Compliance with WHO and FAO Standards for Treated Water from the Nouaceur and Mediouna’s Wastewater Treatment Plants for Reuse in Watering and Irrigation

Abstract

For a decade, the preservation of water resources has become a major environmental concern in Morocco, through the National Sanitation Program which aims to collect and treat wastewater efficiently by using valuable wastewater treatment plants (WWTP) for the reuse of cleaned wastewater in agricultural irrigation, urban watering, and recovery of rivers. The acute drought that has hit Morocco and the Mediterranean basin in the last five decades has pushed the Moroccan government to issue a new law on water saving and the reuse of purified water: law 10–95. To be reused, the treated water must comply with the standards imposed by the law 10–95 and the WHO. The Casablanca region with 4 million inhabitants evacuates more than 350,000 m³ of wastewater into the sanitary network. Only 100,000 pass through wastewater treatment plants installed in the peri-urban area. The cities of Casablanca and Mohammedia use an outlet that discharges 250,000 m³ into the Atlantic Ocean without extensive treatment. The cities of Mediouna and the airport area have wastewater treatment plants based on membrane reactor technologies, and activated sludge, respectively, generate purified water with different purification yields. In this context, we studied the conformity of cleaned water in wastewater treatment plants in the peri-urban environment of Casablanca using the WHO and FAO standards for irrigation waters by analyzing different physicochemical and bacteriological parameters. Our partnership with ‘Lyonnaise des Eaux of Casablanca’ allowed us to take regular samples from two main WWTPs, surrounding Casablanca City (Mediouna and Nouaceur airport zone) and make a quality monitoring and comparative study of treatment degree of the two WWTPs. The follow-up interests: Temperature, pH, electrical conductivity (EC), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), NH₄⁺, NO₃⁻, NKT, PO₄³⁻, and fecal coliforms. The physicochemical and bacteriological analyses of samples taken during the second half of the year 2021 showed that at the level of the station of Mediouna the registered abatement rate reached 90.9% for COD, 99.25% for BOD5, 99.1% for total suspended solids (TSS), 95.59% for Total Kjeldahl Nitrogen, and 80.20% for orthophosphate. For the airport zone, the registered abatement rate reached 90.2% for COD, 98.41% for BOD5, 99.02% for TSS, 80.07% for orthophosphate, and 83% for Total Kjeldahl Nitrogen. At the same time, the level of physicochemical quality (pH and EC) and hygienic quality for the two WWTPs are found to comply with WHO and the FAO intended for watering and irrigation.