CHARACTERIZATION OF TREATED WASTEWATER REUSED FOR AGRICULTURE IN THE VEGETABLE FARMING AREA OF SEBKHA IN NOUAKCHOTT, MAURITANIA

Abstract

The study assessed the microbiological and physicochemical parameters of wastewater collected between October 2011 and September 2012 from the effluent of the WWTP in vegetable farming area of Sebkha inNouakchott.

The results of physicochemical analysis presented in this work have shown those the values of pH varied from 7.3 to 8. The EC values of experimental samples varied from 1050 to 1650 μS/cm. The turbidity values of experimental samples varied from 26.5 to 51.2 NTU. Effluents from the WWTP are characterized by a maximum iron and manganese content respectively of 412 µg/L and 22 µg/L and a minimum of 210 µg/L and 4 µg/L. Effluents from the WWTP are characterized by a maximum ammonia and orthophosphates content respectively of 120 mg/L and 60 mg/L and a minimum of 10 mg/L and 13.8 mg/L. The  values of COD  recorded  at  the WWTP  effluent  ranged  from  25 mg/L and  75  mg/L. The microbiological  results  show  that  the microbial  load of  fecal  coliforms  and  fecal  streptococci  is very  important. The levels of fecal coliforms and fecal streptococci ranged respectively between 3.10³ to 8.10³ CFU/100 mL and from 5.10³ to 9.10³ CFU/100 mL. The  microbiological analysis  revealed  high  concentrations  of  faecal  coliforms  and  faecal  streptococci,  values exceeding  the  microbiological  standards  of  the WHO.   

The  application  of  Principal  Component Analysis  indicates  that  two  groups  of wastewater:  a  group  of wastewater turbid characterized by a mineral salt, some metals and  organic and inorganic matter  expressed  by COD and a  group  of wastewater consists of very  high levels of fecal  loads, ammonium and phosphates.