1.1 Background of Study
Biogas is the mixture of gases produced by the breakdown of organic matter in the absence of oxygen (anaerobically), primarily consisting of methane and carbon dioxide. Biogas can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste. Biogas is a renewable energy source (Wikipedia, 2021).
Biogas produced in anaerobic digesters consists of methane (50%–80%), carbon dioxide (20%–50%), and trace levels of other gases such as hydrogen, carbon monoxide, nitrogen, oxygen, and hydrogen sulfide. Anaerobic digestion is a biological process in which organic material is decomposed by bacteria in the absence of air. The general technology of anaerobic digestion of complex organic matter is well known and has been applied for over 60 years as part of domestic sewage treatment to stabilize organic wastes. Bal & Dhagat (2001) points out that the anaerobic process is more advantageous than the aerobic process in organic waste treatment because of the high degree of waste stabilization, low production of excess biological sludge, low nutrient requirement and production of methane gas as a useful byproduct. Several studies have been carried out for evaluating kinetic parameters and model equations for anaerobic digestion by Siles et al. (2010), Borja et al. (2005), Jimenez et al. (2004), Raposo et al. (2009), Rincon et al. (2009) and Hu et al. (2002); these are all based on the Monod kinetic model (Monod 1950) and on the revised kinetic model developed by Chen et al. (1980) and Hashimoto et al. (1981).
In the microbiology of methanogenic process four different bacterial groups are identified as being responsible for carrying out the anaerobic digestion of complex organic matter. The first group of bacteria is a hydrolytic bacterium which catabolizes carbohydrate, protein, lipid and other minor components of organic matter to fatty acids, H2 and CO2. The second group of bacteria is hydrogen producing acetogenic bacteria which catabolizes certain fatty acids and neutral end products to acetate, CO2 and H2. The third group of bacteria is homo acetogenic which synthesizes acetate using H2, CO2 and formate, and hydrolyzes multi carbon compound to acetic acid. Finally, the fourth group of bacteria i.e. methanogenic bacteria utilizes acetate, carbon dioxide and hydrogen to produce methane. The concerted action of these four bacterial groups ensures process stability during anaerobic digestion of the complex organic matter.
1.2 Statement of Problems
The study reveals the following problems associated with the impact of heavy metals content and waste material obtained during biogas generation for sustainable energy and agriculture application;
- Lack proper estimation of heavy metals content using AAS and FTIR,
- Inadequate information relating to the waste material obtained during biogas generation,
- Lack of proper and precise information relating to the sustainable energy and agricultural application.
- Lack of proper and precise information relating to the hexane removal from pretreated orange wastes.
1.3 Objectives of Study
The aim of this study was to determine the impact of heavy metals content and waste material obtained during biogas generation for sustainable energy and agriculture application. Therefore, the objectives of this research were:
- To estimate the heavy metals content using AAS and FTIR,
- Provision of information relating to the waste material obtained during biogas generation,
- To provide information relating to the sustainable energy and agricultural application.
- To identify the hexane removal from pretreated orange wastes.
1.4 Significance of the Study
This research work when completed and implemented it will help to estimate the heavy metals content using Atomic absorption spectrometry (AAS) and Fourier Transform Infrared Spectroscopy (FTIR), provide information relating to the waste material obtained during biogas generation, which will be beneficial to;
- Lab scientist,
- Doctors.
- Geologist
- Agricultural Engineer
Besides, the study will serve as reference material for subsequent researcher in the field or related topics.
1.5 Scope of Study
The study focuses on the impact of heavy metals content and waste material obtained during biogas generation for sustainable energy and agriculture application.
1.6 Research Hypothesis
The purpose of this study was to identify and determine the impact of heavy metals content and waste material obtained during biogas generation for sustainable energy and agriculture application. Therefore, the study is based on the following null hypotheses:
- Mean heavy metal content using AAS and FTIR are within acceptable or safe limits.
- Waste materials obtained during biogas generation for sustainable energy of different types do not have equal metal concentrations.
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Establishment Policies: Establishment policies posed a serious limitation as most staffs are not ready to release information needed for this project work. There were lots of information needed from the staffs of this institution to enhance the study which took them time to release or they did not release at all for security purposes, hence the scope was reduced.
1.8 Definition of Technical Terms
Heavy: having great weight; also characterized by mass or weight.
Metal: Metals are opaque, lustrous elements that are good conductors of heat and electricity. Most metals are malleable and ductile and are, in general, denser than the other elemental substances
Adverse Effect: An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery.
AAS: Atomic absorption spectrometry (AAS) is an analytical technique that measures the concentrations of elements.
FTIR: Fourier Transform Infrared Spectroscopy, also known as FTIR Analysis or FTIR Spectroscopy, is an analytical technique used to identify organic, polymeric, and, in some cases, inorganic materials.
