Effect of pond shape and vegetation heterogeneity on flow and treatment performance of constructed wetlands
2005 (English)In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 301, no 04-jan, 123-138 p.Article in journal (Refereed) Published
A model framework is developed for nitrogen transformations in a constructed wetland by combining both hydraulics and chemical transformation of nitrogen species. The nitrogen concentration of the effluent water is represented in terms of a convolution between the probability density function of the hydraulic residence Limes and a chemical transformation function describing the rate of mass-removal of total nitrogen with time in the water as a first-order reaction. Closed-form solutions to the treatment efficiency is derived and related to the nitrogen reduction in wetland Alhagen in Nynashamn, Sweden. Further. the model coefficients are explored by numerical simulations and expressed in terms of heterogeneity of the flow resistance. i.e. in vegetation, and the aspect ratio of the wetland. Heterogeneity in vegetation contributes to increasing the variance of the water residence time and this increases the effluent concentration of nitrogen. Based on the theory and the data from Alhagen. the residence time probability density function for water can have a significant influence, on the treatment, and particularly the aspect ratio markedly affects the active water volume and the treatment efficiency.
Place, publisher, year, edition, pages
2005. Vol. 301, no 04-jan, 123-138 p.
constructed wetland, nitrogen reduction, wastewater, mathematical modelling, solute transport, residence time approach, waste-water treatment, emergent vegetation, removal, model
IdentifiersURN: urn:nbn:se:kth:diva-14456DOI: 10.1016/j.jhydrol.2004.06.038ISI: 000226243200010OAI: oai:DiVA.org:kth-14456DiVA: diva2:332497
QC 201005252010-08-052010-08-05Bibliographically approved