The identifiability of kinetic parameters of trichloroethylene biodegradation by phenol‐oxidizing cultures grown from various conditions

Abstract

Accurate determination of kinetic coefficients, involving k (maximum specific degradation rate), K_s (half‐velocity coefficient), and T_c (transformation capacity), is critical for successfully modeling trichloroethylene (TCE) cometabolic transformation. This study evaluates the identifiability of these parameters for phenol‐oxidizing cultures degrading TCE with resting cells and formate addition, by using three approaches. The correlation coefficient between k and K_s is first calculated, then the contour lines in k and K_s parameter space are visually examined, and finally the identifiability of k/K_s and T_c is analyzed. Results concerning the uniqueness of these parameters for each culture in degrading TCE are interpreted and compared. Analysis results indicate that k is highly correlated with K_s in the three cultures with resting cells. The parameter can be more easily identified when formate is supplied as reducing power for TCE transformation. However, this improvement varies with the conditions in which the cells are cultivated: it is the greatest for both Suspended Cells and least for Attached Cultures. When used as two independent parameters in modeling TCE transformation, transformation capacity, T_c, and, the ratio k/K_s show no correlation. Of these two parameters, the ratio k/K_s appears the more informative and the higher the correlation between k and K_s, implies a more identifiable parameter k/K_s.

Key words:

• Trichloroethylene
• phenol‐oxidizing bacteria
• identifiability
• least square estimate