Renewable Energy Potential of Sewage in Zambia ()
ABSTRACT
This study was aimed at investigating the renewable energy potential of
com- munal and municipal wastewater through methane production in biogas
digesters and the use of the captured methane for energy production in biogas engines. It was conducted on biogas digesters
receiving and pre-treating communal and municipal wastewater in the Zambian
city of Livingstone. Wastewater inflow rates into biogas units including the
wastewater turbidity, total dissolved solids (TDS), temperature, pH,
conductivity and Chemical Oxygen Demand (COD) were measured during the study.
And all the produced biogas was measured and combusted on-site during the
course of the research. In order to know the methane content of the gas, the CO2 content in the biogas was measured with a CO2 indicator. The study
showed that the predominant factor affecting the process of methane production
from wastewater to the greatest extent is the COD concentration of the
inflowing wastewater and not the system hydraulic retention times (HRT’s). The
COD treatment levels of the tested systems ranged between 27 and 86 percent and
the degree of breakdown primarily depended on
the COD concentration of the influent wastewater. On renewable energy
fuel production, about 3.54 kilograms of COD in each system produced a kilogram
of methane. Communal wastewater was able to produce an average of 600 grams of
methane per cubic meter of wastewater treated whilst municipal wastewater with
less COD concentration was only able to produce about 64.5 grams of methane per
cubic meter wastewater treated. With the use of a 45 kw Cummins 6 BT biogas
engine, the respective wastewaters had potential to produce about 2.6 kWh and
0.1 kWh of electric energy per cubic meter of wastewater treated at a levelized
cost of USD 9 cents per kilowatt-hour. Temperature also showed that it has
significant effect on methane production as a degree temperature rise in the
anaerobic system increased the methane production mass rate by 1.2 percent.
Share and Cite:
Simwambi, A. , Yamba, F. , Hibler, S. and Mulenga, K. (2020) Renewable Energy Potential of Sewage in Zambia.
Open Journal of Applied Sciences,
10, 328-350. doi:
10.4236/ojapps.2020.106025.