Srivastava-2006-Isolation and proces.docxVIP

Bioresource Technology 97 (2006) 1167–1173 Isolation and process parameter optimization of Aspergillus sp. for removal of chromium from tannery e?uent Shaili Srivastava a, Indu Shekhar Thakur b,* a Environmental Biotechnology Laboratory, Department of Environmental Sciences, College of Basic Sciences and Humanities, G.B. Pant University of Agriculture and Technology, Pantnagar, Uttaranchal 263 145, India b School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, India Received 25 February 2005; received in revised form 17 May 2005; accepted 26 May 2005 Available online 14 July 2005 Abstract Five morphologically di?erent fungi were isolated from leather tanning e?uent in which Aspergillus sp. and Hirsutella sp. had higher potential to remove chromium. The potential of Aspergillus sp. for removal of chromium was evaluated in shake ?ask culture in di?erent pH, temperature, inoculums size, carbon and nitrogen source. The maximum chromium was removed at pH 6, temper- ature 30 C, sodium acetate (0.2%) and yeast extract (0.1%). Aspergillus sp. was applied in 2 l bioreactor for removal of chromium, and it was observed that 70% chromium was removed after 3 days. 2005 Elsevier Ltd. All rights reserved. Keywords: Aspergillus sp.; Bioreactor; Chromium; Hirsutella sp.; Biosorption; Fungi Introduction Chromium is considerable environmental concern as it is widely used in leather tanning, electroplating, metal ?nishing and chromate preparation. Chromium occurs in aqueous system in trivalent and hexavalent forms ( HYPERLINK \l _bookmark18 Horitsu et al., 1987). Chromium(III) is used in tannery as chromium sulphate, which may be converted into chromium(VI) in the e?uent. Hexavalent chromium may be converted to Cr(III) under reduced environment, which is much less toxic and less soluble by several microorganism possess chromate reductase, and thus reduction by these enzymes a?ords a means of chromate bioremediation. Chromium(III) proved to be b