THE PRODUCTION OF BIOGAS USING COW DUNG AND FOOD WASTE
Abstract
In Nigeria, the scarcity of petroleum supply particularly kerosene has become a national concern. Biogas technology has gained national interest. This research was to generate biogas using cow dung and food wastes. Food wastes (corn cobs and plantain peels at the ratio of 1;1) were collected from the Abia State Polytechniccanteen and cow dung from Aba North LGA slaughter house as feedstock for the anaerobic digestion system to produce biogas energy. This design was to combined feedstock with high caloric content and anaerobic microbes. The proximate composition revealed that the two feedstock contained energy yielding nutrients but at varying concentrations. The study revealed that the pH decreased possibly as the bacteria produce acids in the digester. The decrease was more observed in the cow slurry experiment as it recorded acidic at the 4th day than the combined waste slurry which recorded acidic at 12th days. The data showed the volume of biogas production in respect of number of days under the various slurry. It can be deduced from the data that gas production increased in the earlier days of the experiments and then started decreasing as acid concentration increases as indicated by the decrease in pH. This observation was more pronounced in combined waste slurry than the cow dung slurry. The result supported the observation that acid concentration greatly affects the biogas production. Thus the combined waste slurry produces more gas (30.58ml) than cow dung slurry (19.20ml) as food wastes contain more nutrients than the dung. It has been demonstrated by this study that by using combine feedstock (cow dung and food wastes) the efficiency of biogas generation can be increased.
THE PRODUCTION OF BIOGAS USING COW DUNG AND FOOD WASTE, Keywords: Biogas technology, Cow dung, Food waste
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF STUDY
Biogas is a renewable energy source produced from the anaerobic digestion of organic matter. It is a mixture of methane, carbon dioxide, and trace amounts of other gases. Biogas can be used for cooking, heating, and electricity generation. The production of biogas from cow dung and food waste is gaining popularity due to its potential to mitigate environmental problems, such as greenhouse gas emissions and waste management issues. This essay will discuss the production of biogas using cow dung and food waste and its benefits. Cow dung and food waste are both rich in organic matter and can be used as feedstock for biogas production. The anaerobic digestion process involves the breakdown of organic matter by microorganisms in the absence of oxygen.
During this process, biogas is produced, which is primarily composed of methane and carbon dioxide. The production of biogas from cow dung and food waste has several benefits. Firstly, the production of biogas from cow dung and food waste can help to reduce greenhouse gas emissions. Methane is a potent greenhouse gas that contributes to climate change. When cow dung and food waste are left to decompose naturally, they release methane into the atmosphere. By using anaerobic digestion to produce biogas, the methane is captured and used as a renewable energy source, thus reducing greenhouse gas emissions.
A biogas plant or latrine when successful is an appropriate and sustainable method to deal with human or animal waste. This system produces two extremely useful products from the waste: biogas and slurry. Using biogas for cooking and lighting reduces the strain on the environment by decreasing the use of biomass and the production of green house gases (as methane that is produced normally from manure is now captured and used). The biogas system also provides a barrier protecting ground water from contamination from untreated waste (Ocwieja, 2010).
To save the environment from further deterioration and also supplement the energy needs of the rural populace, a strategy incorporating local resources and new technology as biogas technology can be effectively utilized (Ahmadu, 2009). More so, with the declining quantity of fossil fuels it is critical today to focus on sustained economic use of existing limited resources and on identifying new technologies and renewable resources, e.g., biomass, for future energy supply (Deublein and Steinhauser, 2008).
Biogas systems are highly friendly to the environment. In fact, the contribution of a methane molecule (CH4) to the greenhouse effect is 21 times greater than that of a carbon dioxide molecule. Therefore burning methane, even though producing CO2, reduces its impact on the environment. The digested slurry coming out of the plant is used for organic fertilizer production. Besides, Biodigesters can be used to treat municipal waste and
generate electricity. One of the options to utilize biogas is to produce electricity using a gas engine or gas turbine (Karki et al, 2005).
As well as being better for the climate, Anaerobic Digestion has other benefits over traditional waste management technologies. Plants can be small and low rise so may be situated in towns, reducing haulage distances and associated traffic pollutants. They are faster to build and to get planning permission for, as proposals are more acceptable to local residents than with other technologies. Anaerobic Digestion also produces less air and solid emissions than incineration, landfill and pyrolysis and gasification (Friends of the earth, 2007).
The process of fermentation in biodigesters results in transformation of organically bound carbon into gaseous carbon dioxide and methane. The anaerobic environment and extended retention time also inhibit the growth of most pathogenic organisms and prevent the survival of intestinal parasites. It is therefore to be expected that both the chemical and biological parameters of livestock excreta will be improved upon by passage through biodigesters (www.fao.org).
The prospect of this technology is bright in developing countries like Nigeria. This is because Nigeria is an energy resource rich country in terms of both fossil fuels (such as crude oil, natural gas, coal), and renewable energy resources like solar, wind and biomass (Mshandete and Parawira, 2009). The technology can be utilized to provide energy for households, rural communities, farms and industries.
Biogas is a flammable gas produced by the biological fermentation of organic materials such as agricultural waste, manure and industrial effluents in an anaerobic (oxygen deficient) environment to produce methane, carbon-dioxide and traces of hydrogen sulphide, (Ahmadu, 2009).
Fig. 1.2: Biogas from Organic Wastes (Igboro, 2011).
STATEMENT OF THE RESEARCH PROBLEM
Energy consumption in Nigeria has been increasing on a relatively high rate. On a global scale, Iwayemi (2008) opined that the Nigerian energy industry is probably one of the most inefficient in meeting the needs of its customers. This is most evident in the persistent disequilibrium in the markets for electricity and petroleum products, especially kerosene and diesel. The dismal energy service provision has adversely affected living standards of the population and exacerbated income and energy poverty in an economy where the majority of the people live on less than $2 a day.
Energy in form of electricity has been identified as an important element in achieving national development goals. It is an established fact that its availability in terms of sufficient quality and quantity at affordable prices will stimulate economic growth yet, the recent facts on the state of electricity in the country revealed that Nigeria currently generates an average of 4,500 Megawatts against a demand in excess of 25,000 MW (http://www.enownow.com/news). It therefore implies that the nation is meeting only 18% of her electricity need which is grossly inadequate.
The abundant hydrocarbon natural resource (crude oil and natural gas) in Nigeria is the mainstay of over 80% of revenues to the nation. This has not served as a catalyst for economic growth neither has it served as the major source of energy in the mix of energy supplies (Machunga-Disu and Machunga-Disu, 2012). Furthermore, the ever increasing prices of petroleum products globally, has made kerosene, which is the most commonly used fuel for cooking and lighting unaffordable to many, especially the rural dwellers, (Ahmadu, 2009). This therefore moves a larger percentage of the populace to seek solutions to their energy needs from other sources which in most cases are detrimental to the environment. For instance, there was a 5.5% increase in the dependence on wood fuel for cooking between 2007 and 2008 (NBS, 2009). More so, 79.6% of the households depend on wood fuel for their cooking while kerosene, coal, gas and electricity comes behind from distant 18.5%, 1.1%, 0.6% and 0.2% respectively (NBS, 2009).
Poorly managed forests have to shoulder immense burden to meet the increasing demand for energy caused by both the rising population and the lack of development alternative energy resources. Wood fuel has been and still is the major source of fuel daily used by rural mass in Nigeria. This total dependence on wood fuel as the source of energy for cooking has resulted in deterioration of the quality and quantity of forests and has posed a serious threat in maintaining ecological balance, thereby manifesting various problems like deforestation, flood, Global warming, soil erosion , landslides, climate change etc. Thus, an alternative energy source that would be affordable and environmentally friendly becomes necessary if the green forest must be preserved. Furthermore, there exist abundant evidence that climate change is a severe threat to socio-economic development and can substantially affect a nation’s GDP, as it affects water, forest, sanitation, food security, industrial development, housing, energy, health and the very air we breathe (Machunga-Disu and Machunga-Disu, 2012). Thus, development of biogas technology is a suitable alternative energy source that would be affordable and environmentally friendly that would help preserve the green forest thus achieving the 7th mandate of the Millennium Development Goal on environmental sustainability.
Moreover, governments and industries are constantly on the lookout for technologies that will allow for more efficient and cost-effective waste treatment. In addition to meeting the dire need for waste treatment options to enhance a clean environment, alternative processing technologies, such as anaerobic digestion, offer some potential for recovery of value from organic wastes (i.e., waste to wealth) by producing biogas and soil-conditioning composts. Furthermore, with the enormous cattle population especially in the northern part of the country, millions of tonnes of dung released daily emit a lot of methane gas when exposed to the atmosphere, which is 320 times more harmful to human health than carbon dioxide (Thakur, 2006). In addition Cymbopogon citratus (Lemon grass) is a well known medicinal plant as due to its citral content (Tajidin et al., 2012). After it is boiled for medicinal purpose and the citral content is extracted, the remains of the grass become waste
and could constitute nuisance to the environment. There is therefore an urgent need for development of adequate means to recycle these wastes and generate wealth from them. Thus biogas technology could be an appropriate means for recycling organic waste thereby achieving the goal one of the Millennium Development Goals (MDGs) of eradicating extreme poverty (UN, 2005) via waste to wealth initiative. Thus the organic waste becomes a channel for wealth creation as they are harnessed as feed materials for the production of biogas as well as biofertilizers that would accrue from the digestate. It is for these reasons that researches like the present one are desirable to chart a course for sustainable energy production and utilization while a cleaner and safer environment is enhanced.
JUSTIFICATION OF STUDY
Kerosene and other oil based sources of fuel are scarce and costly to be easily available for small marginal and medium farmers residing in rural areas. Furthermore, frequent alarming hike in prices of imported oil and chemical fertilizer have serious economic threat to the rural poor. In this context, to reach the self-sufficiency in energy and fertilizer and to minimize the pressure on traditional biomass fuel, biogas technology has been the best alternative energy solution, which could be achieved through the active mobilization and economic utilization of local indigenous resources available in the country.
It has been estimated that Nigeria produces about 227,500 tonnes of fresh animal waste daily. Since 1 kg of fresh animal waste produce about 0.03 m3 biogas, then Nigeria can potentially produce about 6.8 million m3 of biogas every day from animal waste only (Mshandete and Parawira , 2009). A recent study that assessed Nigeria’s biogas potentials (minimum value) from solid waste and livestock excrements revealed that in 1999,
Nigeria’s biogas potential represents a total of 1.382×109 m3 of biogas/year or an annual equivalent of 4.81 million barrels of crude oil (Ojolo et al, 2007).
In addition, 20 kg of municipal solid waste (MSW) per capita has been estimated to be generated in the country annually (Mshandete and Parawira , 2009). By the 2005 census figure of about 140.4 million inhabitants, the total generated MSW will be at least 2.81 million tonnes every year. With increasing urbanization and industrialization, the annual MSW generated will continue to increase.
Biogas production may therefore be a profitable means of reducing or even eliminating the menace and nuisance of urban wastes in many cities in Nigeria.
Moreover, the methane content of biogas depends to a significant extent on the nature of the feed material with succulent grass having the highest value of about 70% (Sasse, 1988). Most of the previous biogas researches in Nigeria used animal dung and kitchen wastes as
feedstock substrates while the use of succulent plants for biogas production have been
limited to water lettuce, water hyacinth, cassava leaves and Eupatorium odoratum (Akinbami et al., 1996, 2001; Okagbue, 1988; Ubalua, 2008, Odeyemi 1981). These plants are mostly found in the riverine regions of the country. There is no record of any research on the potential of Cymbopogon citratus (Lemon grass) which is more widely distributed in Nigeria than the other plants previously tested. Cymbopogon citratus popularly known as Lemon grass belong to the family Grami-neae and the genus Cymbopogon (Akhila, 2012). It is native of the warm temperate and tropical regions of the old world. Lemon grass can tolerate a wide range of soils and climatic conditions (Sugumaran et al., 2005). Since Cymbopogon citratus is not as widely available as the animal wastes, co-digesting it with animal dung would provide a good synergy for improved gas production. Thus, the animal waste provides the high volume while the quality of the resultant gas is optimized by the
Cymbopogon citratus.
With the rapidly increasing waste generation threatening to prevent humans from carrying out their activities for lack of space, the society is therefore faced with the choice to either allow this biomass waste to continue polluting the environment; methane and carbon dioxide production, to continue to increase global warming or boldly take the initiative of converting the biomass into alternative energy (Igboro, 2011).
The study therefore explores means of converting this and other organic waste to energy as a very attractive option for adequate treatment that will enhance environmental sustainability, which is one of the eight Millennium Development Goals set by the UN.
It is therefore necessary in moving towards a sustainable energy society. While converting waste into energy is especially appealing conceptually, there is still much to be done before the technology becomes commonplace. Also, the research is necessary in order to optimize the technologies, build confidence in their effectiveness, and prepare them for the market (Igboro, 2011). This will require significant efforts in outreach. Policy makers, farmers, engineers, the business community and the rural community need to know about issues of sustainable development which confront us and biogas utilization would just be the panacea for our energy problem.
AIM AND OBJECTIVES OF STUDY
The research aims at the Production Of Biogas Using Cow Dung And Food Waste
The study has the following specific objectives:
- To design and construct biogas digester plants that would operate under existing weather conditions;
- To utilize the biogas digesters so constructed for the digestion of Cow Dung and Food Waste;
- Optimisation of the anaerobic digestion of cow dung and chicken droppings for maximum energy production via co digestion of each with lemon grass;
-
To establish the technical performance of the anaerobic digestion of Cow Dung and Food Waste as well as their co-digestions with lemon grass respectively as biomass
SCOPE OF THE STUDY
This study is on The Production Of Biogas Using Cow Dung And Food Waste. This study is limited to cow dung from Zango abattoir
SIGNIFICANCE OF THE STUDY
The study on the production of biogas using cow dung and food waste has significant implications for various stakeholders. Some of the potential significance of the study includes:
Environmental sustainability: Biogas production using cow dung and food waste is an environmentally friendly way to manage waste. Instead of disposing of these wastes in landfills, they can be used to generate biogas, which can be used as a renewable energy source, reducing reliance on fossil fuels.
Energy security: The production of biogas using cow dung and food waste can contribute to energy security by providing a reliable source of renewable energy. This can reduce the dependence on traditional sources of energy, which are often subject to price volatility and geopolitical risks.
Rural development: Biogas production using cow dung and food waste can provide a source of income for rural communities. Farmers can sell their cow dung and food waste to biogas plants, which can generate revenue for them. This can also create employment opportunities in the biogas production sector, contributing to rural development.
Reduced greenhouse gas emissions: Biogas production can help reduce greenhouse gas emissions by capturing methane, a potent greenhouse gas, from cow dung and food waste. Methane can be used as a renewable energy source, reducing reliance on fossil fuels and mitigating climate change.
Waste management: Biogas production can provide an effective waste management solution by converting cow dung and food waste into biogas and fertilizer. The fertilizer can be used to improve soil fertility, reducing the need for chemical fertilizers that can harm the environment.
Overall, the study on the production of biogas using cow dung and food waste is significant as it can contribute to environmental sustainability, energy security, rural development, reduced greenhouse gas emissions, and effective waste management.
THE PRODUCTION OF BIOGAS USING COW DUNG AND FOOD WASTE
