Effect of filter media and hydraulic retention time on the performance of vertical constructed wetland system treating dairy farm wastewater

This study deals with the dairy wastewater treatment using laboratory scale vertical flow (VF) constructed wetlands <i>Canna indica</i> plantation over wetland beds due to phytoremediation capabilities. Three VF CWs (CW-A, CW-B and CW-C) each an area of 0.135 m2 filled gravel (CW-A: 20 mm; CW-B:10 mm gravel) sand (CW-C) receiving 0.04 m3 d-1 were operated for purification. Each unit was at three hydraulic retention times (HRTs) i.e. 12 h, 24 h 48 assessing its effect on purification . Among all units, removal rates fluctuated as: total suspended solids (TSS): 64.2–74.5%; biochemical oxygen demand (BOD): 45.3 – 63.1%; ammonium nitrogen (NH4–N): 29.6 56.5% phosphate phosphorous (PO4–P): 20.5 57.8% different HRTs. Increase in HRT showed better pollutants CWs. Moreover, maximum excluding TSS NH4-N achieved HRT. similar provided PO4-P (57.8%), BOD (63.1%) chemical (COD): 67.4%. size filter media, from (0.25 mm) resulted higher NH4 -N wastewater.