Treated Industrial Wastewater as a Water and Nutrients Source for Tomatoes Cultivation: an Optimisation Approach

The need to meet growing demands for food products is heavily associated with intensive exploitation of energy and water resources to drive the operations for irrigation, production of fertilisers, transportation and machinery amongst other key operations, which result in the emissions of greenhouse gases (GHG). The reuse of treated industrial wastewater (TIW) represents a promising alternative for growing food products in water scarce regions, as it reduces the reliance on renewable water sources whilst remaining an important source of nutrients. In this work, the potential for using TIW to cultivate tomato is investigated through a mixed-integer linear program aimed at minimising the environmental impact represented by the global warming potential (GWP). The optimisation model developed determines the optimal configuration of industries generating TIW that satisfy the crop water requirement and nutrients intake. Transportation emission along with the offset of GHG generated from fertilisers production are used as criterions impacting the selection of the optimal sources of TIW generating industries. Outcomes suggest that for the practise to be carbon neutral, tomato water requirements should be obtained from various sources to meet water and nutrients whilst minimising the GWP emissions. To satisfy the potassium requirements, fruit and vegetable processing plants along with cement industries represent the most optimal TIW sources. As for the nitrogen intake, it should be fulfilled from TIW originating from meat and poultry slaughterhouses.