Comparison of constructed wetland and stabilization pond for the treatment of digested effluent of swine wastewater

A laboratory-scale horizontal subsurface flow constructed wetland (HSFCW) and a stabilization pond (SP) were constructed to compare their performances on the treatment of digested effluent of swine wastewater. After 457 days of operation, the removal efficiencies of the HSFCW were as follows: chemical oxygen demand (COD), 17-54%; total phosphorus (TP), 32-45% and ammonia nitrogen NH4+ -N, 27-88%, while they were 25-55%, 31-56% and 56-98%, respectively, for the SP, with a hydraulic retention time of 54 days and hydraulic loading of 0.01 m(3) m(-2) d(-1). The average removed loads for the HSFCW were as follows: COD, 0.25-4.33; TP, 0.01-0.11 and NH4+ -N, 0.34-2.54 gm(-2) d(-1), while they were 0.25-4.45, 0.02-0.13 and 0.72-2.87 gm(-2) d(-1), respectively, for the SP. The SP performed better than the HSFCW because the SP showed a 20% of higher removal efficiency for NH4+ -N than the HSFCW. Especially, the COD removal rate of SP was 10% higher than the HSFCW when the influent concentration was at the lowest and highest stages. Meanwhile, given the lower costs, the SP is more suitable for the treatment of digested effluent of swine wastewater than the HSFCW.