Mixture of dyes-study of zootoxicity and removal by selected fungal strains

Synthetic dyes, due to their toxicity and low biodegradability, belong to hazardous and hardly removable contaminants present in environment. Even bigger problems are caused by their mixtures. The aim of the study was the analysis of caused by mixtures of dyes (dyes from various classes) for aquatic organisms and the effectiveness of mixtures removal by strains of basidiomycota fungi. Two-component mixtures consisting of anthraquinone remazol brilliant blue R (RBBR), azo Congo red and triphenylmethane brilliant green (concentration range of mixtures 0.01-0.15 g/dm3) were tested. Zootoxicity was tested on Daphnia magna. Three strains of fungi were used: Strains BWPH and K4 belonging to the Pleurotus ostreatus species and RWP17 belonging to the Polyporus picipes species. Removal of dyes was analyzed at the wavelengths corresponding to the highest absorbance. It was found that mixtures of dyes are much more toxic to the test organism than single dyes. In decolorization studies with increasing of the concentration of mixture 1 (CK+RBBR), increased removal of colour by BWPH and K4 strains was observed. This mixture was well removed by the RWP17 strain and decolorization efficiency decreased with increasing concentration (from 95 % to 75 %). Removal of mixture 2 (CK + ZB) was very high for Pleurotus strains-increase of the dye concentration caused a decrease in the efficiency of the process (from 100 % to 0%). Studies have showed that the presence of dye mixtures in water is dangerous for organisms and the removal of them is very challenging. Efficiency of the process depends on the mixture composition, concentration and the strain used.