Role of wastewater in achieving carbon and water neutral agricultural production

Wastewater reuse for food production represents an opportunity to alleviate the stress on freshwater resources. Over the millennia, the purpose of wastewater treatment has transformed from contaminant reduction to resource recovery in different forms including struvite, nutrient rich streams and bio-solids. This has enabled wastewater treatment systems to not only reduce their environmental burden but also to offset burdens from other systems. Producing nutrient rich streams from wastewater treatment plants can be achieved at a lower global warming potential as compared to other alternatives. In the agricultural sector, nutrient rich streams can cause soil greenhouse gas emissions but they can also replace utilisation of fertilisers and improve carbon sequestration. In addition, reclaiming wastewater for the purpose of agricultural irrigation can improve water availability, access, and utilisation. It can also minimize grey water footprint since agricultural lands can assimilate high levels of nutrients. To date, there is no study that comprehensively assessed the potential of wastewater reuse in achieving carbon and water neutral agricultural production, and there is also no review that aggregates all the published work about the implications of wastewater reuse for irrigation on the carbon and water cycles. This review aggregates all the necessary parameters that need to be considered for a complete assessment of the environmental implications of wastewater reuse for agricultural production in terms of carbon and water. It can be used as basis to accurately examine the potential of wastewater reuse and treatment systems in achieving carbon and water neutral food production.