The consumption of chicken is steadily increasing due to its high protein content. However, the resulting waste, particularly feathers, is often improperly discarded in lakes, rivers, open land, and ponds—contributing to environmental pollution. According to 2019 data, India consumed approximately 1,560 million chickens, generating around 31,200 tons of waste feathers. These feathers are typically treated as waste, leading to uncontrolled methane emissions, which negatively impact the environment. Anaerobic digestion presents an economical and efficient method to convert the proteins found in chicken feathers into methane gas. Utilizing this technique not only helps manage poultry waste but also provides a renewable source of energy. This can reduce dependence on fossil fuels, which are finite and increasingly unreliable for meeting growing energy demands such as vehicle fuel and electricity generation. Moreover, this approach supports a cleaner, more sustainable environment by minimizing pollution.

• Waste Chicken; Environmental pollution; India; Biogas Recovery

Srinivasan S, Ramesh Kumar PL (2026) Biogas Recovery from Waste Chicken Feathers through Anaerobic Digestion. Chem Eng Process Tech 11(1): 1108.

Chicken feathers represent one of the most abundant keratin-rich biomasses globally [1]. Their disposal poses a significant challenge for the poultry industry. Conversely, these feathers are a valuable source of protein, making their recovery an important aspect of organic solid waste management and bioenergy production. Anaerobic digestion is a viable technique to recover proteins from waste chicken feathers and convert them into biogas [2]. Following digestion, the residual slurry can be repurposed as a nutrient-rich fertilizer for agricultural use [3]. The methane extracted from this process can power electricity-generating plants, while its high methane content (typically 70–90% in Compressed Natural Gas) also makes it suitable as an alternative fuel for automotive engines [4]. India ranks among the top poultry producers worldwide. Rising incomes and urbanization have driven a sharp increase in poultry consumption, which reached over 3.9 million metric tons in 2020 [5]. The Indian poultry sector has experienced sustained growth of 8–15% annually over recent decades, making the country the third-largest egg producer and the seventh-largest broiler producer globally [6]. Domestic consumption in recent years remains high, with projections indicating continued growth [7]. Rural small-scale farmers play a key role in this industry, emphasizing the need for integration with allied agricultural sectors. The growing trend of dining out, along with the expansion of quick-service restaurant chains, is also influencing consumption patterns in India. The current per capita chicken consumption stands at approximately 13 kg annually and is expected to double within the next five years [8]. In addition to energy applications, chicken feather waste can be utilized in construction. When mixed with gypsum plaster, it enhances the thermal properties of mortars, offering potential use in walls and ceilings [9].

The Figure 1indicates the consumption of chicken across word from the year 1960. 

Figure 1 Consumption of Chicken in across the world

In the year of 1960 the consumption of chicken by a person per year was about 1.6 to 2 kg only but now it has increased to around 13kg [10-15]. In a few years the production and consumption will be increased. In the current financial year the total consumption of chicken in India is 1560 million and the each chicken gives an average amount of 20 grams feathers.

Amount of feathers contain in 1560 million chicken = 1560000000 x20grams

= 31200000000 grams

= 31200000 kilograms

= 31,200 tones

Therefore the total weight of the chicken feathers available for fuel generation per year = 31,200 tones Disposing this large amount of chicken feathers is a very big concern to the poultry industries. Practically

in actual human life these wastages are disposed into the atmosphere and it causes pollution and diseases. The waste chicken feathers can be used very effectively for producing methane gas by using a feasible technology. In this project we have tried to develop a technology for producing methane gas from the chicken feathers.

Components used in the present study

The following components were used in this project to extract methane gas from chicken feathers through the anaerobic digestion process:

   1.  Digital pH meter

   2.  200 ml glass bottles with plastic corks

   3.  Digital weighing machine

   4.  Incubator with temperature control

   5.  Beakers with graduated scales

Materials used in the present study

The following materials were utilized in this project for the extraction of biogas from waste chicken feathers:

• Waste chicken feathers – used as the primary bio resource for biogas production.

• Lime water (Ca(OH)?) – employed for the chemical pretreatment of feathers, primarily to accelerate reaction rates and aid in keratin breakdown.

• Phosphate buffer (NaOH or CO?) – used to regulate and maintain the pH levels of the pretreated feather samples, ensuring optimal conditions for digestion.

• Enzymes – added to enhance the digestion process, facilitating more efficient breakdown of the feather proteins during anaerobic digestion.

Sample Preparation and Extraction of Biogas Collection of Waste Chicken Feathers

Collection of Waste Chicken Feathers: In this study, waste chicken feathers were collected in the required quantity for biogas extraction. A total of 200 grams of feathers were used to generate methane through the anaerobic digestion process. Once collected, the feathers were thoroughly washed using lukewarm water (approximately 38°C), a step essential for removing contaminants. Care must be taken during washing, as direct contact with the feathers may cause skin irritation. After washing, the feathers were dried—either by placing them under sunlight during the day or using an oven. Once dried, they were ground into smaller particles using a grinding machine. For this project, a household mixer grinder was used due to the relatively small amount of material. Grinding should also be conducted with caution, as inhaling fine feather particles can pose health risks. Following grinding, the processed feathers were subjected to chemical pretreatment using lime to aid in the breakdown of keratin during digestion (Figure 2).

Figure 2 Grinded waste Chicken Feathers for biogas extraction

The chicken feathers are chemically treated under following three conditions,

1. Fully grinded chicken feathers with various lime concentrations.

2. Partially grinded chicken feathers with various lime concentrations.

3. Fully and partially grinded chicken feathers with various lime concentrations.

Totally ten numbers of samples in fully grinded chicken feathers, five numbers of samples in partially grinded chicken feathers and five numbers of samples in mixing of fully and partially grinded chicken feathers were prepared for the anaerobic digestion process and various lime concentrations were added to them as shown in the Tables 1, 2 & 3

Table 1: Fully Grinded Feathers with various Concentrations of Lime and Water

Table 2: Partially Grinded Feathers with various Concentrations of Lime and Water

Table 3: Fully and Partially Grinded Feathers with various Concentration of Lime and Water

Steps Involved

After adding different concentrations of lime to the samples, they are heated at 100°C for 30 minutes. Following heating, the samples are cooled to room temperature, and their pH is measured using a pH meter. Since lime is added to pre-treated chicken feather samples, the pH increases to around 11. However, anaerobic digestion typically requires a pH of approximately 8.3. Therefore, the pH of the samples is adjusted back to around 8.3 by adding NaOH. Finally, all samples are incubated at a favorable temperature of 55°C using an incubator. The step-by-step process of converting waste chicken feathers into biogas is illustrated in Figure 3.

Figure 3 Process involved in Converting Waste Chicken Feather into Biogas.

Measurement Technique

The measurement of gas produced in each sample bottle was conducted using a simple displacement method based on fluid dynamics. The principle involves a closed container filled with water and fitted with two small openings—one at the top and one at the bottom. When the top hole is left open to the atmosphere, air enters the container, allowing water to flow out from the bottom. However, when the top hole is sealed, the outflow of water from the bottom stops due to the vacuum created inside. In this research, the same principle was applied to estimate the volume of gas generated during anaerobic digestion. As biogas formed inside the sealed bottle, it displaced the water, and the volume of displaced (Figure 4).

Figure 4 Measurement of biogas extracted

A small tube equipped with a flow control valve was connected from the gas-containing sample bottle to the top opening of the measurement container. When the valve was opened, the gas produced from the sample entered the container through the top, displacing the water inside. As the gas flowed in, water exited from the bottom of the container. The volume of displaced water was carefully measured, and this value directly corresponded to the volume of gas produced.

To calculate the total gas volume in milliliters, the standard conversion factor was used:

1 m³ = 1000 liters = 1,000,000 milliliters.

Thus, the measured water displacement (in milliliters) provided an accurate estimate of the biogas generated in each sample bottle.

For quick understanding,

Height of water collected in the beaker for the sample of 5gms (FG) feather with 8ml lime, 42ml water (h)= 3.45 cm = 0.0345m

Therefore the total amount of gas formed for the sample of 5grams (FG) feather under the Condition of 8ml lime and 42 ml water = 33.19 ml

Result of Samples of Fully Grinded Chicken Feathers

The results obtained from the pretreated samples of fully ground chicken feathers after 30 days of incubation are presented below. When the feathers were completely ground and treated with varying concentrations of lime, the corresponding methane yields were recorded, as shown in Table 4.

Table 4: Output of samples of the fully grinded chicken feathers

The highest methane yield—33.19 mL—was achieved with a treatment mixture containing 16% lime and 84% water. However, increasing the lime concentration beyond 16% led to a reduction in methane production. For example, when the lime concentration was increased from 16% to 18%, the methane yield decreased to 28.80 mL, indicating an inverse relationship beyond the optimal point. This suggests that the ideal ratio for maximum methane yield is 16% lime to 84% water.

Figure 5 Output of samples of the fully grinded chicken feathers

Figure 5 illustrates the variation in methane yield corresponding to different lime concentrations applied to the pretreated, fully ground chicken feather samples.

Output of Samples of Partially Grinded Chicken Feathers

The followings are the results which were obtained for the pre-treated samples of partially grinded chicken feathers during 30 days of incubation of samples. When the feathers are grinded partially and treated with varying lime concentrations. Then the obtained methane yield has been shown in the Table 5.

Table 5: Output of samples of the partially grinded chicken feathers

The methane yield obtained in this case is very lower than the methane obtained in the previous case. From this it is understood that the maximum methane yield can be achieved only when the waste chicken feathers are grinded fully and treated with various lime concentrations (Figure 6).

Figure 6 Output of samples of the partially grinded chicken feathers

Output of Samples of Fully and Partially Grinded Chicken Feathers

The following results were obtained from pretreated samples of fully and partially ground chicken feathers after 30 days of incubation. When the feathers were subjected to varying lime concentrations, the resulting methane yields were recorded and are presented in Table 6.

Table 6: Output of samples of the fully and partially grinded chicken feathers

In this scenario, the methane yield was found to be slightly higher than that obtained in the second case, but lower than the yield recorded in the first case, indicating that both the degree of grinding and lime concentration significantly influence methane production during anaerobic digestion (Figure 7).

Figure 7 Outputs of samples of the fully and partially grinded chicken feathers

A significant improvement in methane yield from waste chicken feathers was achieved using the anaerobic digestion process over a 30-day incubation period with pretreated samples. The highest methane production, measured at 33.19 mL, was obtained from fully ground chicken feathers pretreated with a mixture containing 16% lime and 84% water. It was observed that increasing the lime concentration beyond 16% led to a decrease in methane yield. For example, when lime content was increased to 18%, methane production dropped to 28.80 mL, demonstrating an inverse relationship beyond the optimal concentration. To achieve maximum biogas output, the sample preparation must follow a specific ratio: for every 1 gram of chicken feathers, a total of 10 mL of the treatment solution (comprising 16% lime and 84% water) should be used. This proportion ensures optimal conditions for methane generation. Additionally, partially ground feathers resulted in a lower methane yield, indicating that complete grinding is essential for efficient digestion and gas production. This negative effect of incomplete grinding is supported by the data shown in the related table. In conclusion, as chicken consumption continues to rise, the resulting feather waste—often dumped in open land, lakes, and rivers—contributes to environmental pollution and poses risks to animal and human health. Instead of treating these feathers as waste, they can be repurposed through anaerobic digestion to produce biogas. This approach not only helps manage organic waste but also contributes to a cleaner environment. Given the uncertainties surrounding future fossil fuel availability for transportation and power generation, this sustainable technology offers a promising alternative. We believe this project has the potential to serve as a viable source of renewable energy in the coming years.

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