construction and working of biogas plant pdf

Construction and working of biogas plant pdf

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The pros and cons of biogas: is it the answer to a circular economy?

Types of bio waste processed at biogas plant:

Important Terms from A to Z

Design and Fabrication of a Plastic Biogas Digester for the Production of Biogas from Cow Dung

The secret to understanding the most common biogas plant construction and working stages, is explained here for he most common AD plant type.

The pros and cons of biogas: is it the answer to a circular economy?

Biogas digester dimensions and materials of construction are important factors of consideration during the design and fabrication phase. The aim of this study is to provide a detailed analysis of the design and fabrication of a 2. To establish this, a design equation covering the volume of the digester, inlet and outlet chambers, and digester cover plate were developed considering the shape of the digester.

The study was motivated due to some limitations such as leakage associated with previous designs. In the present study, a ventilation test was conducted after the fabrication to ensure the digester is leak free. Results obtained showed a total volumetric methane gas yield of 2. The developed plastic biogas digester has been found to be appropriate for biogas production using cow dung as substrate.

For future energy security and improvement in the use natural resources, the depletion of conventional energy resources such as fossil fuel can be solved by the use of renewable energy sources. In the midst of numerous renewable energy sources and their production means is the sustainable generation of biogas through anaerobic digestion technology [ 1 ].

Anaerobic digestion is a microbial process whereby organic carbon are converted by subsequent oxidation and reductions to its most oxidized state CO 2 and reduced form CH 4. It is a biological route that is catalyzed by the activities of microorganism in the absence of oxygen [ 2 ]. Biogas is a gaseous fuel obtained from waste fermentation, which is of interest in producing energy for electricity, cooking, heating, and biofuels for vehicles [ 3 , 4 ].

The production of biogas from waste fermentation offer some additional benefits, namely, reduction in pathogens, foul odor, and methane emission from landfill sites where these wastes are ordinarily disposed. Anaerobic digestion of organic waste in digesters occurs in four stages, namely, hydrolysis, acidogenesis, acetogenesis, and methanogenesis in a system called biogas digester [ 5 ]. Interestingly, biogas is considered a low carbon fuel source, which is of interest to rural communities in meeting their energy need for cooking.

Biogas digesters are mostly designed and constructed using bricks, cement, metals, and reinforced concrete, while in some cases, the dome of the gas holder is made up of fiberglass. These biogas digesters encounter some challenges such as leakages at the edges of the brick structure after a short period of operation. There are some few biogas digester designs that utilize reinforced plastic; however, some of the reinforced plastic of the biogas digester deteriorates and creates holes due to the effect of ultraviolet UV radiations.

Furthermore, the effect of corrosion that mostly occurs in biogas digesters built from metals results in their failure. In addition to the limitations aforementioned, the construction of the biogas digester using bricks or cement block is quite expensive due to high labor cost and materials.

To overcome these weaknesses and challenges associated with the various materials mentioned, an alternative construction material was investigated in this study.

Therefore, to minimize the high cost of construction of these previous designs, a more cost-effective design is proposed. The choice of a plastic for the study is based on it being noncorrosive, a good insulator, cost-effective, and easy to maintain.

Another factor that made the present study different from previous design is the subjection to the ventilation test to ensure leak free, which will result to more biogas yield and production.

The introduction and use of this technology involving composite materials will help to generate biogas for research purposes and serve as a perfect fertilizer used in the university farm; all these motivated the need for this study. Therefore, the study fills this knowledge gaps existing in biogas digester designs, hence making it easier to consider a composite material for biogas digester design. The detailed knowledge of the design equations and the nature of material used in the construction of the biogas digester will be helpful to the energy engineer, researcher, and academic contributions to the development of biogas technology.

Hence, the objective of the study is to formulate a design equation used for the construction of the biogas digester and to carry out a ventilation test to certify the digester a leak free one, which is not usually common in previous studies.

This section presents the design equations used to determine the volume of the digesters from various authors and the material used for the fabrication and construction.

The volume of the digester was taken as the response parameter because it determines the rate of the biogas yield. Agu and Igwe [ 6 ] conducted a study on the design and construction of an indigenous biogas plant from plastic with the aim of generating alternative energy from animal wastes.

The equation considered in their study includes the volume of the slurry chamber and the volume of the gas chamber. The volume of the digester chamber slurry chamber was calculated using. The gas chamber has a shape of frustum from which a cone-like shape was obtained. Hence, the volume of the frustum was obtained from the volume of a large cone and a small cone.

Mathematically, this is given as. The study resulted in a biogas yield of 0. However, the volume of the biogas digester was not reported in the study. Bello and Alamu [ 7 ] designed and constructed a metal biogas digester aimed to provide solution towards exploration and development of biogas in rural communities.

The volume of the digester chamber V dc was determined using. While the volume of the gas chamber was calculated using. The digester volume was reported to be 0. Another study designed and fabricated a low-cost plastic rectangular-shaped digester, fed with poultry and pig manure. Mathematically, the digester chamber volume was determined using.

From equation 5 , the volume of the digester chamber and gas storage chamber were found to be 0. This digester gave a biogas yield of 6. In Jekayinfa et al. This gave a total biogas digester volume of 0. Nwankwo et al [ 10 ] designed and fabricated a household plastic biogas digester. The total volume of the digester was determined using. This resulted in a total volume of 3. In the study by Mukumba et al.

The digester was installed for the purpose of research, which serves as a pilot study for rural community engagement. Due to availability of cow dung in the University farm, the digester was fed with cow dung. The biogas digester of the present study was made from a high-density polyethylene HDPE plastic. It has the following parts: the inlet chamber feed entrance , outlet chamber removal of digested waste , and the gas storage chamber.

The inlet and outlet chambers were built with bricks and cement mortar, which were made locally out of a mixture of cement and sand. The fabricated biogas digester was installed underground and above-ground as shown in Figure 2.

A four equal-sided plain wood was used as cover for the inlet and outlet chambers to prevent impurities from entering the chambers. The digester cover was made of the same HDPE plastic material that could withstand harsh environmental conditions and still maintain anaerobic condition. The slurry and gas temperature were monitored using a K -type thermocouple inserted into the digester through the cover of the digester. The cow dung was collected from University of Fort Hare Diary Farm, and some samples of it were subjected to laboratory analysis.

The following physiochemical characteristics were determined prior to the cow dung being fed to the digester: total solids, volatile solids, chemical oxygen demand, calorific value, and pH. Table 2 presents the physiochemical characteristics of the cow dung used in the study. After the first day of feeding, the gas valve was left open for 72 hours to allow expulsion of any air [ 13 ]. The volume of the designed and fabricated biogas digester is 2. Total digester volume took into consideration digester neck volume where the digester cover was fixed, gas storage volume , and the slurry or fermentation chamber volume.

For the fabrication of the biodigester, the design calculation of the digester neck, gas storage section, and slurry chamber were considered. Figure 3 shows the schematic design calculation of the volume of the biogas digester. The three shapes used in describing the different compartments of the biogas digester include the cylindrical shape that formed the neck, the spherical shape for gas storage , and the frustum shape of the slurry chamber.

The volume of each of these shapes contributed to the total volume of the biogas digester. Therefore, the volume of the neck of the digester neck was obtained to be 0. Here, the radius of the hemisphere is 0.

Hence, the volume of gas storage is 0. Finally, the volume of the slurry or fermentation chamber is calculated from the volume of the frustum, which is equal to the volume of the large pyramid-volume of the small pyramid. The volume of pyramid either large or small is calculated as where h is known as the apothem length.

This results in a frustum volume of 1. Therefore, the total volume of the fabricated biogas digester was found to be 2. The volume of the digester chamber was chosen on the basis that the design is a small family size digester that could be used to meet family cooking need, since the study is a pilot study for installation of biogas digester in rural communities.

Other criteria considered in the choice of volume include the availability of feed stock and retention time. This in turn might cause a reduction in biogas production. Hence, the digester chamber was built in an inclined angle of This will enable the smooth downward flow of slurry from the inlet chamber.

A continuous feeding mode was employed in the digester. Although the volume of the biogas digester 2. Moreover, the bacteria growth rate are also more in continuous compared to batch feeding [ 14 ], which helps during the production of biogas.

The schematic layout of the designed biogas digester is shown in Figure 4. The geometric configuration of the inlet and outlet chambers of the constructed biogas digester is a rectangular prism. Inlet and outlet chambers of the biogas digester were built a little above the fabricated digester to create pressure for enhanced biogas production.

Figure 5 shows the calculated volume of the inlet and outlet chambers of the biogas digester and the pressure exerted on the inlet and outlet chambers. The schematic view of the biogas digester in Figure 5 illustrates the calculation of the pressure exerted by the inlet and outlet chambers. Assumption 1. The forces in input and output chamber are equal. Introducing as the angle, Making F the subject of the formula gives From equation 17 , Substituting equation 18 into equation 16 gives The inlet pipe is of circular diameter; therefore, the area of a circle is.

This indicates that the pressure in the outlet chamber will be greater than that of the inlet chamber. Hence, as gas was produced at the top of the biogas digester, pressure was exerted in the outlet chamber. This is why the volume of the outlet chamber is greater than the inlet chamber.

The digester cover plate was made from the same material HDPE used for fabrication of the digester. The placing of gas storage over the slurry unit or digester chamber can induce stress on the cover plate.

Types of bio waste processed at biogas plant:

Biogas technique introduction The design aspects dealt with below concentrate solely on the principles of construction and examples of simple biogas plants, i. The symbiotic relationships existing between a wide variety of microorganisms leads, under air exclusion, to the degradation and mineralization of complex biomass in a sequence of intermeshing stages. The resultant biogas, consisting primarily of methane CH 4 and carbon dioxide CO 2 and the mineralized slurry constitute the ultimate catabolites of the participating bacteria and residual substances. The process of anaerobic fermentation can be illustrated in the form of a three-stage model, as shown in figure 5. Table 5.


The amount of manure fed into a digester each day has an important effect on its operation. This is measured by volume added in relation to the volume of the.


Important Terms from A to Z

Blue Sphere Corporation 8-K. Exhibit Dated: 4 December Annexes to this Agreement.

I have replied and mailed guidelines to almost all of the queries and I hope that helped them in their quest for building their Biogas plant. As you can see in the last step of this instructable, I was invited by Hajee Karutha Rowther Howdia College, Uthamapalayam, Theni District in Tamil Nadu, India, to present a keynote address on Biogas and Panchagavya an organic product made from produce from cow. This event was supported by the Tamil Nadu State Council for Science and Technology, Chennai, attended by local farmers, self-help group members and students.

Design and Fabrication of a Plastic Biogas Digester for the Production of Biogas from Cow Dung

Biogas is a clean and efficient fuel.

Design and Fabrication of a Plastic Biogas Digester for the Production of Biogas from Cow Dung

Biogas digester dimensions and materials of construction are important factors of consideration during the design and fabrication phase. The aim of this study is to provide a detailed analysis of the design and fabrication of a 2. To establish this, a design equation covering the volume of the digester, inlet and outlet chambers, and digester cover plate were developed considering the shape of the digester.

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. Biogas is produced by anaerobic digestion with methanogen or anaerobic organisms , which digest material inside a closed system, or fermentation of biodegradable materials. Biogas is primarily methane CH 4 and carbon dioxide CO 2 and may have small amounts of hydrogen sulfide H 2 S , moisture and siloxanes. The gases methane , hydrogen , and carbon monoxide CO can be combusted or oxidized with oxygen.

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