[Construction of a landscaping-type wetland system for wastewater treatment construction of a landscaping-type wetland system for wastewater treatment and analysis of plant denitrifying effect].
A pilot landscaping-type wetland system for wastewater treatment was constructed by introduction of 15 selected ornamental plant species (including 4 terrestrial plant species). The pilot system consists of 2 sequenced treatment units and 12 sub-units, i.e., a primary treatment unit with 4 parallel cells and a secondary treatment unit with 8 subsurface flow cells. Designed experiments were conducted in the established system to investigate the characteristics of nitrogen accumulation in different plants and the contribution of plant nitrogen uptake to total nitrogen removal of the constructed wetland system. The result shows that the direct contribution by plant uptake to the total nitrogen removal is low, ca. 1%-3% within the nitrogen concentration range 37.5-55.6 mg/L in the influent. Plant uptake does not fully reflect the important role of the plant species in the constructed wetland system for wastewater treatment as the function of the plant should include further its interaction with microorganisms and wetland fillers by enhancing microbial activities and filler adsorption capacities. The plant denitrifying effect, defined as the difference in nitrogen removal rates between units with and without plants, has been used to represent the contribution in nitrogen removal due to presence of plant in the system. The plant denitrifying effect thus includes both the plant nitrogen uptake and the interaction effect of plant with microorganisms and wetland fillers, the later being found to account for more than 80% of the total nitrogen removal in the established treatment system.
Chen
Ming-li
ML
Institute of Environment Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China. chml18@163.com
Wu
Xiao-fu
XF
Chen
Yong-hua
YH
Jiang
Li-juan
LJ
Ji
Zhi-hui
ZH
Ma
Qun
Q
D001673:Biodegradation, Environmental; D058440:Denitrification; D063245:Plant Development; D010944:Plants / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods*; D053833:Wetlands