Fermentasi Anaerobik Biogas Dua Tahap Dengan Aklimatisasi dan Pengkondisian pH Fermentasi

Purwinda Iriani, Yanti Suprianti, Fitria Yulistiani

Abstract


Produksi biogas pada skala rumah tangga umumnya menggunakan teknologi fermentasi anaerobik di dalam satu biodigester (satu tahap), yang mengakomodasi dua tahap utama prinsip pembentukan biogas, yakni tahap asetogenesis dan tahap metanogenesis. Permasalahan yang muncul dari penggunaan digester biogas satu tahap adalah ketidakseimbangan proses fermentasi (peningkatan laju beban organik, waktu retensi senyawa organik yang lebih cepat, dan produktivitas biogas yang menjadi tidak maksimal). Untuk mengatasi hal tersebut, dilakukan penelitian yang bertujuan melakukan produksi biogas melalui sistem fermentasi anaerobik dua-tahap (two-stage anaerobic digestion), yang didukung dengan pengaturan pH pada proses metanogenik. Pada penelitian ini telah dilakukan proses aklimatisasi (aktivasi) bakteri yang menunjang proses asetogenik dan metanogenik pada skala laboratorium (19 L), dan selanjutnya menjadi inokulum untuk proses fermentasi skala pilot dengan kapasitas biodigester asetogenik 125 L dan metanogenik 500 L. Hasil proses aklimatisasi bakteri asetogenik pada media kotoran sapi menunjukkan adanya kestabilan pH yang dibutuhkan untuk reaksi asetogenik, yaitu pada kisaran pH 5-6, sedangkan kontrol menunjukkan perubahan pH yang masih ada di rentang pH netral yaitu 6-7. Kotoran sapi yang telah melalui proses asetogenik selama 2 minggu (pH awal 5,5), menjadi bahan baku pembuatan biogas pada digester metanogenik. Hasil dari proses metanogenik menunjukkan terjadinya peningkatan volume biogas dan komposisi gas metana (CH4) di dalam biogas. Komposisi CH4 tertinggi diperoleh pada hari ke-20 yakni 74,82% dengan volume produksi biogas tertinggi ada pada hari ke-22, dengan laju 8,87 L/hari. Potensi energi tertinggi yang diperoleh mencapai 217,66 kJ/hari.

Generally, biogas production on the household scale is using one-stage anaerobic fermentation technology, which accommodates two main processes of biogas production, namely acetogenesis and methanogenesis. An obstacle of using one-stage biogas digester is the imbalance of the fermentation process that indicated by the increase of organic load rate and shorter retention time that lead to un-optimal biogas productivity. This research undertook the application of two-stage anaerobic digestion, supported by adjusting the initial pH for both acetogenic and methanogenic processes. Firstly, the research initiated by acclimatization (activation) process of acetogenic and methanogenic bacteria via fermentation in laboratory scale (19 L) digesters, separately. The results of acetogenic bacteria acclimatization process on cow dung media showed the pH stability needed for the reaction acetogenic, in the range of 5-6, while the control showed the pH changes still in the neutral pH range (6-7). The substrate from lab-scale acetogenic and methanogenic digester, then used as a starter for pilot-scale digester (125 L and 500 L, respectively). The mixture of water and cow dung were adjusted at initial pH 5.5 on acetogenic digester for 2 weeks. Those material were used for biogas production in the methanogenic digester. The result of the methanogenic process showed an increasing volume of biogas and the composition of methane (CH4) in the biogas. The highest CH4 composition was obtained on the 20th day, which reached 74.82%, and the highest volume of biogas production was at day 22, with the rate of 8.87 L/day. The highest energy potential obtained was 217.66 kJ/day.


Keywords


biogas; digester; methane; two-stage fermentation

Full Text:

PDF

References


S. S. Patil, N. V. Ghasghse, A. P. Nashte, S. S. Kanase, R. H. Pawar, Anaerobic Digestion Treatment of Cheese Whey For Production of Methane in two Stage Upflow Packed Bed Reactor, International Journal of Advanced Science, Engineering and Technology, vol. 1, no. 1, hal. 1-7, 2012.

A. S. Nizami, A. Orozco, E. Groom, B. Dieterich, J. D. Murphy, How much gas can we get from grass?, Applied Energy, vol. 92, hal. 783–790, 2012.

J. -R. S. Ventura, J. Lee, D. Jahng, A comparative study on the alternating mesophilic and thermophilic two-stage anaerobic digestion of food waste, Journal of Environmental Sciences, vol. 26, no. 6, hal. 1274-1283, 2014.

S. Asplund, The Biogas Production Plant at Umea Dairy Evaluation of Design and Start-Up Treatment, Biotechnol. Bioeng., vol. 14, hal. 2539-2556, 2005.

S. Simamora, Salundik, S. Wahyuni, Surajudin, Membuat Biogas Pengganti Minyak dan Gas dari Kotoran Ternak, Jakarta: Agromedia Pustaka, 2006.

L. Ni’mah, Gas from Solid Waste of Tofu Production and Cow Manure Mixture: Composition Effect, Chemica., vol. 1, no. 1, hal 1-9, 2014.

T. A. Seadi, Biogas Handbook, Esbjerg: University of Southern Denmark, 2008.

M. H. Gerardi, The Microbiology of Anaerobic Digesters, New Jersey: Wiley-Interscience, 2003.

C. Kavuma, Variation of Methane and Carbon Dioxide Yield in Biogas Plant, M.Sc. thesis, Dept. of Energy Technology, KTH Royal Institute of Technology, Stockholm, Sweden, 2013.

D. Liu, D. Liu, R. J. Zeng, I. Angelidaki, Hydrogen and methane production from household solid waste in the two-stage fermentation process, Water Research, vol. 40, 2230–2236, 2006.




DOI: http://dx.doi.org/10.33795/jtkl.v1i1.16

Refbacks

  • There are currently no refbacks.


Copyright (c) 2017 Purwinda Iriani, Yanti Suprianti, Fitria Yulistiani

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.