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Chromium Removal from Chromit Polluted Water by using Aspergillus niger in the Bench Scale

Authors:
[ Nourisepehr, M ] - Dept. of Social Medicine , School of Medicine , Semnan University of Medical Sciences
[ yaghmaian. K ] - Dept. of Environmental Health Engineering , Health School, Semnan University of Medical Sciences

Abstract:

Introduction. The natural sources of chromium (+3) in the water resources is chromit . Chromium ( +3 ) when disposed to the environment, it is changed to hexavalent chromium with several health hazardous effects . Aspergillus niger is one of the species of fungi that can be used for industerial uses and removing heavy metals , such as chromium .No studies have found in our country on this field . The objective of this research, as a basic and applied, was to study the behavior ofA.niger in tanning effluent for chromium removal. At the first stage of this research , the possibility of A. niger growth was studied in order to determination the fungi tolerance limits Materials and methods.: Samples with different concentration of chromium ( 122.5 -1102.5 mg/1) with adjusting of carbon to nitrogen ratio and pH=3 , was prepared . A.niger biomass was inoculated with different size (0.04 - 0.24 %, dry weight) to the samples . The samples put for 24 h. in the shaker incubator at the 30 °C and 150 rpm . Then biomass growth rate estimated. Resultes. Results also showed that the fungi growth rate was increased in effluent at concentration 122.5 to 612.5 mg/1 and in concentration of 1102.5 mg/1 , fungi growth has been stopped .The best of inoculation size was obtained 0.08% ( dry weight ) . At concentration, 122.5, 245 and 367.5 mg/1 and best inoculation size (0.08 %) , the dry mass weight to chromium concentration ratio have been obtained to 23.7 , 18 and 13.1 mg/mg respectively. Conclusion : A.niger had most growth at the chromium concentration 122.5- 245 mg/1 .Statistical studies showed that, chromium concentration of effluent was effective on biomass fungi growth . The correlation test with 95 % confidence (R2 = 0.9129) showed when increasing concentration of chromium, dry mass weight to Cr+3 concentration ratio , will lead to decrease .

Keywords:

Chromite, chromium Removal, polluted Water, Aspergillus niger