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The performance of anaerobic co-digestion of cow manure and POME was evaluated. The anaerobic composting process was carried out by using semi-continuous reactors under the mesophilic condition (35 ± 1℃). The addition of POME to the on-going anaerobic composting of cow manure was applied stepwise within a cycle of HRT (20 days). Results showed that the anaerobic co-digestion reactor could produce methane at about six times higher (7.2 L CH4) than the control reactor (1.3 L CH4). An increasing of POME loaded to the on-going anaerobic composting cow manure culture (4% to 64%) did not affect pH of the culture in which pH was still stable between 7.11 and 7.5. Assessment of biodegradation efficiency revealed that nitrogen removal of the anaerobic co-digestion reactor was six times higher (21%) than the nitrogen removal of the control reactor (3.4%). This suggested that the anaerobic co-digestion reactor performed sufficiently well in which no organic acid as well as ammonia accumulated in the reactor that could be effective to decompose the organic matters.

Anaerobic co-digestion of oil palm empty fruit bunches with cow manure was studied. The research focus was on the evaluation of feeding different solid concentrations of the substrate in the on-going process of anaerobic digestion. The solid concentrations ranged from 0.5 to 12% TS. Results of the study showed that the maximum methane production could be reached with the reactor digesting substrates with 4 to 8% TS, in which the methane produced was from 1300 to 1400 mL per day. A significant drop of pH from 7.02 to 5.97 occurred when the reactor was digesting substrates with 10 and 12% TS. Acidic condition caused by organic matter overloads lowered the efficiency of organic conversion represented in the low removal of COD, which was only 22.4%. This finding is highly significant for the waste management industries in terms of dealing with the digester upset due to the digestion of large amount of organic wastes.

Pemanfaatan limbah peternakan sapi (kotoran sapi) sebagai sumber bahan bakar dalam bentuk biogas merupakan salah satu alternatif yang sangat tepat untuk meningkatkan nilai tambah bagi masyarakat petani. Pemanfaatan kotoran ternak sebagai sumber energi, tidak mengurangi jumlah pupuk organik yang bersumber dari kotoran ternak. Hal ini karena pada pembuatan biogas kotoran ternak yang sudah diproses dikembalikan ke kondisi semula yang diambil hanya gas metana (CH 4 ) yang digunakan sebagai bahan bakar. Kotoran ternak yang sudah diproses pada pembuatan biogas dipindahkan ke tempat lebih kering, dan bila sudah kering dapat disimpan dalam karung untuk penggunaan selanjutnya sebagai pupuk organik. Tandan kosong sawit (TKS) merupakan limbah dari pabrik kelapa sawit yang pemanfaatnya masih terbatas sebagai pupuk organik yang memiliki nilai tambah yang rendah. Setiap produksi kelapa sawit menghasilkan limbah berupa tandan kosong sawit sebesar 23%, sehingga berdasarkan produksi kelapa sawit tahun 2010 dan 2011 berpotensi dihasilkan limbah tandan kosong sawit sebesar 5 juta ton. Akumulasi limbah TKS dari tahun ke tahun jika tidak dimanfaatkan secara optimal maka dapat berakibat buruk bagi lingkungan. Penelitian ini bertujuan untuk melihat potensi produksi biogas melalui teknologi anaerobik digesi ( anaerobic digestion ) kotoran sapi dan anaerobik co-digesi kotoran sapi dengan limbah TKS. Hasil penelitian menunjukkan bahwa pada proses fermentasi dengan hydraulic retention time (HRT) 25 hari dan pemberian suhu panas yang sama terdapat hasil yang berbeda terhadap produksi biogas kotoran sapi digesi dan juga kotoran sapi co-digesi dengan tepung TKS dengan hasil produksi biogas total lebih tinggi pada fermentasi co-digesi, dimana produksi gas yang dihasilkan adalah 1.015 mL pada kotoran sapi digesi dan 13.830 mL pada kotoran sapi co-digesi. Penambahan tepung TKS meningkatkan nutrisi substrat yang dimanfaatkan mikroba untuk menghasilkan gas metan, namun tetap memperhatikan tingkat ke optimuman derajat keasaman (pH) pada angka 6,8-7,5. Production of Biogas from Cattle Manure Digestion and Co-Digestion with Oil Palm Empty Fruit Bunch under Digestive Anaerobic Method Abstract. Utilization of livestock waste (manure) as biogas is one of the most appropriate alternatives to overcome the rising prices of fertilizers and fuel oil scarcity. The use of livestock manure as an energy source, does not reduce the amount of organic fertilizer that comes from livestock manure. This is because in the production of biogas manure that has been processed is returned to its original condition, only methane (CH4) is used as fuel. Livestock manure that has been processed in the making of biogas is moved to a drier place, and when it is dry it can be stored in a sack for further use as fertilizer. Oil palm empty fruit bunches (TKS) are waste from palm oil mills is still limited use as organic fertilizer and has low added value. Each palm oil production produces waste in the form of 23% oil palm empty fruit bunches, so that according to the palm production on 2010 and 2011, the potential production of this waste could reach 5 million tons. The accumulation of this waste from year to year will harm our environment. This study aims to look at the potential for biogas production from cow manure digestion and co-digestion with palm oil fruit bunch waste under the anaerobic process. Results showed that for 25 days hydraulic retention time (HRT) and the use of mesophilic temperature, the biogas production by using anaerobic co-digestion of cow manure with TKS (13,830 mL) was higher than the biogas production by using the anaerobic digestion of cow manure (1,015 mL). The addition of TKS flour had increased the nutrient of substrate used by microbes to produce methane gas, but the acidity (pH)of substrate should be controlled at 6.8-7.5.