Edmond-Jacques Nyns

Clostridium Autoethanogenum, Sp-nov, An Anaerobic Bacterium That Produces Ethanol From Carbon-monoxide

A strictly anaerobic, gram-positive, sporeforming, rod-like, motile bacterium was enriched from rabbit feces, and isolated using carbon monoxide as sole source of energy and carbon. The isolate metabolizes CO with ethanol, acetate and CO2 as end-products. Other substrates used as carbon and energy sources include CO2 plus H2, pyruvate, xylose, arabinose, fructose, rhamnose, and l-glutamate. The optimum temperature for growth is 37°C. The optimum pH for chemolithotrophic growth lies around 5.8 to 6.0 Sulfate is not reduced. Growth is inhibited either by penicillin, chloramphenicol, tetracyclin or ampicillin, each at 100 μg per ml. The isolate has a DNA-base composition of 25.9±0.6% guanine plus cytosine. The isolate represents a new species of Clostridium for which the name Clostridium autoethanogenum is proposed. The type strain is strain JA1-1

Landfill Gas - From Environment To Energy

A survey was recently achieved, on behalf of the Commission of the European Communities, to scrutinise the state-of-the-art of landfill gas control and exploitation. The survey is divided into 8 parts After an Executive Summary, part I deals with the environmental impact of landfill gas and details 166 reported cases of landfill gas damages in uncontrolled landfills. The second one details the process of landfill gas generation and the technology of landfill gas control by its exploitation. The third part surveys the methodologies for monitoring landfill gas emissions for landfill gas potential evaluation and for safety. The fourth part deals with policies and legal aspects of landfill gas in the European Community and in the World. The fifth part estimates landfill gas potentials and overviews the economics of landfill gas control and exploitation, notably by the exhaustive assessment of 6 case studies. The sixth part gives the status of landfill gas exploitation in the European Community and in the World. The two final parts list utilities and references.

Fluorimetric Monitoring of Methanogenesis in Anaerobic Digesters

The fluorimetric determination of co-factor F420. a specific co-enzyme of methanogenic bacteria (1) in mixed liquors during complex laboratory, pilot or industrial biomethanations, leads to a series of new parameters which help, to design improved digesters, to monitor the methanogenic digestions, to obviate operational deviations and to promote optimization of the process. These parameters are: (a) the concentration in co-factor F420 as mol F420 × 1–1 mixed liquor or µmol F420 × g-1 volatile solids in mixed liauor: (b) the food to microorganism ratio CMF420 as g volatile solids added × µmol-5 F420 in mixed liquor × d-1; (c) the specific methane production ratio: QCH4(F420)and 1 CH4 produced × µmol-1 F420 in mixed liquor × d-1; (d) the rate of biosynthesis of co-factor F420 as µmol F420 × 1–1 mixed liquor × d-1; (e) the yields: either YCH4/F420 as 1 CH4 × µmol F420 synthesized or YVSe/F420 as g volatile solids eliminated × µmol-1 F420 synthesized.

Biomethanation of the marine algae Tetraselmis

Biomethanation of algae is an elegant way to convert solar energy into a chemical fuel, i.e. methane. The microbiological process of methanogenesis is leading to a reliable technology. Favorable running conditions were elicited by experiments at the laboratory scale. The process is being developed at the 1-m/sup 3/ scale at Lamezia (Italy). From these experiments, conceptual parameters for a full-scale demonstration plant are calculated.

Abiotic transformation of catechol and 1-naphthol in aqueous solution - Influence of environmental factors

The abiotic transformation of catechol and 1-naphthol singly and in mixtures was tested in sterile Tris-HCl buffer with regard to several environmental factors including temperature (7 degrees C, 20 degrees C and 30 degrees C), lighting conditions, pH (between 7.0 and 8.5) and dissolved oxygen (at partial pressures of 0.0, 220, 2200, 11000 and 22000 Pa). Irrespective of lighting conditions. catechol autoxidation was confirmed in aerated medium with a rate independent of the presence of 1-naphthol but proportional to the dissolved oxygen concentration, to the pH (its half-disappearance occurred in 24h at pH 8.5) and, to a lesser extent, to the incubating temperature (at 20 degrees C, 20% disappeared in 10 days at pH 7.0). Under alkaline conditions, the reaction of the anionic form (catecholate) with an equimolar concentration of molecular oxygen (O2) led presumably to hydrogen peroxide anion (HO2-) and coloured polymerization products. When tested alone, 1-naphthol was not significantly influenced either by lighting conditions, incubating temperature or dissolved oxygen concentration. It was also found to be quite stable with respect to pH, with a 15-fold weaker transformation rate than for catechol at the highest pH used. When tested in a mixture with catechol, 1-naphthol was found to be involved in a new chemical oxidation reaction catalyzed by catecholate. The transformation of one mole of 1-naphthol consumes four moles of oxygen. In the presence of catechol, the stoichiometry of the 1-naphthol transformation, under the influence of oxygen, suggests the possible formation of 2,5,6,8-tetrahydroxy 1,4-naphthoquinone via Lawsone (2-hydroxy 1,4-naphthoquinone) and naphthopurpurine (2,5,8-trihydroxy 1,4-naphthoquinone) as hypothetic intermediates. This is the first report of the autoxidation of 1-naphthol, catalyzed by catechol, in aqueous solution, in the absence of UV irradiation.

New concept for the evaluation of rural biogas management in developing countries

Abstract In rural sectors of developing countries, the development and management of biogas technology have not been entirely satisfactory in recent years. The usual economic analyses cannot give an appropriate assessment of this phenomenon. The present work develops a new concept, the Biogas Producer-Consumer Combination Problem (BPCCP), that gives an integrated explanation of the nature of this particular situation. The key role played in the real acceptance of the rural digester is the adopters motivation which is influenced by different kinds of factors. The BPCCP concept further entails some suggestions and recommendations for future development and management of biogas technology.

Volatile fatty acids, an important state parameter for the control of the reliability and the productivities of methane anaerobic digestions

Abstract The importance of the presence of the volatile fatty acids, acetate, propionate or higher homologues, either in methanogenic substrates, or in digestion mixed liquors, was examined with regard to the reliability of the digestion process and/or the methane productivities, through a number of appropriate experiments. From these and other observations, guidelines for the prevention of occurrence or the removal of these volatile fatty acids in digestion mixed liquors, whenever harmful, are proposed.

Differentiation between acetate and higher volatile acids in the modeling of the anaerobic biomethanation process

This paper presents a model for the single-stage completely-mixed anaerobic digestion of complex substrates containing no volatile acids. In the model, volatile acids produced by the acidogenic bacteria are no longer considered together. Acetate is assumed to be representative of the substrate and propionate and butyrate act only as inhibitors for the methanogenic bacteria.

Biogas: exploitation of a renewable energy in Latin America

Exploitation of biogas is scrutinized in Latin America. Among the developing countries, biogas technology has been most widely applied in this region of the world. Four sectors are successfully using biogas. In the agricultural sector, 9440 digesters have been identified. In the industrial sector, 25 types of wastes have been either investigated for biogas production or are already in full-scale application. Latin America is now the worlds leading user of biogas technology in the municipal raw sewage treatment. Thirty-three R&D projects have been reported. Since 1977, five projects of biogas exploitation from sanitary landfills have been implemented. This makes Latin America the leading user of landfill gas technology in the developing countries. High-rate biogas fermentation processes are being developed and increasingly utilized. Several techniques of biogas treatment have been applied. Biogas is mainly used for cooking, lighting, as town gas or as vehicle fuel. The quantity of biogas produced in Latin America is estimated at 217 million m3 per year. Future R & D in biogas technology requires not only technological efforts, but also incitations by national governments and non-governmental organizations (NGO) in order to promote favourable conditions for the exploitation of this renewable energy.

An Improved Method for the Quantitative-evaluation of the Potential for Methane Production of Mixed Microbial Communities in Digestion Mixed Liquors Through the Determination of the Content in Coenzyme-f420

Abstract The potential for methane production in anaerobic digestion mixed liquors can be estimated from their content of the specific coenzyme F420. This can be determined spectrofluorimetrically by its emission at 470 nm when excited at 420 nm. With most methane digestion mixed liquors, however, severe interferences hamper the spectrofluorimetric measurements. The determination of coenzyme F420 can be substantially improved by performing the extraction at pH 8·5 after a centrifugation step. It was found that a large portion of the spectrofluorimetric interferences was associated with soluble matter whereas only particulate-bound coenzyme F420 is of significance as a measure of the potential for methane production. A further substantial portion of the spectrofluorimetric interferences could be eliminated by oxidation of the aqueous extract with KMnO4. The success of the latter step depended on the pH of oxidation, the duration of oxidation and the amount of KMnO4 added, but not on the temperature of oxidation nor on the amount of H2O2 added to destroy the excess KMnO4. A small part of the coenzyme F420 was destroyed in the oxidation process but in a sufficiently reproducible way as not to hamper proper determination.