## 1 Introduction  
Worldwide, there is large-scale production and use of a vast range of pharmaceutically active compounds (PhACs), including antibiotics. Different regions of the world have different levels of restriction on prescription and sales of drugs. In Jordan, self-medication is common practice, and drugs can easily be purchased from drugstores without prior prescription, despite laws prohibiting the sale and dispensing of non-prescribed antibiotics [1, 2]. In the study by [PERSON] et al. [2], more than 70% of drugstores investigated antibiotics, without prescription, for medical issues that included sore throat, urinary tract infection, diarrhea, and otitis media. Antibiotic resistance genes in different types of bacteria have been reported in isolates from the human population in Jordan [3, 4]. After ingestion, PhACs (including antibiotics, stimulants, and illicit drugs) and their metabolites end in human exceta (urine and faeces) and reach the environment via direct discharge or discharge of treated effluents from municipal wastewater systems [5, 6]. Many low and middle-income countries host pharmaceutical industries that produce wastewater, which often receives poor treatment, e.g., ending up in the environment or discharged into municipal sewage systems [7, 8, 9]. For effective removal of PhACs from wastewater, tertiary treatment steps involving nanotechnologies, adsorption, membrane technologies,or advanced oxidation processes (UV, H\({}_{2}\)O\({}_{2}\), photooxidation) are needed [10; 11; 12; 13]. These technologies are generally expensive and demand significant resources for maintenance and operation. In many parts of the world, wastewater treatment facilities are overloaded, compromising the treatment efficiency, or not applying a tertiary treatment [14; 15; 16; 17]. Consequently, effluents from WWTP constitute a significant source of PhACs, which lead to pollution of water resources, e.g., surface, ground, and lake water upon discharge. Pollution of water resources with PhACs has been reported around the world. Still, most of the research focusing on these pollutants had been conducted in industrial and high-income countries, e.g., Japan, Europe, and the USA [9; 18; 19; 20; 21; 22; 23; 24]. In Jordan, a middle-income country in the Mediterranean, wastewater treatment often does not include a tertiary step, and drug prescriptions and sales regulations are not regulated strictly. According to the Ministry of Water and Irrigation, 29 wastewater treatment plants (WWTPs) operate in Jordanian cities, with an estimated annual treated discharge of around 120 Mm\({}^{3}\) of wastewater [25]. The Assamra plant is the largest of Jordan's 29 WWTPs, treating wastewater from more than two million people, mainly in the Amman and Zaraq Governates [26]. Government and non-government agencies in Jordan are currently promoting the reuse of treated wastewater to mitigate the chronic water shortage in the country and for nutrient recovery, i.e., recycling of phosphorus from sewage back to arable land. As a result, more than 92% of the treated wastewater produced in the main cities in Jordan, i.e., Amman and Zaraq, is used for irrigation [25], mainly in the Zarqa River basin. The Zarqa River (ZR) is an ecosystem component of great importance for food supply and socioeconomic development in Jordan, as the river water is used to irrigate a wide range of vegetables, fodder crops, and industrial/cash crops in surrounding fields and gardens. The remaining ZR water flows down into King Talal Reservoir, a major water reservoir feeding King Abdullah Canal, from which water is taken for irrigation in the lower Jordan valley [26]. The annual average flow rate in ZR is around 360,000 m\({}^{3}\) day\({}^{-1}\). Concerning water sources, ZR receives more than 325,000 m\({}^{3}\) day\({}^{-1}\) of treated effluent from Assamra WWTP and surface water from Amman, Zarqa, Jerash, and parts of Mafraq [26].