Reclaimed water in agriculture: A plot-scale study assessing crop uptake of emerging contaminants and pathogens

Nowadays, water is a scarce resource, hence, water management is crucial as demand for agricultural, urban, and industrial purposes increases. The use of reclaimed water in agriculture can be a suitable solution. However, pathogens and chemical contaminants of emerging concern (CECs) present in reclaimed water can accumulate in the soil and ultimately, in the crop. To evaluate the potential transfer of biological and chemical pollutants from water to crop, two plots were designed for the cultivation of lettuce under field conditions. In this study, the influence of water quality, soil composition, and irrigation system on plant uptake of CECs and pathogens was assessed. The applied reclamation process reduced total suspended solids, E. coli (3-5 ulog), sulfite-reducing clostridia spores (1 ulog), Helminth eggs, and Legionella spp levels (complete removal) in water. Sodium adsorption ratio (SAR) and electric conductivity (EC) in the soils irrigated with reclaimed water were lower, and E. Coli was not detected. In lettuces, E. coli was only present in the crops irrigated with wastewater. Pharmaceuticals were the most frequently detected CECs in soils and waters, whereas UV filters achieved the highest concentrations. Diclofenac and salicylic acid were the most accumulated in soils, and diclofenac, ofloxacin, and benzophenone-4 were the most prevalent in the WWTP effluent. The irrigation water quality was the factor driving the transfer of CECs to the crops. Results show that the best combination to reduce pathogens and CECs was the use of reclaimed water, soils with high content of clay, and a sprinkling irrigation system.

This research was supported by the Spanish Ministry of Science and Innovation (Project ROUSSEAU CTM2017–89767-C3–1-R and Project CEX2018–000794-S). The authors are also grateful to Project MARADENTRO (PCI2019–103603) and Consorci d′Aigües Costa Brava Girona (CACBG) for the access to the facility and treated water supply, to the staff of the WWTP for their help, and BEKOlut®, for the provision of the QuEChERS kits.

Peer reviewed