DOI: https://doi.org/10.61435/ijred.2026.61811
View PDF Download fulltext

Assessment of tea processing waste as a potential co-substrate for biogas production through physicochemical and elemental analysis

Department of Agricultural and Biosystems Engineering, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya

Received: 23 Sep 2025; Revised: 16 Aug 2026; Accepted: 7 Oct 2026; Available online: 21 Oct 2026; Published: 1 Nov 2026.
Editor(s): H Hadiyanto
Open Access Copyright (c) 2026 The Author(s). Published by Centre of Biomass and Renewable Energy (CBIORE)
Creative Commons License This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Citation Format:
Abstract

Tea processing generates substantial organic residues that can be utilized for biogas production through anaerobic digestion. This study evaluates the suitability of tea processing waste (TPW) for anaerobic co-digestion with cow manure, emphasizing elemental composition and physicochemical properties. Solid wastes from sorting, withering and drying, as well as liquid waste from the cleaning channel and lagoons, were collected from Theta tea factory in Kenya. Cow manure and the inoculum were sourced from Jomo Kenyatta University of Agriculture and Technology. Standard laboratory and American Public Health Association (APHA) methods were employed to analyse total solids (TS), volatile solids (VS), pH, chemical oxygen demand (COD), ammonium nitrogen, carbon-to-nitrogen ratio (C/N ratio), oil/lipid content, and elemental composition. Fatty acid and inhibitor (polyphenols, tannins and caffeine) profiling was conducted using Gas Chromatography-Mass Spectrometry (GC-MS). Results revealed wide variability; TS ranged from 0.26±0.1 to 92.63±5% and VS from 0.21±0.1 to 83.25±15%, with solid TPW showing the highest values. C/N ratios varied from 10 to 30, while COD ranged from 5333±3695 to 14400±1529 mg/L and ammonium nitrogen from 49±8.4 to 1529±500 mg/L. pH values ranged between 4.83 and 7.31, with the solid TPW being the most acidic and cow manure the most alkaline. GC-MS revealed that solid tea waste from withering (STPW1) was dominated by saturated fatty acids, suggesting greater digestion stability, while other fractions contained more than 60% (up to 90%) unsaturated fatty acids. Inhibitory compounds were also detected in both solid and liquid TPW: polyphenols (19.4 ±4.8 to 1512.9 ±45.3 mg GAE/100g), tannins (197.5 ± 9.0 to 9656.8 ±214.4 mg CAE/100g) and caffeine (29.6 to 43.8 mg/L in solid waste TPW; 7.3-21.2 mg/L in liquid TPW). Co-digestion trials demonstrated that a 25:75 ratio of withering stage tea waste to cow manure yielded the highest methane concentration (58.3%). The findings of this study suggest that solid TPW, particularly STPW1, is a promising substrate for biogas production when co-digested with cow manure. Optimizing digestion parameters could enhance methane yield, supporting sustainable energy initiatives in Kenya’s tea industry. 

Keywords: Methane yield; Anaerobic Co-digestion; Inhibitor; Substrate suitability; Inhibitor profiling
Funding: African Development Bank through Jomo Kenyatta University of Agriculture and Technology

Article Metrics:

Article Info
Section: Original Research Article
Language : EN
Recent articles
Flexible scheduling strategy and optimization algorithm for container resources in power environment Enhance EV station charge and discharge based on deep learning forecasting method incorporating renewable energy sources and multi-objective optimization algorithm Hard-template synthesis of Ti–V–Mn ternary photocatalysts using gelatin-modified mesoporous silica for efficient methylene blue degradation More recent articles
Most cited articles
Comparison of single and double stage regenerative organic rankine cycle for medium grade heat source through energy and exergy estimation Solmap: Project In India's Solar Resource Assessment Thermal effects investigation on electrical properties of silicon solar cells treated by laser irradiation Production of Solid Fuel by Torrefaction Using Coconut Leaves As Renewable Biomass Bioelectricity Generation From Single-Chamber Microbial Fuel Cells With Various Local Soil Media and Green Bean Sprouts as Nutrient More cited articles
  1. Aaqil, M., Peng, C., Kamal, A., Nawaz, T., Zhang, F., & Gong, J. (2023). Tea harvesting and processing techniques and its effect on phytochemical profile and final quality of black tea: A review. Foods, 12(24), 4467. https://doi.org/10.3390/foods12244467
  2. Abhiram, G., Diraj, R., & Eeswaran, R. (2023). Optimization of black tea drying temperature in an endless chain pressure (ECP) dryer. AgriEngineering, 5(4), 1989-1999.AgriEngineering, 5(4), 1989–1999. https://doi.org/10.3390/agriengineering5040107
  3. Ahmed, S., & Stepp, J. R. (2013). Green tea: The plants, processing, manufacturing and production. Tea in Health and Disease Prevention, 2, 19-31
  4. Aksay, M. V., Özkaymak, M., & Calhan, R. (2018). Co-digestion of Cattle Manure and Tea Waste for Biogas Production. International Journal of Renewable Energy Research, 8(3), 1346–1353. https://doi.org/10.20508/ijrer.v8i3.7543.g7442
  5. Algapani, D. E., Qiao, W., Su, M., di Pumpo, F., Wandera, S. M., Adani, F., & Dong, R. (2016). Bio-hydrolysis and bio-hydrogen production from food waste by thermophilic and hyperthermophilic anaerobic process. Bioresource Technology, 216, 768-777. https://doi.org/10.1016/j.biortech.2016.06.052
  6. Amanatidou, E., Trikoilidou, E., Samiotis, G., Benetis, N. P., & Taousanidis, N. (2012). An easy uncertainty evaluation of the COD titrimetric analysis in correlation with quality control and validation data. Method applicability region. Analytical Methods, 4(12), 4204-4212. https://doi.org/10.1039/C2AY25518F
  7. Angelidaki, I., Alves, M., Bolzonella, D., Borzacconi, L., Campos, J. L., Guwy, A. J., ... & Van Lier, J. B. (2009). Defining the biomethane potential (BMP) of solid organic wastes and energy crops: a proposed protocol for batch assays. Water Science and Technology, 59(5), 927-934. https://doi.org/10.2166/wst.2009.040
  8. Angelidaki, I., & Sanders, W. (2004). Assessment of the anaerobic biodegradability of macropollutants. Reviews in Environmental Science and Bio/Technology, 3(2), 117–129. https://doi.org/10.1007/s11157-004-2502-3
  9. American Public Health Association (APHA), American Water Works Association (AWWA), & Water Environment Federation (WEF). (2017). Standard methods for the examination of water and wastewater (23rd Ed.). American Public Health Association. https://www.apha.org/Publications-and-Periodicals/Standard-Methods
  10. Appels, L., Baeyens, J., Degrève, J., & Dewil, R. (2008). Principles and potential of the anaerobic digestion of waste activated sludge. Progress in Energy and Combustion Science, 34(6), 755–781 https://doi.org/10.1016/j.pecs.2008.06.002
  11. Arelli, V., Begum, S., Anupoju, G. R., & Kuruti, K. (2018). Dry anaerobic co-digestion of food waste and cattle manure: Impact of total solids, substrate ratio and thermal pretreatment on methane yield and quality of biomanure. Bioresource Technology, 253, 273-280. https://doi.org/10.1016/j.biortech.2018.01.011
  12. Aremanda, R. B., & Debretsion, S. (2023). Competence of Cow Manure as a Sustainable Feedstock for Bioenergy and Biofertilizer Production. International Journal on Food, Agriculture and Natural Resources, 4(2), 59–67. https://doi.org/10.46574/mora.v4i2.115
  13. Ayilara, M. S., Olanrewaju, O. S., Babalola, O. O., & Odeyemi, O. (2020). Waste management through composting: Challenges and potentials. Sustainability, 12(11), 4456-4465. https://doi.org/10.3390/su12114456
  14. Bader, A. C., Hussein, H. J., & Jabar, M. T. (2022). BOD: COD ratio as indicator for wastewater and industrial water pollution. International Journal of Special Education, 37(3), 2164-2171
  15. Basumatary, S., Das, S., Kalita, P., & Goswami, P. (2021). Effect of feedstock/water ratio on anaerobic digestion of cattle dung and vegetable waste under mesophilic and thermophilic conditions. Bioresource Technology Reports, 14, 100675. https://doi.org/10.1016/j.biteb.2021.100675
  16. Basumatary, V., Saikia, R., Narzari, R., Bordoloi, N., Gogoi, L., Sut, D., & Kataki, R. (2018). Tea factory waste as a feedstock for thermo-chemical conversion to biofuel and biomaterial. Materials Today: Proceedings, 5(11), 23413-23422 https://doi.org/10.1016/j.matpr.2018.11.021
  17. Bhat, T. K., Singh, B., & Sharma, O. P. (1998). Microbial degradation of tannins–a current perspective. Biodegradation, 9(5), 343-357. https://doi.org/10.1023/A:1008397506963
  18. Bi, W., Zhou, J., & Row, K. H. (2011). Decaffeination of coffee bean waste by solid-liquid extraction. Korean Journal of Chemical Engineering, 28(1), 221-224. https://doi.org/10.1007/s11814-010-0348-1
  19. Bouhzam, I., Cantero, R., Margallo, M., Aldaco, R., Bala, A., Fullana-i-Palmer, P., & Puig, R. (2023). Extraction of bioactive compounds from spent coffee grounds using ethanol and acetone aqueous solutions. Foods, 12(24), 4400. https://doi.org/10.3390/foods12244400
  20. Broadhurst, R. B., & Jones, W. T. (1978). Analysis of condensed tannins using the Vanillin–HCl assay. Phytochemistry, 17(6), 1393–1396. https://doi.org/10.1016/S0031-9422 (00)94601-1
  21. Chapleur, Olivier, Céline Madigou, Raphaël Civade, Yohan Rodolphe, Laurent Mazéas, and Théodore Bouchez (2016). Increasing concentrations of phenol progressively affect anaerobic digestion of cellulose and associated microbial communities. Biodegradation 27(1), 15-27. https://doi.org/10.1007/s10532-015-9751-4
  22. Chen, Y., Cheng, J. J., & Creamer, K. S. (2008). Inhibition of anaerobic digestion process: a review. Bioresource technology, 99(10), 4044-4064
  23. Chen, R., Jiang, H., & Li, Y. Y. (2018). Caffeine degradation by methanogens: Efficiency in anaerobic membrane bioreactor and analysis of kinetic behavior. Chemical Engineering Journal, 334, 444-452. https://doi.org/10.1016/j.cej.2017.10.056
  24. Creamer, K. S. (2010). Impact of ammonia and long chain fatty acids on thermophilic anaerobic digestion of swine wastes, (Doctoral dissertation, North Carolina State University). ProQuest Dissertations and Theses Global. (Publication No. 3432726)
  25. Deaver, J. A., Diviesti, K. I., Soni, M. N., Campbell, B. J., Finneran, K. T., & Popat, S. C. (2020). Palmitic acid accumulation limits methane production in anaerobic co-digestion of fats, oils and grease with municipal wastewater sludge. Chemical Engineering Journal, 396, 125235. https://doi.org/10.1016/j.cej.2020.125235
  26. Dhull, P., Lohchab, R. K., Kumar, S., Kumari, M., Shaloo, & Bhankhar, A. K. (2024). Anaerobic digestion: advance techniques for enhanced biomethane/biogas production as a source of renewable energy. BioEnergy Research, 17(2), 1228-1249. https://doi.org/10.1007/s12155-023-10693-5
  27. Diamantis, V., Eftaxias, A., Stamatelatou, K., Noutsopoulos, C., Vlachokostas, C., & Aivasidis, A. (2021). Bioenergy in the era of circular economy: Anaerobic digestion technological solutions to produce biogas from lipid-rich wastes. Renewable Energy, 168, 438-447. https://doi.org/10.1016/j.renene.2020.12.034
  28. Ebner, J. H., Labatut, R. A., Lodge, J. S., Williamson, A. A., & Trabold, T. A. (2016). Anaerobic co-digestion of commercial food waste and dairy manure: Characterizing biochemical parameters and synergistic effects. Waste Management, 52, 286-294. https://doi.org/10.1016/j.wasman.2016.03.046
  29. GIZ, KTDA, Ethical Tea Partnership, & Strathmore University. (2019). Thermal Manual. Available (accessed on 5th May 2024): https://www.ethicalteapartnership.org/w
  30. Hakiki, G., & Sari, N. (2020). Biogas Development of Tea Dregs and Cow Manure: Study of CN Ratio and Pretreatment on Liquid State Anaerobic Co-Digestion. Journal of Global Environmental Science 1 (1), 1–6.doi.org
  31. Intergovernmental Panel on Climate Change. (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories: Volume 2 – Energy. Eggleston, H. S., Buendia, L., Miwa, K., Ngara, T., & Tanabe, K. (Eds.). Hayama, Japan: Institute for Global Environmental Strategies. https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol2.html
  32. Jiang, Y., Dennehy, C., Lawlor, P. G., Hu, Z., McCabe, M., Cormican, P., ... & Gardiner, G. E. (2018). Inhibition of volatile fatty acids on methane production kinetics during dry co-digestion of food waste and pig manure. Waste Management, 79, 302-311. https://doi.org/10.1016/j.wasman.2018.08.009
  33. Karuri, A. N. (2020). Adaptation of small-scale tea and coffee farmers in Kenya to climate change. African Handbook of Climate Change Adaptation, 1-19. https://doi.org/10.1007/978-3-030-42091-8_38-1
  34. Kavisa, G. H., Sari, N., Matin, H. H. A., & Budiyono, B. (2020). The effect of C/N ratio and pretreatment in making biogas from tea waste and cow manure in liquid state anaerobic co-digestion. Waste Technology, 8(1), 1-7. https://doi.org/10.14710/wastech.8.1.1-7
  35. Kayembe, K., Basosila, L., Mpiana, P. T., Sikulisimwa, P. C., & Mbuyu, K. (2013). Inhibitory effects of phenolic monomers on methanogenesis in anaerobic digestion. British Microbiology Research Journal, 3(1), 32-41. https://doi.org/10.9734/BMRJ/2013/2398
  36. Kipkemei, I., Simiyu, G. M., & Rono, M. (2019). Production of biogas from waste tea leaves: A case of integrated waste management at DL Koisagat tea factory, Nandi Hills. Africa Environmental Review Journal, 3(2), 34-41
  37. Kumari, M., & Chandel, M. K. (2023) Advancing anaerobic digestion of dewatered sewage sludge: Exploring pretreatments, microbial diversity shifts and sustainable energy gains. Bioresource Technology, 371,128646 https://doi.org/10.1016/j.biortech.2023.128646
  38. Kumar, K. R., Dashora, K., Kumar, S., Dharmaraja, S., Sanyal, S., Aditya, K., & Kumar, R. (2023). A review of drying technology in tea sector of industrial, non-conventional and renewable energy based drying systems. Applied Thermal Engineering, 224, 120118. https://doi.org/10.1016/j.applthermaleng.2023.120118
  39. Kumar, V., Kaur, J., Tanwar, B., Goyal, A., Gat, Y., Kumar, A., & Kaur, P. (2018). Tea processing. Beverages: Processing and Technology, Chapter 10, pp 190-209
  40. Kwietniewska, E., & Tys, J. (2014). Process characteristics, inhibition factors and methane yields of anaerobic digestion process, with particular focus on microalgal biomass fermentation. Renewable and Sustainable Energy Reviews, 34, 491-500. https://doi.org/10.1016/j.rser.2014.03.041
  41. Lalman, J. A., & Bagley, D. M. (2001). Anaerobic degradation and methanogenic inhibitory effects of oleic and stearic acids. Water research, 35(12), 2975-2983. https://doi.org/10.1016/S0043-1354 (01)00005-1
  42. Li, P., Zhao, H., Cheng, C., Hou, T., Shen, D., & Jiao, Y. (2024). A review on anaerobic co-digestion of sewage sludge with other organic wastes for methane production: Mechanism, process, improvement and industrial application. Biomass and Bioenergy, 185, 107241
  43. Li, Y., Zhao, J., Krooneman, J., & Euverink, G. J. W. (2021). Strategies to boost anaerobic digestion performance of cow manure: Laboratory achievements and their full-scale application potential. Science of the Total Environment, 755, article 142940. https://doi.org/10.1016/j.biombioe.2024.107241
  44. Lu, X., Jin, W., Xue, S., & Wang, X. (2017). Effects of waste sources on performance of anaerobic co-digestion of complex organic wastes: taking food waste as an example. Scientific Reports, 7(1), Article15702. https://doi.org/10.1038/s41598-017-15956-6
  45. Macedo, A., Fragoso, R., Silva, I., Gomes, T., Martins, C. F., Freire, J. B., & Duarte, E. (2023). Mango peel nanofiltration concentrates to enhance anaerobic digestion of slurry from piglets fed with laminaria. Membranes, 13(4), Article 371. https://doi.org/10.3390/membranes13040371
  46. Makkar, H.P.S. (2003). Effects and fate of tannins in ruminant animals, adaptation to tannins, and strategies to overcome detrimental effects of feeding tannin rich feeds. Small Ruminant Research, 49(3), 241–256. https://doi.org/10.1016/S0921-4488 (03)00142-3
  47. Mangenya, T., Kariuki, D., Kinyua, J., Obanda, M., Ochanda, S. O., & Moriasi, G. (2024). Proximate and elemental composition of tea effluents obtained from various tea processing factories in Kenya. African Journal of Food, Agriculture, Nutrition and Development, 24(12), 25267–25290. https://doi.org/10.18697/ajfand.135.24430
  48. Manyi-Loh, C. E., & Lues, R. (2023). Anaerobic digestion of lignocellulosic biomass: Substrate characteristics (challenge) and innovation. Fermentation, 9(8), 755-781. https://doi.org/10.3390/fermentation9080755
  49. Manyuchi, M. M., Mbohwa, C., & Muzenda, E. (2018, July). Biogas and Bio solids production from tea waste through anaerobic digestion. In Proceedings of the International Conference on Industrial Engineering and Operations Management, Vol. 2018 (July), pp 2519-2525. https://www.researchgate.net/publication/325947120
  50. Mazzei, R., et al. (2019). Caffeine as an inhibitor in microbial processes: implications for biogas production. Waste and Biomass Valorization, 10, 123–132. https://doi.org/10.1007/s12649-017-0035-x
  51. Mekonnen, T., et al. (2020). Valorization of coffee and tea residues: biochemical composition and inhibitory effects in anaerobic digestion. Renewable Energy, 145, 1235–1245. https://doi.org/10.1016/j.renene.2019.06.067
  52. Mohammadian, M., Mosayebi, M., & Omidi, M. (2014). Seasonal variation of phenolic components in two clones of tea (Camellia sinensis (L.) O Kuntze). Iranian Journal of Plant Biology, 6(20), 17–28
  53. Morozova, I., Nikulina, N., Oechsner, H., Krümpel, J., & Lemmer, A. (2020). Effects of increasing nitrogen content on process stability and reactor performance in anaerobic digestion. Energies, 13(5), 1139. https://doi.org/10.3390/en13051139
  54. Mrosso, R., Mecha, A.C. and Kiplagat, J. (2023). Characterization of kitchen and municipal organic waste for biogas production: Effect of parameters. Heliyon, 9(5), Article e16360. https://doi.org/10.1016/j.heliyon.2023.e16360
  55. Naughton-Treves, L., Kammen, D. M., & Chapman, C. (2007). Burning biodiversity: woody biomass use by commercial and subsistence groups in western Uganda’s forests. Biological Conservation, 134(2), 232-241. https://doi.org/10.1016/j.biocon.2006.08.021
  56. National Environment Management Authority (NEMA). (2006). Environmental Management and Coordination (Water Quality) Regulations, 2006. Nairobi: Government of Kenya. (Amended 2015)
  57. Nwokolo, N., Mukumba, P., Obileke, K., & Enebe, M. (2020). Waste to energy: A focus on the impact of substrate type in biogas production. Processes, 8(10), 1224. https://doi.org/10.3390/pr8101224
  58. Oduor, W. W., Wandera, S. M., Murunga, S. I., & Raude, J. M. (2022). Enhancement of anaerobic digestion by co-digesting food waste and water hyacinth in improving treatment of organic waste and bio-methane recovery. Heliyon, 8(9), 2405-8840. https://doi.org/10.1016/j.heliyon.2022.e10454
  59. Onduru, D. D., De Jager, A., Hiller, S., & Van den Bosch, R. (2012). Sustainability of smallholder tea production in developing countries: Learning experiences from farmer field schools in Kenya. International journal of Development and Sustainability, 1(3), 714-742
  60. Orhorhoro, E. K., Ebunilo, P. O., & Sadjere, G. E. (2017). Experimental determination of effect of total solid (TS) and volatile solid (VS) on biogas yield. American. Journal. of Modern. Energy, 3(6), 131-135. https://doi.org/10.11648/j.ajme.20170306.13
  61. Otedo, B. O., Cherop, P. T., & Osore, E. E. (2024). Optimization of drying parameters for minimization of moisture content in black tea production. Science Mundi, 4(2), 198-210
  62. Özarslan, S., Abut, S., Atelge, M. R., Kaya, M., & Unalan, S. (2021). Modeling and simulation of co-digestion performance with artificial neural network for prediction of methane production from tea factory waste with co-substrate of spent tea waste. Fuel, 306, 121715-121745. https://doi.org/10.1016/j.fuel.2021.121715
  63. Popich, M. R., Nogueira, M., & Fragoso, R. (2026). Anaerobic Digestion of Flower Waste: A Review on Biomethane Potential, Process Optimization, and Sustainability Perspectives. Energies, 19(2), 289. https://doi.org/10.3390/en19020289
  64. Procházka, J., Dolejs, P., Maca, J., & Dohanyos, M. (2012). Stability and inhibition of anaerobic processes caused by insufficiency or excess of ammonia nitrogen. Applied Microbiology and Biotechnology, 93(1), 439–447. https://doi.org/10.1007/s00253-011-3647-2
  65. Pudipeddi, M., Zannou, E. A., Vasanthavada, M., Dontabhaktuni, A., Royce, A. E., Joshi, Y. M., & Serajuddin, A. T. (2008). Measurement of surface pH of pharmaceutical solids: a critical evaluation of indicator dye-sorption method and its comparison with slurry pH method. Journal of Pharmaceutical Sciences, 97(5), 1831-1842. https://doi.org/10.1002/jps.21105
  66. Qu, Y., Lv, X., Qin, N., Zhang, K., Ding, X., Luo, L., & Sun, Y. (2024). Mechanism of ball milling pretreatment to improve the anaerobic digestion performance and energy conversion efficiency of corn straw. Fuel, 366, 131409-131600. https://doi.org/10.1016/j.fuel.2024.131409
  67. Rahman, M. A., Shahazi, R., Nova, S. N. B., Uddin, M. R., Hossain, M. S., & Yousuf, A. (2023). Biogas production from anaerobic co-digestion using kitchen waste and poultry manure as substrate—part 1: substrate ratio and effect of temperature. Biomass Conversion and Biorefinery, 13(8), 6635-6645. https://doi.org/10.1007/s13399-021-01646-0
  68. Rasouli, M., Babaei, H., & Ataeiyan, B. (2023). The effect of lignocellulosic waste on treatment of municipal wastewater in anaerobic digestion process. Journal of Environmental Engineering and Science, 18(2), 61-69. . https://doi.org/10.1680/jenes.22.00014
  69. Serrano-Meza, A., Garzón-Zúñiga, M. A., Barragán-Huerta, B. E., Estrada-Arriaga, E. B., Almaraz-Abarca, N., & García-Olivares, J. G. (2020). Anaerobic digestion inhibition indicators and control strategies in processes treating industrial wastewater and wastes. Revista Mexicana de Ingeniería Química, 19(1), 29-44. https://doi.org/10.24275/rmiq/Bio541
  70. Seth, D., Athparia, M., Singh, A., Rathore, D., Venkatramanan, V., Channashettar, V., & Kataki, R. (2025). Sustainable environmental practices of tea waste—a comprehensive review. Environmental Science and Pollution Research, 32(12), 7449-7467. https://doi.org/10.1007/s11356-024-35801-x
  71. Sicchieri, I. M., Quadros, T. C. F. de, Bortoloti, M. A., Fernandes, F., & Kuroda, E. K. (2022). Selection, composition, and validation of standard inoculum for anaerobic digestion assays. Biomass & Bioenergy, 164, 106558-106578. https://doi.org/10.1016/j.biombioe.2022.106558
  72. Sluiter, A., Hames, B., Ruiz, R., Scarlata, C., Sluiter, J., Templeton, D., & Crocker, D. L. A. P. (2008). Determination of structural carbohydrates and lignin in biomass. Lab. Anal. Proced, 1617(1), 1-16.Laboratory Analytical Procedure NREL/TP-510-42618
  73. Sousa, D. Z., Salvador, A. F., Ramos, J., Guedes, A. P., Barbosa, S. ½., Stams, A. J., ... & Pereira, M. A. (2013). Activity and viability of methanogens in anaerobic digestion of unsaturated and saturated long-chain fatty acids. Applied and Environmental Microbiology, 79(14), 4239-4245. https://doi.org/10.1128/AEM.00401-13
  74. Sun, Z., Liu, Q., Li, Y., Mazarji, M., Feng, L., & Pan, J. (2024). Deciphering the impact of lignin on anaerobic digestion: Focus on inhibition mechanisms and methods for alleviating inhibition. ACS Omega, 9(44), 44033-44041. https://doi.org/10.1021/acsomega.4c06212
  75. Szaja, A., Montusiewicz, A., & Lebiocka, M. (2023). Variability of micro-and macro-elements in anaerobic co-digestion of municipal sewage sludge and food industrial by-products. International Journal of Environmental Research and Public Health, 20(7), 5405. https://doi.org/10.3390/ijerph20075405
  76. Tauseef, S. M., Abbasi, T., & Abbasi, S. A. (2013). Energy recovery from wastewaters with high-rate anaerobic digesters. Renewable and Sustainable Energy Reviews, 19, 704-741. https://doi.org/10.1016/j.rser.2012.11.056
  77. Tiwari, S.B., Dubey, M., Ahmed, B., Gaur, R.Z., Khan, A.A., Rajpal, A., Kazmi, A.A. and Tyagi, V.K. (2019). Prioritization of solid concentration and temperature for solid state anaerobic digestion of pearl millet straw employing multi-criteria assessment tool. Scientific Reports, 9(1), 12168. https://doi.org/10.1038/s41598-019-48598-1
  78. Toftegaard, M. B., Brix, J., Jensen, P. A., Glarborg, P., & Jensen, A. D. (2010). Oxy-fuel combustion of solid fuels. Progress in Energy and Combustion Science, 36(5), 581-625. https://doi.org/10.1016/j.pecs.2010.02.001
  79. Tutuş, A., Kazaskeroğlu, Y., & Çiçekler, M. (2015). Evaluation of tea wastes in usage pulp and paper production. BioResources, 10(3), 5407-5416. https://doi.org/10.15376/biores.10.3.5407-5416
  80. Unyay, H., Altay, H. O., Perendeci, N. A., Szufa, S., Ozdemir, F., & Angelidaki, İ. (2025). Valorisation potential of black tea processing wastes for bioactive compounds recovery and renewable energy production. Journal of Environmental Chemical Engineering, 13(3), 117124. https://doi.org/10.1016/j.jece.2025.117124
  81. Van der Wal, S. (2008). Sustainability issues in the tea sector: A comparative analysis of six leading producing countries. Stichting Onderzoek Multinationale Ondernemingen, June, CSR-1290005987
  82. Van Peteghem, L., Sakarika, M., Matassa, S., & Rabaey, K. (2022). The role of microorganisms and carbon-to-nitrogen ratios for microbial protein production from bioethanol. Applied and Environmental Microbiology, 88(22), e01188-22. https://doi.org/10.1128/aem.01188-22
  83. Wang, J., Wang, X., Chen, J., & Fei, Z. (2019). Experimental Exploration for Measurement of Ammonia Nitrogen in Water by Nessler's Reagent Colorimetry. Civil and Environmental Research, 11(1), 08-15
  84. Wang, X., Lu, X., Li, F., & Yang, G. (2014). Effects of temperature and carbon-nitrogen (C/N) ratio on the performance of anaerobic co-digestion of dairy manure, chicken manure and rice straw: focusing on ammonia inhibition. PloS One, 9(5), e97265. https://doi.org/10.1371/journal.pone.0097265
  85. Wang, Z., Ahmad, W., Zhu, A., Zhao, S., Ouyang, Q., & Chen, Q. (2024). Recent advances review in tea waste: High-value applications, processing technology, and value-added products. Science of the Total Environment, 946, article 174225. https://doi.org/10.1016/j.scitotenv.2024.174225
  86. Welfle, A., Chingaira, S., & Kassenov, A. (2020). Decarbonising Kenya's domestic & industry Sectors through bioenergy: An assessment of biomass resource potential & GHG performances. Biomass and Bioenergy, 142, article 105757. https://doi.org/10.1016/j.biombioe.2020.105757
  87. Wu, H. Z., & Cao, A. (2013). Preparation and adding methods of Nessler's Reagent having effects on determination of water quality ammonia nitrogen. Advanced Materials Research, 726, 1362-1366. https://doi.org/10.4028/www.scientific.net/AMR.726-331.1362
  88. Yang, Q., Wu, B., Yao, F., He, L., Chen, F., Ma, Y. ... & Li, X. (2019). Biogas production from anaerobic co-digestion of waste activated sludge: co-substrates and influencing parameters. Reviews in Environmental Science and Bio/Technology, 18(4), 771-793. https://doi.org/10.1007/s11157-019-09514-6
  89. Zarrinmehr, M. J., Daneshvar, E., Nigam, S., Gopinath, K. P., Biswas, J. K., Kwon, E. E. ... & Bhatnagar, A. (2022). The effect of solvents polarity and extraction conditions on the microalgal lipids yield, fatty acids profile, and biodiesel properties. Bioresource Technology, 344, 126-303. . https://doi.org/10.1016/j.biortech.2021.126303
  90. Zhang, C., Su, H., Baeyens, J. and Tan, T. (2011). Restriction of linoleic acid inhibition of methanization of piggery wastewater and enhancement of its mineralization by adding calcium ions. Journal of Chemical Technology and Biotechnology, 86(4), 548–554. https://doi.org/10.1002/jctb.2550
  91. Zhang, Ke, W., H., Li, S., Xue, Y., Wang, Y., Dong, W. ... & Zhang, G. (2022). Influence of condensed and hydrolysable tannins on the bacterial community, protein degradation, and fermentation quality of alfalfa silage. Animals, 12(7), 831. https://doi.org/10.3390/ani12070831
  92. Zhang, H., Xiong, X., Zhou, J., & Huang, Y. (2020, March). Characteristics and optimization of anaerobic digestion of tea waste for biogas production. In IOP Conference Series: Earth and Environmental Science, 453(1), 012036). IOP Publishing. https://doi.org/10.1088/1755-1315/453/1/012036
  93. Zhang, H., Chen, Y., Guo, Y., Xu, W., Wang, W., Wu, S. ... & Huang, Y. (2021). Label-free quantification proteomics reveals the active peptides from protein degradation during anaerobic fermentation of tea. Lwt, 150, 111950. https://doi.org/10.1016/j.lwt.2021.111950
  94. Zhao, X. F., Yuan, Y. Q., Chen, Q. K., Li, Q., Huang, Y., Wu, D., & Li, L. (2021). Effect of total solids contents on the performance of anaerobic digester treating food waste and kinetics evaluation. In E3S Web of Conferences, 272, 01026. EDP Sciences. https://doi.org/10.1051/e3sconf/202127201026

Last update:

No citation recorded.

Last update: 2026-10-20 06:59:15

No citation recorded.