Judul: Produksi biogas dari limbah cair pabrik minyak kelapa sawit dengan menggunakan digester dua tahap
Abstrak: Biogas adalah campuran beberapa gas yang merupakan hasil fermentasi dari bahan organik dalam kondisi anaerobik, dengan gas yang dominan adalah gas metana (CH4) dan gas karbon dioksida (CO2). Salah satu bahan organik yang memiliki potensi cukup besar adalah limbah cair pabrik minyak kelapa sawit yang dicampurkan dengan lumpur aktif dari feses sapi segar, sehingga dapat digunakan sebagai substrat. Proses fermentasi biogas terjadi secara empat tahap reaksi di dalam digester yang dirangkai secara dua tahap selama waktu retensi yang ditentukan. Proses yang terjadi pada kedua tahap digester ini berbeda, sehingga volume produksi biogas yang dihasilkan pun berbeda. Hal ini berhubungan dengan perubahan kandungan bahan organik selama masa fermentasi, salah satu parameternya adalah nilai total volatile solid (TVS). Tujuan penelitian ini adalah untuk mengetahui volume gas yang dihasilkan dari campuran limbah cair dan lumpur aktif dari feses sapi segar, serta prosentase peningkatan produksi gas pada digester tahap II dibandingkan digester tahap I, mengetahui pengaruh waktu fermentasi terhadap produksi gas berbagai kombinasi limbah cair dan lumpur aktif pada digester tahap I dan digester tahap II, mengetahui pengaruh waktu fermentasi terhadap nilai pH berbagai kombinasi limbah cair dan lumpur aktif pada digester tahap I dan digester tahap II, serta mengetahui pengaruh kombinasi limbah cair dan lumpur aktif terhadap nilai TVS akhir.
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Judul: Potensi hasil samping produksi biogas dari limbah cair pabrik kelapa sawit dengan penambahan aktivator kotoran sapi potong sebagai pupuk organik
Abstrak: Indonesia merupakan salah satu negara yang memiliki perkebunan kelapa sawit yang sangat luas. Hal ini ditandai dengan bertambahnya luasan perkebunan kelapa sawit setiap tahun dan semakin banyak pabrik-pabrik pengolahan kelapa sawit. Limbah cair kelapa sawit merupakan salah satu hasil samping dari proses pengolahan pabrik kelapa sawit. Pemanfaatan limbah cair kelapa sawit menjadi biogas merupakan salah satu alternatif untuk mengurangi tingkat pencemaran lingkungan. Hasil samping produksi biogas ini dapat dimanfaatkan juga sebagai pupuk organik. Penelitian ini bertujuan untuk menganalisis potensi hasil samping produksi biogas dengan penambahan aktivator kotoran sapi potong sebagai pupuk organik.
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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