Bioremediation of crystal violet using air bubble bioreactor packed with Pseudomonas aeruginosa

Seven water and sediment samples were collected and tested for decolorizing crystal violet. Pseudomonas aeruginosa was the most effective isolate for dye decolorization. The LC50 of the crystal violet (115 mg/l) was measured using Artemia salina as a biomarker. The effect of different heavy metals on crystal violet decolorization was investigated. Cd2+ and Fe3+ ions showed marginal enhancement of the decolorization process, the rate was 1.35 mg/l/h compared to 1.25 mg/l/h for the control. Phenol and in-cresol showed no effect on crystal violet decolorization, meanwhile p-cresol and p-nitrophenol reduced the decolorization rate to 1.07 and 0.01 mg/l/h, respectively. P. aeruginosa cells were immobilized by entrapment in agar-alginate beads. The beads were cultivated and reused in Erlenmeyer flask and in an air bubble column bioreactor and they enhanced the crystal violet decolorization rate to 3.33 and 7.5 mg/l/h, respectively. (C) 2004 Elsevier Ltd. All rights reserved.