Decolorization of azo dye using PVA-immobilized microorganisms.
A microbial consortium having a high capacity for rapid decolorization of azo dye (RED RBN) was immobilized by a phosphorylated polyvinyl alcohol (PVA) gel. The immobilized-cell beads exhibited a color removal capability of 75%, even at a high concentration of RED RBN (500 mg l(-1)) within 12 h using flask culture. The continuous operation was conducted at a hydraulic retention time (HRT) of 5-20 h in which the dye loading rate ranged from 240 to 60 mg dye h(-1). A removal efficiency exceeding 90% was obtained at the HRT higher than 10 h. No recognizable destruction of bead appearance was observed in the 6-month operation. Examination of the mechanism of the decolorization process by cell beads indicated that it proceeded primarily by biological decolorization associated with partial adsorption of the dye onto the entrapped cells and gel matrix. Microscopic observation revealed that the microbial consortium contained in the gel beads was at least made up of three kinds of bacterial species. From the economical viewpoint, alternative cheaper nitrogen sources such as fish meal, soybean meal, pharmamedia and vita yeast powder were examined.
Chen
Kuo-Cheng
KC
Department of Chemical Engineering, National Tsing Hua University, 300 Hsinchu, Taiwan, ROC. kcchen@che.nthu.edu.tw
Wu
Jane-Yii
JY
Huang
Chang-Cheng
CC
Liang
Yu-Min
YM
Hwang
Sz-Chwun John
SC
D001391:Azo Compounds / Q000378:metabolism*; D001420:Bacteria, Aerobic / Q000166:cytology / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D018914:Cells, Immobilized / Q000378:metabolism; D003116:Color; D003124:Colorimetry / Q000379:methods; D004396:Coloring Agents / Q000378:metabolism*; D005240:Feasibility Studies; D007220:Industrial Waste / Q000517:prevention & control; D008863:Microspheres; D010865:Pilot Projects; D011142:Polyvinyl Alcohol; D011786:Quality Control; D012722:Sewage / Q000382:microbiology*; D014874:Water Pollutants, Chemical / Q000378:metabolism
D001391:Azo Compounds; D004396:Coloring Agents; D007220:Industrial Waste; D012722:Sewage; D014874:Water Pollutants, Chemical; D011142:Polyvinyl Alcohol