Analysis of urban agriculture solid waste in the frame of circular economy: Case study of tomato crop in integrated rooftop greenhouse

• Published in: The Science of the total environment Vol. 734; p. 139375
• Main Authors: Manríquez-Altamirano, Ana, Sierra-Pérez, Jorge, Muñoz, Pere, Gabarrell, Xavier
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10-09-2020
• Subjects: Agro-urban solid waste; Circular economy; Integrated rooftop greenhouse; Organic waste substrat; Tomato stems; Integrated rooftop greenhouse; Circular economy; Tomato stems; Organic waste substrat; Agro-urban solid waste
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.139375

Within urban agriculture (UA), integrated rooftop greenhouses (i-RTG) have great growth potential as they offer multiple benefits. Currently it is intended to improve environmental benefits by taking advantage of the water, nutrients and gases flows. On the other hand, solid waste (SW) generated by the UA is a new type of waste within cities that has not well been classified or quantified for its use. This could become a new problem for the waste management system within cities in the future, mainly the organic fraction.
The objective of this research is to identify what type of i-RTG SW has the potential to be used from a circular economy (CE) perspective and propose a type of management for its material valorization.
The results of the case study show that, of the SW generated in i-RTG, the biomass has the greatest potential to be used locally as an eco-material, particularly the tomato stems. Its use is proposed as a substrate for two experimental lettuce crops in i-RTG. The results show that tomato stems have a better yield as a substrate after a prewash treatment, since at first the values of electrical conductivity (EC) are very high with respect to the control substrate, which is expanded perlite.
In conclusion, we can say that it is possible to increase the environmental benefits of i-RTG by taking advantage of its biomass locally, helping to foresee a possible future problem regarding the management of the residual biomass of i-RTG within cities. In this way, the paradigm about the perception of the SW of the UA could be changed to give them a by-product treatment from the beginning.
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•Solid waste (SW) from urban agriculture (UA): a new typology of waste within cities•Use of UA SW from a circular economy (CE) perspective•Biomass as a by-product of integrated rooftop greenhouse (i-RTG)•Use of tomato stems from i-RTG as a substrate for lettuce crops•Reduction of the UA SW within the cities and closure of the UA life cycle