COMPARATIVE STUDY OF PILOT-SCALE SOIL BASE HORIZONTAL SUBSURFACE FLOW CONSTRUCTED WETLAND UNDER DIFFERENT OPERATIONAL CONDITIONS FOR WASTEWATER TREATMENT.

The effectiveness of a horizontal subsurface flow constructed wetland (HSFCW) for treating domestic wastewater (DWW) effluent was investigated over a six-month period under a variety of operational conditions, including vegetation (planted or unplanted "canna indica and Typha letifolia," media type (various types of soil, sand, and aggregate), and mode of wastewater feeding (continuous and submerged). All contaminants, with the exception of phosphorus, were significantly affected by plants (P< 0.05) in terms of removal effectiveness and mass removal rate. The average maximum removal efficiencies for total suspended solids (TSS), biological oxygen demand (BOD5), chemical oxygen demand (COD), soluble reactive phosphorus (SRP), and total Kjeldahl nitrogen (TKN) were 96.1%, 75.4%, 59.0%, 64.7%, and 49.4%, respectively, for planted beds versus 89.1%, 69.2%, 55.9%, 65.2%, and 42.4%, respectively, for unplanted beds under both conditions. On the removal efficiency of COD and BOD5, neither the media type nor the feeding mode system had a significant impact. When compared to gravel, soil media considerably (P <0.05) improved the wetland's ability to remove SRP, especially in the planted beds. Comparing the continuous mode (HRT 0.5 days) to the submerged mode (HRT 02 days), the continuous mode was more efficient at removing SRP. [ABSTRACT FROM AUTHOR]