Bacteriological and physicochemical quality of treated wastewater of the Mzar treatment plant

Abstract

In order to use purified wastewater on watering green spaces of Agadir city, we conducted this study to assess the bacteriological and physicochemical quality of treated wastewater in Mzar treatment plant. To realize these objectives, we analyzed four types of waters: raw water (RW), decanted water, purified water and purified water treated by the ultraviolet radiation (PWUV). The biologically analyzed parameters are fecal coliforms (FC) and fecal enterococci (FE). The physicochemical parameters are: pH, electrical conductivity, chemical oxygen demand (COD), five-day biological oxygen demand (BOD5) and total suspended solids (TSS). The results showed a high level of bacterial contamination in all types of waters, and the average loads of FC were between 4.71 × 106 CFU/100 mL (RW) and 1.45 × 103 CFU/100 mL (PWUV), while loads of FE were between 2.62 × 105 CFU/100 mL (RW) and 7.92 CFU/100 mL (PWUV). The physicochemical parameters show a pH close to neutrality and a high electrical conductivity (3261 μS/cm) in PWUV. In all stages of wastewater treatment, values of COD, BOD5 and TSS were under the limit values recommended by Moroccan standards. Except for the electrical conductivity and FC, all the studied parameters were under the limit values requested by the Moroccan standards. The microbiological quality of PWUV is unstable, and if these waters are reused, they can affect the microbiological and physicochemical quality of green spaces and groundwater.