This paper presents a comparative study of two experimental systems, stabilization ponds without macrophytes and macrophytic ponds, to purify wastewater under arid climate of Marrakesh. Organic load (COD, TSS), bacterial load (SF, CF) and parasitical load (helminth eggs) are significantly reduced in both systems. Even though water loss was more important at the macrophytic ponds (evapotranspiration reaches 60% of influent flow), this system shows generally the best efficiency in purifying wastewater. In summer time, TSS and COD depletion is better on macrophytic ponds (TSS: 95%, COD: 87%). The stabilization ponds are more efficient to reduce nutrients: NH4+: 72%. PO4: 63% at the same period. Fecal streptococci and fecal coliforms are reduced more in stabilization ponds (CF: 99.4%, SF: 99.7%) than macrophytic ponds (CF: 96.2%, SF: 94.7%). No helminth eggs were found in the effluent from either system. The two systems ensure optimal removal of parasites allowing the eventual reuse of the treated effluents for agricultural purposes.
