Judul: Konversi sampah organik pasar dengan sistem fermentasi media padat menjadi biogas dan pupuk organik.
Abstrak: In 2010 Indonesia produced 200 thousand tons of waste everyday. It causes problems for the society and for environment. The purposes of this research are to design and get an optimal process condition for solid medium fermentation to convert organic waste from traditional market into bioenergy and organic fertilizer, to characterize biogas, digestate, and leachate. The experiments were conducted with 1.5 L and 10 L reactors . Composition of organic waste from traditonal market that gave higest volume of biogas are banana leaf 7.5%, cornhusk 24.2%, bitter melon 14.8%, cabbage 19.9%, chicory 6.2%, water spinach 8.0%, mustard 8.0%, carrots 11.5% (w/w). It produced 4500 ml biogas/kg biomass and the maximum production was reached within 17 days. This equal to biogas production of 37.63 ml biogas/gram VS. Fermentation process in 10 liter reactor with adition of 75% feed, 50% of feed, and 100% feed produced 12378 ml, 10908 ml, and 16707 ml biogas, respectively leachate consists nitrogen 473-4500 ppm, phosphat 47-150 ppm, and COD 8333-12500 mg/l, while the digestate consists of carbon 28-49%, nitrogen 0.7-1.7%, phosphat 0.2-0.4%, and COD 16000-18000 mg/kg. Concentration of methane in biogas is still low and hence futher experiments needed to increase methane concentration. Keywords : organic waste, biogas, digestate, leachate, solid state fermentation
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Judul: Influence of sludge addition and particles size reduction on market organics waste conversion to 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: Hedging strategy for loan with interest rate Cap.
Abstrak: A bank usually charges a specific nominal interest for a loan, which is influenced by the market’s interest rate. When the market interest rates fluctuate, the customer will face financial loss with the growing burden. Interest rate cap is one of the solutions to anticipate any negative impacts of increasing interest rate, by limiting the maximum interest rate paid by customer to the bank. Thus, customer gets a guarantee against increase in interest rate. To obtain this guarantee, the customer is required to pay a premium. The aims of this paper are to analyze the form of a loan with the interest rate cap strategy, and to discuss Vasicek model approach to determine the amount of the premium. A numerical illustration is given to show the advantage of the interest rate cap strategy. The results show that the interest rate cap will provide protection to the customer as the market interest rates fluctuate. Vasicek model states that the price cap interest rate can be expressed as an expected value of a random variable that has bivariate normal distribution. Numerical results show that this strategy provides benefits in the form of lower amortization cost than that of a loan without interest rate cap.
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