Water, Air, & Soil Pollution

, Volume 212, Issue 1, pp 281–297

Effects of Vegetation, Season and Temperature on the Removal of Pollutants in Experimental Floating Treatment Wetlands

Authors

    • Department of Applied Analytical and Physical Chemistry, Laboratory of Analytical Chemistry and Applied EcochemistryGhent University
  • Erik Meers
    • Department of Applied Analytical and Physical Chemistry, Laboratory of Analytical Chemistry and Applied EcochemistryGhent University
  • Niels De Pauw
    • Department of Applied Ecology and Environmental Biology, Laboratory of Environmental Toxicology and Aquatic EcologyGhent University
  • Filip M. G. Tack
    • Department of Applied Analytical and Physical Chemistry, Laboratory of Analytical Chemistry and Applied EcochemistryGhent University
Article

DOI: 10.1007/s11270-010-0342-z

Cite this article as:
Van de Moortel, A.M.K., Meers, E., De Pauw, N. et al. Water Air Soil Pollut (2010) 212: 281. doi:10.1007/s11270-010-0342-z

Abstract

The research and interest towards the use of constructed floating wetlands for (waste)water treatment is emerging as more treatment opportunities are marked out, and the technique is applied more often. To evaluate the effect of a floating macrophyte mat and the influence of temperature and season on physico-chemical changes and removal, two constructed floating wetlands (CFWs), including a floating macrophyte mat, and a control, without emergent vegetation, were built. Raw domestic wastewater from a wastewater treatment plant was added on day 0. Removal of total nitrogen, NH4–N, NO3–N, P, chemical oxygen demand (COD), total organic carbon and heavy metals (Cu, Fe, Mn, Ni, Pb and Zn) was studied during 17 batch-fed testing periods with a retention time of 11 days (February–March 2007 and August 2007–September 2008). In general, the CFWs performed better than the control. Average removal efficiencies for NH4–N, total nitrogen, P and COD were respectively 35%, 42%, 22% and 53% for the CFWs, and 3%, 15%, 6% and 33% for the control. The pH was significantly lower in the CFWs (7.08 ± 0.21) than in the control (7.48 ± 0.26) after 11 days. The removal efficiencies of NH4–N, total nitrogen and COD were significantly higher in the CFWs as the presence of the floating macrophyte mat influenced positively their removal. Total nitrogen, NH4–N and P removal was significantly influenced by temperature with the highest removal between 5°C and 15°C. At lower and higher temperatures, removal relapsed. In general, temperature seemed to be the steering factor rather than season. The presence of the floating macrophyte mat restrained the increase of the water temperature when air temperature was >15°C. Although the mat hampered oxygen diffusion from the air towards the water column, the redox potential measured in the rootmat was higher than the value obtained in the control at the same depth, indicating that the release of oxygen from the roots could stimulate oxygen consuming reactions within the root mat, and root oxygen release was higher than oxygen diffusion from the air.

Keywords

Wastewater treatment Combined sewer overflow Nitrogen Phosphorous COD Heavy metals

Copyright information

© Springer Science+Business Media B.V. 2010