An Integrated Environmental Analysis Framework for Multi-Functional Urban Food Production Utilizing Nutrient Recycling from Organic Waste Streams

Abstract

Increasing enthusiasm for local food, including urban agriculture, has piqued research interest in the tenets underlying perceived benefits of localizing food production. This study develops and demonstrates the application of a comprehensive framework for the life cycle environmental assessment of the utilization of urban organic wastes in urban agriculture, specifically fruit and vegetable production. Results indicate that this full “urban nutrient cycle” may have significant environmental benefits in terms of land area requirements, water use, wastewater generation, nutrient recovery, environmental contamination and green infrastructure potential, compared to more conventional methods of waste processing and food production. Urban intensive food production using soil amendments produced from locally-sourced organic wastes in Northern and Eastern U.S. cities could meet up to 70% of current vegetable and 17% of current fruit consumption needs. Urban food production at this level would require 2,000 - 4,000 hectares for a population of one million, and has significant green infrastructure potential. Potential water savings from urban production are in the range of 10 - 17% of the urban area’s annual domestic use, and this “virtual water” can offset irrigation water use in more arid production areas. Optimizing resource recovery by separating sources of organic wastes results in 1-2% lower wastewater generation and up to 44% greater phosphorus recovery compared to current baseline methods. Source separation also reduces contaminant types and levels. Overall, energy and emissions benefits of urban nutrient recycling and food production are in the range of 1-2% of the city’s annual totals. The benefits of shorter transportation loops for both organic wastes and food are negligible. The lifecycle environmental impacts of alternative methods of food waste processing and reuse vary depending on policies at the local, state, and federal level. This research suggests how the LCA framework can inform policy analysis. Policies for waste processing, urban agriculture, and green infrastructure affect the relative environmental performance of different approaches to managing food waste. Evidence-based policy utilizing the framework developed here may outperform conventional approaches on a number of sustainability metrics. The framework can be applied to inform location-specific policy regarding food waste processing and urban food production.