiers de bovins, une ressource à fort potentiel pour la filière de méthanisation en France ?

Agricultural biogas is a growing sector that will need unused resources. Cattle manure is a potential resource for this sector. In this study, an inventory of French cattle manure production was undertaken by crossing different databases from Agricultural Statistics (2010 French Agricultural Census, 2010 Cattle National Database Inventory) and livestock practices found on the French territory. The main results of this study show that total cattle manure production amounts to 87 million tons per year and solid manure is the most effluent produced 69 million tons each year. Compact and very compact manure with total solids content higher than 18 %, represent a large part of the total cattle manure production (70%). Based on their physico-chemical composition, valorisation of these manures in biogas plants by solid state anaerobic digestion may be considered. However, the cattle manure resource is highly fragmented in the national territory and on the basis of current technical and economic criteria, only some farms could integrate the agricultural biogas sector. In order to better mobilize this resource it will be necessary to pool the manure produced by several farms or to add co-substrates with higher methanogenic potential or either switch to another biogas valorisation mode.La méthanisation agricole est un secteur en développement qui fera appel à des ressources encore non exploitées. Les fumiers de bovins constituent une ressource à fort potentiel pour cette filière. Un inventaire du gisement de fumiers de bovins a été entrepris en croisant différentes bases de données de la statistique agricole (Recensement agricole 2010, Base de Données Nationale de l'Inventaire 2010) et les pratiques d'élevage retrouvées sur le territoire Français. Les principaux résultats de cette étude montrent que la production totale de déjections bovines s'élève à 87 Millions de tonnes par an et que les fumiers sont le principal effluent produit avec 69 Millions de tonnes chaque année. Les fumiers compacts et très compacts ayant des teneurs en matières sèche supérieures à 18 %, représentent une grande part de l'ensemble des fumiers de bovins produits (70%). De par leur composition physico-chimique, la valorisation de ces derniers dans des unités de méthanisation par voie « solide » peut être envisagée. Cependant, ce gisement de fumiers de bovin est très morcelé sur le territoire national et sur la base des critères technico-économiques actuels, peu d'exploitations agricoles sont susceptibles d'intégrer le secteur de la méthanisation agricole. Afin de mieux mobiliser cette ressource il sera nécessaire soit de mutualiser les fumiers produits par plusieurs exploitations, soit d'adjoindre des co-substrats à fort potentiel méthanogène ou de basculer vers un autre mode de valorisation du biogaz produit

New insights into the role of PPARs.

Peroxisome proliferator-activated receptors (PPARs) are fatty acid-activated transcription factors belonging to the nuclear hormone receptor family. While PPARs are best known as regulators of energy homeostasis, evidence also has accumulated recently for their involvement in basic cellular functions. We review novel insights into PPAR functions in skin wound healing and liver, with emphasis on PPARβ/δ and PPARα, respectively. Activation of PPARβ/δ expression in response to injury promotes keratinocyte survival, directional sensing, and migration over the wound bed. In addition, interleukin (IL)-1 produced by the keratinocytes activates PPARβ/δ expression in the underlying fibroblasts, which hinders the mitotic activity of keratinocytes via inhibition of IL-1 signaling. Initially, roles were identified for PPARα in fatty acid catabolism. However, PPARα is also involved in downregulating many genes in female mammals. We have elucidated the mechanism of this repression, which requires sumoylation of PPARα. Physiologically, this control confers protection against estrogen-induced intrahepatic cholestasis