Modelling COD Removal in Water Hyacinth Constructed Wetland

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University of Dar es Salaam
The main aims of this project are to develop a model for COD removal using water hyacinth plants and to investigate the effect of retention time on COD removal. The pilot plant was run at three retention of 3, 6 and 12 days and daily samples up to three times the retention times were collected and analysed. The retention time with the best effluent quality and percentage removal (12 days) was used for the development of the model. In the development of the model, plug flow hydraulic regime was assumed. It was further assumed that COD in particulate matter is removed after settling. COD was assumed to be removed through sedimentation, biofilm activities and activities of suspended bacteria. Stella6.01 software, which uses forth order Runge Kutta approximation, was used for optimisation. Calibration was done using observed data and yielded a coefficient of regression 40.9% and the dominant route according to the model for COD removal were biofilm activity (61.5%) followed by uptake by suspended bacteria 36.1% and the least was sedimentation 2.41%. The model was validated and it yielded a coefficient of regression of 40.6% this shows that the model is consistent.
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF QH87.3.T34B37)
Water, Removal
Barrie, A (2002) Modelling COD Removal in Water Hyacinth Constructed Wetland, Master dissertation, University of Dar es Salaam. Dar es Salaam.