Selection of Suitable Filter Materials for Horizontal Subsurface Flow Constructed Wetland Treating Swine Wastewater

This research aims to assess different filter materials in horizontal subsurface flow constructed wetland (CW) planted with combined Phragmites australis Cav. and Cyperus alternifolius L. for treatment of real swine wastewater at a large pig farm in Vietnam. Four CW models including CW1 (gravel), CW2 (gravel, limestone), CW3 (gravel, limestone, and sand), and CW4 (gravel, limestone, and rice husk) were designed and conducted during 90 days of the experiments. The results showed that the removal efficiencies of chemical oxygen demand (COD), total suspended solids (TSS), nitrogen, and phosphorus from swine waster by the CW3 and CW4 models were higher than those by CW1 and CW2. The highest removal efficiency of COD, NH 4 + -N, TN, and TP by CW3 was 82 ± 2%, 82 ± 4%, 77 ± 1%, and 82 ± 3%, respectively. The result of this study indicates the capacity of combined gravel, limestone, and sand as suitable substrate filter for swine wastewater treatment.