Hydrological and Environmental Impact of Wastewater Treatment and Reuse on Zarqa River Basin in Jordan

Treated wastewater is an important component of the water resource in Jordan. As Samra wastewater treatment plant-the largest treatment plant in Jordan-discharges similar to 110 MCM per year of secondary treated municipal wastewater to Zarqa River, and eventually to Jordan Valley. This research aims at assessing the impact of treated wastewater reuse on the hydrology and environment in the most vulnerable areas within Amman-Zarqa Basin, specifically from As Samra treatment plant to Jerash Bridge. Historical data is collected, field survey is performed, and chemical and biological analyses are performed at eleven selected locations along the study area. Afterwards, all collected data is managed using suitable tools to address the impact. The findings of this research demonstrate high improvement in biological and microbial parameters along the flow path, yet the salinity is increased downstream. It is found that this increase is due to brackish water intrusion, apparently from sandstone aquifer. Analysis of BOD and COD carried out as part of this research showed effective system recovery with COD reduction from 130 mg/L at the effluent to less than 50 mg/l in the downstream. Moreover, microbial activities are reduced, mainly due to self-purification in the river.