Judul: Bioremediasi Tanah Tercemar Diazinon Secara Ex Situ dengan Menggunakan Kompos Limbah Media Jamur (Spent Mushroom Compost)
Abstrak: Pesticide is a xenobiotic compound and rexalcytran which should be handled seriously in order to prevent human and environment from those negative effects. One of the methods which can be utilized is bioremediation technique which is utilizing fresh spent mushroom compost (SMC). The diazinon contaminated soil whith the concentration of 500 ppm, 1000 ppm and1500 ppm, was added with SMC of 10%, 20% and 30%, then incubated for 28 days. The reduction of diazinon concentrate was analyzed every week through extracted sample with etyl acetat and measured by spectrophotometer. The data processing was conducted by using respon surface method (RSM). Based on this analysis, the maximum point of diazinon concentrate reduction was 88% with the treatment of combination of 30% compost and 1000 ppm diazinon, it was obatined on the 14th. On the 21st day the diazinon concentration reduction was 91.8%. It was the result from combination of 25% compost and 1000 ppm diazinon. On 28th day, the diazinon concentration reduction was 97.5%, result from the treatment of 26% compost and 1000 ppm diazinon. The diazinon degradation process can be effectively ferformed by adding 15-30% compost, with 1000 ppm of diazinon within 21 days incubation. Some of bacteria have been isolated from SMC. that were, Bacillus mycoides, Bacillus cereus, Bacillus brevis, Pseudomonas stutzeri, dan Chromobacterium spp. Those bacteria were able to growth in solid medium which contains diazinon up to 500 ppm, except Bacillus brevis. The ability of bacteria to degrade diazinon based on their properties is forming a clear zone around the colony which is growth in solid medium of mineral salt peptone yeast (MSPY). Apparently, it is only Bacillus cereus is able to degrade diazinon up to 1700 ppm.
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Judul: Bioremediasi Lahan Tercemar Profenofos Secara ex-situ dengan Cara Pengomposan
Abstrak: Pesticide have significantly increased agricultural yields while impacting detrimentally on the food chain of wildlife and human. Composting bioremediation strategy relies on mixing the primary ingredients of composting with contaminated soil, wherein as the compost matures, the pollutant will be degraded by the active microorganisms within the mixture. Composting is a relatively new clean-up strategy and because of this, there are a limited number of studies. This study was carried out to determine the concentration of profenofos decomposition rate of profenofos-contaminated soil composted with agricultural wastes (such as saw dust, carrot leaves, beef manure). The mixed of them was based on C/N ratio 40, 35 and 30. The degradation of profenofos was measured during the composting. The composting with C/N ratio 30 mineralized profenofos rapidly than the others after 28 days of composting (98% of profenofos). Bioremediation could be increased the crop yield compared to unbioremediated soil. Some kinds of bacteria have been isolated from the compost mixture. Three of them were able to grow in solid medium containing 1500 ppm of profenofos. The ability to degradate the profenofos was tested in mineral salt peptone yeast (MSPY) medium by changing from opaque medium to clear medium. It’s ability was indicated by the formation of clear zones surrounding the bacteria.
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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