The possible reuse of wastewater treated by lagooning for the irrigation of field crops

At the output from the lagooning system in the rural community of Saint-Coulomb, the effluent is of acceptable physical-chemical quality for the purposes of irrigation but care should be taken with regard to the irrigation of boron-sensitive plants. As far as contamination by metals is concerned, the effluent is of the domestic type and can therefore be used without restriction.

Monitoring of effluent quality during the summer months reveals that levels of thermotolerant coliform contamination do not always lie below the value fixed by the C.H.S.P.F. for the irrigation of plants eaten raw (10⁴ 1^-1). However, no intestinal helminth eggs or salmonellaewere detected.

The levels of thermotolerant coliform contamination do not reveal any significant differences (at the 5% level) between plants irrigated with treated wastewater and plants not irrigated at all. Nor is there any significant difference between plants irrigated with standard water (TTC < 10⁴ 1^-1) and substandard water. The thermotolerant coliform contamination does not only correspond to contamination by faecal coliforms.