Biodegradation kinetics for BTEX-degrading culture in immobilized beads

• Main Authors: Chih-min Shen, 沈之敏
• Other Authors: Chi-wen Lin
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/03154201172705859400

碩士 === 雲林科技大學 === 環境與安全工程系碩士班 === 98 === BTEX (benzene, toluene, ethylbenzene, and xylenes) are commonly found petroleum pollutants. It is not easy to be metabolized by human, and BTEX could cause damages to the central nervous system. Bioremediation is one of the common treatment methods for BTEX. The degradation efficiency may be boosted if cell-immobilized technology is incorporated into an existing biological treatment system. The enhancement of removal efficiency using cell-immobilized beads is believed to due to the advantages of protecting microorganisms from unpleasant environmental conditions, easier recovery of beads from solution, and reuse of the microorganisms. The degradability of BTEX by Pseudomonas sp. YATO411 in suspended culture and immobilized culture systems were both investigated. Moreover, the biodegrading data have been assessed using non-linear-regression technique to determine the kinetic parameters. Subsequently, different types kinetic model were verified. Results of the research show that: (1) The immobilized beads of Pseudomonas sp. YATO411 can provide protection for the cell. Under high concentrations of benzene or toluene, the biodegradation rate in immobilized cultures is much better than in suspended culture. (2) Toluene can stimulate Pseudomonas sp. YATO411 to degrade p-xylene. (3) Under single substrate condition, Haldane’s model is fitted kinetic data better than Monod’s model. (4) Under single substrate condition, the half saturation constant (Ks) increases with the substrate concentration. It reveals that the increase of substrate concentration decreases the affinity of microorganism. (5) Under single substrate and high substrate conditions, affinity for immobilized culture is higher than suspended culture. (6) Competitive model is fitted better for two substrate conditions with toluene+benzene and toluene+ethylbenzene. (7) Non-competitive model is fitted better for two substrate conditions with toluene+p-Xylene. (8) Under low benzene concentration (43.9 mg/L), immobilized bead can be reused at least 20 times (over 200 hours).