115


This hypothesis can also be supported by the fact that the

amounts of sludge added did not affect the degradation rates

because the numbers of added bacteria were small compared to

the bacterial populations harbored on the soil matrix in the

columns.


 This column study demonstrated a promising results with

respect to in-situ biodegradation of phenolic compounds but

still left unaddressed the fate of the phenolic compounds

adsorbed on the soils. To solve this question, 50 g samples

of soil were taken from the top, middle and bottom of each

column. These were each extracted with 10 ml of methanol

and analyzed. This extraction method had an average of 72%

recovery for PCP at low levels of adsorbed mass (obtained

from previous mass balance calculations, data presented in

Appendix A), and the result showed only trace concentrations

(recognizable peaks in the chromatograms, roughly equivalent

to 0.05 mg/l, but not measurable with confidence) of PCP in

methanol, providing an indication that adsorbed amounts of

all three phenolic compounds were later desorbed and

biodegraded.


5.5.2 Column Biodegradation II.


 The second column experiment involved different phenol

to DCP to PCP concentration ratios, and was designed to

examine the effects of PCP co-degradation in the presence of

phenol. In this experiment phenol concentrations were not

monitored because of the huge differences in concentrations