Wioletta Przystaś

Biological Removal of Azo and Triphenylmethane Dyes and Toxicity of Process By-Products

Increasing environmental pollution is connected with broad applications of dyes and imperfection of dyeing technology. Decolourization of triphenylmethane brilliant green and disazo Evans blue by bacterial and fungal strains and toxicity (phyto- and zootoxicity) of degradation by-products were investigated. Influence of incubation method on dyes removal was evaluated (static, semi-static, shaken). Dead biomass was used for sorption estimation. Toxicity of treated dyes was measured to estimate possible influence on aquatic ecosystems. The zootoxicity test was done with Daphnia magna and phytotoxicity with Lemna minor. Samples were classified according to ACE 89/BE 2/D3 Final Report Commission EC. The best results of removal for all tested strains were reached in shaken samples. In opposite to fungi, bacterial strains decolourized brilliant green more effectively than Evans blue. The most effective bacterial strain was Erwinia spp. (s12) and fungal strains were Polyporus picipes (RWP17) and Pleurotus ostreatus (BWPH and MB). Decolourization of brilliant green was connected with decrease of zootoxicity (D. magna) and phytotoxicity (L. minor). Removal of Evans blue was connected with no changes in zootoxicity and decrease of phytotoxicity in most of samples.

Efficiency of decolorization of different dyes using fungal biomass immobilized on different solid supports

Different technologies may be used for decolorization of wastewater containing dyes. Among them, biological processes are the most promising because they seem to be environmentally safe. The aim of this study was to determine the efficiency of decolorization of two dyes belonging to different classes (azo and triphenylmethane dyes) by immobilized biomass of strains of fungi (Pleurotus ostreatus – BWPH, Gleophyllum odoratum – DCa and Polyporus picipes – RWP17). Different solid supports were tested for biomass immobilization. The best growth of fungal strains was observed on the washer, brush, grid and sawdust supports. Based on the results of dye adsorption, the brush and the washer were selected for further study. These solid supports adsorbed dyes at a negligible level, while the sawdust adsorbed 82.5% of brilliant green and 19.1% of Evans blue. Immobilization of biomass improved dye removal. Almost complete decolorization of diazo dye Evans blue was reached after 24 h in samples of all strains immobilized on the washer. The process was slower when the brush was used for biomass immobilization. Comparable results were reached for brilliant green in samples with biomass of strains BWPH and RWP17. High decolorization effectiveness was reached in samples with dead fungal biomass. Intensive removal of the dyes by biomass immobilized on the washer corresponded to a significant decrease in phytotoxicity and a slight decrease in zootoxicity of the dye solutions. The best decolorization results as well as reduction in toxicity were observed for the strain P. picipes (RWP17).

BIODEGRADATION OF PETROLEUM HYDROCARBONS BY KERATINOLYTIC FUNGI

The chapter reviews available data on the ability of keratinolytic fungi to remove hydrocarbons from different media and on the ecology of these fungi in oil-contaminated environments. In pure culture, these fungi were able to remove hexane, toluene, hexadecane, pristane and autoclaved crude oil from mineral media. The hydrocarbon removal process was much more effective when hair or peptone was added to the media. Thus, the process was dependent on fungal proteolytic or keratinolytic activity, specifically on the readily available protein content in the media. The ability for hydrocarbon removal was found to be species- and strain-specific. In pure culture, keratinolytic fungi removed polar products of petroleum biodegradation from the media. In a soil environment, the degradation process was slowed down due to the accumulation of these polar products.

THE POTENTIAL OF KERATINOLYTIC AND KERATINOPHILIC FUNGI FOR DEGRADATION OF PETROLEUM HYDROCARBONS IN SOIL

The goal of work was to determine potential of keratinolytic fungi for degra- dation of crude oil. Two strains belonging to species Chrysosporium kerati- nophilum and Trichophyton ajelloi were isolated form sewage sludge and oil waste-contaminated soil from a refinery. Preliminary experiment was per- formed in liquid media with increasing concentration of peptone with and without presence of hair(source of keratin). The mean value of hydrocarbons loss was 39,8% during degradation of peptone and 49,2% during degradation of peptone and hair. The ability for removal of hydrocarbons was characteris- tic for fungal strains and probably associated with their high degree of adap- tation for living in habitats heavily contaminated with petroleum hydrocar- bons. It was observed that petroleum hydrocarbon removal rates depended on fungal proteolytic activity, biomass production, and easily degradable protein content in the medium. The main goal of work was determination of effect of fungi inoculum on the petroleum hydrocarbon removal rate in soil covered and not covered with hair. The hair was the major nutrient for keratinolytic fungi and other soil mi- croorganisms. The fungal inoculum accelerated the petroleum hydrocarbon biodegradation process during the first month of the experiment. The highest petroleum hydrocarbon removal rate was observed in soil inoculated with na- tive fungal strains. The lowest removal rate was observed in soil not inocu- lated with fungi (60%). The hair applied as additional nitrogen, sulfur and carbon source did not impact, or slightly inhibited, the petroleum hydrocar- bon biodegradation process. The fungal inoculum caused dramatic changes in soil fungal qualitative composition.