Judul: Biodegradasi limbah minyak berat  (heavy oil waste / how) dengan teknik bioslurry menggunakan Salipiger sp. my7 dan Bacillus altitudinis my12
Abstrak: Bioremediation is the application of biological treatment to clean up of hazardous chemicals, included petroleum hydrocarbon such as heavy oil waste by using microorganisms. The final design must provide the controls to manipulate the environment for enhancing biodegradation of the target compounds. One of bioremediation techniques is bioslurry which has some advantages to degrade heavy oil waste. The experiment was conducted at laboratory scale and then continued to scale up phase using bacteria Salipiger sp. MY 7 and Bacillus altitudinis MY 12. Process of biodegradation was observed in 14 days for lab scale and 28 days for scale up. In lab scale, the best combination for bioslurry was using 15% TPH and 10% solid which has 80,16% of TPH degradation. The availability of microorganisms in bioslurry bioreactor was 4,1x107 -1,6x109 CFU/ml . Acidity (pH) of the slurry was in range of 6 – 7 which is normal condition for microorganisms to grow well, and with temperature in range of 31 – 34oC. The decreasing in TPH during the scale up phase (28 days) was from 18,82% to 11,93%. Biodegradation rate can achieved at 44,57 mg/L TPH/day at first week, and 37,57 mg/L/day at second week. Acidity (pH) was 7-9 and temperature was 28oC-30o C which is normal condition for microorganisms for doing biodegradation of heavy oil waste.
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Judul: Degradasi Heavy Oil Waste Menggunakan Bioslurry dengan Ragam Ukuran dan Konsentrasi Contoh
Abstrak: Petroleum waste is classified as a hazardous waste that cause pollution and damage to the environment. The remediation of petroleum polluted environment could be done by using microorganism capability. Grinding the petroleum waste into three different diameters which were 0.5; 0.7; and 0.9 cm, would facilitate good contact between microorganism and the nutrients provided. In this research, each sample size was made into two concentrations, i.e. 5 and 10%. The observed parameter were pH, amount of hydrocarbon dispersed in water (TPH), amount of organic compounds dispersed in water (COD), and turbidity. The decreasing pH value indicated that microorganisms were actively degrade the waste. The result showed that sample with 0.7 cm diameter size and concentration 10% was the best condition for petroleum waste degradation. It was showed with TPH, COD, and turbidity values at the end of degradation of 6694 ppm, 77915.2 mg/L, and 141250 NTU, respectively.
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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