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: Effect of Inhibitor on Biokinetic Estimation of Anaerobic Process in Anaerobic Contact Stabilization Reactor Treating Palm Oil Mill Effluent
Abstrak: Indonesia and Malaysia have become the largest palm oil contributors in the world. Palm oil production in Indonesia and Malaysia covers 80% of global palm oil demand. One of the palm oil industry’s secondary products negatively impacting the environment is palm oil mill effluent (POME). The concentrations of COD, BOD, oil and grease, TSS, and TN in POME are 50,000-150,000 mg/L, 25,000-75,000 mg/L, 4000 mg/L, 40,000 mg/L, and 750 mg/L, respectively. The concentration of organic compounds in POME has exceeded the quality standard established by the Indonesian governors. POME potentially pollutes the environment due to the direct discharge of POME into the environment without appropriate wastewater treatment. Therefore, the Anaerobic-Contact Stabilization (ACSt) reactor was utilized as the biological treatment for POME. In order to satisfy the requirements in the field, biokinetic modeling was conducted. The research was conducted from November 2022 until July 2023. Several procedures conducted in this research were designing the reactor, inoculum preparation, laboratory examination, and biokinetic modeling. The COD percent removal in each variation was around 96.60%-99.47%, while the TSS percent removal in each variation was around 98.63%-99.86%. The COD and TSS percent removal in v.1 and v.2 satisfied the desired value. The biokinetic parameters were estimated using the Monod and Hinshelwood model. The accuracy of the model was evaluated using the student’s t test and MAPE. The data obtained from model and experiment was concluded similar and the MAPE of each modeling was below 50%. Therefore, the models were classified as reasonable forecasting ability.
Keyword: anaerobic, biokinetic, inhibitor, POME, UASB

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