Jean-Claude Revel
École Normale Supérieure
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Featured researches published by Jean-Claude Revel.
Journal of Hazardous Materials | 2008
Soumia Amir; Georges Merlina; Eric Pinelli; Peter Winterton; Jean-Claude Revel; Mohamed Hafidi
The composting process involves a succession of different communities of microorganisms that decompose the initial material, transforming it into a stable final product. In this work, the levels of phospholipid fatty acid (PLFA), neutral lipid fatty acid (NLFA) and sterol were monitored in compost versus time, as indicators of the activity of various microorganisms (Gram-positive or Gram-negative bacteria, fungi, etc.). During composting, the PLFA and NLFA from Gram-negative bacteria and eukaryotes (2-OH 10; 3-OH 12; 2-OH 14; 13:0; 16:1; 18:1 trans) as well as some sterols of plant origin (e.g. monostearin sterols) decreased until the end of composting. In contrast, the branched fatty acids with iso- and anteiso-forms (i-15:0; a-15:0; i-16; i-17) increased mainly in the thermophilic phase, but decreased right after. The PLFA 18:2 (6; 9), which is used as an index of the occurrence of some fungi, rose strongly at the beginning of composting, but fell after peak heating. In contrast, the other main sterol indicative of fungi, ergosterol, decreased at the beginning of the thermophilic phase, but increased strongly by the end of composting. Accordingly, cluster and PCA analysis separated the PLFA of Gram-negative bacteria and eukaryotic cells from those of Gram-positive bacteria and long-chain fatty acids. The fungal PLFA considered, 18:2 (9, 12), was clustered more closely to iso- and anteiso-branched PLFAs. Stigmasterol, squalene and cholesterol occurred in the lower right part of the loading plot and were clustered more closely to iso-, anteiso-branched PLFAs and 18:2 w 6,9 suggesting their relationship to microbial activities. We also observed the tendency of resistance of fatty acid PLFAs and NLFAs of long chain (19:0 (cis-9); 20:0) and some recalcitrant sterols, e.g. sitosterol, at the end of composting. The presence of high levels of the latter in the final stage indicates their contribution to the structural stability of organic matter fractions. These recalcitrant components were more clustered and occurred in the lower right part of the loading plot.
Bioresource Technology | 2008
H. El Hajjouji; Farid Barje; Eric Pinelli; J.-R. Bailly; Claire Richard; Peter Winterton; Jean-Claude Revel; Mohamed Hafidi
Olive mill wastewater (OMW) was treated by photocatalysis using TiO2 under UV irradiation on the laboratory scale. The chemical oxygen demand, the coloration at 330nm, and the level of phenols all showed decreases which, after a 24-h treatment, reached 22%, 57% and 94%, respectively. The differences between these three values indicate the persistence of colourless, non-phenolic compounds. Application of the novel Fictitious Atomic-Group Separation method showed an increase in carbon oxidation state and confirmed that the attack primarily concerns, aromatic moieties. A fine spectroscopic study revealed the occurrence of three successive phases during the degradation process, thought to correspond to three different categories of molecules in the OMW and the presence of pectin compounds.
Journal of Hazardous Materials | 2009
G. Ait Baddi; J. Cegarra; G. Merlina; Jean-Claude Revel; Mohamed Hafidi
Olive-mill wastes represent a significant environmental problem in Mediterranean areas due to their important production during a short period of time. Their high polyphenol, lipid and organic acid concentrations turn them into phytotoxic wastes. This work examined the evolution of polyphenolic compounds during the composting of an olive-mill waste-wheat straw mixture by using quantitative (Folin-Ciocalteu) and qualitative (High Pressure Liquid Chromatography, HPLC) analyses. The polyphenol content decreased strongly by 93% while the significant correlations obtained between polyphenol content and different humification indices and lignin losses suggested that polyphenols contribute to the synthesis of humic substances. In addition, the significant correlation found between germination index, polyphenols and humification indices must be related to the progressive substrate detoxification as humification process progressed, leading to a non-phytotoxic and partially humified end-product. Nine polyphenolic compounds were identified by HPLC, most of which had disappeared by the end of composting, when only traces of hydroxytyrosol, caffeic and syringic acids and oleuropein were detected.
Bioresource Technology | 2008
Mohamed Hafidi; Soumia Amir; Abdelmajid Jouraiphy; Peter Winterton; M. El Gharous; G. Merlina; Jean-Claude Revel
The level and fate of 16 polycyclic aromatic hydrocarbons (PAHs), targeted by the US Environmental Protection Agency (USEPA), has been studied over 90 days of composting of activated sludge with green waste, under a semi-arid climate. The total PAH calculated from the sum of the amounts of the 16 PAHs in the initial mixture of activated sludge and green waste, was lower than accepted European Union cut-off limits by about 0.48mgkg(-1). The treatment by composting led to a decrease of all PAHs mainly in the stabilization phase, but some differences could be observed between PAHs with three or fewer aromatic rings (N< or = 3) and those with four or more (N> or = 4). The former (except phenanthrene) exhibited a continuous decrease, while the latter PAHs with N of four or more and phenanthrene showed increases in the intermediate stages (30-60 days). This indicates the high potential sorption mainly of PAH with high molecular weight (> or = N4) plus phenanthrene, their tight adsorption makes them inaccessible for microbial attack. The high molecular weight PAHs showed a greater reduction of their bioavailability than those of low molecular weight. Naphthalene, with the lowest molecular weight, showed the smallest decrease (about 67.8%) compared to other PAHs of higher molecular weight (decrease reaching 100%). This is in agreement with the fact that the adsorption is less reversible with increased numbers of fused aromatic rings or an increase of their hydrophobicity.
Bioresource Technology | 2008
Rajae Abouelwafa; Soumia Amir; Salah Souabi; Peter Winterton; Victor Ndira; Jean-Claude Revel; Mohamed Hafidi
Sludge resulting from the treatment of effluent from a vegetable oil mill, was composted mixed with domestic waste in a pile for five months. Different proportions of sludge and dry waste were mixed: M1 (1v/2v) and M2 (1v/1v). Monitoring different physical-chemical parameters showed the effect of the substrate on the microbiological activity and on the formation of fulvic acids, affecting the maturity of the final compost. Elemental analysis revealed that the fulvic acids of mixes M1 and M2 presented very low concentrations of carbon, hydrogen, and oxygen and a high level of nitrogen. The FTIR spectroscopy results showed a decrease during composting of the intensity of absorbance of the easily assimilable compounds that are predominant in the initial mixtures i.e. the carbohydrates (1170-1080 cm(-1)) in M1 and long aliphatic chains (2920 cm(-1)) in M2. For mix M1 there was enrichment in compounds bearing oxygen-containing moieties. In M2 it was the nitrogen-containing compounds (in the form of stable amides) which predominated at the end of composting. The first component of PCA analysis, PC1, accounted for 83% of the difference between two distinct groups of parameters governing degradation and restructuration of the fulvic acids during composting. PC2 (17%) explained the variance due to the level of free or less polycondensed compounds in the two mixtures. Oxidised polyphenolic and polysaccharide structures were the least free, or most polycondensed, in the fulvic structures of M1. In M2 fulvic acids however, it was the polyphenols and peptide structures that were involved in the bonding, most likely of the polyphenol-peptide type.
The Journal of Agricultural Science | 2000
R. A. Bidegain; M. Kaemmerer; M. Guiresse; M. Hafidi; F. Rey; P. Morard; Jean-Claude Revel
Two organic fertilizers were prepared from the same initial mixture of poplar sawdust, blood and flour either by composting in a reactor or by chemical oxidation. Both processes resulted in loss of c . 30% of the organic matter. Composting required 90 days in comparison to only a few hours with chemical oxidation. Extraction of the organic residues with 1 N KOH gave solutions containing 24·6 and 15·1 g/l of humic substances respectively. These humic solutions were applied to pot-grown Lolium multiflorum Lam. at 4 and 10 mg carbon per pot to assess the short-term uptake of macro and microelements by the plants. When the plants were short of phosphorus, the humic substances from the chemically decomposed sawdust supplied at 10 mg C per pot improved total P uptake and yield. Humic substances also increased copper and manganese uptake, and by enhancing root development, also improved nitrogen uptake and biomass yield.
Revista do Instituto Geológico | 2005
Yves Tardy; Maria Cristina Motta de Toledo; Jean-René Bailly; Maritxu Guiresse; Jean-Claude Revel
This paper presents a model for understanding the thermodynamic stability of humic substances in soil-plant-water environments. During the past few decades, a great amount of research has been devoted to the structural and physico-chemical properties of humic substances, and very many results have accumulated. As a contribution to interpretations of the evolution of organic matter in soils, this paper presents an approach based on an imaginary atomic-group differentiation (CH2O-CO-CH2-C) derived from the elemental species composition (CHON) and on the stoichiometry of the reactions, without which it would seem impossible to outline any thermodynamic reasoning, and to delineate any mass balance or account for transfers in soil - plant - water systems.
Chemistry and Ecology | 2006
J. F. Richard; G. Ait Baddi; C. Costa; M. Guiresse; M. Kaemmerer; Mohamed Hafidi; Jean-Claude Revel
In order to determine the role of termites in the recycling of organic matter and in humification processes, organic matter from the mound of a wood-feeding termite (Nasutitermes sp.) and from the litter directly below has been studied in secondary forest on the campus of Belem University, in Brazil. The carbon content was slightly lower in the litter (just beneath the mound) than in the mound, but nitrogen was much more abundant in the mound. As a consequence, the C/N ratio of fragmented litter total organic matter is very high, which shows that the humification process is not complete. Therefore, plant debris seemed to be more degraded in the mound than in the litter, indicating a humification gradient from mound to litter. Humic acid extracted from the mound and from the litter was compared by using elemental, E4/E6 ratio, spectroscopic (FTIR) analyses, and Sephadex gel chromatography. First, humic acids were more abundant in the mound than in the litter, showing that humification processes were more advanced in the mound than in the litter. Gel-permeation chromatography showed that the humic acids of the mound contained more low-molecular-weight fractions than those of the litter. In addition, the results of infrared spectra, E4/E6 ratio and elemental composition can confirm the fulvic character of mound material and the humic character of litter material. Therefore, the plant debris seems to follow two different humification pathways in the two environments, as long as the mound is alive.
Chemistry and Ecology | 2005
Mohamed Hafidi; G. Ait Baddi; Véronique Gilard; P. Ramos; K. Alimi; Jean-Claude Revel
Elemental analysis, fluorescence spectroscopy and differential scanning calorimetry (DSC) were applied to the study of fulvic acids isolated from different stages during olive mill waste composting. The fulvic extracted acids are characterized by a high nitrogen content and O/C ratio values that may result from the high degree of humification and the synthesis of more condensed humic complexes. This was confirmed by fluorescence spectroscopy in the synchronous-scan mode by the decrease of shoulder intensities at intermediate wavelengths indicating the increase of polycondensation and conjugation of unsaturated structures and the greater uniformity of fluorophores. Fluorescence spectra in the emission, excitation and synchronous modes became simpler with compost maturation. This was confirmed by DSC results which proved the high degree of polycondensation of aromatic nuclei of fulvic acid molecules during olive mill waste composting.
Chemosphere | 2005
Soumia Amir; Mohamed Hafidi; Georges Merlina; Jean-Claude Revel