Browsing by Author "Pamba, Siajali"

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    The potential use of mangrove constructed wetland for domestic waste water treatment
    (University of Dar es Salaam, 2008) Pamba, Siajali
    The potential use of Mangrove Constructed Wetlands (MCWs) as a cheaper and yet effective and appropriate method for nitrogen removal from domestic wastewater of coastal zone in per urban cities, was investigated at different times from August 2006 to March 2007. The study was conducted to determine the optimum inundation time and sewage loading for optimal performance of mangrove constructed wetlands (MCWs). The experimental plots were constructed at Jangwani beach in Dar es Salaam. The experimental setup consisted of thirty six cells with specification of 3x 3x 1 m. The first set of 12 cells was planted with Avicenna marina, another 12 cells were planted with Rhizophora mucronata and the remaining 12 cells were not planted. For optimal inundation time, most of the nutrients removal (NH4+, TKN and PO4+) was high in four cells within 12 hours. The maximum removal rate of NH4-N, NO3-N and TKN in Avicenna marina cells was 27.13%, 95.75% and 82%, respectively. In Rhizophora mucronata cells, the maximum removal rate of NH4-N, NO3-N and TKN was 50%, 93.20% and 82%, respectively. The model simulation was performed using STELLA® software and it was found that, the volatilization process was the major removal route of nitrogen in Avicenna marina ells accounting for mean of 17.08% (0.7936 ± 0.5030 mg/m2.c1 -1) while in Rhizophora inucronata, nitrification was the maj al route of Nitrogen accounting for mean or remove of 24.10% (0.3915 ± 0.540 mg/m24-1).
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    Transport and dispersion pattern of suspended particulate matter in estuaries of Tanzania: a case of Pangani estuary
    (University of Dar es Salaam, 2015) Pamba, Siajali
    The transport and dispersion pattern of Suspended Particulate Matter (SPM) in the Pangani estuary were investigated by employing in situ measurements, hydrodynamic modelling and satellite remote sensing methods. The sediment traps, refractometer, MIKE 21 model and MERIS FR were used for determining SPM fluxes, determination of salinity, simulating hydrodynamic regime and mapping the dispersion of SPM respectively. Based on the satellite image analysis, the distribution of SPM concentration in Pangani estuary is classified into three categories: area with high SPM (4.5 -15 g m-3), moderate SPM (4.5 to 1.5 g m-3) and low SPM (0-1.5 g m-3). The deposition of SPM fluxes increased exponentially on either side of the river mouth forming a parabolic curve with a minimum value occurring at about 3.3 km north/south of the central axis. The transport, dispersion and deposition of SPM in Pangani estuary are influenced by SE and NE monsoon wind pattern, waves, tidal currents and the Pangani River discharges. The River discharges and tidal currents influenced the salinity stratification, salinity intrusion and SPM input. The data on monthly river discharges positively correlated with SPM concentration. The highest fresh water discharges occurred during April – July, corresponding with highest input of SPM and salinity stratification and lowest extent of salinity intrusion. The locus of SPM deposition on the mouth of the estuary was influenced by the monsoonal seasonal changes, with preferential deposition on the northern side of the estuarine mouth. If the current trends of SPM deposition are left unabated, the preferential deposition of SPM on specific locations of the Estuary will pose considerable negative socio-economic and ecological impacts.