Heavy metal interrelationships in soil in the presence of treated waste water

An experiment was conducted in a greenhouse located in Agrinion, Greece, in order to study
the effect of the treated municipal wastewater (TMWW) on the soil heavy metal interactions,
in comparison to ordinary well irrigation water, denoted as control. The ultimate aim was the
establishment of sound scientific basis for the TMWW reuse in the irrigation of vegetable
production. A randomized block design was used including TMWW and the control, in six
replications, the vegetable of Brassica oleracea var. Gemmifera (Brussels sprouts) being
used as a test crop.
The following were found:
Forty interactions took place in the soil between heavy metals Pb, Ni, Co, Cd, Cu and Zn. Of
these, 11 were significant under both the TMWW and the Control, respectively. Also, under
only TMWW 15 interactions or 37.5% were statistically significant, while under the Control 21
or 52.5%. It was also shown that the effect of TMWW on most of the statistically significant
interactions between heavy metals, did not differ significantly from that of the control,
suggesting that from this point of view, the TMWW could be used for reuse in vegetable
irrigation, provided that health risk related to microbiological factor is taken into account.