Judul: Kajian proses degradasi bahan organik limbah cair pada kondisi anaerobik dengan konsentrasi garam tinggi
Abstrak: Waste with high level of salinity is usually difficult for microorganism to degrade because the high level of saliity concentration in the environment or waste can hamper microorganism to reduce organic materials in it. High level of salinity can hamper the function of bacteria metanogen in reducing organic material and asetat acid to become gas or metan. Reduction of sulfate and metabolism H2 may also be hampered in high level of salinity concentration. In ecosystem, anaerobic fermentation can produce CO2, C& and H2S. However, this is hard to do in waste with high level of saliity where there is an acummulation of VFA and H2. Generally, ecosystem with high level of salidity can hamper and limit the growth of bacteria and microorganism. The optimum limit of salinity concentration for vertebrate (Tilapia spp.) is around 10 percent. Above this level, only invertabrate species such as brine shrimp (Artemia salina) or brine tlies, alga genus (Dunaliella salina), bacteria (wich belong to Halobacteriaceae and Haloanaerobiaceae, methanogen, etc.), and cyanobacteria (Oscillatoria spp.) which have been identified. This research was aimed at studying degradation process of organic materials in anaerobic condition with high level of salinity concentration and determining kinetic parameter value for liquid waste with high level of salinity concentration. The main research was conducted with three operation conditions with inoculum as much as 15 % out of total sample volume in which a number treatments in terms of adding salt fiom 0 mgkg (reactor l), 32 mgkg (reactor 2), to 52 mgkg (reactor 3). This research was used some synthetic liquid waste (molases) with inoculum came fiom salt made location. The initial COD content in molases which has been made into liquid is averagely out of two test was 400000 mg/l. The COD content required for this reserach was 4000 mg/l. The analyses conducted were those of COD, MLSS, MLVSS, and gas production. It also analysed caused of addition of trace element and the calculation of kinetic parameter.
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Judul: Pengaruh Penambahan Sludge dan Pengecilan Ukuran Bahan pada Konversi Sampah Organik Pasar Menjadi Biogas
Abstrak: The principal problems which have become the main focus of society are environmental problem and energy scarce. The main cause of the problems is the high consumption of fossil fuels. The purpose of this research is to find out effect of sludge composition and particle size reduction on organic waste convertion to biogas. The fermentation were conducted with 1.5 L reactors and fermentation during 21 days. Composition of organic waste from traditional market were banana leaf 7.5%, corn husk 24.2%, bitter melon 14.8%, cabbage 19.9%, chicory 6.2%, water spinach 8.0%, mustard greens 8.0%, carrots 11.5% (w/w). The maximum gas production was reached 14.414 L/kg TS in 1st running and 22.028 L/kg TS in 2nd running or 0.005215 L/g VS (1st running) and 0.005172 L/g VS (2nd running) with COD value was 0.459 g/kg by composition 3:5 and size 0.1 to 0.5 cm. All treatments had a pH interval 4.80 to 6.67. The highest phosphate levels produced by sludge 5:3 (0.1 to 0.5 cm) was1.97 %, the carbon highest in sludge 3:5 (1.5 to 2 cm) was 10.25 %, and nitrogen in sludge 5:3 (1.5 to 2 cm) was 2.20 %.
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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