Suitability of pumice (murram) soils for wastewater treatment in subsurface flow constructed wetland (SSFCW).

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University of Dar es Salaam
The primary objective of wastewater treatment is to improve the quality of water and reduce the pollution of the receiving water bodies. Constructed wetlands have been used for decades for this purpose. Phosphorus for example, is removed by attaching to a substrate, and the efficiency is improved by using suitable substrates. Locally available substrates namely murram and limestone were employed in this study. Murram is porous material and appears reddish brown, an indication of high amounts of Fe, an element important for removal of phosphorus. Analysis was done in laboratory to determine the adsorption capacity of murram as well as other properties. Field experiments consisted of four constructed wetland cells, three of which were planted with Phragmites mauritianus plants while one cell without plants was used as a control cell. The first cell was filled with murram, the second was the control cell. The third was filled with a mixture of murram and limestone at 1:1 ratios and the last was filled with limestone. Parameters analysed were phosphorus (ortho and total), COD, DO, EC, pH and temperature. These parameters were monitored for 15 weeks. The results from laboratory have indicated that murram has a good adsorption capacity for phosphorus. Particle size of 5000 u*m adsorption of 855.6 mg P/kg soil. The field experiments have shown that the cells with murram had better P removal as compared with limestone or their mixture. An average removal efficiency for the cell with murram and plants for the first four parameters were: ortho-P: 41.83%,total P: 71.43%,COD: 33.29% and DO: 72.93%. These results have shown that murram soils have a potential to be used as substrate materials for wastewater treatment in constructed wetlands.
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Constructed wetlands, Pumice soils, Suitability, Wastewater treatment
Mng'anya, S. E. (2002). Suitability of pumice (murram) soils for wastewater treatment in subsurface flow constructed wetland (SSFCW). Masters dissertation, University of Dar es Salaam. Available at (