Pengaruh Pretreatment Jerami Padi pada Produksi Biogas dari Jerami Padi dan Sampah Sayur Sawi Hijau Secara Batch

Abstract

Dalam dekade terakhir, tingkat konsumsi energi semakin tinggi, sedangkan sumber energi fosil terbatas. Diperlukan usaha-usaha untuk mendapatkan energi terbarukan. Di sisi lain, limbah pertanian dan sampah pasar melimpah dan dapat dibuat biogas yang merupakan energi terbarukan. Tujuan penelitian ini adalah untuk mengetahui pengaruh pretreatment jerami terhadap yield biogas dan kadar metana. Sampah sayuran sawi hijau (Brassica Juncea) dan jerami padi dicampur dengan komposisi tertentu sampai diperoleh perbandingan molar C/N = 20. Starter inokulum dari cairan hasil biodigester dimasukkan ke dalam erlenmeyer yang kemudian ditambahkan air sehingga volume totalnya menjadi 350 ml. pH awal campuran diukur dan campuran dialiri gas N2 supaya kondisi anaerob tercapai sementara erlenmeyer dalam keadaan tertutup rapat. Fermentasi dilakukan pada suhu 35°C. Volume biogas dan pH diukur setiap hari sementara kadar metana dianalisis setiap tujuh hari. Proses fermentasi diamati selama 49 hari. Hasil terbaik diperoleh dari jerami ukuran 0,5 cm yang dikenakan perlakukan awal penambahan EM-4, dimana hasil yield biogas rata-rata 0,03 L/g VS pada hari ke-21. Kadar metan tertinggi sebesar 64,78% dihasilkan pada hari ke-28 diperoleh dari jerami padi yang dibuat serbuk. Perlakuan awal jerami padi secara biologis dengan penambahan EM-4 terbukti dapat meningkatkan yield biogas sebesar 188,48%. Kata kunci: jerami padi, sawi hijau, EM-4, biogas, metana, yield biogas In the recent decades, population growth has increased energy consumption level. On the other hand, fossil energy sources are very limited and therefore the need to seek renewable energies as alternatives is inevitable. Agricultural and traditional market wastes can be used to produce biogas as renewable energy. The objectives of this study was to investigate the potential of rice straws and green mustard (Brassica Juncea) to produce biogas and the effect of pretreatment on the biogas production. Vegetable waste of green mustard and rice straws were mixed so that the C to N ratio was 20. Inoculums starter taken from bio-digester effluent was put into an erlenmeyer and water was then added to a total volume of 350 ml. Initial mixture pH was measured and nitrogen was fed to the reactor to get anaerobic condition while the erlenmeyer was isolated. Fermentation was conducted at temperature of 35°C. Volume and pH of the resulting biogas were measured everyday, while the methane content was analyzed every seven days. The fermentation process was observed for 49 days. Experimental results showed that the highest result was obtained from rice straw that was pretreated by adding EM-4 with the average biogas yield of 0,030 L/g VS after 21 days. The highest methane content was obtained after 28 days with a purity of 64,78% from the powdered rice straw. The experimental results showed that the rice straw pretreated with EM-4 addition could increase biogas yield by 188,48%. Keywords: rice straw, green mustard, EM-4, biogas, methane, yield of biogas