Evaluating Wastewater Reuse in Urban Agriculture from a Systems Perspective: Focus on Linkages with Water, Energy, and Health

When cities grow rapidly, they often displace surrounding agricultural lands and appropriate water previously used for irrigation. Sanitation infrastructure may struggle to contain flows and urban agriculture tends to move downstream of urban/riverine discharges. Irrigation of urban agriculture with domestic wastewater provides an opportunity for capturing valuable nutrients and water prior to release into nearby waterbodies. Cities invest capital and energy resources in wastewater treatment infrastructure in efforts to provide environmental and health benefits. Complex interactions in this food-energy-water-health (FEW-Health) nexus are location-specific; therefore, multiple impacts are explored in a site study in Hyderabad, India. Varying qualities of irrigation water (treated wastewater, untreated surface water, and groundwater) were evaluated, and the following impacts were quantified: water use, energy use and GHG emissions, nutrient uptake, and crop pathogen quality. Treatment plus reuse is shown to provide GHG mitigation when compared to the untreated case; however, land use needs are high to extract nutrients from dilute effluents. Also, harvesting practices and environmental factors contribute to crop pathogen content. Urban agriculture together with wastewater treatment and reuse is beneficial, but system-wide tradeoffs are complex. This chapter reveals key environmental, physical, and behavioral factors that constrain achievable benefits at the urban FEW-health nexus.