||In Benin, wastewater treatment remains a recurrent problem. While new technologies are in use around the world, sewage
treatment process, adapted to the contexts of developing countries is almost inexistent. To overcome these deficiencies and
provide practical experience for domestic wastewater treatment, phyto-purification tests on domestic wastewater has been
conducted on the Campus of the University of Abomey-Calavi (CUAC). The work focused on three floating species which
are Eichhornia crassipes Mart. Solms-Laub. (Water hyacinth), Pistia stratiotes L. (Water lettuce) and Lemna minor L.
(Duckweed). A mini system was installed and consisted of an anaerobic lagoon and three different floating macrophyte
ponds. The parallel position of the floating macrophyte ponds allowed, during the first phase, to assess the wastewater
purification efficiency of individual floating macrophytes.; this was achieved by monitoring the pollution level of the
wastewater in terms of its : SS, COD, BOD5, TKN, N-NO3- ,P – PO43-, fecal coliforms and fecal streptococci and
monitoring operational parameters such as T, pH, EH , turbidity, electrical conductivity. The results of the first phase
showed that water hyacinth has been effective in the removal of carbon and nitrogen for COD 70%, 52.8% BOD5, TKN
78.3% while water lettuce achieved nitrogen (N-NO3-) and P –PO43-, forms abatement at 20.0%, and 92.6% respectively.
Duckweed was successful in reducing 35.6% of TKN, and 100% of coliform and fecal streptococci. The complementary
effect of the potential of the studied species in a mixed system of floating lagoon gives even better returns, provide that the
limit of the salinity content to 1.126 µS / cm in wastewater tolerable by the macrophytes is observed.