Harvest to harvest: Recovering nutrients with New Sanitation systems for reuse in Urban Agriculture

Decentralized Valorization of Residual Flows as an Alternative to the Traditional Urban Waste Management System: The Case of Peñalolén in Santiago de Chile

“…Within the linear approach, these flows are usually directed towards end-of pipe solutions such as landfills or wastewater treatment plants (WWTP) where they are contained or partially treated and recovered, thereby still causing unwanted emissions to be released into the natural environment. At the same time, on the supply side, these nutrients need to be brought to the agricultural sector and/or urban agriculture (UA) where food consumed in the city is being produced, causing negative impacts, particularly resource depletion (i.e., phosphorus) and indirect energy consumption (i.e., artificial nitrogen fertilizer production) [3][4][5][6].Alternative destinations for these outflows can be found, such as: City green spaces, accelerated regeneration of natural disaster sites (fires, floods), erosion-prone hillsides in the city, selling the nutrients to external buyers, and/or for UA [5,7]. In particular, UA is a suitable and increasingly popular destination for recovered nutrients as it allows for closing cycles locally, reducing transport distances for residues, fertilizers, and food, offering many advantages for citizens (e.g., increased green space), and avoiding fossil-based artificial fertilizers (see [7]).…”

“…At the same time, on the supply side, these nutrients need to be brought to the agricultural sector and/or urban agriculture (UA) where food consumed in the city is being produced, causing negative impacts, particularly resource depletion (i.e., phosphorus) and indirect energy consumption (i.e., artificial nitrogen fertilizer production) [3][4][5][6].Alternative destinations for these outflows can be found, such as: City green spaces, accelerated regeneration of natural disaster sites (fires, floods), erosion-prone hillsides in the city, selling the nutrients to external buyers, and/or for UA [5,7]. In particular, UA is a suitable and increasingly popular destination for recovered nutrients as it allows for closing cycles locally, reducing transport distances for residues, fertilizers, and food, offering many advantages for citizens (e.g., increased green space), and avoiding fossil-based artificial fertilizers (see [7]). Despite the potential for closing nutrient, water, or energy flows, in practice, the implications of closing cycles in urban systems is not evident, due in part to the lack of information about the possibilities in matching demand and supply considering the quantity and quality of flows, its time and space availability, as well as user practices and disposition for changing household practices.Circular economy is gaining attention in Chile, both at private and public institutions.…”

The Role of Urban Agriculture as a Nature-Based Solution: A Review for Developing a Systemic Assessment Framework

“…However, urban forest is a crucial provider of ecosystem services, such as microclimate regulation and recreation [104]. Their contribution to urban food supply is, according to our review, mostly neglected and only three papers focus on edible forests [105][106][107]. In terms of management implications, one paper addresses the potentials of urban forests for fruit production and part of the urban edible landscape which should be fostered by urban planning [107].…”

“…So far, the focus of current research is clearly on community gardens (n = 58), followed by residential gardens/backyards (n = 24), and rooftop gardens and rooftop greenhouses (n = 23). Less often investigated were, for instance organic farms (n = 1) [106] or orchards (n = 2) [72,163]. For mapping different forms of UPA, Google Earth and web-mapping services can be used as demonstrated on the residential garden, community garden, urban farm, institutional garden, and illegal garden [175].…”

Life Cycle Environmental Impact Assessment of Circular Agriculture: A Case Study in Fuqing, China

“…As a result, a series of models for circular agriculture are gradually being developed in various areas, such as the pig-biogas-grain model [13], straw recycling model [14], "four-in-one" courtyard recycling model [15], the circular and clean farmland production model of double cropping rice and wheat [16], and the recycling agricultural production model of cow-biogas-forage [17]. Among these models, a core agricultural industry that utilizes materials from multi-level recycling and the multiple levels of energy of other agricultural industries has been widely used to achieve the goal of combining planting and farming [18,19]. Currently, many scholars have conducted a wide range of evaluations on this circular agriculture model from the perspective of inputs and outputs [20][21][22] as well as energy [23,24], but these scholars have seldom quantified the potential harm to the environment.…”