ARBA MINCH UNIVERSITY COLLEGE OF NATURAL SCIENCES SCHOOL OF GRADUATE STUDIES DEPARTMENT OF CHEMISTRY

Abstract

Ecological disruptions and loss of productivity are foreseeable dangers facing Lake Abaya and the surrounding wetlands. This in turn affected communities whose livelihood depends on fish and other Lake resources. The purpose of this study is to produce biofuel from Water hyacinth as a feedstock for a win-win eco-sanitation approach to halt ecological disruption, so that the community can access Lake resources sustainably. Specifically, the study was designed to: determine the physicochemical characteristics of Water hyacinth; optimize its biogas production potential; evaluate the bioethanol and biodiesel production potentials; and develop a technology that converts Water hyacinth to energy briquettes. Succeeding pretreatment process, the study has found 89.04 %, 9.45 %, 29.7 % and 4.52 % of moisture, crude oil, carbon and hydrogen, respectively. The composition of nonmetals (C, H, N, S and O) was analyzed using Elemental Analyzer. The C:N ratio was found as 20.25:1 which is within the ideal recommended range for biogas production. The cellulose, hemicellulose and lignin contents of Water hyacinth was determined as 34.69 %, 38.80 % and 5.58 %, respectively. High holocellulose content has made possible to produce bioethanol. The hydrolysis of 10 g biomass in 10 % H2SO4 yields highest (682 ± 3.00 mg/g) amount of fermentable sugar. The XRD analysis revealed that % crystallinity index of Water hyacinth and its fermentable sugar was 33.13 % and 94.13 % respectively. The biogas production potential estimation and optimization were made by developing laboratory scale setup using seed microbes from ruminant and cow manure. The maximum biogas production was 28.42 L at 2:1:12 ratio of 1000 g powdered Water hyacinth to 500 g cow manure in 6000 mL of water, respectively. Bioethanol was obtained by fermentation of hydrolyzed substrates using Saccharomyces cerevisiae and was analyzed qualitatively (dichromate and FTIR methods) and quantitatively (spectroscopic and specific gravity methods). Among the three fermentation conditions, highest yield (0.42 g/g) of bioethanol was obtained from hydrolysate of 10 g biomass in 100 mL of 10 % H2SO4. Biodiesel was produced under transesterification and it was analyzed using FTIR spectroscopic method, the result confirmed availability of biodiesel from the weed. The production of fuel briquettes was made by incinerating the dried biomass in a kiln followed by blending of the char with binder. The briquettes production was possible and successful. The XRD of the sample was undertaken to measure the crystallinity index of biochar and fuel briquettes in comparison with the untreated Water hyacinth. The result is confirmed the potential of Water hyacinth to produce biofuel. In doing so, the existing invasive nature of the weed could be halted by consuming huge amount of weed biomass from Lake Abaya so that the ecology of the Lake could be restored and community livelihood could be guaranteed.