




































    

 Academic Journal of Science, Engineering and Technology 

Vol. 9, Issue 2; March -April 2024; 

ISSN: 2837-2964 

Impact Factor: 6.67 

1252 Columbia Rd NW, Washington DC, United States 

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15 | A c a d e m i c  J o u r n a l  o f  S c i e n c e ,  E n g i n e e r i n g  a n d  T e c h n o l o g y  

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FABRICATION OF BIOGAS DIGESTER AND PRODUCTION OF FUEL 

FROM ANIMAL DROPPINGS USING HIGH-DENSITY POLYETHYLENE 

AND POLYVINYL CHLORIDE 

 

Okolotu G.I. 

Department of Agricultural Engineering, Faculty of Engineering, Delta State University of Science and 

Technology, P.M.B. 05, Ozoro, Nigeria. 

DOI: https://doi.org/ 10.5281/zenodo.11121963 

 

Abstract: A portable biogas digester was fabricated to obtain combustible methane gas from livestock waste 

using HDPE plastics and PVC pipes. The structure was made airtight, and fitted with an inlet channel, gas outlet 

channel, waste outlet channel, and emergency pressure outlet channel. A domestic water purification filter with 

filtration elements of activated charcoal, iron filings, and local potash was modified for biogas upgrading. All 

filter composite materials were dried, and mixed with charcoal, potash, and iron filings in the ratio of 4:3:l. 

Leak proofing was done using PVC gum, silicon bonds, and rubber gaskets to ensure gas-tight seals. HDPE 

thread tape was also used as screw-able elements. Upon fabrication completion, a leak test was carried out 

using one (1) liter of water, and no leakages were observed. The animal droppings of poultry (three bags of 50 

kg) were - filled into the digester, mixed, and allowed to generate uniform mass for appropriate environmental 

conditions for microbial processes of anaerobic digestion, involving the breakdown of microorganisms in the 

absence of oxygen, for the emission of the gas (methane). Gas collection was achieved through the outlet pipe 

(connected from the filter) which is the flexible hose connected to the gas cylinder valve, allowing direct 

capture of upgraded methane in the metal cylinder. The bill of engineering measurement and evaluation 

(BEME) for the fabrication was made. The obtained methane gas produced was purified - able to biomethane, 

which is burnable to obtain electricity and heat using combined heat and power (CHP) plants, usable as fuel, 

and inject - able to the natural gas. 

Keywords: Biogas; Digester; Anaerobic Digestion; Digestion System Designs; Biogas Applications; 

Biomethane; etc. 

 

1. INTRODUCTION 

The world population is on the increase even with a declining growth rate (Okolotu and Oluka, 2021; Okolotu 

et al, 2024). The need for the conservation of the environment as well as proper management of natural 

resources is vital for future sustenance. Currently around 3.5 Mton of biomethane are produced worldwide 

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ISSN: 2837-2964 

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(IEA, 2024). Europe, Asia, and the United States are the major producers. Europe, the people’s republic of 

china (hereafter “China”), and the United States account for 90 % of the global production (IEA, 2024). 

1.1 Biogas: Biogas is the mixture of gases produced by the breakdown of organic matter in the absence of 

oxygen (anaerobic), primarily consisting of methane and carbon dioxide. Biogas is a mixture of methane, CO2 

and small quantities of other gases produced by anaerobic digestion of organic matter in an oxygen free 

environment (IEA, 2024). 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. 

Biogas is produced by anaerobic digestion during which digestion (fermentation) of organic (biodegradable) 

material occurs inside a closed system (Appels et al., 2008). This closed system is called an anaerobic digester, 

biodigester or a bioreactor. Biogas is primarily composed of methane (CH4) and carbon dioxide (CO2), and 

usually contains small amounts of hydrogen sulfide (HS), moisture and siloxanes. Methane gas in particular is 

combustible, and this energy release allows biogas to be used as a fuel. It can be used for any heating purpose, 

such as cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat. 

Biogas can be compressed after removal of carbon-dioxide, the same way as natural gas is compressed and used 

to power motor vehicles (Abatzoglou & Boivin, 2009). Biogas is considered to be a renewable resource because 

its production and use cycle is continuous. As organic material grows, it is converted and used. It then re - 

grows in a continually repeating cycle. For future energy security and improvement in the use of natural 

resources, the depletion of conventional energy resources such as fossil fuel can be solved by the use of 

renewable energy sources. Generation of biogas through anaerobic digestion technology is a renewable energy 

source. The agriculture chain (from production through processing to use) results in several byproducts. Many 

of which are disposed of as waste. 

Anaerobic digestion provides a means of reducing the hazards associated with the byproducts of agricultural 

production and processing. The concentration of hazardous gases is reduced, and the resultant sludge is an 

excellent addition to soil organic matter. This work provides technical details on the fabrication of portable 

biogas digesters. Data generated from this work will be useful in making decisions that will aid the efficient 

fabrication of larger portable biogas digesters. Bio gas collection for anaerobic digestion for production is vital 

for resource management. A typical example of biogas recovery is presented in figure below; 

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Vol. 9, Issue 2; March -April 2024; 

ISSN: 2837-2964 

Impact Factor: 6.67 

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Figure 1: Details of the elements of a biogas recovery system (EPA, 2024) 

1.2 Anaerobic Digestion: Anaerobic digestion is a process involving the breakdown of organic matter by 

micro-organisms in the absence of oxygen. Much of the fermentation used industrially to produce food and 

drink products, as well as home fermentation, uses anaerobic digestion (Wikipedia, 2024). A typical digester is 

a closed system where a certain temperature is maintained and where the released gas is captured, stored and 

used. An anaerobic digester is a sealed, heated tank which provides a suitable environment for naturally – 

occurring anaerobic bacteria to grow, multiply, and convert manure to biogas and a low – odor effluent (PSU, 

2023). The main component of this biogas is methane gas, which is a fuel. Methane is also one of the 

greenhouse gases implicated in global warming. Capturing and using the gas therefore help reduce the emission 

of greenhouse gases to the atmosphere. Biogas could be burned directly or used to run an engine that powers an 

electrical generator, thus producing electricity and heat. The main stages in the anaerobic digestion process are 

presented below, and each relies on a specific group of micro-organisms. 

Stage I - Hydrolysis and Fermentation: Large, insoluble organic molecules are broken down by extra-cellular 

enzymes through hydrolysis. High amounts of cellulose, or other material that is hydrolyzed slowly, can limit 

the performance of the entire system (Poulsen, 2003). Short - chain fatty acids (acetic acid, formic acid, etc.) are 

formed by the enzymes while by - products undergo fermentation to produce alcohols, C02. and H2. In this 

stage, certain bacteria breakdown organic polymers like carbohydrates into simple sugars so that the next group 

of bacteria can further process the material (TNDEC, 2024). 

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Vol. 9, Issue 2; March -April 2024; 

ISSN: 2837-2964 

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Stage Il - Acidogenesis: Any short-chain fatty acids longer than acetic acid are oxidized by the acidogenic 

bacteria to produce formic acid, acetic acid, and H2. Valdez - Vazquez et al., (2004) conducted research on 

means of promoting the H2 - producing feature of acidogenic bacteria for use as an alternative fuel source. 

Stage III -Acetogenesis: This is the third step of biogas production from conversion of organic materials. 

TNDEC, (2024) noted that, in this stage, certain bacteria called acetogenic bacteria convert the organic acids 

into acetic, carbon, and hydrogen. 

Stage IV – Methanogenesis: Methanogenic bacteria convert the acetic acid and H2 to methane and carbon 

dioxide. In this stage, certain single cell – called organisms called methanogens convert the intermediate 

products produced in the preceding stages into biogas (primarily methane and carbon dioxide) (TNDEC, 

2024).The methanogenic are the most unstable among these primary groups of bacteria. 

 

 

 

 

  

  

  

  

  

   

 

 

 

 

 

 

Figure 2: Processing and micro - organisms involved in converting organic material to methane and carbon - 

dioxide under anaerobic conditions (Poulsen, 2003). 

Figure two (2) indicates the groups in the anaerobic process. Group IV can either produce acetic acid or break it 

down if the concentration of acetate is too high. Group V oxidizes acetic acid to H2 and C02 (neither group is 

central to the basic understanding of anaerobic digestion). Figure three (3) below, summarizes the main 

processes in a simplified flowchart. 

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 Academic Journal of Science, Engineering and Technology 

Vol. 9, Issue 2; March -April 2024; 

ISSN: 2837-2964 

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19 | A c a d e m i c  J o u r n a l  o f  S c i e n c e ,  E n g i n e e r i n g  a n d  T e c h n o l o g y  

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Figure 3: Carbon flow in anaerobic environments with active methanogens (Ahring, 2003) 

It is important to note that these processes must be in balance with each other. For example, Poulsen, (2003) 

noted that, if the methanogenic bacteria do not use the hydrogen produced by the acidogenic bacteria almost 

immediately, the higher hydrogen concentration will increase the production of alcohols and fatty acids, causing 

the system to collapse. The following are important parameters which must be considered in the design of an 

anaerobic digestion system; 

I. Temperature: Three temperature ranges exist for anaerobic digestion: (i) Psychrophilic range between 5o 

and 25 oC, character sized by slower methane production and longer retention times. (ii) Mesophilic range 

between 30 0 and 40 0C, is the most widely used of the three, and this range balances heating costs with methane 

production. (iii) Thermophilic range from 50 0 to 600 C, produces the most methane but is also the most 

sensitive, due to fewer bacterial species in existence. Once a stable temperature is reached, fluctuations should 

be kept within 5 0C to avoid killing the desired bacteria. Thermophilic tolerance is generally less than that of 

lower temperatures. Each temperature ranges at which the digester can be operated have its own advantages. 

The thermophilic process has been found to be superior to the mesophilic process from an energy balance and, 

thus, "profit point of view (Ahring, 2003). Thermophilic digesters usually achieve better degradation of long-

chain fatty acids, have a shorter retention time, and require less biomass compared to the quantity of methane 

produced. The thermophilic process also achieves higher pathogen and weed seed destruction than the 

mesophilic process alone (El - Mashad et al., 2004). However, the risk of ammonia inhibition is greater and 

more energy is required to operate a thermophilic digester. Thermophilic processes are considered to be more 

prone to instability than mesophilic due to fluctuations in input quality. The start - up time of thermophilic 

digesters is however longer than that of mesophilic reactor due to the low numbers of thermophilic bacteria in 

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Vol. 9, Issue 2; March -April 2024; 

ISSN: 2837-2964 

Impact Factor: 6.67 

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organic waste. Most of the agricultural digesters in the United States are mesophilic (Kramer, 2009). The lower 

heating requirements of mesophilic temperatures translate into lower costs. Psychrophilic digesters require a 

solids retention time approximately twice as long as mesophilic. These digesters require the least amount of 

energy input. Biogas production is slow but gas quality and other parameters indicate favourable process 

stability. These systems are commonly found in the form of a covered lagoon and, as such, they are usually 

subject to fluctuations in temperature. 

ii Loading Rate: This is expressed as the weight of volatile solids (VS) per unit of volume of digester capacity 

per unit of time. High loading rates use the digester volume more efficiently. They also increase solids 

concentration, retention time and alkalinity, which are taken into consideration. 

iii Retention Time: The Hydraulic Retention Time (HRT) and Solids Retention Time (SRT) are the average 

lengths of time the liquid or solid portion of manure remains in the digester. Generally, the lower the operating 

temperature (e.g. psychrophilic digestion) the higher the retention time needed. 

iv Solids Concentration: This is normally reported as the percentage dry matter and the volatile solid 

percentage of that dry matter. The solids concentration is necessary to determine the loading rate. The solids 

concentration also helps to determine the most suitable type of digester. 

v Alkalinity And pH: The methanogenic bacteria have optimum pH conditions ranging between 6.4 to 7.6 

(average), while other bacterial species are more tolerant to pH levels outside of this range. 

1.3 Digestion System Designs: Different systems have been designed for anaerobic digestion. The following 

are basic descriptions of the popular systems used on farms. 

i Plug Flow System: The plug flow digesters are primarily used at dairy operations that collect manure by 

scraping (EPA, 2024). The plug flow system usually takes the form of a long concrete tank with a slight grade 

over the length. They are often designed as long, narrow concrete tanks with rigid or flexible cover (ABC, 

2022). Influent is either continuously or intermittently added to one end and flows by gravity to the opposite 

end. The contents are not mixed mechanically. The retention time is thus a function of channel length, channel 

grade, and the loading rate. Mixed plug flow systems have been used at a wider variety of operations because 

they can tolerate a broader range of solid concentrations (EPA, 2024). 

ii Complete Mixed System: This is also known as a completely stirred tank reactor (CSTR). The complete 

mixed system is most commonly a circular tank with a mechanical agitator. The mixing prevents settling and 

maintains contact between bacteria and the manure. Electricity input costs are higher due to the intermittent 

mixing of the systems. However, the mixing can cause foaming in the tank, which is undesirable because it 

occupies digester volume and can clog gas lines. Complete mix digesters often dilute the mix of feedstock to aid 

mixing, like the consistency of a thick ‘soup’ (ABC, 2022). Influent is often added to the digester as effluent is 

excreted in small quantities at regular intervals. Therefore the retention period of manure in a complete mix 

digester is not necessarily uniform. 

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Vol. 9, Issue 2; March -April 2024; 

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21 | A c a d e m i c  J o u r n a l  o f  S c i e n c e ,  E n g i n e e r i n g  a n d  T e c h n o l o g y  

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iii Fixed Film System: The fixed film system contains structures like corrugated plastic drainage pipe inside 

the vessel to help retain more anaerobic bacteria. The structures increase the surface area available for the 

bacteria to adhere to, thereby reducing the numbers of bacteria washed out in the effluent. The anaerobic 

process begins faster and stronger compared to a plug - flow or completely mixed system. The advantage of the 

fixed film system is the shorter retention time - a retention time of 20 days in a conventional completely mixed 

system can be shortened to 4 days with fixed film system. 

iv Covered Lagoon: The covered lagoons are typically not heated, so their use is restricted to areas with a 

relatively warm climate. The hydraulic retention times for covered lagoons range from 40 to 60 days, depending 

on regional climate. Electricity generation is not usually practical with a covered lagoon because biogas 

production varies with temperature. The covered lagoon systems produce less biogas in colder temperatures and 

little or no gas below 4 0C. Most covered lagoons used to be open manure lagoon on a farm that have added an 

engineering flexible cover added to capture biogas (ABC, 2022). 

v Centralized Systems: The centralized systems are much larger anaerobic systems than the typical on - farm 

installation. A number of farms within a designated geographical area are usually required for the economical 

operation of a centralized anaerobic system. The advantages of a centralized system include less individual risk, 

favourable economies of scale, and less individual farmer involvement. The disadvantages include the typically 

high-level costs required to haul inputs and outputs, higher capital costs, and the need for daily management of 

the system by a trained operator. 

1.5 Biogas Applications: There are many uses for the gas produced by anaerobic digestion. Biogas can be 

substituted for any application designed for natural gas. A boiler will convert the methane to heat. Micro 

turbines, gas turbines, internal combustion engines and fuel cells convert biogas into both electricity and heat. 

i Heat Boiler: The heat boilers represent the simplest use of anaerobic produced gas. Biogas can be used in heat 

boilers to directly produce high quality hot water or steam. The hot water or steam may be used to heat the 

digester and be used in secondary systems such as absorption chillers or space heaters. The gas could also be 

used directly in any natural gas fired appliance 

ii Flare: There are two basic types of flares available: open and enclosed. The open flares usually consist of a 

burner with a small windshield. The open flares are usually constructed several metres off the ground in order 

to protect both workers and supply pipes from the radiated heat. The open flares are mostly suited for temporary 

or test uses. The enclosed flares are usually ground - based permanent structures. The burner is kept in an 

enclosed cylinder lined with refractory material. The insulation and control of air mixture contribute to a more 

uniform burn as well as lower emissions. 

iii Internal Combustion Engines: The use of internal combustion (IC) engines with biogas is long established. 

IC engines are sub - divided into two categories: compression engines, and spark ignition engines. Both types of 

engines may be converted to run using the biogas produced by anaerobic digestion. The biogas operation of 

compression engines is known as "dual fuel" operation, because a small amount of diesel fuel is combined with 

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Vol. 9, Issue 2; March -April 2024; 

ISSN: 2837-2964 

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22 | A c a d e m i c  J o u r n a l  o f  S c i e n c e ,  E n g i n e e r i n g  a n d  T e c h n o l o g y  

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the gas for ignition purposes. The spark ignition engines are operated on a mixture of biogas and air, as ignition 

is caused by a spark plug. In a dual fuel engine, a mixture of biogas and air, mixed in an external device is 

sucked into the engine chamber and ignited with a small amount of diesel fuel. 

1.6 Biomethane: Biomethane (also known as “renewable natural gas”) is a near – pure source of methane 

produced either by “upgrading” biogas (a process that removes any CO2 and other contaminants present in the 

biogas) or through the gasification of solid biomass followed by methanation (IEA, 2024). Biogas can be 

cleaned and upgraded to natural gas standard when it becomes biomethane. Bio methanation is the chemical 

process of creating methane by combining gaseous carbon oxides with hydrogen (EBA, 2024). 

II MATERIALS 

The materials used in actualization of this work are presented below; 

The major materials used are the research study areas: Agricultural engineering departmental processing 

laboratory, and Agricultural engineering departmental demonstration site, both located in Engineering faculty, 

Delta state university of science and technology, Ozoro, Nigeria. 

Other materials include: HDPE drum, water purification filter, Potash, iron sponge, charcoal, HDPE tape, 

rubber gaskets, PVC gum, silicon bond, Socket joints, elbows, tees, valves, PVC and rubber pipes of various 

size, 25 liters - plastic gallon, funnel, gas cylinders, multipurpose thermometer with sensing probe, Poultry 

droppings, water, etc. 

III METHODS 

A portable biogas digester was produced in the processing laboratory of the Department of Agricultural 

Engineering, Delta State University of Science and Technology, Ozoro. The holding tank was a HDPE drum. A 

water purification filter was modified as a biogas filter and packed with local potash, activated charcoal and iron 

filings in order to remove unwanted gases. Four openings were provided: a substrate inlet (the coverable PVC 

pipe on the drum seal for pouring in solvents and solutions after corking the seal), substrate outlet (the PVC 

pump below the tank for removal of wastes), gas outlet (the PVC plastic pipe attached to the rubber tube, 

connected to the drum through the seal for the collection of produced gas from fermentation process for 

appropriate transmission of gas to the cylinder), and emergency pressure valve (the PVC pipe with tap 

connected, on the drum seal to regulate internal reaction within the gas production unit). Upon mixing, at ratio 

of 1:1 water to Poultry droppings, fermentation was allowed for thirty - two (32) days in the air tight vessel, and 

within the period, gas collection was carried out. 

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Digester Fabrication: The biogas digester was made from high-density polyethylene (HDPE) plastic, chosen 

for durability reasons. The drum was fitted with four openings (substrate inlet, gas outlet; emergency gas release 

point, and substrate outlet) of circular holes drilled. Socket joints were attached with gaskets to the holes to 

ensure air tight fit. These can be seen in figure four (4) below; 

 
Figure 4: Socket joints and drilled holes.  

In section I, hole boring was achieved using hot metallic material. This was followed by filing and fitting in 

(section ii) which gave a resultant functional fitted three openings (section iii) in figure four (4) above.  

Details of the various openings are presented in table one (1) below; 

Table 1: Digester openings size and placement 

S/N Type of opening Diameter (cm) Location 

1 Substrate inlet 6 Top (cover) 

2 Emergency gas release 4.5 Top (cover)  

3 Gas outlet 4.2 Top (cover) 

4 Substrate outlet 6 Base 

Filter Fabrication: A domestic water purification filter was modified for upgrading of the biogas. The filtration 

elements used are activated charcoal, iron filings and local potash, according to Orhorhoro et al. (2018). All 

filter composite materials were dry, and were mixed with the charcoal, potash and iron filings in the ratio of 4:3: 

l. 

Leak Proofing: Upon fabrication completion, a leak test was carried out using approximately 1 litre of water to 

ensure that no leakages were made. 

The digester was loaded to approximately 60% capacity (about 0.074m3) with poultry droppings in slurry form.  

 

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Figure 5: Mixing of the droppings 

The mixed droppings were further balance by adding more solvent through the inlet unit using the funnel after 

corking the digester seal. 

The bill of engineering measurement and evaluation (BEME) for the fabrication of the digester was made. 

IV RESULTS 

The produced digester is presented below; 

 
Figure 6: Biogas digester 

The result of the filter element produced is presented in figure seven (7) below; 

 
Figure 7: Filter element 

Leak proofing experiment result indicated a gas tight seals. Methane gas was produce. 

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The result of the bill of engineering measurement and evaluation (BEME) for the fabrication of the digester is 

presented in table two (2) below; 

Table 2: Bill of Engineering Measurement and Evaluation (BEME) for fabrication of the digester 

S/N Item Description Quantity Unit Cost 

(N) 

Total Cost  

Naira (N) 

Cost in 

 Dollar ($) 

1. Receptacle  HDPE drum  1 35,000 35,000 26.92 

2. Pressure gauge Analog (kPa) 1 19,000 19,000 14.62 

3. Pipes  PVC and rubber pipes of various sizes  As reqd. 11,500 11,500 8.85 

4. Fittings Socket joints, elbows, tees, valves, etc. As reqd. 11,550 11,550 8.88 

5. Glue PVC gum, silicon bond, etc. As reqd. 7,500 7,500 5.77 

6. Labour Specialized labour (plumbing)  22,000 22,000 16.92 

7. Miscellaneous HDPE tape, rubber for gaskets, etc. As reqd. 8,200 8,200 6.31 

8. Transport expenses Purchase, movement of waste etc.  As reqd. 15,000 15,000 11.54 

9. Filter  Water purification filter  1 4,000 4,000 3.08 

10. Filter components  Potash, iron sponge, charcoal  As reqd.  7,000 7,000 5.38 

TOTAL  140,750 108.27 

V DISCUSSIONS 

In the gas collection, the outlet pipe from the filter which is the flexible hose with a valve at the end, allow for 

direct capture of upgraded methane in a metal cylinder. Retention time affected gas pressure built up in the 

digester. The gas produced at the beginning of harnessing was low relative to fermentation rate which increased 

with respect to time. The system produced combustible methane gas at the end of the retention time. Gas 

production was low in the first few days and increases with time. 

The PVC pipes and fittings connected to the drum served as controls to excessive fermentation products (to 

avoid explosion from unbalance internal reaction within the tank gas storage). This emergency release valve 

was fitted with a short length of polyvinyl chloride (PVC) pipe and a valve, in order to make room for 

emergency release of the pressurized contents. In leak proofing, PVC gum, silicon bond, and rubber gaskets 

were used to ensure air tight seals. HDPE thread tape was also used as screw able elements. 

VI CONCLUSION 

Methane gas was produced (from the portable digester) and purify – able to biomethane, which is burnable to 

obtain electricity and heat using combined heat and power (CHP) plants, usable as fuel, and inject – able to the 

natural gas. 

RECOMENDATION 

The usage of biogas especially in Africa is minimal though it is on the increase, it should be encourage for 

future sustenance. 

 

 

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REFERENCES 

EBA, 2024. About Biogas And Biomethane. European Biogas Association. P 11. 

www.europeanbiogas.eu/about-biogas-and-biomethane/ 

EPA, 2024. How Does Anaerobic System Design and Technology. US Environmental Protection Agency. P 1. 

www.epa.gov/agstar/anaerobic-system-design-and-technology#waste-handling-system 

IEA, 2024. An Introduction To Biogas And Biomethane. International Energy Agency (IEA). P 1, 4 & 8. 

www.iea.org/reports/outlook-for-biogas-and-biomethane-prospects-for-organic-growth/an-introduction-

to-biogas-and-biomethane 

Okolotu G. I., Akpoghelie P. O., Akwenuke O. M., Okoronkwo K. A., Adaigho D. O., Ogbodhu C. U., 

Owheruo J. O., Uguru H., & Nyorere O., 2024. Nutrient Compositional Characteristics Of Coconut 

Kernel, Palm Kernel, Cocoa Seed, Bitter Kola, Breadfruit And African Yam Bean. American Journal Of 

Applied Sciences And Engineering. Vol. 5, Issue 1. p 1. DOI: 

Https://Doi.Org/10.5281/Zenodo.10892455 

TNDEC, 2024. Anaerobic Digestion. Tennessee State Government Department of Environment And 

Conservation. P 2. www.tn.gov/environment/program-areas/sw-mm-organics/anaerobic-digestion.html  

Wikipedia, 2024. Anaerobic Digestion. p 1. www.en.m.wikipedia.org/wiki/Anaerobic_digestion 

PSU, 2023. Anaerobic Digestion: Biogas Production and Odor Reduction. Penn State University Extension. P 3. 

www.extension.psu.edu/anaerobic-digestion-biogas-production-and-odor-reduction 

ABC, 2022. Anaerobic Digestion. Official website of American  Biogas Council. P 3. 

www.americanbiogascouncil.org/resources/what -is-anaerobic-digestion/ 

Okolotu, G. I., & Oluka, S. I. (2021). Shore reclamation for agricultural use, a combat to shoreline erosion. 

Advance Journal of Science, Engineering and Technology, 6 (5), 14. 

Orhorhoro, E.K. Orhorhoro, O.W. & Atumah, E.V. (2018). Performance evaluation of design AD system biogas 

purification filter. International Journal of Mathematical, Engineering and Management Sciences 3(1): 

17-27. 

mailto:topacademicjournals@gmail.com
http://www.europeanbiogas.eu/about-biogas-and-biomethane/
http://www.iea.org/reports/outlook-for-biogas-and-biomethane-prospects-for-organic-growth/an-introduction-to-biogas-and-biomethane
http://www.iea.org/reports/outlook-for-biogas-and-biomethane-prospects-for-organic-growth/an-introduction-to-biogas-and-biomethane
http://www.en.m.wikipedia.org/wiki/Anaerobic_digestion
http://www.extension.psu.edu/anaerobic-digestion-biogas-production-and-odor-reduction


    

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Abatzoglou, N. & Boivin, S. (2009). A review of biogas purification processes. Biofuels, Bio-products and Bio 

refining 3(1): 42-71. 

Kramer, J. (2009). Wisconsin agricultural biogas casebook. Madison: Energy Center of Wisconsin. 

Appels, I., Baeyens, Jan., Degreve, Jan. & Dewil, R. (2008). Principles and potential of the anaerobic digestion 

of waste-activated sludge. Progress in Energy and Combustion Science 34 (6): 755-781. 

El-Mashad, H.M., Zeeman, G., van Loon, W.K.P., Bot, G.P. & Lettinga, G. (2004). Effect of temperature and 

temperature fluctuation on thermophilic anaerobic digestion of cattlemanure. Bioresource Technology 

95: 191-201. 

Ahring, B.K. (2003). Status on science and application of thermophilic anaerobic digestion. Water Science 

Technology 30 (12): 241-249. 

Poulsen, T.G. (2003). Anaerobic Digestion. Aalborg: Aalborg University Press.  

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