Microbial and Physiochemical Profiling of Zarqa River Supplemented with Treated Wastewater: A High-Resolution PCR Analysis

Background: This study aims to evaluate the quality of treated wastewater flowing in the Zarqa River to determine its suitability for agricultural use. The assessment is based on physicochemical and biological parameters in accordance with Jordanian standards (JS 893:2021), the CCME water quality index, and the weighted arithmetic water quality index (WAWQI). Additionally, a microbial assessment was conducted to identify the presence of pathogens in the treated wastewater. Methods: A total of 168 water samples were collected from seven different sites along the Zarqa River over a 24-month period. This study focused on microbial assessment and selected parameters from the JS 893:2021, including total dissolved solids (TDSs), biochemical oxygen demand (BOD), dissolved oxygen (DO), chemical oxygen demand (COD), and E. coli levels. Furthermore, data were gathered on additional physicochemical parameters such as pH, mineral content (including Na, Ca, K, Mg, and Cl), salts (HCO3, SO4, NO3, and PO4), and heavy metals (Fe, Cu, Pb, Mn, and Co). The CCME water quality index and weighted arithmetic WQI scores were calculated to determine the water quality from all seven study sites. Results: In terms of Jordanian standards, Site 1 had the lowest TDS and DO values along with E. coli concentration. Further, in terms of minerals and salts, the maximum concentrations found for the sites are given herewith: Site 2 (K+ and NO3), Site 3 (Cl−, Na+), Site 5 (Ca, HCO3), and Site 7 (Mg2+, PO4, and SO4). In terms of pH, all the study sites had pH values within the acceptable range, i.e., between 6 and 9, for irrigation purposes. The concentrations of certain heavy metals, specifically lead (Pb), manganese (Mn), and cobalt (Co), were observed to be negligible. In contrast, Site 6 exhibited the highest concentration of iron (Fe) (0.0178 mg/L), while Site 5 recorded the maximum concentration of copper (Cu) (0.0210 mg/L) among the study locations. Site 1 demonstrated the most favorable water quality among the seven sites evaluated, whereas Site 6 exhibited the poorest water quality. Overall, the water quality from the majority of the sites was deemed suitable for drainage and for irrigating crops classified under the B category. However, based on the weighted arithmetic water quality index (WQI) values, none of the sites achieved a classification of good or excellent water quality, although the water quality at these sites may still be utilized for irrigation purposes. The current study is the first to report the presence of SARS-CoV-2 in Zarqa River water samples. Conclusions: The current study outcomes are promising and provide knowledgeable insights in terms of water quality parameters, while public health aspects should be considered when planning the WWTPs in parallel to reclaiming the wastewater for irrigation purposes.