Abstract：
Urban agriculture (UA) activities are increasing in popularity and importance due to greater food demands and reductions in agricultural land, also advocating for greater local food supply and security as well as the social and community cohesion perspective. This activity also has the potential to enhance the circularity of urban flows, repurposing nutrients from waste sources, increasing their self-sufficiency, reducing nutrient loss into the environment, and avoiding environmental cost of nutrient extraction and synthetization. The present work is aimed at defining recovery technologies outlined in the literature to obtain relevant nutrients such as N and P from waste sources in urban areas. Through literature research tools, the waste sources were defined, differentiating two main groups: (1) food, organic, biowaste and (2) wastewater. Up to 7 recovery strategies were identified for food, organic, and biowaste sources, while 11 strategies were defined for wastewater, mainly focusing on the recovery of N and P, which are applicable in UA in different forms. The potential of the recovered nutrients to cover existing and prospective UA sites was further assessed for the metropolitan area of Barcelona. Nutrient recovery from current composting and anaerobic digestion of urban sourced organic matter obtained each year in the area as well as the composting of wastewater sludge, struvite precipitation and ion exchange in wastewater effluent generated yearly in existing WWTPs were assessed. The results show that the requirements for the current and prospective UA in the area can be met 2.7 to 380.2 times for P and 1.7 to 117.5 times for N depending on the recovery strategy. While the present results are promising, current perceptions, legislation and the implementation and production costs compared to existing markets do not facilitate the application of nutrient recovery strategies, although a change is expected in the near future.
摘要：
由于粮食需求增加和农业用地减少，城市农业（UA）活动越来越受欢迎和重要，还倡导增加当地粮食供应和安全，以及社会和社区凝聚力的观点。这项活动也有可能增强城市流动的循环性,从废物来源重新利用营养，增加他们的自给自足，减少营养流失到环境中，避免了营养提取和合成的环境成本。本工作旨在定义文献中概述的回收技术，以从城市地区的废物源中获得相关的养分，例如N和P。通过文献研究工具，定义了废物来源，区分两个主要群体：(1)食物，有机,生物废弃物和（2）废水。针对食品确定了多达7种恢复策略，有机,和生物废弃物来源，虽然针对废水定义了11种策略，主要集中在N和P的回收，这在UA中以不同的形式适用。在巴塞罗那大都市区，进一步评估了回收的养分覆盖现有和未来UA站点的潜力。从该地区每年获得的城市来源有机物的堆肥和厌氧消化以及废水污泥的堆肥中回收养分，对现有污水处理厂每年产生的废水中的鸟粪石沉淀和离子交换进行了评估。结果表明，根据恢复策略，P可以满足该地区当前和未来UA的要求2.7至380.2倍，N可以满足1.7至117.5倍。虽然目前的结果是有希望的，当前的看法，立法以及与现有市场相比的实施和生产成本不利于营养回收策略的应用，尽管预计在不久的将来会有变化。
