"UPTAKE": AGRICULTURAL REUSE OF WASTEWATER AND SEWAGE SLUDGE: UPTAKE AND DISTRIBUTION OF CONTAMINANTS OF EMERGING CONCERN IN TOMATO PLANT AS A MODEL

The use of treated wastewater (TWW) as irrigation water and treated solids (TS) as a soil amendment in agriculture is in line with circular economy targets of Water Resource and Recovery Facilities (formally Wastewater Treatment Plants). It offers a solution for meeting irrigation requirements in regions suffering from water scarcity and the problem of sewage sludge disposal. However, the use of TWW and TS is problematic since they could contain contaminants of concern (CEC), which can accumulate in soil and plants, enter the food chain, and pose a risk to animals (feed) and humans (food). Regulation on the agricultural use of TWW in the EU was amended in 2020. Besides listing minimum quality requirements for some traditional organic, solids and bacteriological parameters, it states the key elements of a risk assessment associated with reusing TWW such as emerging contaminants, e.g., pharmaceuticals, pesticides, disinfection by-products and microplastics. However, it fails to specify which compounds to monitor. In contrast, regulations covering soil amendment with biosolids originates from 1986 and addresses only standard parameters. Many experts now believe it is just a question of time before the EU regularly recognises the need to monitor selected CECs in TWW and TS intended for agriculture. A further step is assessing the risks of using TWW and TS, which involves understanding complex interactions and physical/biological processes involved in plant uptake, making assessing the long-term impact of exposure to CECs from TWW and TS amended crops challenging. To date, studies on plant uptake of CEC have focused mainly on pesticides and legacy compounds or have been limited to selected pharmaceuticals in simplified experimental conditions. At the same time, limited data exist concerning endocrine-disrupting compounds such as bisphenols and micro/nano plastics. The UPTAKE project aims to address these knowledge gaps by studying the uptake of 30 CEC with diverse physicochemical properties (broad Kow) and micro/nanoplastics and under different growing regimes, including field conditions. The contaminants will be assessed in different environments (water, sludge, soil, plant tissues). The study will include hydroponic and soil-water systems (pots) experiments using TWW and biosolids with and without added CECs and field studies using lysimeters (with and without added CECs). Potable water and peat substrate will be used as control. We will apply target (30 CEC) and non-target analysis to assess the uptake and risk associated with CECs and their residues (metabolites/transformation products). Also, the effects of microplastic deriving from TS and TWW on soil in a pot and lysimeter experiment will be studied, and independent hydroponic experiments studying the uptake of nanoplastics will be performed for the first time. The research will focus on tomatoes as a model plant. In addition to experiments, a model will be developed and tuned to experimental data, which can then be used to predict plant uptake of other contaminants. Machine learning methods are expected to help identify the most influential and nonlinear relationships between physicochemical parameters of contaminants and their accumulation in soil or plant tissues. The data will estimate the potential health risk associated with human exposure to hazards present in the tomato fruit. Performing this work will require a multidisciplinary effort; for this reason, UPTAKE, led by the Jožef Stefan Institute, will build a team of five leading national academic institutions, seven European and International academic institutions and seven co-financing partners providing 38% co-financing (25% are required) proving the importance of research. UPTAKE also has the full support of the Chamber of Commerce and Industry and the Association of Municipalities and Towns of Slovenia.