A strategic approach to sustainable wastewater management and reuse in Saudi Arabia

The Kingdom of Saudi Arabia (KSA) faces challenges in protecting its limited natural water resources. The centralized sewage treatment plants (STPs) contribute to conserving natural water resources in various regions of KSA. For sustainable wastewater management strategies in arid environments, the performance of STPs needs to be assessed for various beneficial uses in addition to the existing regulations. The present study used extensive effluent quality data of four STPs to develop a performance assessment approach using multi-criteria and principal component analyses. The performance levels were derived from the compliance rate of effluent standards with different reuses and the efficacy of biosolids management. The proposed approach evaluated the STPs based on the planned applications of treated effluents, considering the land use characteristics of each plant’s disposal point. The factors loadings obtained for the STPs, encompassing total suspended and dissolved solids, and total dissolved solids, oxidizing demanding pollutants (BOD and COD), and nutrients (NO _3 and PO _4 ), with 3 to 4 principal components demonstrating above 60% of the effluent monitoring data, established the importance of the effluent quality parameters. The effluent quality index (EQI) was developed for existing and potential reuses, e.g., irrigation, landscaping, fishery, and recreation, during dry (summer) and wet (winter) periods. All STPs showed high EQI for both periods for the present reuse standards of unrestricted irrigation and landscaping. The overall performance index, aggregating EQI and the efficacy of sludge management practices, illustrated declining performance, suggesting staged improvements (tertiary-level treatment, air floatation, sludge digestion, and waste-to-energy) through a periodic assessment process. STPs must enhance their sludge management efficacy to produce Class-A biosolids and waste-to-energy. The proposed approach will help make strategic decisions regarding improvements for STPs and the allocation of financial resources to protect natural resources in various regions across KSA.