Treatment effect of domestic sewage by constructed wetland

Treatment effect of domestic sewage by horizontal subsurface flow constructed wetland with different plants, such as Phragmites communis and Typha latifolia, was studied. The results showed that: (1) the removal rates of CODcr, total phosphorus (TP), total nitrogen (TN) were related to seasons, which were summer>autumn > spring. (2) The removal rates of CODcr, TP, TN in Phragmites communis & Typha latifolia wetland were lower than those from Phragmites communis wetland or Typha latifolia wetland, when they were planted in the same density. This illustrated that there should be some antagonistic actions between Phragmites communis and Typha latifolia. (3) The removal rates of pollutants were different, when wetlands were planted in different density of Phragmites communis. For example, the TP removal effect in summer was: NO.1 (92.1%) >NO.2 (91.1%) >NO.3 (79.3%), while the Phragmites communis density was: NO.1 (125 plants /m2) >NO.2 (94 plants /m2) >NO.3 (63 plants /m2). This illustrated that 125 plants /m2 was a reasonable density. (4) The removal rates of CODcr, TN and TP in NO.1 wetland were, 57.6–81.8%, 45.3–79.6% and 71.1–92.1%, respectively.