Evaluation of hexavalent chromium removal in a continuous biological filter with the use of central composite design (CCD)

JOURNAL OF ENVIRONMENTAL MANAGEMENT

卷:92

Article

Dalcin, Maurielem Guterres¹  Pirete, Marcelo Melo¹  Lemos, Diego Andrade¹  Ribeiro, Eloizio Julio¹  Cardoso, Vicelma Luiz¹  de Resende, Miriam Maria¹ 

[1] Univ Fed Uberlandia, Fac Chem Engn, BR-38400902 Uberlandia, MG, Brazil

关键词: Hexavalert chromium;    Biological filter;    Central composite design (CCD);   

DOI  :  10.1016/j.jenvman.2010.11.022

来源: Elsevier

【 摘 要 】

Hexavalent chromium is frequently found in industrial effluents as a result of the industrial applications of this compound and its anti-corrosive features. However, hexavalent chromium is extremely toxic, and its discharge in water is regulated, with a maximum limit of 0.1 mg/L in accordance with legislation established by CONAMA-Brazil (no. 397, April 3, 2008). To achieve lower discharge values, it is necessary to reduce from Cr(VI) to Cr(III), which is less toxic, and an economic alternative involves biological removal of this compound. Residence time distributions (RTDs) were measured to evaluate the behavior of actual biofilter operation conditions in a biofilter flow. The medium residence time distributions used were 8 and 24 h (recommended by the legislation). To optimize this process, a central composite design was used, considering the initial chromium concentration and pH as the independent variables and the removal of hexavalent chromium as the response. The boundary curves and surface response showed optimal behavior at 3.94 mg/L [Cr-0] and a pH of 6.2. The removal process of hexavalent chromium is mathematically described by the Michaelis-Menten kinetic model. This model appropriately represents the variation of chromium concentration along the bioreactor. (C) 2010 Elsevier Ltd. All rights reserved.

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