Anaerobic sequencing batch reactor as initiating stage in complete pentachlorophenol biodegradation.

Biodegradation of pentachlorophenol (PCP) has been studied in a sequence of two completely mixed reactors. Investigation on the first anaerobic sequencing batch reactor (AnSBR) is discussed in detail in this paper. Key technological and microbiological features were studied: two different types of adaptation process of anaerobic sludge towards PCP detoxication; the influence of the sludge concentration upon the rate of PCP biodegradation; minimum retention time for PCP degradation in dependence on the PCP concentration; modeling of the PCP degradation process; effluent COD and SS concentrations; changes in the micro- and macrostructure of the sludge during acclimatization process.

Bacterial bioavailability and biodegradability of high-molecular weight hydrocarbons from oil refinery wastes.

A general problem for oil refineries is the proper disposal of production sludges generated during the processing of crude oil. Dumping of sludges leads to environmental pollution, and particularly to sediment contamination. High-molecular weight-PAHs are important constituents of refinery wastes. These are toxic and recalcitrant pollutants, several of them being known mutagens or carcinogens. Research on biodegradability of the compounds is hampered by the insolubility in aqueous media. We analysed the chemical composition of a refinery waste sludge and determined the contents of mineral oils and PAHs. In a microbial investigation of the same sludge fractions we isolated several bacterial strains having a significant potential for breakdown of mineral oils and PAHs. Many techniques have already been applied to offer these compounds as substrates for microorganisms. Linking of the water-insoluble substrates (the PAHs, fluoranthene and chrysene, or the mineral oils) to Chromosorb beads and supplying them in a fluidised bed reactor as a single carbon source to bacterial isolates, offers a practical alternative in research on biodegradation. Even, this system resembles the common soil conditions, where bio-availability is reduced by linking of the contaminants to soil particles or accumulation of the products in hydrophobic pockets. After incubation of the carrier beads in an appropriate medium, the liquid fraction from the fluidised bed reactor and the carrier beads were collected separately and analysed for longchain hydrocarbons and for PAHs. In six days of incubation in an adapted broth formulation, biodegradation amounts 60.1% for fluoranthene and 47.2% for chrysene. Heavy hydrocarbons ranging from C10 up to C40 have been utilised in a thirty-day period for 72.4%. This project is a logical extension of our previous studies on the bio-availability of PAHs in contaminated sediments. We evaluate the potential use of pure cultures as a remedial solution to enhance the solubility and biodegradation of residual PAHs due to contamination by heavy fuels.

Biodegradation of dimethylterephthalate by mixed microbial cultures.

The microbial association 189 was isolated from soil treated with dimethylterephthalate (DMT) for a long time. The dynamics of its growth, respectively the degradation of the terephthalate ester known as an environmental pollutant has been studied.

Influence of some physicochemical factors on dimethylterephthalate biodegradation.

The mixed microbial culture 189 possesses high biodegradation capacity against dimethylterepthalate (DMT)--a basic substance in polyester fibres production and an environmental pollutant. The process of its degradation was followed and the effect of some external factors (pH, concentration, accompanying substrates) on the growth of the association was shown.

Effectiveness of phenol biodegradation as a function of the physicochemical parameters of the medium (II).

The effectiveness of phenol biodegradation as a function of the physicochemical parameters of the medium: temperature, pH, aeration, form of the inorganic source of nitrogen, presence of trivial substrates in the medium was studied. Using a two-factor dispersion analysis, the degree of influence of the various physicochemical parameters with regard to specificity of the biological factor was determined. Evaluation was made of the possibility to control the biodegrading process by means of physicochemical parameters of the medium.

Dependence of the microbiological degradation of aryl-containing xenobiotics on their concentration.

The effect of concentration of the toxic substrates: phenol, oNph, mNph, pNph on their microbiological degradation was studied. The dependence was investigated at biocenotic and population levels. The aryl-catabolic properties of 55 biodegrading cultures were studied at an increasing gradient of phenol substrates. The degradation dynamics has been studied at different initial phenol concentrations on 3 bacterial and one yeast strains.

[Effect of inorganic detergent components on the biodegradation of alkyl benzenesulfonates]. / Wirkung anorganischer Waschmittelkomponenten auf die Biodegradation von Alkylbenzolsulfonaten.

The rate of biodegradation of the alkyl chain of alkylbenzene sulphonates (ABS) carried out of the alkyl chain by pure adapted cultures of Pseudomonas fluorescens and Aspergillus sp. has been examined in the presence of four anorganic test compounds of commercial detergents. The strains were isolated from sewages by elected cultures. It has been established that the sodium perborate gave a completely different effect on the microbial metabolism of ABS than that obtained with polyphosphate, sulphate and silicate. The perborate possesses an inhibitory effect on the growth and the surfactant-degradative ability of the strains. The authors concluded from it that the presence of 20% perborate in the formula of commercial detergents must be kept in mind where environmental problems are concerned.