Wastewater-derived contaminants of emerging concern in the water-soil-plant continuum

The growth in cultivated lands, along with the increase in population, urbanisation, and the rising impacts of climate change such as increasing temperatures and frequent and severe droughts are increasing the pressure on freshwater resources on a global scale. To overcome these challenges, water conservation and new nonconventional water sources have been introduced, mainly desalinated water and reclaimed wastewater. These water sources are regarded as reliable which can reduce the growing pressure on freshwater resources. Water reuse can be divided into seven categories: urban reuse, impoundment (i.e., storage in reservoirs), environmental reuse, industrial reuse, groundwater recharge, potable, and agricultural reuse (i.e., irrigation) which is a major water reuse application worldwide. Despite the evident advantages to the water cycle and the advanced treatment, treated wastewater effluents were found to contain contaminants of emerging concern. These contaminants were not fully removed during conventional wastewater treatment and include pharmaceuticals, personal care products, corrosion inhibitors, perfluoroalkyl and polyfluoroalkyl substances (PFAS), microplastics, and antibiotic-resistant microbes and genes. As a result, contaminants of emerging concern were reported in various environmental niches such as rivers and streams, aquifers, irrigation water, irrigated soils, marketed crops, human urine, human breast milk, and human blood. This chapter will concentrate on international guidelines governing the use of treated wastewater for irrigation, as well as emerging contaminants in irrigation water-soil-plant and in-planta continuum, and future outlooks.