Physico-chemical analysis of the Nkolfoulou landfill effluent and treatment using a pilot reed bed filter system.

Abstract

In this study, some physico-chemical properties of leachate and water around the water bodies of Nkolfoulou landfill were analyzed in order to ascertain the level of pollution. The properties determined were pH, conductivity, cations (potassium, magnesium, calcium) and anions (chloride, nitrate, phosphate and sulphate ions). The pH and conductivity were measured in-situ while the cations and anions were measured in the laboratory using Ion Chromatography. The leachate samples were collected from three specific points of the active dumpsite. The water samples were collected from five specific points around the water bodies. In a pilot-scale reed bed filtration system constructed to treat the leachate from the landfill, samples were also collected from the inlet and outlet streams to see it efficiency. The results obtained for water samples revealed lower level of cations and anions compared to the WHO limit for drinking water quality except for K+ at the up-stream river (42.55 mg/L) and down-stream river (31.96 mg/L) compared to 10 mg/L. This is because these points are closer to the landfill. At the active dumpsite, the level of cation and anions of K+ and Cl- in Z3A (1550.93, 534.6) mg/L, Z3E (1836.41, 581.05) mg/L, basin1 (4385.75, 136487) mg/L and NO3-, (PO33- 278.18, 234.8, 324.22) mg/L respectively turn to be high at these points. In the treatment system, the level of Mg2+ (1539) mg/L, Ca2+ (46.50) mg/L and SO42- (77.20 mg/L) turn to increase in the outlet stream compared to the inlet stream. This increase is due to the contributions of these ions from gravel and sand present in the reed bed system. This implies that the system is not able to treat these ions. However the level of K+, NO3- and Cl- reduces implying that these ions are treated. Though the level of these cations and anion turn to increase, the system still serves as an efficient one for the treatment of the leachate since all the values lie below the Standard limit of WHO for drinking water except for K+ 576.91 mg/L. Phosphate ion turn to be absent in all the points since it acts as a sedimentation agent in the treatment of drinking water and control algae in raw and public water supply.