TY - JOUR
T1 - Application of rhamnolipid and surfactin for enhanced diesel biodegradation-Effects of pH and ammonium addition
AU - Whang, Liang Ming
AU - Liu, Pao Wen G.
AU - Ma, Chih Chung
AU - Cheng, Sheng Shung
N1 - Funding Information:
This work was financially supported by the Ministry of Economic Affairs of Taiwan, Republic of China (92-EC-17-A10-S1-0013 and 93-EC-17-A-10-S1-0013). The authors gratefully acknowledge Dr. Jo-Shu Chang at the National Cheng Kung University and Dr. Yu-Hong Wei at the Yuan-Ze University for their generosity in providing surfactin and rhamnolipid during this study.
PY - 2009/5/30
Y1 - 2009/5/30
N2 - This study investigated the effects of pH and ammonium concentrations on the potential application of two biosurfactants, surfactin (SF) and rhamnolipid (RL), for enhanced diesel biodegradation with a series of bench-scale experiments. In general, compared to the experiments without biosurfactant addition, adding RL or SF to diesel-water systems at concentrations above their critical micelle concentration (CMC) values benefited diesel emulsification, and therefore enhanced diesel biodegradation. The effects of pH on RL or SF-enhanced biodegradation of diesel were in good agreement with the trends of emulsion index values for RL or SF addition, respectively, under different pH conditions, suggesting that enhanced diesel emulsification by RL or SF addition promoted biodegradation of diesel. In diesel-water systems with 50 mg/L of RL addition, an optimum pH condition for microbial growth and diesel biodegradation was found to be at a pH 7.2, while decreasing pH to 5.2 or increasing it to 8.4 reduced those parameters considerably. For the cases where 40 mg/L of SF was added, the enhancing ability shared a general trend with that observed for adding 50 mg/L of RL as the pH increased from 5.2 to 7.2. Further increase of pH to 8.4, however, did not seem to negatively influence biodegradation and biomass growth. With respect to the effects of ammonium concentration on diesel biodegradation in diesel-water systems with 50 mg/L of RL addition, an optimum ammonium addition for microbial growth and diesel biodegradation was found between 200 and 300 mg-N/L, but a dramatic decrease in growth and biodegradation occurred at ammonium addition up to 450 mg-N/L. For the cases where 40 mg/L of SF was added, an increase of ammonium addition from 50 to 200 mg-N/L substantially increased microbial growth and biodegradation of diesel. Further increase of ammonium concentration to 450 mg-N/L, however, did not further improve diesel biodegradation.
AB - This study investigated the effects of pH and ammonium concentrations on the potential application of two biosurfactants, surfactin (SF) and rhamnolipid (RL), for enhanced diesel biodegradation with a series of bench-scale experiments. In general, compared to the experiments without biosurfactant addition, adding RL or SF to diesel-water systems at concentrations above their critical micelle concentration (CMC) values benefited diesel emulsification, and therefore enhanced diesel biodegradation. The effects of pH on RL or SF-enhanced biodegradation of diesel were in good agreement with the trends of emulsion index values for RL or SF addition, respectively, under different pH conditions, suggesting that enhanced diesel emulsification by RL or SF addition promoted biodegradation of diesel. In diesel-water systems with 50 mg/L of RL addition, an optimum pH condition for microbial growth and diesel biodegradation was found to be at a pH 7.2, while decreasing pH to 5.2 or increasing it to 8.4 reduced those parameters considerably. For the cases where 40 mg/L of SF was added, the enhancing ability shared a general trend with that observed for adding 50 mg/L of RL as the pH increased from 5.2 to 7.2. Further increase of pH to 8.4, however, did not seem to negatively influence biodegradation and biomass growth. With respect to the effects of ammonium concentration on diesel biodegradation in diesel-water systems with 50 mg/L of RL addition, an optimum ammonium addition for microbial growth and diesel biodegradation was found between 200 and 300 mg-N/L, but a dramatic decrease in growth and biodegradation occurred at ammonium addition up to 450 mg-N/L. For the cases where 40 mg/L of SF was added, an increase of ammonium addition from 50 to 200 mg-N/L substantially increased microbial growth and biodegradation of diesel. Further increase of ammonium concentration to 450 mg-N/L, however, did not further improve diesel biodegradation.
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U2 - 10.1016/j.jhazmat.2008.09.006
DO - 10.1016/j.jhazmat.2008.09.006
M3 - Article
C2 - 18950937
AN - SCOPUS:62649145104
SN - 0304-3894
VL - 164
SP - 1045
EP - 1050
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
IS - 2-3
ER -