| Livestock Research for Rural Development 37 (4) 2025 | LRRD Search | LRRD Misssion | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
Renewable energy is derived from abundant natural sources, including sunlight, wind, water, geothermal energy, and biomass. By replacing fossil fuel energy sources with new renewable energy sources, we can reduce the greenhouse gas emissions that contribute to climate change and other negative environmental impacts. Biogas energy is one such alternative energy source. Biogas is the end-product gas of anaerobic digestion and degradation in an environment without oxygen or air by methanogenic bacteria. Biogas is one of the most efficient and effective renewable alternative energy sources available. Biogas technology utilizes organic matter content for the growth of microorganisms that have the potential to produce biogas. Biogas can be produced from various organic materials through anaerobic digestion. Some organic materials commonly used in the manufacture of biogas include animal, food, agricultural, industrial waste, and plant bioenergy. However, biogas produced using these various types of waste has a fairly low level of purity; therefore, there are several different ways of purifying biogas. In this study, we aimed to optimize the mixture of bioslurry and dolomite to increase the concentration of methane in biogas. The use of a mixture of bioslurry-dolomite with the right composition can enhance the purification of methane content in biogas.
Keywords: biogas, bioslurry, purification, dolomite, methane
Energy is a fundamental necessity for both rural and urban communities, supporting socioeconomic development, health, education, and overall quality of life (Razeghi et al 2025). In Indonesia, energy demand continues to rise along with population growth, which reached over 268 million in 2019, resulting in increasing consumption and waste generation (Setyono & Kiono 2021). Dependence on fossil fuels, especially fuel oil and kerosene, has led to economic burdens due to subsidies and declining national reserves, projected to be depleted within the next few decades (Outlook Energy Indonesia 2013; Jupesta 2010). Since becoming a net oil importer in 2004, Indonesia has faced kerosene scarcity in rural areas, forcing communities to rely on firewood, which threatens environmental sustainability (Farobie & Hartulistiyoso 2022; Indow et al 2022). Therefore, the development of renewable energy sources is urgently needed to ensure sustainable energy security and reduce dependence on fossil fuels.
Indonesia, as a tropical country, has enormous renewable energy potential, with an estimated capacity of 3687 GW, but only a small portion, namely 12,736.6 MW, has been utilized (Gani et al 2024). Biogas technology is carried out by utilizing organic matter content for the growth of microorganisms that have the potential to produce biogas (Siswanto & Susanto 2018). Some farmers have a low perception of the use of agricultural biomass waste as biogas (Arianti et al 2024). The good news is that small-scale livestock farmers in rural areas are now beginning to realize the benefits of biogas in reducing operational costs, protecting the environment, and obtaining affordable energy sources (Haryanto et al 2025). Apart from livestock manure, converting fruit waste into biogas through anaerobic digestion is one of the opportunities for developing renewable energy in Indonesia (Purwasih et al 2025). Reusing agricultural waste in biological digestion processes can reduce its negative effects on the environment (Sulistyo et al 2024).
Biogas consists of about 50-70% methane (CH4) and 30-50% carbon dioxide (CO2), and contains small amounts of other gases such as nitrogen (N2), hydrogen sulfide (H2S), and water vapor (Awe et al 2017). The process of forming biogas occurs in a biogas digester, where microorganisms such as bacteria and archaea decompose organic matter into simpler compounds (Khalil et al 2019). The stages in the process of anaerobic digestion involve hydrolysis (breakdown of complex compounds), acidogenesis (production of organic acids), acetogenesis (production of acetic acid and hydrogen) (Setyobudi et al 2015), and methanogenesis (methane production). Biogas has several important uses. Biogas can be produced from various organic materials through anaerobic digestion. Some organic materials that are commonly used in the production of biogas include animal waste, food waste, agricultural waste, industrial waste, and plant bioenergy. However, biogas produced from various types of waste typically has a low level of purity due to the presence of several impurities such as carbon dioxide (CO₂), hydrogen sulfide (H₂S), moisture, and trace contaminants (Ghatak & Mahanta 2016). Desulfurization is a process for removing sulfur compounds such as hydrogen sulfide (H2S) from biogas (Zhang et al 2021), Adsorption is a method that involves the use of adsorbents such as activated carbon or zeolite, to remove contaminants such as siloxane from biogas (Widyanuriawan 2014), Absorption is a method that involves the use of special solvents, such as amines, to adsorb certain compounds from biogas (Ghatak & Mahanta 2016).
Biogas purification is commonly used for methane purification, which uses adsorption methods that use carbon charcoal or zeolite (Bareschino et al 2020). In addition, studies from Nadliriyah & Triwikantoro 2014 can purify biogas using sedimentary rock Ca(OH)2, which in this study can produce methane with high purity. In previous studies, we used dolomite (CaMg(CO3)2) to assist in the biogas purification process (Sulistyo & Yanti 2022). In that study,we mixed sludge in a 1:1 ratio, but in that study, we did not achieve optimal results. In this study, we aimed to optimize the mixture of bioslurry and dolomite to increase the concentration of methane gas in biogas.
This research was conducted at Izzah Farm in Sambi District, Boyolali Regency, Central Java. This study used the adsorption method to purify biogas. In this study, we used a mixture of bioslurry and dolomite with ratios of 1:1, 1:2, and 1:3. We also compared the quality of the mixture of bioslurry and dolomite with allophane and activated carbon. In this study, adsorption was installed on a PVC pipe with a diameter of 4 inches. The gas sampler is installed before and after the pipe containing the adsorber. In each experiment, we took data at 30, 60, 90, 120, 150, and180 minutes. At the outlet of the PVC pipe, a gas bag is installed to catch the biogas produced.
|
| Figure 1. Biogas purification system illustration |
Figure 1 shows an illustration of a biogas purification device. The biogas is then tested for quality at the Laboratory of the Agricultural Environment Instrument Standards Testing Center (BPSI), Jaken, Pati, Central Java, Indonesia. All data obtained were analyzed using the RStudio (R version 4.1.0) computer application (Team 2009).
Methane purification is essential because CH₄ is the main energy-rich component of biogas. By reducing impurities such as CO₂, N₂, and H₂O the energy efficiency and applicability of biogas significantly increase. By purifying methane, the energy efficiency of biogas increases because it increases the methane content and reduces components that do not contribute significantly to the energy value. Biogas that has undergone methane purification can be used in a wide variety of energy applications, such as power generation, heating, drying, heat treatment, and other uses. Pure methane allows the use of biogas in machines and equipment that require a higher quality. In this study, we used a mixture of bioslurry and dolomite with a ratio of 1:1, 1:2, and 1:3. We also compared the quality of the mixture of bioslurry and dolomite with allophane and activated carbon to purify the methane content in the biogas production process.
 |
| Figure 2. Methane content in biogas after purification with various absorbent variables |
Figure 2 shows the content of methane in ppm in the biogas purification process using each absorbent variation. Figure 3 shows the percentage of methane produced after the purification process. Based on Figure 2, the highest methane content was shown by activated carbon charcoal absorbent, with the highest value of 8.27 × 10^5 ppm at 60 minutes after testing, but after 60 minutes, the methane content increased and decreased, which fluctuated actively. The use of a mixture of bioslurry and dolomite that contains methane is best shown by bioslurry and dolomite with a ratio of 1:3, where, after 30 minutes of testing, the methane content of this variable continues to increase until the end of the test time, with the highest value being 5.1 × 10^5 ppm. This was followed by bioslurry : dolomite with a ratio of 1:2 and 1:1. The highest percentage of methane content produced after the biogas purification process was produced by activated carbon, followed by bioslurry : dolomite with a ratio of 1:3. One study found that using coconut shell charcoal as activated carbon increased the methane content from 90.20% to 98.14% at an optimal flow rate of 2 liters per minute (Lestari et al 2020). Activated carbon made from Gigantochloa verticillatabamboo showed promising results, although specific methane content percentages were not detailed (Wangsa et al 2020). Lignocellulosic-Based Activated Carbon was effective in CO₂/CH₄ separation, particularly at lower pressures, although the exact methane content post-purification was not specified (Durán et al 2018) A study using a combination of activated bagasse biochar and zeolite showed an increase in methane content (Amalia et al 2022).
 |
| Figure 3. Percentage of methane in biogas after purification with various absorbent variables |
In general, the CO2 content in biogas ranges from 30% to 50% by volume. The type of organic waste used for anaerobic digestion can influence the CO2 content. Biogas from food waste showed CO2 concentrations between 36% and 56% (Park et al 2020). The specific conditions and technologies used in the anaerobic digestion process, such as temperature and pH, can also affect the CO2 content (Ibrahim et al 2025). Higher CO2 content in biogas reduces its calorific value, making it less efficient as a fuel, so removing CO2 is often necessary to upgrade biogas to biomethane, which has a higher energy content (Heffernan et al 2023).
Figure 4 shows the CO2 content produced after going through the purification process. The most significant decrease in CO2 content was shown by the absorbent with the composition of bioslurry : dolomite with a ratio of 1:3, the absorbent with dolomite content had a relatively stable CO2 content with a maximum value of 1.11 x 105 ppm. Then absorbent with activated carbon composition, bioslurry : dolomite with a ratio of 1:2, and bioslurry : dolomite with a ratio of 1:1. The once-through CO2 chemical absorption process using biogas slurry is noted for its low energy consumption and cost-effectiveness (Duan et al 2024). The biogas slurry, when mixed with biomass ash, not only enhances CO2 absorption but also provides valuable nutrients for agricultural applications, such as improved nitrogen content for plant growth (Liang et al 2024).
 |
| Figure 4. CO2 content in biogas after purification with various absorbent variables |
Normal or typical N2O (nitrous oxide) content in biogas ranges from 0.1 to 1,000 ppm (parts per million) or 0.1 to 1 ppb (parts per billion). It is important to note that N2O is a greenhouse gas that has a higher global warming potential than CO2. Therefore, in biogas management, it is important to monitor and control the N2O content to minimize unwanted greenhouse gas emissions. If the N2O content in biogas is too high, process improvement and optimization steps can be taken to reduce N2O production, such as optimizing anaerobic fermentation conditions, properly managing temperature and pH, and maintaining nutrient balance in the biogas system. Figure 5 showed that the use of various kinds of adsorbents did not have a significant effect on reducing N2O levels in biogas. The absorbent content that can have a significant impact on reducing N2O is activated carbon. Activated carbon is known for its high surface area and porosity, which are beneficial for adsorption processes (Sinto et al 2018). Activated carbon can adsorb various gases due to its porous structure, but specific studies on N₂O adsorption in biogas are not detailed, the general principle of gas adsorption by AC is well-established (Sinto et al 2018). The effectiveness of is activated carbon in reducing N₂O may depend on factors such as the type of modification, the specific conditions of the biogas system, and the presence of other gases (Zhan et al 2022). The long-term stability and effectiveness of modified Activated Carbon in continuously reducing N₂O emissions need further investigation (Hagemann et al 2017).
 |
| Figure 5. The content of N2O in biogas after purification with various absorbent variables |
This study demonstrated that a bioslurry-dolomite mixture with a 1:3 ratio is the most effective composition for enhancing methane concentration in biogas purification. The mixture significantly reduced CO₂ levels while maintaining methane enrichment, although its effect on N₂O reduction remained limited. These findings highlight the potential of bioslurry-dolomite as a cost-effective adsorbent for improving biogas quality, with opportunities for further optimization to address N₂O removal.
“There are no conflicts to declare”.
Amalia A P, A Pertiwiningrum A and Fitriyanto N A 2022 The Effect of the Combination of Zeolite and Activated Biochar-Based Sugarcane Bagasse on the Increase of CH 4 in Biogas with A Different Time Variation. IOP Conference Series: Earth and Environmental Science, 1111(1). https://doi.org/10.1088/1755-1315/1111/1/012055
Andriani D, Wresta A, Saepudin A and Prawara B 2015 "A review of recycling of human excreta to energy through biogas generation: Indonesia case," Energy Procedia, vol. 68, pp. 219- 225
Arianti F D, Triastono J, Pertiwi M D, Prabowo A, Prasetyo T, Chanifah C, Haryanto B, Megawati, Astuti W, Djarot I N, Santoso A D and Wijayanti S P 2024 Renewable energy potential of rice straw and paunch manure as bioethanol feedstocks in Central Java, Indonesia. Case Studies in Chemical and Environmental Engineering, 9. https://doi.org/10.1016/j.cscee.2024.100677
Awe O W, Y Zhao Y, Nzihou A, Minh D P and Lyczko N 2017 "A review of biogas utilisation, purification and upgrading technologies," Waste and Biomass Valorization, vol. 8, pp. 267-283.
Bareschino P, Mancusi E, Forgione A and Pepe F 2020 "Biogas purification on Na-X Zeolite: Experimental and numerical results," Chemical Engineering Science, vol. 223, p. 115744.
Duan Y, Liu Y, Liu H, Shi Z, Shen X, Sun X, Zhao S, Yan S and Liang F 2024 CO2 absorption performance of biogas slurry enhanced by biochar as a potential solvent in once-through CO2 chemical absorption process. Carbon Capture Science and Technology, 13. https://doi.org/10.1016/j.ccst.2024.100317
Durán I, Álvarez-Gutiérrez N, Rubiera F and Pevida C 2018 Biogas purification by means of adsorption on pine sawdust-based activated carbon: Impact of water vapor. Chemical Engineering Journal, 353, 197–207. https://doi.org/10.1016/j.cej.2018.07.100
Farobie O, & Hartulistiyoso E 2022 Palm Oil Biodiesel as a Renewable Energy Resource in Indonesia: Current Status and Challenges. Bioenergy Research, 15(1), 93–111. https://doi.org/10.1007/s12155-021-10344-7
Gani A, Mamat R, Nizar M, Yana S, Yasin M H M and Rosdi S M 2024 Prospects for renewable energy sources from biomass waste in Indonesia. Case Studies in Chemical and Environmental Engineering, 10. https://doi.org/10.1016/j.cscee.2024.100880 .
Ghatak M D and Mahanta P 2016 Biogas purification using chemical absorption. International Journal of Engineering and Technology, 8(3), 1600–1605. https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978764777&partnerID=40&md5=48614ba27d212ad0010fc4024fc31001
Hagemann N, Harter J, Kaldamukova R, Guzman-Bustamante I, Ruser R, Graeff S, Kappler A and Behrens S 2017 Does soil aging affect the N2O mitigation potential of biochar? A combined microcosm and field study. GCB Bioenergy, 9(5), 953–964. https://doi.org/10.1111/gcbb.12390
Haryanto B, Sutaryo S, Purnomoadi A, Purbowati E, Putra F A and Chanifah C 2025 Barriers to the Adoption of Biogas Technology in Smallholder Dairy Farming in Indonesia: A Case Study in Semarang Regency, Central Java. BIO Web of Conferences, 164. https://doi.org/10.1051/bioconf/202516403003
Heffernan J K, Lai C Y, Gonzalez-Garcia A, Nielsen L K, Guo J and Marcellin E 2023 Biogas upgrading using Clostridium autoethanogenum for value-added products. Chemical Engineering Journal, 452. https://doi.org/10.1016/j.cej.2022.138950
Ibrahim N A, Majeed H H, Jwaid T A and Silas K 2025 Advancements in anaerobic digestion of organic waste for sustainable biogas production. Environmental Science and Pollution Research, 32(30), 17916–17930. https://doi.org/10.1007/s11356-025-36783-9
Indow L, Maturbongs R A and Prabawardani S 2022 Tree species used for fuelwood by remote indigenous communities in West Papua, Indonesia: Implication of empowerment program. Biodiversitas, 23(7), 3507–3512. https://doi.org/10.13057/biodiv/d230725
Jupesta J 2010 Impact of the introduction of biofuel in the transportation sector in Indonesia. Sustainability, 2(6), 1831–1848. https://doi.org/10.3390/su2061831
Khalil M, Berawi M A, Heryanto R and Rizalie A 2019 "Waste to energy technology: The potential of sustainable biogas production from animal waste in Indonesia," Renewable and Sustainable Energy Reviews, vol. 105, pp. 323-331.
Khiratkar B, Khade S M & Tripathi A D 2022 Biogas: Renewable natural gas. In Biomass and Bioenergy Solutions for Climate Change Mitigation and Sustainability (pp. 119–128). https://doi.org/10.4018/978-1-6684-5269-1.ch007.
Lestari S, Sriana T, Raharjo M S, Sudiarte I N and Anugrah M N 2020 Improvement of methane composition utilizing activated carbon adsorption column for biogas purification from food waste. Journal of Physics: Conference Series, 1517(1). https://doi.org/10.1088/1742-6596/1517/1/012015
Liang F, Wei S, Xue L and Yan S 2024 Adopting green absorbent for CO2 capture and agricultural utilization: Biogas slurry and biomass ash case. Green Carbon, 2(2), 252–261. https://doi.org/10.1016/j.greenca.2024.03.001.
Nadliriyah N and Triwikantoro T 2014 "Pemurnian Produk Biogas dengan Metode Absorbsi Menggunakan Larutan Ca(OH)2," Jurnal Sains dan Seni ITS, vol. 3, no. 2, pp. B107-B111.
Outlook Energy Indonesia 2013 "Badan Pengkajian Dan Penerapan Teknologi," ed: Indonesia.
Park M-J, Jang W-J and Jeong D-W 2020 A Study for Production of Biogas from Two-phase Anaerobic Digestion Process and Hydrogen from Reforming Reaction of Biogas. Journal of Korea Society of Waste Management, 37(1), 51–61. https://doi.org/10.9786/kswm.2020.37.1.51
Purwasih R, Sutaryo S, Purnomoadi A, Purbowati E and Haryanto B 2025 Anaerobic digestion from fruit waste for biogas production to sustainable development: A comprehensive bibliometric analysis. Sustainable Futures, 10. https://doi.org/10.1016/j.sftr.2025.101255
Razeghi M, Yousefi H, Naseri A and Noorollahi Y 2025 Electrification of Urban and Rural Areas Under Energy Justice and Equity Paradigms. In Communities for Clean Energy Justice and Equity in Grid Modernization (pp. 409–439). https://doi.org/10.1002/9781394265749.ch12
Setyobudi R H, Wahono S K, Nindita A, Adinurani P G, Nugroho Y A, Sasmito A and Liwang T 2015 "Biological purification system: integrated biogas from small anaerobic digestion and natural microalgae," Procedia Chemistry, vol. 14, pp. 387-393.
Setyono A E and Kiono B F T 2021 "Dari energi fosil menuju energi terbarukan: potret kondisi minyak dan gas bumi Indonesia tahun 2020–2050," Jurnal Energi Baru dan Terbarukan, vol. 2, no. 3, pp. 154-162.
Sinto J, Nugroho Y W and Naf’An H I 2018 Preparation of Activated Carbon from Banana Peel Waste as Adsorbent for Motor Vehicle Exhaust Emissions. E3S Web of Conferences, 67. https://doi.org/10.1051/e3sconf/20186703020
Siswanto J E and Susanto A 2018 "Analisa Biogas Berbahan Baku Enceng Gondok dan Kotoran Sapi," Chempublish Journal, vol. 3, no. 1, pp. 11-20.
Sulistyo and Yanti Y 2022 "Biogas purification using the biosludge-dolomite mixture to improve methane gas purity in waste management practicum," in IOP Conference Series: Earth and Environmental Science, vol. 1001, no. 1, p. 012043: IOP Publishing.
Sulistyo, Pranoto, Mahajoeno E, Pranolo S H, Sofyan A, Herdian H, Haryanto B and Praptana R H 2024 Global Journal of Environmental Science and Management Utilization of agricultural waste to reduce enteric methane emissions on livestock in tropical environment. Global J. Environ. Sci. Manage, 10, 263–278. https://doi.org/10.22034/gjesm.2024.10.SI.17
Team R D C 2009 "A language and environment for statistical computing," http://www. R-project. org.
Wangsa I P H, Nindhia T G T, Negara D N K P and Surata I W 2020 Performance of activated carbon made from gigantochloa verticillata bamboo for biogas purification. Materials Science Forum, 1013 MSF, 75–80. https://doi.org/10.4028/www.scientific.net/MSF.1013.75.
Widyanuriawan D 2014"Biogas purification using natural zeolite and NaOH," in Applied Mechanics and Materials, vol. 664, pp. 415-418: Trans Tech Publ.
Zhan M-X, Liu Y-W, Ye W-W, Chen T and Jiao W-T 2022 Modification of activated carbon using urea to enhance the adsorption of dioxins. Environmental Research, 204. https://doi.org/10.1016/j.envres.2021.112035.
Zhang Y, Kawasaki Y, Oshita K, Takaoka M, Minami D, Inoue G and Tanaka T 2021 "Economic assessment of biogas purification systems for removal of both H2S and siloxane from biogas," Renewable Energy, vol. 168, pp. 119-130