Browsing by Author "Njau, K. N."

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    Establishment and Growth of Vetiver Grass Exposed to Landfill Leachate
    (2012-05-01) Nyomora, Agnes M. S.; Njau, K. N.; Mligo, L.
    Solid waste dumpsites in Dar es Salaam city are of environmental concern due to their associated leachate release into aquatic systems. They pose health risks to the Dar es Salaam residents due to the environmental pollution they cause. Currently, no control measures are employed. An effort to control leachate from Vingunguti dumpsite in Dar es Salaam using vetiver grass is in progress. Effectiveness of vetiver grass to control soil erosion and to treat wastewater is well researched; however, limited information exists on the response of vetiver grass growth to leachate and their effectiveness in phytoremediation of degraded dumpsites. This study aimed at assessing the survival of vetiver grass to landfill leachate so as to establish the use of vetiver grass in reclamation of dumpsites in Tanzania. Vetiver grass was subjected to various concentrations of leachate (0-50% v/v). The results showed that vetiver grass grew well only when it was exposed to leachate concentration of 10-30 (v/v) %. Above this concentration, vetiver grass growth was greatly reduced and complete death occurred at leachate concentrations of 75% (v/v) and above. Establishment and growth of vetiver grass Vingunguti dumpsite leachate would need approaches that limit the stress to young vetiver plants.
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    Wastewater Treatment for Pollution Control
    (2012) Nzabuheraheza, F. D.; Katima, Jamidu H. Y.; Njau, K. N.; Kayombo, S.; Niyigena, N. A.
    Performance of a Dynamic Roughing Filter (DRF) coupled with a Horizontal Subsurface Flow Constructed Wetland (HSSFCW) in the treatment of a wastewater was studied in tropical conditions. The results show that in HSSFCW planted with Cyperus papyrus and Phragmites mauritianus in series, the removal rates of TDS, TSS, COD and BOD5 were 72.07%, 80.01%, 81.22% and 78.37%, respectively, while in the second HSSFCW planted with Cyperus papyrus only, the removal rates were 71.00%, 79.00%, 73.76 and 75.78%, respectively. HSSFCW planted with mixed macrophytes, performed better than a HSSFCW planted with single macrophyte. This was attributed to synergetic effects of Cyperus horizontal roots and Phragmites vertical plant roots weaved and entangled in cell 1 providing a good filter mat and a better bacterial attachment. Thus the use of two macrophytes planted in series was recognized to be responsible for better performance of HSSFCW cell 1 in pollutants removal from wastewater.