Judul: Sistem Sirkulasi Lindi pada Digester Anaerobik untuk Produksi Biogas dari Limbah Sayuran
Abstrak: Biogas is an alternative energy that can be used as a substitute for fossil fuels. Biogas can be produced from the fermentation of organic matter carried out anaerobikally. Vegetable waste is organic material that can be used as raw material for biogas production. . In addition to the availability of abundant, this waste also has a suitable C/N ratio if added to other materials like cow dung. This study aims to evaluate the utilization of vegetable waste as raw material and comparing the effectiveness of biogas circulation and non- circulation in biogas production and rate of decline COD. Fermentation process conducted in anaerobik digester that have volume 50 Liter for digester with leachate circulation and volume 25 liter for digester without leachate circulation. Fermentation process is done by using the starter of cow dung 20 % of the total material volume for 40 days. Specific production of biogas from digester circulation by controlled pH is 219 L/kg TS of material with rate of decline COD is 24 %, digester circulation without pH control is 117 L/kg TS of material with rate of decline COD is 28 %. Meanwhile, biogas specific production in the digester without leachate circulation have specifik biogas production and rate of decline COD lower than digester with leachate circulation.the spesicific biogas production is 24 L/Kg TS with rate of decline COD is 18 %. The highest specific of biogas production is conducted by digester with leachate circulation and pH control. Leachate circulation and pH control have considerable influence of biogas production.
Keyword: Bogor Agricultural University (IPB), Circulation Leachate, C/N ratio, manure, fermentation

Judul: Desain proses produksi biogas dari jerami padi dan sampah pasar dengan sistem fermentasi media padat
Abstrak: The purpose of this research were to design of fermentation process for converting rice straw and organic waste from traditional market to produce biogas, to know influence of aeration, to obtain the best feed addition in fermentation, and to obtain characteristic of product (digestate and leachate) from fermentation process. Beef cattle manure as substrate was inoculated to anaerobic digestion. Laboratory experiments using 10 l digester were performed in batch mode. The operating temperature was mesophilic condition (35-40oC). Fermentation rice straw with feed addition 75% new feeds and 25% digestate could produce 42.2 l gas/kg VS higher than fermentation rice straw from all new feeds (28.1 l gas/kg VS) and fermentation from 50% new feeds and 50% digestate (15.8 l gas/kg VS). While fermentation waste market from all new feeds could produce 51.8 l gas/kg VS higher than fermentation with feed addition 75% new feeds and 25% digestate (39.7 l gas/kg VS) and fermentation from 50% new feeds and 50% digestate (31.1 l gas/kg VS). The cumulative volume of biogas produced was used to measure the biodigester performance. The research gave the kinetic parameters of biogas production for rice straw i.e. biogas production rate constants (Rmax), maximum biogas production (A), and minimum time to produce biogas (λ) were 1.37-2.07 (l/kg VS.day), 15.82-42.25 (l/kgVS), and 0.4-2.0 days, respectively. While the organic waste from market gave the kinetic parameters U, A, and λ of 1.58-3.55 (l/kgVS.day), 31.09-51.84 (l/kgVS), and 0.2-1.2 days, respectively.
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Judul: Socioeconomic and psychological variables influencing household debt
Abstrak: The overall objective of this study was to examine factors influencing total debt, total debt payment, and patterns of debt payments. The study examined the impacts of both psychological (credit attitudes and perception of future income) and socioe- conomic variables on total debt, total debt payment and patterns of debt payments. A conceptual model for this study was developed by incorporating the theory of borrower risk, the economic and psychological economic theory of borrowing, and the results of previous studies. This model identifies socioeconomic and psycholog- ical variables that influence total debt, total debt payment, and patterns of debt payments. Socioeconomic variables included in the model are gender, race, mari- tal status, employment status, household size, age, education, and household assets. Psychological variables are credit attitudes toward the use of credit, and perception of future income. This study used data from the 1989 Survey of Consumer Finances. The survey was sponsored by the Federal Reserve in cooperation with some other federal agencies. Data for the survey were collected by the Survey Research Center at the University of Michigan between August 1989 and March 1990. dst ...
Keyword: Gender