Judul: Biodegradasi Limbah Minyak Berat Menggunakan Isolat Tunggal dan Campuran dengan Tambahan Alkilbenzena Sulfonat Linear
Abstrak: Oil spill incident in petroleum industry is inevitability event that caused environmental pollution. Bioremediation is one of the safe methods to handle petroleum polluted environment using bacterial activity. Bacterial were isolated from polluted soil and nourishment by cow and horse manure. The degradation process was improved with linear alkyl benzene sulphonate. The best three isolated microbes and its combination were applied to degrade heavy oil waste combined with linear alkyl benzene sulphonate. The observation parameters were solid Total Petroleum Hydrocarbon (TPH), liquid TPH, Total Plate Count (TPC), Chemical Oxygen Demand (COD), and pH. MY7, MY12, and MYFlr were selected as the best three isolated microbes as shown by their highest percentage of degradation, namely 32.26, 58.25, and 40.74%. The addition of linear alkyl benzene sulphonate proved to augment oil solubility in water, as shown by decreasing solid TPH, increasing liquid TPH, and increasing COD. The value of solid TPH of the three isolate combination in day-21 were 2.33% (w/w), liquid TPH were 1.68% (w/v), and COD were 246456 mg/mL. The degradation level of the three isolate combinations in 21 day-21 was 81.56%. The bacterial combination showed higher degradation level of the waste as compared to that ot the single microbe.
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Judul: Perombakan Hidrokarbon Dalam Tanah Terkontaminasi Minyak Berat, Minyak Ringan dan Oli Bekas oleh Bacillus sp.
Abstrak: Oil is the main source of energy for humans activities such as industries and transportations. The oil exploration activities have potential to pollute the environment (i.e.soil, water, and air). The sludge released bysuch activities can be degraded by bacteria into non-harmful compounds. Biodegradation process is done to achieve the concentration of Total Petroleum Hydrocarbon (TPH) in the contaminated soil less than 1%. The result showed that the bacteria of Bacillus sp. ICBB 7859, ICBB 9461, ICBB 5071 were able to degrade the concentration of TPH of heavy oil from 9.5082% to 0.4673%, 10.7747% to 0.3607% and 9.2442% to 0.6713%, respectively. The three isolates of bacteria needed nine weeks to complete the process. For light oil, Bacillus sp. ICBB 7859 was able to decrease the TPH from 2.9407% to 0.4378%, ICBB 9461 from 3.1433% to 0.4702%, and ICBB 5071 from 3.0742% to 0.5991% respectively, within four weeks. For iv lubricant wastes, Bacillus sp. ICBB 7859 was able to decrease the TPH of lubricant wastes from 7.6949% to 0.9067, ICBB 9461 from 7.4556% to 0.9222%, and ICBB 5071 from 7.3459% to 0.6796% respectively. The three isolates of bacteria completed the degradation process in different time. Bacillus sp. ICBB 7859 and ICBB 9461 degraded lubricant wastes within six weeks, and Bacillus sp. ICBB 5071 degraded the lubricant wastes within five weeks to reach the TPH concentration of less than 1%.
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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