Treated Wastewater Reuse for Irrigation in Bekaa, Lebanon: Quality Assessment and Public Perception

Abstract

In Lebanon, agriculture consumes 61% of the freshwater resources. In this sector, an estimated water supply-demand gap of 25% in 2020 is predicted to increase with the elevated and unmet water demand and the exacerbating pressure on the water supply. Despite having negligible, unregulated, and challenging water reuse practices, treated wastewater (TWW) is among the alternative water sources for irrigation to increase water availability and reduce the pressure on freshwater resources. However, its safe quality is of utmost concern and a prerequisite for water reuse, including farmers' and consumers' acceptability of this safe practice. Therefore, this study aims to determine the willingness of farmers in Zahle and Ablah, located in two water-scarce agricultural villages in the Bekaa governorate of Lebanon, and consumers from the general Lebanese communities toward safe TWW reuse in agriculture. It further characterizes the quality of TWW effluent from the Ablah and Zahle wastewater treatment plants (WWTPs) for reuse in irrigation to evaluate their environmental and public health risks.

The results revealed that farmers in Zahle and Ablah, potential beneficiaries of the Zahle and Ablah WWTPs, and consumers from the general Lebanese population aged 18 years and above have a very high willingness to safely use (32/34 farmers) and accept the safe usage (245/256 consumers) of TWW for irrigation. Farmers' acceptance was incentivized by the economic benefits of safe reuse, while the consumers mostly care about the environmental benefits of this safe practice. Statistical analysis showed that the economic incentive to increase agricultural yield and environmental incentive to reduce water scarcity in Lebanon significantly increased the willingness of consumers to accept the irrigation of crops that have the lowest health risk category (WTU1) with safe TWW. Their perception of the lack of sustainable access to sufficient freshwater significantly increased the consumers’ acceptance of the irrigation of crops with an increased health risk (WTU2). As for their willingness to accept safe reuse for the highest health risk crops (WTU3), it was significantly correlated with their knowledge that safe TWW conserves fresh potable water.

The main barrier hindering safe water reuse among farmers and consumers is their lack of trust in the authorities in Lebanon to ensure safe quality effluents. This perception matches the reality due to the very restrictive and inconsistent quality effluent of the Zahle and Ablah WWTPs. Based on a 6-month monitoring period (Jan-March and June-August 2022), the quality was found to be only suitable to irrigate Category III crops with the highest degree of restriction. This restriction and variability are mainly influenced by chronic poor governance and the national economic crisis. Despite this severe restriction, some farmers in Zahle and Ablah are irrigating their crops with these water outlets irrespective of the guidelines. Farmers in Bekaa and across Lebanon are also indirect users of wastewater from the 70 to 75% of the national generated WW discharged untreated into water bodies. Hence, some farmers are not fully aware of the actual risks of irrigating with unsafe TWW or even WW (whether direct or indirect irrigation), but they also might not have another alternative because of the worsened water security issues. A major implementation barrier for safe water reuse in Lebanon identified in this study is the gap between the reality, in terms of the unsafe quality of TWW for reuse, the lack of trust in the authorities in ensuring its safety for irrigation, and weak law enforcement for safe discharge of TWW in surface water bodies, and the goal of an integrated WW treatment and safe reuse practices in agriculture.

On the other hand, TWW remains a sustainable alternative that can contribute to bridging the water gap in agriculture, among other interventions. The Zahle and Ablah effluents can be improved in quality to match the intended design abilities and capacities of the treatment plants upon improvement of the general economic and financial situation in the country or through donor support to allow normal operation and maintenance. Some technical recommendations are also proposed in this thesis, to be decided on upon further monitoring and investigation, complemented by some suggested recommendations at the irrigation level to mitigate the risks of a restrictive TWW quality based on the improved quality of the effluent. Most importantly, water reuse projects need to be regulated and enforced by a national policy and standards for TWWR. The Lebanese Standards Institution (LIBNOR) is currently developing those standards based on the FAO draft Lebanese guidelines. A water strategy addressing water reuse management and quality control is fundamental, along with developing effective and appropriate communication mechanisms. To strengthen the trust in the authorities, these initiatives should be based on a transparent and accountable participatory approach from the earliest stages and throughout the entire decision-making process. Lastly, customized awareness raising can further promote safe water reuse in agriculture. This thesis established the groundwork for a more in-depth investigation of water reuse management and implementation and shed some light on current problems of wastewater reuse in irrigation.