Using wastewater from the canning industry

Irrigation with wastewater from the canning industry is not harmful to the quality of agricultural soil and may even, in some cases, improve it. This is the conclusion of Iñigo Abdón Virto Quecedo in his PhD thesis defended at the Public University of Navarre.

The vegetable canning industry, by the very nature of its processes, produces a considerable volume of low-contaminant effluents.

A research project began in 1996 to determine the viability of agricultural irrigation as an alternative to the dumping of this wastewater. To this end, three trials were carried out, two in Villafranca and one in Valtierra, locations in the Ebro river basin region of Navarre with vegetable canning plants located on three agricultural soils representatives of the zone.

Iñigo Virto's research project involved the characterisation of the soils at the three trial sites in order to subsequently evaluate the effect of irrigation with wastewaters from industrial canneries, as a function of the doses received and the type of handling/kind of irrigation undertaken for the crop.

The viability of these kinds of systems depends fundamentally on the nature of the soil under use, the irrigation system and the type of crop planted. These are the factors that have to be considered when installing irrigation systems using wastewater.

Thus, in soils on which there is permanent meadowland, such as alfalfa or ray grass meadows and where sprinkler irrigation has taken place, a 'positive evolution' of the soil was observed, given that "this water is not contaminant but provides a significant injection of organic material and other types of elements that can be positive for the development of the soil". Nevertheless, on these types of soils any kind of irrigated meadow crop enhances the soil, independently of the type of water used for the irrigation.

Also, on the soils where rotation crops were planted (in general, maize, wheat and sunflower) and were flood-irrigated, soil evolution was different due to this handling factor. In short, this investigation showed that soil evolution was not as linked to wastewater irrigation as to the handling and quality of the soil.

So, if the crop type is suitably selected and the irrigation system is perfectly viable with this type of water, there should be no problems from the point of view of the soil.