Studies on Biogas and Bioliquid Production by Fungal Degradation of Banana (Musa sapientum) Leaves
Chapter One
GENERAL OBJECTIVE OF THE RESEARCH
This research aims to produce biogas and bioliquid from banana leaves by fungal degradation at optimum operational conditions.
SPECIFIC OBJECTIVES OF THE RESEARCH
The specific objectives of this research work are to:
- assess the potentiality of banana leaves as a substrate for biogas and bioliquid generation;
- determine the effect of physio-chemical parameters – concentration, temperature, and pH on biogas and bioliquid generation;
- determine the influence of nutritional additives such as urea, blood meal as a source of protein), sugar, lipid (oil), and ethanoic acid on biogas and bioliquid generation;
- assess the combined effect of buffering and addition of urea on biogas production and its composition;
- determine the moisture, ash (inorganic), volatile solids (organic), carbon and nitrogen contents as well as carbon to nitrogen ratio of the fermented and unfermented substrates (banana leaves);
- determine the lignin, crude fiber, crude fat, crude protein, total carbohydrates, and reducing sugar contents of the fermented and unfermented banana leaves;
- assess the maltenes (deasphalted oils) and asphaltenes contents of the illiquid extracted from fermented and unfermented banana leaves;
- analyze the maltenes contents of both the fermented and unfermented banana leaves in terms of saturates, mono-aromatics, di-aromatics, poly-aromatics, and resins and polar contents by column chromatographic method;
- identify by the gas-chromatographic method the organic component of the gaseous degradation products (biogas) using a flame ionization detector (FID), and the inorganic component (CO2) using a thermal conductivity detector (TCD); and
- identify the heavier hydrocarbons in the liquid biodegradation products (bioliquid) by G-C mass spectrometric
CHAPTER TWO
LITERATURE REVIEW
APPROACHES TOWARDS THE DEVELOPMENT OFBIOGAS TECHNOLOGY
It has been reported by Ahmad (2000) that the techniques of biogas production have been in existence since 1850s. Methane was first recognized as having practical and commercial value in the 1890s in England, where a specially designed septic tank was used to generate the gas for the purpose of lighting streets (Garba, 1998). In India, for example, methane generating units and plants using cow dung had been in operation for years; in Taiwan, more than 7,500 biogas generating devices utilizing pig manures have been constracted; in Europe, for example during second world war, methane was produced in order to provide fuel for automobiles; and in the USA, there has been considerable interest in the process of anaerobic digestion as a means to generate safe and clean fuels as well as biofertilizer (Bryant,1979). Presently, in Bangladesh, there are about 22 million cattle that excrete about 0.11 million tones of dung per night that can produce an average of 1.48 x 109m3 of biogas per year which is equivalent to 0.75 x 106 tons of kerosene or 1.52 x 106 tons of coal (Cheremisionff, 1980).
In order to develop the technique as well as to improve the quality of biogas and maximize its utilization, several but different researches were conducted. For instance, Ekwenchi, Akunwanne, Okeke and Ekpenyong (1989) investigated the possibility of obtaining gaseous fuel from fungal degradation of lignocelluloses from elephant grass at 33OC using four cellulolytic fungi and a bacterium, which were harnessed from air, isolated in pure form and identified. The analysis of the gaseous products obtained showed that the biogas contained CH4, C3H8 and CO2. It was also found that the saturates content of the bioliquid of the fermented slurry was very high with no polars at all while the bioliquid of the unfermented slurring was rich in polyaromatics with very little saturates. The research also revealed that two species of fungi, Curvularia Spp. and Penicillium, were responsible for the degradation. The other two, Fusarium species and Aspergillus niger, including the bacterium gave no gaseous products.
In their own contribution, Singh, S.K, Singh, A. and Pandey (1992) studied the effect of additives on bioconversion of biomass into methane; they used Na, Mg, Fe, Al, Sn and Cd salts as additives on Enchorial Crassipes at different concentrations. The work revealed that addition of Na and Al salts enhanced biogas production; Fe, Mg and Cd salts showed inhibitory effects; and Sn salt completely stopped the production of the biogas.
Anaerobic biodegradation of lignocellulose from water hyacinth using specific fungus (Curvularia Spp.) was investigated by Airehrour (1994). The work revealed that at low temperature (28oC), the activity of the Curvularia was low compared with the activity at relatively higher temperatures (330C and 380C). But above 380C, the curvularia’s activity drastically decreased.
CHAPTER THREE
MATERIALS AND METHODS
MATERIALS
The materials used for the research were banana leaves, water and yeast.
CHEMICALS/REAGENTS
The chemicals/reagents used for the research were of good purity. The chemicals were obtained from the British Drug House (BDH), May and Baker (M&B), Fluka – Granite (F-G), Hopkins and Williams (H&W) and Philips- Harris (P-H). The Table below gives the names, reagent grades, manufacturers and percentage purities of some of the chemicals used:
CHAPTER FOUR RESULTS
DESCRIPTION OF THE TABLES OF RESULTS
Table 5 shows the average volumes of biogas generated (cm3) daily for the determination of suitable water content. From the table, it could be seen that digesters A, B,C, D and E in which the respective volumes of water used in making the slurries were 15cm3, 20cm3, 25cm3, 30cm3 and 35cm3 generated 36.00cm3, 45.00cm3, 56.50cm3, 36.50cm3 and 8.00cm3, respectively.
CHAPTER FIVE
CONCLUSION
All the physio-chemical parameters employed in this research enhanced both the generation of biogas and bioliquid at optimum operational conditions. Though, addition of urea, addition of buffer solution as well as the use of a mixture of urea and buffer solution each showed adverse effect on the quality of the biogas generated by decreasing slightly the CH4 content and increasing slightly the CO2 and H2S contents. But of all the adverse effects of some of the nutritive additives used, the composition of the biogas generated was in accordance with the composition needed for biogas of good fuel value.
The bioliquid generated in this work was composed of n-alkanes, iso-alkanes and cyclic hydrocarbons, which could serve as source of fuel (biofuel) with quality similar to those kerosene and fuel oil, and could also serve as a source of lubricants and waxes.
Recommendations
From the analyses carried out and the results obtained in this research, it would be of paramount importance if the following recommendations would be taken into consideration:-
- For the generation of biogas rich in CH4with low environmental hazards, banana leaves could be used as
- The substrate (banana leaves) could be used for the generation of biogas of good fuel
- The substrate should not be used for large scale biogas
- The substrate could be used for large scale bioliquid
- The use of buffer solutions; the use of urea as a nutritive additive; and the use of a mixture of buffer solution and urea for the generation of biogas of good fuel value and low environmental hazards should be
- For rapid and high production of biogas and bioliquid, the use of nutritive additives: sugar, oil, ethanoic acid and blood meal should be
- The substrate could be used in animal feeds for energy supply, because it contains a lot of reducing
SUGGESTIONS ON THE AREAS OF FURTHER WORK
The analyses carried out in this research were only restricted to a limited scope of interest. In order to have a thorough knowledge of biogas and bioliquid, the following investigations have to be carried out:
- Determination of paraffinicity and aromaticity of
- Comparative analysis of the organic components of the gaseous degradation product (biogas) from different
- Qualitative analysis of polyaromatics compounds in
- Quantitative analysis of nalkanes in
- Analysis of the fuel value of biogas generated from different sources
- Isolation of resins and polars from asphaltenes in their pu
- Determination of the element(s) associated with the aromatic compound of the polar component of
- Comparative analysis of the maltenes and asphaltenes contents of bioliquid of different269
- Studies of the influence of micro-organisms other than yeast on the compositions and quantities of biogas and biloliquid from banana leaves.
SUMMARY OF THE FINDINGS
The percentage of the organic matter consumed due to fungal degradation was found to be 13.93% of which 3.88% was biogas and 10.05% was bioliquid.
The weights of the gaseous degradation product (biogas) and liquid degradation product (bioliquid) generated from 40.0g banana leaves were 1.551g and 4.020g, respectively. And it was found that the greater part of the degradation was due to the protein and total carbohydrate (especially the reducing sugar) contents of the substrate while the least degraded components were the fibre and lignin.
The quantity of the bioliquid generated from the unfermented slurry was higher than the one generated from the fermented slurry; the quantity of the maltenes generated from the fermented slurry was higher than the one generated from the unfermented slurry; and the quantity of asphaltenes in the unfermented slurry was higher than that in the fermented slurry.
In the fermented slurry, the saturates contents of the maltenes were found to be higher than all the other components while resins and polars were the least. On other hand, in the unfermented slurry, polyaromatics were the highest while saturates were the least.
The gaseous degradation products (biogas) was composed of CH4 and CO2, and the components of the liquid degradation products (bioliquid) identified were n-alkanes, iso-alkanes and cyclic hydrocarbons in the order n-alkanes> iso-alkanes> cyclic hydrocarbons.
CONTRIBUTION TO KNOWLEDGE
The research has greatly contributed to knowledge in the following areas:
- Renewable energy:- From the composition of the biogas generated, the research revealed that banana leaves (as an agricultural waste) can be used to produce gaseous fuel (biogas) of good fuel
- Environmental Science:– The emphasis given in the research on the use of wastes instead of firewood by rural populace for fuel, could help to protect the land environment from erosion and desertification as well as air pollution, provided that the technology of biogas and bioliquid production is employed. The research also emphasized on the process of converting wastes into useful products, which also serves as a measure of controlling wastes, improving health and encouraging environmental sanitation.
- Agricultural Science:- The research highlighted the advantage of using digested slurry in improving soil fertility and enhancing aquaculture production. It also highlighted the importance of agricultural wastes (banana leaves inclusive) for energy generation needed for crops processing as well as a source of energy for animals (when used as animal feeds) because of its high reducing sugar content.
- Organic Synthesis:- The research revealed that important organic products such as saturates, aromatics, resins and polars could be generated and isolated from banana
- Biological Science:- The research also revealed the conditions under which a fungus (yeast) can be made inactive, which could also be applied to other fungi to control their infections by deactivation.
REFERENCES
- Ababio, O.Y. (1985). New school chemistry certificate science series, (revised edition), African FEB Publishers Ltd. Pp393 – 472.
- Ahmad, U. (2000). Nutrients determination of biogas produced from three different aquatic weeds. unpublished M.Sc. thesis, submitted to the Department of Pure and Applied Chemistry, Usmanu Danfodiyo University, Sokoto – Nigeria, Pp 1 – 52.
- Airehrour, T.A. (1994). Anaerobic biodegradation of lignocellulose from water hyacinth (Curvularia Spp.) unpublished M.Sc. thesis, Submitted to the Dept. of Chemistry, University of Jos. Pp 21 – 99.
- Akor, A.S. (1999). Effect of urea on fungal degradation of lignocollulose from Elephant-grass. unpublished B.Sc. Project, submitted to the Department of Chemistry, University of Jos.
- Aliyu, M., Dangoggo S.M. and Atiku A.T. (1996). Effect of seeding on biogas production using pigeon droppings, Nigerian Journal of Renewable Energy. 4. (1) Pp 19 – 23.
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