Use of a Constructed Wetland for Post-Treatment of Swine Wastewater

The three-stage treatment scheme (solid separation followed by anaerobic and aerobic treatment) has been applied by most hog farms in Taiwan for wastewater treatment. The objective of this study was to examine the efficacy of using a modified free water surface (FWS) constructed wetland to polish the treated swine wastewater. The FWS wetland was installed on a hog farm to conduct the treatability study. The floating plant (Pistia stratiotes L.) was grown in the wetland system and small gravels were used as the media. In the first part of this study, effluent after the aerobic treatment unit was pumped into the system for posttreatment at two different hydraulic retention times (HRTs) (2 and 4 days). In the second part of this study, effluent after the anaerobic treatment unit was pumped into the system for treatment, and the system was operated at 5- and 7-day HRTs. Influent and effluent samples were analyzed for water quality parameters including chemical oxygen demand (COD), biochemical oxygen demand (B...