Judul: The reduction of contaminant compounds of palm oil mill effluent by two phase anaerobic fermentation using two-stage anaerobic digester
Abstrak: Palm oil is one of the potential comodities in Indonesia. Production of crude palm oil (CPO) will produce solid, liquid, and gas waste. Wastewater from palm-oil plant which also known as palm oil mill effluent (POME) has very high contaminant charge. It can contaminate environment if it is directly loosed away. This research aimed to investigate the mixture of POME and activator ratio with palm oil contaminant charge decreasing considered from BOD, COD, and TSS value by anaerobic processing during 40 days. This research was done at Animal Science Laboratory, Bogor Agricurtural University. Raw material used in this research was POME and activator. Activator is mixture of biogas sluge and cattle beef feces (20:80). Equipment used in this research was two stage anaerobic digester. The treatment were ratio of POME and activator 70%:30% (P70S30), 80%:20%(P80S20), and 90%:10% (P90S10). The physico-chemical analysis has resulted from the first condition show high value of influent BOD, COD, and TSS. The BOD value of influent P70S30, P80S20, and P90S10 consecutively are 8871 mg/l, 8871 mg/l, and 6653 mg/l. The COD value of influent P70S30, P80S20, and P90S10 consecutively are 15480 mg/l, 17028 mg/l, and 13588 mg/l. The TSS of influent P70S30, P80S20, and P90S10 consecutively are 17010 mg/l, 23250 mg/l and 6530 mg/l. The result of this research showed that the highest decrease of percentage of BOD value was about 80% in first digester which P70S30, followed by P90S10 (69,96% ) and P80S20 (58,99%). The decrease of COD value was about 74% in digester P70S30, followed by P80S20 (73,24%) and P90S10 (67,03%). The decrease of TSS value was about 66% in digester P70S30, 66,60% in digester P80S20 and 61,40% in digester P90S10. The decrease of POME contaminant value was proceed from organic material decomposition by microorganisms in anaerobic biodegradation during 40 days fermentation. Beside on differentiation of contaminant compounds decreasing (digester A and digester B) showed that first digester have higher contaminant compounds reduction than second digester , The best mixture of POME and activator was digester which added 30% activator, followed by digester which added 20% and 10% activator.
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Judul: Performance of Modification Hybrid Attached Growth Biofilm on Suspended Media on Anaerobic-Aerobic Unit in Treating Palm Oil Mill Effluent
Abstrak: Produksi minyak sawit mentah (CPO) di Indonesia hingga tahun 2022 telah mencapai 48,3 juta ton dari total produksi dunia sebanyak 75,45 juta ton dan tingginya produksi CPO menyebabkan peningkatan Limbah Cair Kelapa Sawit (LCKS) atau Palm Oil Mill Effluent (POME). Penelitian ini bertujuan untuk efektifitas pengolahan LCKS dengan variasi waktu detensi (HRT) yang berbeda pada Reaktor Anaerobic Contact-Stabilization (ACSt). Penelitian ini juga berfokus pada kajian mengenai parameter biokinetika pada unit Integrated Fixed-Film Contact Stabikization (IFCS) untuk estimasi nilai substrat di efluen. Penelitian terdiri atas tahap persiapan reaktor, aklimasasi, konfigurasi reaktor, dan pengoperasian reaktor, dan analisis data. Berdasarkan penelitian diketahui bahwa perubahan variabel operasional HRT berpengaruh terhadap persen penyisihan substrat sCOD pada pegolahan menggunakan Reaktor ACSt (Variasi 1 = 99,41%, Variasi 2 = 99,17%, Variasi 3 = 99,65%, Variasi 4 = 98,633% dan Variasi 5 = 96,47%). Selain itu, perhitungan parameter biokinetika untuk pengolahan LCKS menggunakan Reaktor ACSt pada unit IFCS memperoleh hasil nilai Kec, Kea, Yc, Ya, μmax-c, μmax-a, Ks-c, Ks-a dengan nilai berturut-turut sebesar 0,04 hari-1, 0,0018 hari-1, 3,51 mgMLVSS/mgCOD, 1,95 mgMLVSS/mgCOD, 2,33 hari-1, 2,09 hari-1, 75,55 mg/L, dan 49,57 mg/L, Production of crude palm oil (CPO) in Indonesia until 2022 has reached 48.3 million tons of the world's total production of 75.45 million tons and the high production of CPO can increase Palm Oil Mill Effluent (POME). This study aims to determine the effectiveness of POME processing with various detention time (HRT) in Anaerobic Contact-Stabilization (ACSt) Reactor. This research also focuses on the study of biokinetic parameters in the Integrated Fixed-Film Contact Stabikization (IFCS) unit to predict the value of the substrate concentration in the effluent. This research starts with reactor preparation, acclimation, reactor configuration, reactor operation, and data analysis. Based on the research, it is known that changes in HRT operational variables affect the percentage of sCOD substrate removal in processing using the ACSt Reactor (Variation 1 = 99.41%, Variation 2 = 99.17%, Variation 3 = 99.65%, Variation 4 = 98.633% and Variation 5 = 96.47%). In addition, the calculation of biokinetic parameters for LCKS processing using the ACSt Reactor in the IFCS unit yielded the values of Kec, Kea, Yc, Ya, μmax-c, μmax-a, K_s-c, K_s-a with consecutive values of 0.04 day-1, 0.0018 day-1, 3.51 mgMLVSS/mgCOD, 1.95 mgMLVSS/mgCOD, 2,33 day-1, 2.09 day-1, 75.55 mg/L, and 49.57 mg/L.
Keyword: Anaerobic Contact Stabilization, bioball, biokinetic, Hydraulic Retention Time, Palm Oil Mill Effluent

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf