Impacts of wastewater irrigation on Mediterranean soil and food: A three-year case study in Italy

Water supply for irrigation is a limiting factor for agriculture in Mediterranean countries. A strategy for increasing water availability proposes to use low quality water for irrigation to avoid irrigation with precious and high cost potable water. A drawback about using waste water is the potential heavy metal accumulation in soil and foodstuff. In this study, primary or secondary treated municipal wastewater went through supplementary cleaning steps with a low-cost device and was used to irrigate tomatoes and potatoes in an experimental field in Italy. We monitored heavy metals in soil, food and processed food during three years. We measured no accumulation neither in soil, nor in food after this period. Variations of metal concentrations in soil and food were mainly due to common farm practices such as fertilisation and pesticide applications. This study demonstrates that irrigation with wastewater is achievable with a low-cost treatment device that can be used elsewhere to decrease pressure on water resources. • “We provide a low-cost farm-scale solution for waste-water treatment for irrigation”. • “Tests were conducted under normal farming conditions over three years”. • “No water quality related impact on soil and crop quality has been observed". • "Variations in heavy metals in soil and crops are rather due to agricultural practices”. • “Our solution is able to reduce water scarcity in European Mediterranean agriculture".