Judul: Kemampuan Konsorsium Mikrob dari Kotoran Sapi dan Kuda pada Proses Biodegradasi Limbah Minyak Berat
Abstrak: Heavy oil waste (HOW) which is produced by petroleum industry has become environment problem until now. Bioremediation is a method that can recover the polluted environment. This research was carried out to evaluate microbe consortium from cow and horse manure in biodegradation of heavy oil waste with adjustment of total petroleum hydrocarbon (TPH) 5% (w/v) and 10% (w/v). The observed parameters were solid TPH, liquid TPH, total plate count, chemical oxygen demand, and pH. The highest percent degradation was obtained from 5% TPH. Microbes were easier in degrading 5% TPH than that of 10% TPH. This is because the low toxicity of TPH 5%. TPH degradation at the 21st day reached 40.36% with addition of horse manure consortium enriched by 5% TPH, while with cow manure consortium was only reached 22.77%. TPH degradation at the 21st day was reached with addition of horse manure consortium enriched by 10% TPH, while with cow manure consortium was reached 16.80% of TPH degradation. It also showed that microbes in consortium of cow’s manure were better on degrading HOW than microbes in horse manure consortium.
Keyword: 

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.
Keyword: 

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