Jurgen Klein

Degradation of phenanthrene, fluorene and fluoranthene by pure bacterial cultures

SummaryBacterial mixed cultures able to degrade the polycyclic aromatic hydrocarbons (PAH) phenanthrene, fluorene and fluoranthene, were obtained from soil using conventional enrichment techniques. From these mixed cultures three pure strains were isolated:Pseudomonas paucimobilis degrading phenanthrene;P. vesicularis degrading fluorene andAlcaligenes denitrificans degrading fluoranthene. The maximum rates of PAH degradation ranged from 1.0 mg phenanthrene/ml per day to 0.3 mg fluoranthene/ml per day at doubling times of 12 h to 35 h for growth on PAH as sole carbon source. The protein yield during PAH degradation was about 0.25 mg/mg C for all strains. Maximum PAH oxidation rates and optimum specific bacterial growth were obtained near pH 7.0 and 30°C. After growth entered the stationary phase, no dead end-products of PAH degradation could be detected in the culture fluid.

MICROBIAL METABOLISM OF FLUORANTHENE: ISOLATION AND IDENTIFICATION OF RING FISSION PRODUCTS

SummaryThe degradation of fluoranthene by pure cultures of Alcaligenes denitrificanss WW1, isolated from contaminated soil samples, was investigated. The strain showed maximum degradation rates of 0.3 mg fluoranthene/ml per day. A denitrificans was able to utilize also naphthalene, 1- and 2-methylnaphthalene, phenanthrene, and anthracene as sole carbon sources and to co-metabolize fuuorence, pyrene, and benzo(a)anthracene. During growth on fluoranthene in batch culture two metabolic products that were completely degraded before growth entered the stationary phase were detected in the culture fluid. Anslyses by UV, mass and NMR spectroscopy identified the products as acenaphthenone and 3-hydroxymethyl-4,5-benzocoumarine. Fluoranthene-grown resting cells of A. denitrificans showed degradative activity towards 2,3-dihydroxybenzoic acid, pyrogallol, salicylic acid, and catechol. The enzymatic activities in extracts of fluoranthene-induced cells indicate a meta ring fission involved in the degradation of fluoranthene. From these data new aspects of the biodegradative pathway of fluoranthene have been predicted.

Pyrolysis of coal in hydrogen and helium plasmas

The rate of formation of acetylene, the most interesting product of coal pyrolysis in hydrogen plasma, is determined by heat transfer to coal and by the kinetics of pyrolysis and homogeneous gas phase reactions. Experiments were carried out with the inert gas helium and hydrogen in order to distinguish between pyrolysis and reactions with hydrogen. The time resolution of the apparatus facilitated measurement of the increase of non-condensable reaction products. The experiments were performed with a high volatile bituminous coal (particle size 100 μm) at temperatures between 1000 °C and 2000 °C. the coal particles are rapidly heated to a temperature lower than the gas temperature, then volatiles are released, which react with highly reactive plasma species as far as these are available. When the pyrolysis of coal is finished after about 4 ms, the char is heated up to gas temperature. Coal can burst in the plasma jet to very fine particle sizes, thus enhancing the acetylene yield.

Pyrolysis of some gaseous and liquid hydrocarbons in hydrogen plasma

Abstract The reactions of the volatiles released from coal play an essential part in acetylene production from coal in hydrogen plasma. For that reason, gaseous and liquid hydrocarbons were used as model substances for coal volatiles to study their reactions in a hydrogen plasma jet at atmospheric pressure and average temperatures between 1000 and 2000 °C. Plasma pyrolysis cannot be described by conventional kinetic pyrolysis data. The hydrocarbons undergo very fast reactions with highly reactive plasma species and then stop to react. The product distribution depends on the hydrocarbon employed. The residence times of a few milliseconds were not sufficient to attain thermodynamic equilibrium nor to form soot in measurable amounts.

Relation between coal properties and acetylene yield in plasma pyrolysis

Abstract If coal is injected into hydrogen plasma generated by arc discharge the volatiles are released within a few milliseconds and form acetylene as the main product by reaction with the plasma. Experiments with different coals indicate that the yield of acetylene is determined not only by the amount of volatiles but depends also on their composition. Oxygen compounds in the coal and, in some cases, even the oxygen content of the mineral matter decrease the acetylene yield.

Purification of Wastewater from Coking and Coal Gasification Plants Using Activated Carbon

Abstract Activated carbon is suitable for the removal from wastewater of organic compounds, resistant to biological treatment, with regeneration of the saturated carbon. The design of a purification plant depends on the concentration and the kind of dissolved substances and on the desired degree of purification. Different types of activated carbon have been used to establish adsorption isotherms of the water to be cleaned. The wastewater is passed through a fixed bed of carbon showing the highest adsorption capacity, and the speed of displacement of the mass-transfer zone and its extent are determined. In this way the size of the adsorption vessel and the amount of carbon to be discharged into the regeneration unit can be calculated. The saturated carbon is regenerated in a fluidized bed operated by hot steam. The desorption of compounds reversibly adsorbed on the carbon and the decomposition by steam of substances irreversibly adsorbed have been studied under fluidized-bed conditions. In pilot plant test...

Bioassays for risk assessment of coal conversion products

Abstract Traditional as well as biotechnological processing of coal leads to complex mixtures of products. Besides chemical and physical characterization, which provides the information for product application, there is a need for bioassays to monitor properties that are probably toxic, mutagenic or cancerogenic. Investigations carried out focused on the selection, adaptation and validation of bioassays for the sensitive estimation of toxic effects. Organisms like bacteria, Daphnia magna and Scenedesmus subspicatus, representing different complexities in the biosphere, were selected as test systems for ecotoxicological and mutagenicity studies. The results obtained indicate that bioassays are, in principle, suitable tools for characterization and evaluation of coal-derived substances and bioconversion products. Using coal products, coal-relevant model compounds and bioconversion products, data for risk assessment are presented.

Development of Microbiological/Adsorptive Methods for Remediation of PAH-Contaminated Soils

Sites of closed-down coke oven plants and gas works are frequently contaminated with organic harmful compounds and need to be decontaminated. Experience has shown that any decontamination is expensive and time consuming. Besides thermal and physical methods also biotechnical decontamination methods gain more and more importance. For these methods suited microorganisms convert within months, in less favourable cases in several years time, the pollutant contained in the soil, either in-situ or after the soil having been excavated (on site). Experience gained from known pilot decontamination projects have shown that the microbial degradability as well as the bio-availability of the contaminants are the key factors for the success of such decontamination measures. At present insufficient understanding of the phenomena involved, prevents to predict the suitability of biological decontamination methods and their effectiveness.

Entwicklung Mikrobiologisch/Adsorptiver Methoden zur Dekontaminierung von Pak-Belasteten Böden

Fruhere Standorte von Kokereien und Gaswerken sind haufig in einem solchen Umfang mit organischen Schadstoffen kontaminiert, das sie saniert werden mussen. Aller Erfahrung nach ist jede Sanierung teuer und langwierig. Neben thermischen und physikalischen Methoden gewinnen auch biotechnische Sanierungsverfahren zunehmend an Bedeutung, bei denen entweder an Ort unde Stelle (in-situ) oder nach Ausgraben des Bodens (on-site) geeignete Mikroorganismen innerhalb von Monaten, ungunstigenfalls von Jahren, die Schadstoffe zu ungefahrlichen Verbindungen abbauen. Erfahrungen aus bisher bekannt gewordenen Sanierungen bzw. Pilotsanierungen zeigen, das die mikrobielle Abbaubarkeit der Schadstoffe sowie die Zuganglichkeit der Schadstoffe fur die Mikroorganismen wesentlichen Einflus auf den Sanierungserfolg haben. Aufgrund mangelnder Kenntnisse ist es bislang nicht moglich, Vorhersagen uber einzusetzende biologische Sanierungstechniken und den zu erwartenden Erfolg einer Sanierungsmasnahme fur kontaminierte Standorte zu machen.