Sustainable farming by implementing the water-energy-food nexus between piggery production and wheat cultivation

Abstract

Piggery farms constitute hotspots of contamination due to their highly polluted wastewater discharged. However, from a circular-economy perspective, these effluents are very attractive for recovering renewable energy (in the form of biogas) and nutrients, which can be channeled to agricultural activities. This work shows a full-scale case study interconnecting piggery farming with wheat cultivation to achieve a sustainable water-energy-nutrients nexus. An average of 600 m³/day of piggery wastewater was treated in an anaerobic lagoon and the produced biogas (ca. 2300 m³/day) was utilized for electricity generation, which potentially yields 1.71 GWh/year. The treated effluent was used for fertigation of a 50-ha field of wheat (Triticum durum), which promoted an enhanced yield (7.3 vs 6.9 Ton/ha as compared to a control parcel irrigated with water from a local well) by the extra nutrients (nitrogen and phosphorus) provided. Furthermore, nearly 50,000 m³ of water could be saved by applying the treated effluent for fertigation, which is particularly relevant as the cultivation was performed in an arid region (Yaqui Valley, northwestern Mexico). Overall, this strategy illustrates the convenience of linking piggery farming with agriculture to accomplish sustainable management of organic-rich wastes through the production of biogas and the recycling of nutrients.