Effect of Subcritical Water Pre-Treatment on Empty Fruit Bunch for Volatile Fatty Acid Production: A Response Surface Methodology Study
DOI:
https://doi.org/10.36877/aafrj.a0000622Abstract
Empty fruit bunch (EFB), a lignocellulosic byproduct from palm oil in the extraction process, offers a promising feedstock to produce volatile fatty acids (VFA), which serve as precursors for biogas production. The present study explores the impact of subcritical water pre-treatment process for EFB to enhance VFA production via pre-treatment for following anaerobic co-digestion. A central composite design (CCD) in response surface methodology (RSM) was used to optimise the pre-treatment parameters. The parameters included temperature ranging from 120 to 180°C, reaction time between 10 and 30 minutes, and a liquid-to-solid (L/S) ratio of 10:1 to 20:1. Under optimal conditions of 179.94°C for 29.98 minutes and an L/S ratio of 20:1, the findings indicated that subcritical water pre-treatment significantly improved the digestibility of EFB, yielding a peak VFA production of 1.43 g/L. The enhancement of VFA production subsequently improves the co-digestion process, resulting in a 2.87-fold increase in biogas production. The RSM model demonstrated strong predictive capability, achieving a coefficient of determination (R² = 0.8952). The results indicate that subcritical water pre-treatment is an effective method for converting EFB into VFAs, thereby supporting sustainable waste management and the production of bioenergy.
References
Ahmad, A., Yadav, A. K., Singh, A., et al. (2024). A comprehensive machine learning-coupled response surface methodology approach for predictive modeling and optimization of biogas potential in anaerobic Co-digestion of organic waste. Biomass and Bioenergy, 180: 106995. https://doi.org/10.1016/j.biombioe.2023.106995
Aili Hamzah, A. F., Hamzah, M. H., Nurulhuda, K., et al. (2024). Utilization of subcritical water for improving methane production from oil palm empty fruit bunch by anaerobic co-digestion: Process optimization, compositional, chemical, and morphological analysis. Renewable Energy, 231: 121013. https://doi.org/10.1016/j.renene.2024.121013
Aili Hamzah, A F; Hamzah, M H; Nurulhuda, K; et al. (2025). Formation of soluble organics and sugar degradation byproduct during hot compressed water pre-treatment of empty fruit bunch for biogas production. Biomass and Bioenergy, 199: 107960. https://doi.org/10.1016/J.BIOMBIOE.2025.107960
Aili Hamzah, A. F. F., Hamzah, M. H. H., Mazlan, N. I. I., et al. (2022). Optimization of subcritical water pre-treatment for biogas enhancement on co-digestion of pineapple waste and cow dung using the response surface methodology. Waste Managament, 150: 98–109. https://doi.org/10.1016/j.wasman.2022.06.042
Alonso-Riaño, P., Ramos, C., Trigueros, E., et al. (2023). Study of subcritical water scale-up from laboratory to pilot system for brewer’s spent grain valorization. Industrial Crops and Products, 191: 115927. https://doi.org/10.1016/j.indcrop.2022.115927
APHA (1998). Standard Methods for Examination of Water and Wastewater, 20th ed.
Castro, L. E. N., Barroso, T. L. C. T., Sganzerla, W. G., et al. (2024). Subcritical water hydrolysis of grape pomace as a sustainable pretreatment for anaerobic digestion in a biorefinery concept. Fuel, 363: https://doi.org/130899. 10.1016/j.fuel.2024.130899
Chan, Y. J., Lee, H. W., and Selvarajoo, A. (2021). Comparative study of the synergistic effect of decanter cake (DC) and empty fruit bunch (EFB) as the co-substrates in the anaerobic co-digestion (ACD) of palm oil mill effluent (POME). Environmental Challenges, 5: 100257. https://doi.org/10.1016/j.envc.2021.100257
Chanthong, S., Kongjan, P., Jariyaboon, R., et al. (2024). Synergistic integration of hydrothermal pretreatment and co-digestion for enhanced biogas production from empty fruit bunches in high solids anaerobic digestion. Heliyon, 10(15): 2405–8440. https://doi.org/10.1016/j.heliyon.2024.e34817
Chen, T-H., Shen, M-Y., Chen, C-Y., et al. (2023). Biogas production from food waste hydrolysate using a subcritical water pretreated process and pulp wastewater seed sludge. Sustainable Energy Technologies and Assessments, 59: 103392. https://doi.org/10.1016/j.seta.2023.103392
Chen, W-H., Carrera Uribe, M., Kwon, E. E., et al. (2022). A comprehensive review of thermoelectric generation optimization by statistical approach: Taguchi method, analysis of variance (ANOVA), and response surface methodology (RSM). Renewable and Sustainable Energy Reviews, 169: 112917. https://doi.org/10.1016/j.rser.2022.112917
Čolnik, M.,; Irgolič, M.,; Perva, A., et al. (2025). Hydrolytic decomposition of corncobs to sugars and derivatives using subcritical water. Processes, 13(1): 267. https://doi.org/10.3390/pr13010267
de Oliveira, M. B., dos Santos, M. S. N., Pogorzelski, E. S., et al. (2022). Potential of canola feedstocks for fermentable sugars production by subcritical water hydrolysis. Biomass and Bioenergy, 162: 106505. https://doi.org/10.1016/j.biombioe.2022.106505
Hamzah, M. H., Zulkefli, N., Hamzah, A. F. A., et al. (2024). Optimization of process parameters using response surface methodology for essential oil extraction from Canarium odontophyllum kernels by subcritical water treatment. Food Analytical Methods, 17(0123456789): 910–929. https://doi.org/10.1007/s12161-024-02624-7
Hong, J-W., Gam, D-H., Kim, J-H., et al, (2021). Process development for the detoxification of fermentation inhibitors from acid pretreated microalgae hydrolysate. Molecules, 26(9): 2435. https://doi.org/10.3390/molecules26092435
Iweka, S. C., Owuama, K. C., Chukwuneke, J. L., et al. (2021). Optimization of biogas yield from anaerobic co-digestion of corn-chaff and cow dung digestate: RSM and python approach. Heliyon, 7(11). https://doi.org/10.1016/j.heliyon.2021.e08255
Liew, Z. K., Chan, Y. J., Ho, Z. T., et al. (2021). Biogas production enhancement by co-digestion of empty fruit bunch (EFB) with palm oil mill effluent (POME): Performance and kinetic evaluation. Renewable Energy, 179: 766–777. https://doi.org/10.1016/j.renene.2021.07.073
Ma, X., Zhao, Y., Lü, J., et al. (2024). Enhanced subcritical water pretreatment by water-ethanol system for bioethanol production from corn straw. Industrial Crops and Products, 210: 118165. https://doi.org/10.1016/j.indcrop.2024.118165
Nabaterega, R., Kieft, B., Hallam, S. J., et al. (2022). Fractional factorial experimental design for optimizing volatile fatty acids from anaerobic fermentation of municipal sludge: Microbial community and activity investigation. Renewable Energy, 199: 733–744. https://doi.org/10.1016/j.renene.2022.08.145
Náthia-Neves, G., and Alonso, E. (2024). Optimization of the subcritical water treatment from sunflower by-product for producing protein and sugar extracts. Biomass Conversion and Biorefinery, 14(2): 1637–1650. https://doi.org/10.1007/s13399-022-02380-w
Okwu, M. O., Samuel, O. D., Ewim, D. R. E., et al. (2021). Estimation of biogas yields produced from combination of waste by implementing response surface methodology (RSM) and adaptive neuro-fuzzy inference system (ANFIS). The International Journal of Energy and Environmental Engineering, 12(2): 353–363. https://doi.org/10.1007/s40095-021-00381-5
Park, Y. G. (2021). Study for the Bio-CNG recovery of methane gas in the anaerobic co-digestion using Malaysian POME (Palm Oil Mill Effluent). Biotechnology and Bioprocess Engineering, 26(3): 435–446. https://doi.org/10.1007/s12257-019-0401-2
Rahmani, A. M., Tyagi, V. K., Kazmi, A. A., et al. (2023). Hydrothermal and thermal-acid pretreatments of wheat straw: Methane yield, recalcitrant formation, process inhibition, kinetic modeling. Energy, 283: 129083. https://doi.org/10.1016/j.energy.2023.129083
Rosly, M. B., Tamunaidu, P., Huzir, N. M., et al. (2024). Potential of biogas production from anaerobic co-digestion of hydrothermal pre-treated OPEFB and digested sludge. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, 117(1): 155–163. https://doi.org/10.37934/arfmts.117.1.155163
Saelor, S., Kongjan, P., Prasertsan, P., et al. (2024). Enhancing thermophilic methane production from oil palm empty fruit bunches through various pretreatment methods: A comparative study. Heliyon, 10(20). https://doi.org/10.1016/j.heliyon.2024.e39668
Saritpongteeraka, K., Natisupacheevin, K., Tan, C., et al. (2022). Comparative assessment between hydrothermal treatment and anaerobic digestion as fuel pretreatment for industrial conversion of oil palm empty fruit bunch to methane and electricity-A preparation study to full scale. Fuel, 310: 122479. https://doi.org/10.1016/j.fuel.2021.122479
Sganzerla, W. G., Ampese, L. C., Mussatto, S. I., et al. (2022). Subcritical water pretreatment enhanced methane-rich biogas production from the anaerobic digestion of brewer’s spent grains. Environmental Technology, 1–19. https://doi.org/10.1080/09593330.2022.2157756
Suhartini, S., Rohma, N. A., Elviliana., et al. (2023). Comparison of acid and alkaline pre-treatment on methane production from empty palm oil fruit bunches (OPEFB): Effect on characteristics, digester performance, and correlation of kinetic parameters. Renewable Energy, 215: 119009. https://doi.org/10.1016/j.renene.2023.119009
Suksaroj, C., Jearat, K., Cherypiew, N., et al. (2023). Promoting circular economy in the palm oil industry through biogas codigestion of palm oil mill effluent and empty fruit bunch pressed wastewater. Water (Switzerland), 15(12): 2153. https://doi.org/10.3390/w15122153
Tan, Y. Y., Bello, M. M., Abdul Raman, A. A. (2021). Towards cleaner production in palm oil industry: Advanced treatment of biologically-treated POME using palm kernel shell-based adsorbent. Cleaner Engineering and Technology, 2: 100079. https://doi.org/10.1016/j.clet.2021.100079
Tian, W., Chen, Y., Shen, Y., et al. (2020). Effects of hydrothermal pretreatment on the mono- and co-digestion of waste activated sludge and wheat straw. Science of the Total Environment, 732(139312): 1–15. https://doi.org/10.1016/j.scitotenv.2020.139312
Vakalis, S., Georgiou, A., Moustakas, K., et al. (2022). Assessing the effect of hydrothermal treatment on the volatile solids content and the biomethane potential of common reed (phragmites australis). Bioresource Technology Reports, 17: 100923. https://doi.org/10.1016/j.biteb.2021.100923
Venkatachalam, M., Shum-Chéong-Sing, A., Caro, Y., et al. (2021). OVAT analysis and response surface methodology based on nutrient sources for optimization of pigment production in the marine-derived fungus Talaromyces albobiverticillius 30548 submerged fermentation. Marine Drugs, 19(5): 248. https://doi.org/10.3390/md19050248
Yan, S. J., Chan, Y. J., Thangalazhy-Gopakumar, S., et al. (2025). Optimizing anaerobic digestion of palm oil mill effluent (POME) with biochar: Synergistic impact of biochar addition and kinetic analysis. The Journal of Water Process Engineering, 70: 106919. https://doi.org/10.1016/j.jwpe.2024.106919
Yue, P., Hu, Y., Tian, R., et al. (2022). Hydrothermal pretreatment for the production of oligosaccharides: A review. Bioresource Technology, 343: 126075. https://doi.org/10.1016/j.biortech.2021.126075
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