Constructed wetlands (CWs) have been used to treat various types of wastewaters such as urban runoff, acid mine drainage, municipal, industrial, and livestock wastewaters. This study was conducted to evaluate the effectiveness of two constructed wetlands (surface and horizontal subsurface flows) for piggery wastewater treatment after biogas process. The wetland plant Phragmites australis Cav. was used in two CWs. The flow rate of the CWs was 100 liters/day with the hydraulic retention time (HRT) of 3 days. Parameters including pH, chemical oxygen demand (COD), total suspended solids (TSS), NH4 + -N, total nitrogen (TN) and total phosphorus (TP) were measured. After 45 days experiments, the results showed that the horizontal subsurface flow CWs had better treatment performance compared to the surface flow system. The pH of the wastewater after CWs treatment was in the range of to . The removal efficiency of TP, TSS, COD, TN and NH4 + -N by surface flow CWs was 80, 60, 66, 60 and 65 %, respectively while those by horizontal subsurface flow system was 86, 78, , and %, respectively. The water quality of the effluents of both two CWs met the Vietnamese standards for livestock wastewater (QCVN62-MT:2016/BTNMT, column B). | Treatment efficiency of piggery wastewater by surface and horizontal subsurface flow constructed wetlands
