| dc.description.abstract | Over the past 27 years, Kampala, the Capital City of Uganda has witnessed a very high rate of
population growth, urbanization and industrialization. Due to these developments, most wetlands
in the environs of Kampala, especially Nakivubo wetland have been tremendously reduced in size
and their ecological capacity to cleanse domestic, municipal and industrial effluents severely
diminished. Most of the industries in Kampala are located in the precincts of Nakivubo wetland
and discharge untreated effluents to Nakivubo Channel, which drains into Lake Victoria at the
Inner Murchison Bay. The City Abattoir is one of the key sources of pollutants into the bay,
which is the source of potable water for Kampala. This study was undertaken to develop and
evaluate the performance of bioprocesses to enhance the removal of pollutants from the City
Abattoir wastewater and eventually protect the ecology of Murchison Bay. A pilot scale,
consisting of integrated anaerobic and aerobic/anoxic sequencing batch reactors and a constructed
wetland system was developed at the City Abattoir and its performance evaluated for the removal
of organic carbon, nitrogen, phosphorus, turbidity, and faecal coliforms. Furthermore, the
potential of four macrophyte species, namely Cyperus papyrus, Typha domingensis, Phragmites
mauritianus and Miscanthidium violaceum to polish pre-treated abattoir wastewater was evaluated
in experimental mesocosms. Overall, C. papyrus achieved the highest removal rate of nutrients
from abattoir wastewater, attributable to its fast growth rate, high biomass and extensive root
network which provide suitable conditions for physical and biochemical removal mechanisms.
The integrated anaerobic and aerobic/anoxic sequencing batch reactors (SBRs) and constructed
wetland system achieved high removal rates of pollutants and contaminants from abattoir
wastewater. The anaerobic SBR was most important for the removal of faecal coliforms (98%),
chemical oxygen demand (93%) and turbidity (82%). On the other hand, the aerobic/anoxic SBR
was most instrumental in the removal of total nitrogen (80%) and total phosphorus (21%). The
constructed wetland retained all faecal coliforms, considerably reduced turbidity (76%), and total
phosphorus (63%). Each unit in the integrated bioprocess provided unique environmental
conditions that enhanced the degradation and removal of specific components of wastewater. The
City Abattoir management should use the results of this study to implement a full scale treatment
system to treat all process wastewater before discharge. | en_US |
