mixing and dilution of the added solution with the distilled

water in the columns. Sampling and analytical procedures

were the same as described in Section 4.3.2. The

experimental scheme is illustrated in Figure 4-3.


 Column biodegradation II. This experiment was designed

to examine the results of PCP co-degradation in the presence

of phenol and was similar to the experiment in Section 4.3.3

except for using recirculation in columns. Columns were

saturated with 500 ml distilled water for three days before

draining all free water. Distilled water was then refilled

so that each column had 350 ml water (including 250 ml

trapped water and 100 ml free water) in it. A 150 ml of

mixed solution with different concentrations of phenol and

PCP were added to the top of each column which contained

1500 g of soil. To enhance the effects of co-degradation,

phenol concentrations with ten fold difference were used.

The same flow rate setting as in the previous experiment

(2.7 ml/min) was maintained. The experimental scheme is

listed in Table 4-7.