In the mediumscale
continuous experiment, E. coli was inoculated at an initial
density of 1.50 108 ± 3.85 106 (average ± SD) CFU/g substrate
dry weight (Fig. 6). On day 2, E. coli had decreased to 107 CFU/g
dry weight in all treatments and then continued to decrease with
time. There was no difference between the abundance of E. coli
with either 35 g (2-C/LW) or 70 g (3-C/HW) earthworm density
in the system on any day, but the number of E. coli CFU surviving
in treatment 1-C/NW was slightly (but not significantly) greater
on days 9 and 16. The average number of E. coli CFU remaining
decreased below the legal threshold of 103 CFU/g dry weight after
19–23 days in all treatments (Table 1).