FACTORS INFLUENCING THE PERFORMANCE OF HORIZONTAL FLOW CONSTRUCTED WETLAND FOR MUNICIPAL WASTEWATER TREATMENT

Abstract

ABSTRACT This study aims to optimize the different operating conditions for the treatment of municipal wastewater using HFCW planted with Canna lily, Phragmites australis and Cyprus papyrus. Three separates basins of a horizontal flow subsurface constructed wetland (HFCW) pilot plants were designed, implemented and operated at the same operating conditions for almost one year for the treatment of real municipal wastewater. The first Basin (A) was planted with Canna lily, the second basin (B) with Pharagmites australis and the third basin (C) with Cyprus papyrus. To evaluate the performance of each basin at different operating conditions, such as hydraulic loading rate (HLR), hydraulic retention time (HRT) and organic loading rate (OLR), three sampling points at a distance 10 m apart from each others were established along each basin to represents different operating conditions. The results indicated that the pollutant removal efficiencies decreased with increase HLR. The removal efficiency at the first sampling point was the lowest for each basin. The best removal efficiency was at the third sampling point for each basin. The average removals of COD, BOD and TSS in basin A at point (A3) were 75.5 %, 83.4 % and 83.5 %, it reached 84.3%, 88.6 % and 89.1% in basin B at point (B3) while it reached 80.4%, 86.9 % and 87.5 % in basin C at point (C3). These results indicated that the Pharagmites australis proved to be more efficient in the removal of the organic matter compared to other plants.