Avaliação do potencial das Águas Residuais Recuperadas como Recurso para Práticas Agrícolas Sustentáveis

In the context of exploring sustainable agricultural practices, the ASAP-WATER project raises an important question: Can reclaimed wastewater (RW) serve as a viable and environmentally responsible solution to meet agricultural water needs? With a focus on investigating emerging contaminants and analysing different farming systems, the project aims to go beyond the current state-of-the-art by providing an evidence-based assessment of the main benefits and challenges of this practice, in particular potential risks, with the goal of developing alternative strategies for safe, resource-efficient, and eco-conscious agricultural practices. Specific objectives include: a) To study the quality of RW to ensure its compliance with agricultural standards (Activity 1) – establishment of a monitoring plan in wastewater treatment plants (WWTPs) of different sizes and receiving different types of effluents, trying to get a seasonal snapshot of the physicochemical and potential agronomic parameters of these waters (e.g. pH, total organic carbon, COD/BOD5, total suspended solids, nutrient, heavy metal and emerging contaminants levels, microbial indicators). In this study, it will be included pollutants listed in the Urban Wastewater Treatment Directive, the Water Framework Directive Watch List and other compounds that have been commonly identified in WWTP effluents. b) To investigate the impact of RW on soil/substrate (Activity 2) – monitor changes in soil/substrate properties and composition due to RW irrigation and compare results with data from irrigation with conventional water supply, study the persistence/fate of selected emerging contaminants in the irrigated soils/substrates using sorption assays, column leaching studies, dissipation (volatilisation, aerobic/anaerobic degradation, photodegradation) and toxicity tests. c) To evaluate crop uptake of emerging contaminants under different production systems and irrigation practices (Activity 3) – conduct plant uptake experiments with an economically relevant horticultural crop used as model systems (lettuce) grown in soil/substrate and irrigated with RW or produced under hydroponic conditions (worst-case scenario for contaminant exposure). Crop yield and nutritional content will be monitored. Studies analysing the effect of irrigation practice (drip/sprinkler) on both contaminant uptake and irrigation infrastructure (e.g. biofouling causing nutrient depletion, contaminant/pathogen accumulation and clogging of the irrigation water lines) will be conducted. d) To estimate the risks and assess differences in crop yield and production viability for each condition tested (Activities 4-5) – These activities will integrate the information gathered in the previous ones (occurrence of emerging contaminants in RW, occurrence/behaviour/fate of pollutants on irrigated growing media, plant uptake) with data on their effects on soil/human (literature data complemented by toxicity tests performed during the project, including biofilm and pathogen monitoring results). In addition, a comparative study will be conducted between the different production systems tested and conventional agriculture in terms of economic/environmental/social benefits and costs. This project seeks to address one of the major societal challenges: to change the perception of RW from a waste to a valuable resource. Raising awareness and promoting the safe use of RW will, therefore, have a major impact on economic activities.