به منظور حذف بيولوژيلي كروم Aspergillus Niger مطالعه رنگ بري پساب واحد دباغي صنايع چرم سازي به كمك قارچ

Decolorization of tanning house effluent by Aspergillus niger in tannery industries for biological removal of chromium

Introduction. Color is considered as one of the major water resource pollutants and other parts of the environment. In tannery industries the application of trivalent chromium salts in tanning of leather produces a hazardous color whic being disposed directly to environment and it is likely to change to hazardous hexavalent form in the oxidation conditions of the receiving environments. During the last few years, studies have shown the potential of fungi in removing the color of wastewaters in appropriate conditions.The aim of this research was to study decolorization of tanning house effluent by Aspergillus niger in tannery industries for biological removal of chromium. Materials and Methods. The first, quality of tanning house effluent was studied. After adjusting of carbon to nitrogen ration in the effluent, A. nigar was inoculated in the different size into the effluent with different dillutions. The samples for 24 h. put in the shaker incubator. Then, the absorbance rate in the wavelength of 565 nm and biomass growth was estimated. Results. In this research Aspergillus niger was selected as the species of fungi for removing color from tanning house effluent. Results showed that Aspergillus niger is able to grow effectively in the tanning house effluent with dillution percentages of 10% and 20% (or chromium concentration 122.5 and 245 mg/1), with C/N ratio of 10 and pH=3; and can reduce the color, 94.5% and 93.4%, respectively . According to the experiments in this study, the best size of inocculum was determined as 10 ml. The percentage of decolorization was increased due to the increase of dry weight of fungal mass to the concentration of chromium (1.7-23.7 mg dry weight of mass/mg trivalent choromium). The highest chromium removal percentage,94.5%, was obtained in the 23.7 mg/mg ratio. The meaningful relationship of these parameters is confirmed according to the multiple regression coefficient of 0.8836. Conclusion. This study showed that Aspergillus niger can grow in tanning effluent and remove about 95 % of color caused by trivalent chromium. Therefore, can be removed efficiently during the decolorization process.