Treatment of domestic wastewater in a pilot-scale HSFCW in West Iran Original Research Article

This research investigated the feasibility of using constructed wetland system with a second-stage processing, included duckweed lagoon as a polishing stage, as an appropriate technology for treating the domestic wastewater generated by small communities in the economical underdeveloped cold regions. The reed bed pilot included four basins, of which two were used to plant reed and the two others as witness. The duckweed pilot was set up near the reed beds. The pilot plant was tested with six different BOD, COD, TN, TP, TSS and TDS loadings. The test results showed the artificial reed bed with subsurface flow capable of removing TSS by 92%, BOD by 89% and COD by 78%. Moreover it is possible to remove phosphorus and nitrogen containing compounds by 29% and 35%, respectively. The reed bed effluents were discharged into duckweed lagoon and the removal ratios of the above parameters were once again studied. The results showed reductions of 20% in BOD, 10% in COD, 24% in TSS, 8% in TN and 29% in TP. Based on these studies, the use of artificial reed beds for treating household wastewater in small communities is a sound technical and economical solution, while duckweed can be used as a complementary post-treatment process during the warm seasons.