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: Pembuatan Biogas Dari Sampah Buah-Buahan Melalui Fermentasi Aerobik Dan Anaerobik
Abstrak: Solid wastes and energy crisis are created by high growing rate of people. An alternative solving for both problems is biogas technology. Municipal waste can be proceed into biogas and fertilizer by biogas technology. In general, the process of conventional biogas technology has long time about 40 days (in tropical countries) and 100 days (in subtropical countries). The main goal of the research was to shorten the retention time of biogas production by combining its aerobic and anaerobic processes with optimized environmental condition (temperature) and substrate composition (C:N ratio) in anaerobic phase. Hydrolysis and acidogenesis were set in aerobic phase, while asetogenesis was set in anaerobic phase. Fruits waste were set into pre-treatment, minimized waste size between 1-2 cm2 and water addition (1: 1). The mixed ingredients was added by E~ microorganism culture and took into digester to start aerobic process. After 5 days, the process was stopped then substrate took to anaerobic digester to produced biogas (methano~enesis). Anaerobic process was set at different temperatures (30,35 and 40 C) and C:N ratios (20,25 and 30). The beginning of water content and C:N ratio of substrate were 86,24 % and 70,32: 1. Respectively, in aerobic process substrate was degraded by microorganism into simple compound. This process can be analyzed by C:N ratio change of total solid (TS), total volatile solid (TVS), chemical oxygen demand (COD), volatile fatty acid (VF A) and acidity degree (pH). Methanogenesis (anaerobic process) was monitored by the volume of biogas produced and analyzed COD, VF A and pH. The optimum of production rate and volume ofbiogas produced was achieved by treatment in 35°C temperature and 30: 1 C:N ratio, which biogas has produced 26,5 ml in the ftrst day and 42,5 ml biogas in the end of biogas production with the highest production rate was 9,6 mVday. It showed that activity of methanogenic microbe was optimum in that treatment condition.
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Judul: Characteristic of Overshooting Top (OT) Based on  Himawari  8  Satellite  as  a  Convective  Cloud  Feature  that  Generates  Extreme Weather in the Java Island Region
Abstrak: Overshooting Top (OT) is a feature at the top of a convective cloud that is associated with extreme weather. Research on OT in tropical Indonesia is still very limited. The existence of geostationary satellites with wide area coverage and fast frequency observations is useful for observing the fast dynamics of the OT life cycle. Therefore, this study intends to analyze the relationship between OT and extreme weather, updraft and thermodynamic conditions of OT when extreme weather occurs, the best objective method for detecting OT in the day time and night time, and the spatiotemporal distribution of OT in the tropical region of Java Island during the 2018-2021 period. Based on visual analysis using visible channel and Himawari 8 sandwich products, 87% of extreme weather events in Java were accompanied by the appearance of OT. It indicates that the presence of the OT pattern is a convection cloud pattern or feature that is closely related to extreme weather events for the Java Island region. The existence of a time lag between the appearance of OT and extreme weather events on Java Island indicates that the OT of convection cloud can be used as a precursor or nowcasting for the appearance of extreme weather. Most of the convective cloud OT features during extreme weather events on Java Island have altitude that were only able to exceed the altitude of the equilibrium level and few were able to exceed the tropopause level of 9 km – 16 km. The difference in atmospheric conditions during extreme weather events on Java Island, which is in the tropics and subtropics, is a strong and unstable convective energy condition characterized by a larger CAPE, as well as unstable KI, LI, SI and TTI values. It is offset by kinematic factors in the form of a weak vertical wind shear (bulk wind shear 0-6 km) and a higher freezing point height. The difference between extreme weather events in the Java Island region and other tropical regions compared to subtropical regions is the strong updraft speed of convection clouds. The IRW Texture COMB algorithm based on the IRW-Texture Gradient modification and the COMB algorithm shows a significant increase in quality for detecting OT and non-OT pixels in Java. Rainy days with rainfall > 50 mm/day are very common in areas with an altitude of > 500 m. On the other hand, the level of convection activity which is indicated by the presence of OT and lightning is significantly reduced in this area. OT of convective clouds appear more frequently during the DJF season and less frequently during the JJA season. OT often appears during the day time and rarely at night time. Most OTs appear in the central part, away from the south and north coasts of Java Island during the day, while OTs that appear near the south and north coasts of Java Island can appear in the morning or afternoon.
Keyword: convective clouds, extreme weather, Overshooting Tops, Himawari 8 Satellite