being released into the public ground water, were found
to be significantly higher than the standard levels on
both types of swine farm, but the level of Cd was lower
than the standard level as shown in Table 4. Moreover, a
comparison of the levels of E. coli, coliform and heavy
metals in dry manure taken from both farm types to the
standard levels, showed differences in the levels of E. coli,
coliform, Cd and Pb. In contrast, there was no significant
difference in the levels of Zn and Cu between biogas and
non-biogas farms (Table 5).
A comparison of the pH levels in wastewater samples
taken from each sample location on the farms showed
that the pH of wastewater from nursery housing was
lower (p < 0.05) than at other sample locations (Fig. 2a).
Furthermore, the mean E. coli level in nursery sludge was
really significantly different from that in pre-biogas sludge,
post-biogas sludge, and also in dried manure (Fig. 2b).
However, the other parameters did not show any significant
differences between the sample locations.