Simulation of batch-operated experimental wetland mesocosms in AQUASIM biofilm reactor compartment.
In this study, a mathematical biofilm reactor model based on the structure of the Constructed Wetland Model No.1 (CWM1) coupled to AQUASIM's biofilm reactor compartment has been used to reproduce the sequence of transformation and degradation of organic matter, nitrogen and sulphur observed in a set of constructed wetland mesocosms and to elucidate the development over time of microbial species as well as the biofilm thickness of a multispecies bacterial biofilm in a subsurface constructed wetland. Experimental data from 16 wetland mesocosms operated under greenhouse conditions, planted with three different plant species (Typha latifolia, Carex rostrata, Schoenoplectus acutus) and an unplanted control were used in the calibration of this mechanistic model. Within the mesocosms, a thin (predominantly anaerobic) biofilm was simulated with an initial thickness of 49 μm (average) and in which no concentration gradients developed. The biofilm density and area, and the distribution of the microbial species within the biofilm were evaluated to be the most sensitive biofilm properties; while the substrate diffusion limitations were not significantly sensitive to influence the bulk volume concentrations. The simulated biofilm density ranging between 105,000 and 153,000 gCOD/m(3) in the mesocosms was observed to vary with temperature, the presence as well as the species of macrophyte. The biofilm modeling was found to be a better tool than the suspended bacterial modeling approach to show the influence of the rhizosphere configuration on the performance of the constructed wetlands.
UNESCO-IHE Institute for Water Education, P.O Box 3015, 2601 DA Delft, The Netherlands; Department of Civil and Structural Engineering, Masinde Muliro University of Science and Technology, P.O. Box 190_50100, Kakamega, Kenya. Electronic address: njmburu2002@yahoo.com.
Njenga
N
Mburu
Department of Industrial Biological Sciences, Ghent University Campus, Kortrijk, Graaf Karel de Goedelaan 5, 8500 Kortrijk, Belgium.
Diederik P L
DP
Rousseau
Department of Civil Engineering and the Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, USA.
Otto R
OR
Stein
UNESCO-IHE Institute for Water Education, P.O Box 3015, 2601 DA Delft, The Netherlands.
Piet N L
PN
Lens
D001419:Bacteria / Q000254:growth & development; D018407:Bacterial Physiological Phenomena; D018441:Biofilms; D029785:Cyperaceae; D008962:Models, Theoretical; D018517:Plant Roots / Q000382:microbiology; D058441:Rhizosphere; D032401:Typhaceae; D014873:Water Pollutants; D018508:Water Purification / Q000379:methods; D053833:Wetlands
D014873:Water Pollutants
AQUASIM; Biofilm; CWM1; Constructed wetland mesocosms; Multispecies; Simulation