the C =lppm group. Notice that in a first order reaction

the half-life values are independent of initial chemical

concentrations. However, the results showed different half-

life values for the C =5ppm and C =lppm samples under

otherwise same treatments. This deviation is because the

first order reaction kinetics does not address all the

factors (such as toxic effects and substrate availability)

that are influential to biological degradation reactions.

Table 5-12 lists the apparent biodegradation rate constants

for phenol. High correlation coefficient values for log of

concentration versus time indicate that the first order

reaction kinetics describes phenol degradation quite well.


Table 5-12. Apparent biodegradation rate constants for
 phenol.


 Sample C K STD ERR t ,
 (ppm) (lay) of KBD (2Y) R2

 #101 S 5 1.83 0.20 0.38 0.94
 #102 S 5 2.03 0.24 0.34 0.93
 #103 S 5 1.80 0.19 0.39 0.95
 #104 S 5 1.78 0.22 0.39 0.93
 #105 5 1.63 0.26 0.43 0.86
 #106 5 1.75 0.35 0.40 0.84
 #108 S 1 1.20 0.17 0.58 0.90
 #109 S 1 1.16 0.09 0.60 0.97
 #111 1 1.15 0.17 0.60 0.90
 #112 1 1.12 0.17 0.62 0.90

 S: Amended with sludge.
 Linear correlation coefficient for log C vs. time.


 The major difference between degradation rates lies

between the two groups with different initial

concentrations, and no differences were found among the

various nitrogen levels. The higher initial concentration