| dc.description.abstract | The rapid exhaustion of finite non-renewable energy sources like fossil fuels has
resulted in adverse effects on human health, environmental deterioration, and global
climate change. Two primary factors dominate Kenya's energy scene: a heavy
dependence on declining biomass energy resources for the rural household to meet
energy needs and a significant reliance on petroleum imports to meet contemporary
economic needs. The expanded use of renewable energy was one of the factors needed
to drive sustainable development. Production of biogas energy from cow dung in Kenya
using agricultural residues because of the high C/N ratio is one option for producing
energy derived from renewable resources. The altered C/N ratio is partially responsible
for the creation of biogas by co-digestion. The study utilized response surface approach
to maximize the critical parameters that influence biogas output from co-digestion and
Na2CO3 pre-treatment using a digester. The parameters studied were substrates (cow
dung and maize residues) and percentage soda ash. The study's objective was to
examine the influence of the duration of pretreatment of maize stalks regarding biogas
production when cow dung and maize stalks were co-digested in an anaerobic digestion
process. The maize residue was prepared based on the design of the experiment where
different samples were pretreated at different Na2CO3 concentrations and varied
duration. Under different Na2CO3 concentration, the maize stalk pretreated by 7%
Na₂CO₃ concentration for 4 days achieved the highest total solid of 15.15% which was
7.26% higher than that of untreated one, and was subsequently used to carry out co
digestion with the core substrate which was the cow dung. The study found that the
optimum substrate ratio for biogas production by the co-digestion of cow dung, pre
treated maize stalks, and dilution was 1:1:3, with cow dung and maize stalks being in
equal proportions, these optimum substrate ratios and dilution made favorable
conditions for the multiplication of bacteria. The daily average biogas yield produced
by the above-mentioned ratio was 203.64mL which is 2.12 times greater than that of
cow dung mono-digestion as per the experiment. Co–digestion bioreactors operating
with low cow dung concentration vis a vis maize stalks, yielded low biogas compared
with the ones with balanced substrate ratios or cow dung being slightly higher. It was
deduced that co-digestion improves the effectiveness of the digester, resulting in a
higher yield of biogas. The findings demonstrated that higher dilution levels resulted in
greater material degradation, hence enhancing the production of biogas and methane.
Conclusions were made based on proximate analysis, the proportion of biogas
produced, and effects of soda ash as pretreatment media. Therefore, co-digestion of cow
dung and maize stalk residues typically improves the biogas yield compared to
digesting cow dung alone. This is because maize stalk residues add additional organic
matter and increase the carbon-to-nitrogen (C/N) ratio, which can optimize the
anaerobic digestion process. It was recommended that there should always be ensured
that the carbon-to-nitrogen (C/N) ratio is balanced between cow dung and maize stalk
residues and by regular monitoring of this ratio can improve microbial activity and
enhance biogas yield. Furthermore, more research to determine the ideal mixing ratios
of cow dung and maize stalk residues for specific local conditions to maximize biogas
yield and ensure consistent production. | en_US |
