Studi Perbandingan Produksi Biogas Menggunakan Feses Sapi, Cairan Rumen Dan Feses Luwak Pada Co-Digestion - Comparative Study Of Biogas Production By Using Cow-Dung, Rumen Fluid And Civet Faeces In Codigestion

Sumber daya minyak dan gas alam dunia yang berasal dari energi fosil semakin berkurang. Sehingga pengembangan penelitian sumber energi alternatif semakin sering dilakukan, salah satunya adalah produksi biogas. Bahan baku alternatif yang potensial untuk menghasilkan gas metana adalah limbah kulit kopi. Kulit kopi dipilih karena merupakan limbah yang banyak dihasilkan dari proses pengolahan biji kopi. Kopi sendiri merupakan komuditas unggulan di Indonesia. Komposisi limbah kulit buah kopi terdiri dari selulosa 63%, hemiselulosa 2,3%, lignin 17%, protein 11,5%, tanin 1,8-8,56% dan pektin 6,5%. Akan tetapi produksi metana dari limbah kulit kopi masih banyak mengalami kendala karena kandungan zat kimia beracun seperti tanin, kafein, dan polifenol yang dapat menghambat produksi biogas yang diinginkan. Oleh karena itu, dilakukan pretreatment dengan menggunakan kotoran luwak (Paradoxurus hermaphroditus) untuk menghilangkan zat kimia beracun tersebut. Kotoran luwak sendiri dipilih karena memiliki bakteri-bakteri yang memiliki aktifitas enzim yang tinggi antara lain xilanolitik, selulolitik (penghancur sel), dan proteolitik (penghancur protein) yang mampu membantu pencernaan luwak dalam melakukan fermentasi kulit dan biji kopi secara anaerobik di dalam ususnya. Tahap pertama dalam penelitian adalah persiapan alat dan bahan antara lain kulit kopi, kotoran luwak, cairan rumen dan kotoran sapi. Kemudian tahap kedua melakukan pretreatment terhadap kulit kopi menggunakan kotoran luwak dengan memvariasikan jumlah kotoran luwak dan lamanya waktu fermentasi, yang kemudian dipilih variabel mana yang paling baik dalam mendegradasi komponen inhibitor. Tahap selanjutnya yaitu melakukan fermentasi anaerobik selama 40 hari dengan suhu mesofilik (30–40oC) dan pH dijaga 6,8-7,2 pada volume kerja reaktor sebesar 3.6 liter. Terdapat enam reaktor yang masingmasing berisi mikroorganisme cairan rumen (CR), kotoran sapi (KS) dan campuran keduanya yang kemudian dibandingkan dengan hasil pretreatment. Adapun parameter yang diukur antara lain penurunan kandungan inhibitor, Volatile Fatty Acids (VFA), Chemical Oxygen Demand (COD), Total Solid (TS), Volatile Solid (VS), biogas (CH4, CO2, dan H2) dan nilai kalor pembakaran (heating value). Dari hasil penelitian ini didapatkan data bahwa pretreatment dengan menggunakan cairan kotoran luwak dapat menurunkan kandungan inhibitor dalam substrat kulit kopi dan pretreatment tersebut menghasilkan konsentrasi metana lebih tinggi dibandingkan dengan tanpa pretreatment dalam setiap reaktor ======================================================================================================================== Resources of oil and natural gas which are derived from fossil energy are wane more and more. So the research development of alternative energy sources are increasingly being conducted, one of the research of alternative energy are the production of biogas. Potential alternative raw materials to produce methane gas is the waste of coffee skin. Skin (epicarp and mesocarp) coffee been a lot of waste that is produced from the processing of coffee beans. Coffee itself is an excellent commodity in Indonesia. Coffee skin (epicarp and mesocarp) waste composition comprised of 63% cellulose, 2.3% hemicellulose, lignin 17%, 11.5% protein, 1.8 to 8.56% tannin and pectin 6.5%. However, methane production from waste of coffee skin is still much problems because of the content of toxic chemicals such as tannins, caffeine and polyphenols which can inhibit the production of biogas as desired. Therefore, doing pretreatment to remove toxic chemicals are either mechanically (size reduction), thermal (solar radiation) and biological mixed with the addition of rumen microorganisms, cow dung and feses of civet (Paradoxurus hermaphroditus). Civet feses chosen because it has bacteria that have a high enzyme activity, among others xilanolitik, cellulolitic (cells disrupting), and proteolytic (protein disrupting) that can help civet digestion in fermenting skin and coffee beans in the gut anaerobically. The first step in this research is the preparation of tools and materials include coffee skin, civet droppings, rumen fluid and cow dung. Then the second step is doing pretreatment for the coffee skin by using civet droppings by varying the amount of the civet droppings and duration of fermentation, then select variables were most excellent in degrading inhibitor component. The next step is, doing anaerobic fermentation for 40 days at mesophilic temperature (30-40oC) and the pH is maintained from 6.8 to 7.2 on a reactor working volume of 3.6 liters. There are six reactors which each contain different microorganisms, rumen fluid (CR), cow dung (KS) and a mixture of both (KS-CR) and then compared with the results of reactor which is using coffee skin pretreatment. The measured parameters include inhibitor compound decrease, Volatile Fatty Acids (VFA), Chemical Oxygen Demand (COD), Total Solid (TS), Volatile Solid (VS), biogas (CH4, CO2, and H2) and the calorific value of combustion (heating value). This study results that pretreatment with a liquid civet droppings can reduce the inhibitor compound in the substrate of pretreatment coffee skin and produces methane concentrations higher than those without pretreatment in each reactor