Assessment of effective surface area for free water surface constructed wetlands

• Published in: Water science and technology 1999-01, Vol.40 (3), p.83-89
• Main Authors: Khatiwada, N R, Polprasert, C
• Format: Article
• Language: English
• ISSN: 0273-1223

Kinetic models of wetlands based on 2 biofilm geometries were developed to determine the effective specific surface area (as) available for biofilm bacteria and its dimensionless value or area factor (delta) . Reaction rates were assumed to be first order for both suspended and biofilm bacteria. One model considered the biofilm to have slab geometry, the other cylindrical geometry. Both then considered mass transfer across the biofilm to arrive at expressions for as and delta . Kinetic and other physical parameters were taken from the literature. Experimental data were obtained from a laboratory free water surface constructed wetland treating domestic wastewater with 80 per cent removal of COD. Assuming slab geometry for the biofilm, as and delta values were 315 m2 per m3 and 2.2, respectively. Higher results were obtained from the cylindrical biofilm model. The mathematical formulations of the models are tabulated.