Evaluating the purification efficiency of Moroccanwaste stabilization ponds’ systems

Lagoon wastewater treatment systems, introduced in 1970, have become a preferred economic solution in Morocco due to favourable climatic and economic conditions. However, these facilities often face performance problems, particularly related to excessive hydraulic and pollutant loads, resulting in treatment efficiencies below regulatory standards for urban discharges. Waste stabilization ponds in Morocco show average reduction rates of 70 % for chemical oxygen demand, 65 % for biochemical oxygen demand during 5 days, and 62 % for suspended solids. This study aims to evaluate the performance of seven lagoon treatment plants in different regions of the country and identify solutions to ensure compliance with discharge standards. The Moroccan experience in biological lagoon treatment is valuable for improving purification efficiency, with observed reductions of chemical oxygen demand, biochemical oxygen demand during 5 days, and suspended solids of 65 %, 54 %, and 62 % respectively, proposing strategies to optimize these processes and ensure adherence to specific norms.