Browsing by Author "Offei, Felix"

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    Integrated Bioethanol and Bioelectricity production from Ghanaian Seaweed Biomass
    (2021-07-12) Offei, Felix; ;
    This study investigated the potential of integrating bioethanol and bioelectricity production technologies as an efficient means of maximising seaweed biomass utilization. It particularly sought to examine optimal conditions for the production of bioethanol from selected seaweeds, the bioelectricity potential of seaweed residue using microbial fuel cells and the sustainability of the integrated bioethanol and bioelectricity technologies on seaweeds. The motivation for this work is the growing concerns over the dire food securities issues that could occur from the continued use of edible biomass such as maize, cassava and sugarcane in commercial bioethanol production. The study was conducted through the screening of pretreatment methods, optimisation of dilute acid and enzymatic hydrolysis, screening of yeasts strains and screening of ethanol production pathways with seaweeds as substrates. It also included the evaluation of power generation, internal resistances and substrate consumption from microbial fuel cells fed with seaweed bioethanol residue and; an Energy Return on Investment analysis of various seaweed bioenergy production scenarios. The study established that the optimal ethanol yields for Ghanaian seaweeds, U. fasciata, H. dentata and S. vulgare were 5.06, 2.44 and 3.69% dry matter, respectively. This was obtained via the SHF pathway through enzymatic hydrolysis with an optimal cellulase dosage of 8 filter paper unit/g dry biomass and fermentation with S. cerevisiae SI17, C8T17 or PT17 yeast strains. The study also found residues from seaweed bioethanol production to be efficient substrates for use in microbial fuel cells since, it yielded power densities between 0.46 and 0.50 W/m3 which were comparable to sodium acetate by up to 52.62%. The integrated approach to seaweed biomass utilization was considered successful since waste generation was reduced to as low as 24.43% from a potential 79% from seaweed bioethanol production alone. It further established that the production of both bioethanol and bioelectricity from Ghanaian seaweeds would be sustainable based on the Energy Return on Investment value of 4.2 obtained after a Life Cycle Assessment of the bioenergy processes. The study further established that the production of bioethanol alone from seaweeds would not be sustainable commercially despite a net gain in energy from its Life Cycle Assessment.
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    Performance analysis of electrode materials (activated carbon and carbon butts) in microbial fuel cells using domestic wastewater
    (MAY, 2015) Offei, Felix
    The study investigated the performance of activated carbon from palm kernel shells and carbon butts as electrode materials in microbial fuel cells (MFCs) with faecal sludge and grey water as inoculum sources. It particularly sought to examine the power generation and wastewater treatment potential of the selected electrode materials when applied in the MFC technology. The motivation for this work is as a result of the growing demand for decentralized power generation and wastewater treatment systems especially for rural household and schools. The study was conducted through the examination of performance data from MFCs operating with the selected electrode materials and inoculum through the application of electrical, electrochemical and biochemical techniques. The study established that faecal sludge and grey water formed efficient biofilms containing electrogenic bacteria such as Geobacter sp. which initiates substrate oxidation for the release of electrons to the electrode material. It further established that activated carbon from palm kernel shells can be efficiently applied in MFCs since it generated power densities of up to 1.74W/m3 which is comparable to the carbon paper (standard) by up to 86%. Carbon butts were inefficient in MFCs generating negligible power densities of up to 0.001W/m3. Also organic substrate removal efficiencies of up to 72% were achieved by MFCs operating with the activated carbon.