TREATMENT EFFICIENCY OF PIGGERY WASTEWATER BY SURFACE AND HORIZONTAL SUBSURFACE FLOW CONSTRUCTED WETLANDS

Constructed wetlands have been used to treat various types of wastewaters such as urban runoff, acid mine drainage, municipal, industrial, and livestock wastewaters. This study is 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 45 days for the experiments. The CWs were designed to treat up to 100 liters/day with the hydraulic retention time (HRT) of 3 days. Parameters including pH, COD, TSS, NH4+-N, total nitrogen (TN) and total phosphorus (TP) were measured. The pH of the CWs system was in the range of 6.7 to 7.3. The results showed that the horizontal subsurface flow CW had better treatment performance compared to the surface flow system. The removal efficiency of TP, TSS, COD, TN and NH4+-N by surface flow CW was 80, 60, 66, 60 and 65%, respectively while those by horizontal subsurface flow system was 86, 78, 74.6, 67.1 and 74.2%, respectively. The water quality of the effluents of both two CWs met the Vietnamese standards for livestock wastewater (QCVN62/2016-BTNMT, column B)