were no samples with indigenous soil bacteria in the 5 ppm

initial concentration group, but compare #204 (with sludge

amendment in Co=5 ppm group, t/ =8.66 days) with #208, the

half-life for the higher initial concentration sample

appeared longer than its lower concentration counterpart.

The sample #203 was a duplicate of #204 until t=14.5 days

when 1 ml of solution containing phenol degrading bacteria

was added to #203. The effect was drastic as shown in

Figure 5-11 and was evident in half-life values. This was

attributed to either the increase in microorganism

population or to the introduction of some enzymes which were

induced by exposing the bacteria to phenol. The degradation

rate constant and half-life for #203 are only qualitative

because they were a result of the combination of two

treatments.

 Pentachlorophenol also appeared to undergo biological

degradation but with a very different pattern from phenol

and 2,4-dichlorophenol. Figures 5-12 and 5-13 illustrate

the degradation of PCP for different initial concentrations.

Table 5-14 lists the apparent degradation rate constants and

half-lives, and Table 5-15 lists the conservative results,

which were calculated based on the data up to t=60 days.

Because of analytical problems, PCP degradation data showed

day to day variability. In order to depict trends in the

PCP degradation data, variations in concentration versus

time data were dampened by using weighted average

concentrations, C(n), at measurement n, where