STUDY OF PHYSICOCHEMICAL AND BACTERIOLOGICAL QUALITY OF WASTEWATER DISCHARGED INTO COASTAL WATERS FROM THE CITY OF EL JADIDA (MOROCCO) AND PROPOSED A SYSTEM OF TREATMENT BASED ON BIODENITRIFICATION

Abstract

In the city of El Jadida, disposal of untreated wastewater in the ocean has a negative impact on the environment and the health of the populations who live along the urban effluents. The main objective of this study is to monitor the physicochemical and bacteriological quality of raw sewage from the city of El Jadida. Several takings were made at the level of three collectors of the city of El Jadida between year 2011 and 2012. The parameters studied are temperature, pH, electrical conductivity (EC), nitrates (NO3-), nitrites (NO2-), total phosphorus (TP), orthophosphate (PO43-), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total kjeldahl nitrogen (TKN), total suspended solids (TSS), volatile suspended solids (VSS), fecal coliform (FC), fecal streptococci (FS), spore sulfite-reducing anaerobes (SSR). Analysis of wastewater in three collectors (C1, C2 and C3) showed that the concentrations of physicochemical and bacteriological parameters are very high and largely exceeding the Moroccan standards and that can cause very serious problems environmental. In this study, the biological treatment of raw sewage from the sewer in El Jadida (Morocco) had been tested in laboratory by using a bioreactor (immerged bacterial bed) colonized by a heterotrophic denitrifying flora. The obtained results show that parameters of removal efficiency were 97.69, 96, 90, 82.11 and 89.30 % of nitrate (NO3--N), dissolved chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total phosphorus (TP-P) and total Kjeldahl nitrogen (TKN-N) respectively when the system was operated at optimal conditions; pH 8.4, temperature of 28.9°C and COD/NO3--N ratio equal to 5. Consequently, the treated effluent has respected the norms defined in Moroccan’s project for all analyzed parameters.