 BackResearch Article ScienceAsia 30 (2004): 351-357 |doi: 10.2306/scienceasia1513-1874.2004.30.351 Removal of Malachite Green Employing Physical and Biological ProcessesSubuntith Nimrat,1* Pilanya Sawangchit2 and Verapong Vuthiphandchai3ABSTRACT: This work involved the treatment of malachite green, a basic dye, extensively used in industries and aquaculture. A two-step technique associated with physicochemical and biological treatments was established to remove malachite green in terms of color and chemical oxygen demand (COD) reduction by the use of various adsorbents. Activated carbon and soil represented the best adsorbents for removal of the green color of malachite green and COD reduction. The results showed that activated carbon and soil can decolorize the green color of malachite green more efficiently than the use of ground shrimp skeleton, ground oyster shell and ground charcoal. However, all tested adsorbents, except ground shrimp skeleton, could reduce the COD level to similar extents. One millimolar malachite green (1,690 mg/L COD) was passed through activated carbon and soil and then to either aerobic or aerobic denitrifying activated sludge for COD reduction. The results demonstrated that the adsorption of malachite green using activated carbon or soil and treating the filtrate with either aerobic or aerobic denitrifying activated sludge could efficiently decrease the COD level by 77.5% to 86.0%. When a higher concentration of malachite green (2.0 mM) was tested using the same technique, the efficiency for COD reduction improved to 85.8-87.7%. Therefore, the adsorption efficiency with the use of physical and biological systems for COD reduction of malachite green appeared to increase with increasing concentration of the dye.
1 Department of Microbiology and Environmental Science Program, Faculty of Science, Burapha University, Chonburi 20131, Thailand. Received 4 May 2004, Accepted 10 Sep 2004
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