Author(s): Samira Nahim-Granados; Patricia Plaza-Bolanos; Isabel Oller; Sixto Malato; Ana Aguera; Jose Antonio Sanchez-Perez; Maria Inmaculada Polo-Lopez

Linked Author(s):

Keywords: Solar processes; Agroindustrial; Wastewater reuse; Raw-eaten crops; Risk-assessment

Abstract: The intensification of water stress as a consequence of climate change along with population growth generates new water-food challenges for which the implementation of sustainable solutions able to close the water-food-energy nexus and to sustain current and future agriculture are needed. The agro-food sector is one of the larger water consumers associated with the cultivation and industrial vegetable processing. In this sector, the industry that marketed fresh products “ready-to-eat” (mainly leaf salads) stands out due to its extended and growing presence in the global market joint with its huge water consumption, linked with the intensive cultivation mode of the vegetables (ca. 54 m³ per ton) and their exhaustive washing during the industrial processing (up to 11 m³ per ton). Water chlorination is the most common sanitization strategy used to wash the vegetables avoiding subsequent health risks associated with the raw ingestion. However, this practice has been forbidden in some European countries due to the generation of unhealthy disinfection by-products (DBPs) during the washing step as a consequence of the presence of dissolved organic matter. Besides, the wastewater of this industry, excessively chlorinated, could not be directly used in other activities like irrigation in agriculture due to its toxicity against plants, being commonly discharge to surface waters and municipal sewage treatment plants. In this regard, the implementation of solar water treatments as environmentally friendly processes able to reclaim agro-industrial wastewater (without harmful by-products formation) for its subsequent agricultural reuse highlight as a sustainable solution to close the water-food-energy nexus in these industries. In this study, the capability of two solar processes (H₂O₂/solar and a novel photo-Fenton like process based on a commercial iron fertilizer Fe³+-EDDHA/H₂O₂/solar) for the simultaneous disinfection (E. coli O157:H7 and Salmonella enteritidis) and organic microcontaminants (OMCs) removal (a cocktail of 5 OMCs) of synthetic fresh-cut wastewater has been assessed at pilot plant scale and under natural sunlight using a solar Compound Parabolic Collector (CPC, 60 L). Later, reclaimed wastewater was used for in-vivo irrigation assays of vegetables to evaluate contaminants translocation and the potential associated benefit of the fertilizer use (chlorophyll content). Finally, a techno-economic (treatment costs), environmental (eco-toxicity) and health risk viability (quantitative chemical and microbiological risk assessment) evaluation of the global process was done including chlorination as a reference process. Results showed the suitability of solar processes as sustainable alternatives to chlorination in the fresh-cut industry allowing to close the industrial water circle through wastewater reuse reducing the industrial water footprint and the water scarcity through the principles of the circular economy.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022777

Year: 2022