Judul: Isolasi dan seleksi bakteri penitrifikasi dari sampel tanah di sekitar kandang ternak di kabupaten Bogor
Abstrak: Wastewater such as domestic waste and industrial waste, in generally are dump into the waterbody such as river and lake. These wastewater may contain ammonium (NH4 +). Ammonium is nitrogenous compounds that can be toxic at high concentration. One of many methods that can solve the accumulation of ammonium, is the method of nitrification process. Nitrification of ammonium may lower than concetration of ammonium in waste water. This process using of nitrifying bacterial activity. The nitrifying bacteria that commonly reported are Nitrosomonas sp. and Nitrobacter sp. Nitrosomonas sp. are type of bacteria that can oxidize ammonium to nitrite, and Nitrobacter sp. are type of bacteria that can oxidize nitrite to nitrate. The objectives of this research were to isolate ammonium oxidizing bacteria (Nitrosomonas sp.) and nitrite oxidizing bacteria (Nitrobacter sp.), also to evaluate the ability of these bacterial in reducing the ammonium and increased the nitrate concentration. Soil samples around the animals hut (cows, buffaloes, goats, poultry) in 14 locations in Bogor Regency. These bacterial isolated by using enrichment culture method in specific medium which is developed by Verstraete (1981, in Iswandi, 1989) by using three concentration rates of (NH4)2SO4, such as 250 ppm, 500 ppm, and 1000 ppm (NH4)2SO4. Then, ammonium and nitrate concentration measured by using Spectrophotometer. The optimum activity of nitrifying bacterial was found in spesific medium with concentration rate 500 ppm (NH4)2SO4 and 4th day after incubation. The fastest “Nitrosomonas” isolates that can reducing ammonium concentration were NSsp1, NSkm1, NSkm2, NSkm3, and NSsp3, and the fastest “Nitrobacter” isolates that can increasing nitrate were NBsp1, NBkb1, NBam, NBsp5, and NBkm4. These isolates paired, the results got 25 paired of isolates, then also measured the ability in reduced the ammonium and increased the nitrate concentration. The result showed that 5 paired of isolates that had fastest ability in reduced the ammonium and increased the nitrate concentration were NSsp1- NBsp5, NSsp1-NBkm4, NSkm2-NBkb1, NSkm3-NBkb1, dan NSsp3-NBsp5.
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Judul: Isolasi dan karakterisasi bakteri denitrifikasi dari beberapa sawah di Bogor dan Sukabumi
Abstrak: Application of nitrogen fertilizer in agricultural system cannot be avoided to keep the high production of rice. However, nitrogen fertilizer application can increase N20 emision from ricefield. Accumulation of NzO in atmosfer contributes to global warming. N+J can be produced through denitrification process. This research aim were to isolate and characterize nitrate reducing bacteria fiom ricefield in order to control NzO emision for environmental sustainable agricultural system. Water (A) and sediment (S) samples were taken from ricefields in Bogor and Sukabumi. Isolation, purification, selection and characterization were done using denitrification medium.
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Judul: : Persamaan Tunggal sebagai Representasi Kurva Komposit
Abstrak: A mathematical method is introduced to represent a composite curve based on an extension of analytic geometry. The representation is given either with a single equation or with two equations, in the case of parametric representation. This method permits the representation of composite curves in similar manner to the conventional representation of non-composite curves. Some mathematical tools, including Heaviside unit step function and periodizer function, are used in the establishment of a single equation. In this paper, regular equations of regular and irregular polygon, as well as composite curves of two dimensions, are implemented using a computer algebraic system, Mathematica.
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