Judul: Design and Evaluation of Reusable Materials-Based Aerobic Composter for Domestic Organic Waste Management
Abstrak: Limbah organik menjadi kontributor terbesar komposisi sampah di Indonesia pada tahun 2023. Untuk mengatasi hal ini, diperlukan sistem pengelolaan limbah organik skala domestik yang efisien, seperti composting. Penelitian ini bertujuan untuk merancang dan menguji komposter aerob dari barang bekas dengan variasi agen dekomposer: perlakuan larva BSF (P1 dan P2), perlakuan EM4 (P3 dan P4), dan kontrol (P5). Pencacahan limbah organik juga dilakukan pada P1 dan P3. Komposter P1 menunjukkan hasil terbaik dalam biokonversi limbah organik, dengan perubahan berat limbah dan kenaikan suhu paling signifikan serta emisi kebauan paling rendah. Perlakuan ini memiliki nilai reduksi (D) dan waste reduction index (WRI) tertinggi, yaitu 95.73% dan 3.19%/hari. Hasil pengujian kompos padat menunjukkan seluruh perlakuan memenuhi persyaratan yang ditetapkan pada Keputusan Menteri Pertanian Nomor 261 Tahun 2019. Hasil pengujian air lindi tidak memenuhi baku mutu yang dipersyaratkan pada setiap perlakuan, In 2023, Organic waste was the largest contributor to the composition of waste in Indonesia. To address this issue, an efficient domestic-scale organic waste management system, such as composting, is required. This study aims to design and test aerobic composters made from reusable materials with various decomposer agents: BSF larvae treatment (P1 and P2), EM4 treatment (P3 and P4), and control (P5). Shredding of organic waste was also done for P1 and P3. The P1 composter showed the best results in organic waste bioconversion, with the most significant changes in waste weight, the highest temperature increase, and the lowest odor emissions. This treatment had the highest reduction value (D) and waste reduction index (WRI), with 95.73% and 3.19%/day. The solid compost testing results showed that all treatments met the requirements set forth in the Keputusan Menteri Pertanian. The leachate test results did not meet the quality standards requirement
Keyword: performance testing, composter, design, decomposer, Organic waste

Judul: Design and Performance Test of Concrete Composting Bin with Decomposition Agent Black Soldier Fly Larvae
Abstrak: Meningkatnya pertumbuhan ekonomi berdampak pada tingginya jumlah sampah perkotaan. Sebagian besar sampah bersumber dari rumah tangga, dengan komposisi sampah organik yang lebih besar. Metode pengolahan sampah organik yang sederhana adalah pengomposan dengan berbagai macam wadah. Tujuan dari penelitian ini adalah untuk merancang dan membangun bak pengomposan berbahan beton yang kemudian diuji kinerjanya. Desain dilakukan berdasarkan ergonomi tubuh manusia, sistem pemindahan dan pemasangan bak pengomposan, mekanisme keluar masuknya lalat black soldier fly, dan saluran air lindi. Dimensi bak pengomposan berbahan beton pracetak sebesar 60 cm x 50 cm x 50 cm. Uji unjuk kerja bak pengomposan berbahan beton pracetak mengacu pada SNI 19-7030-2004 berdasarkan parameter suhu, warna, dan skala hedonisme kebauan kompos. Suhu maksimum kompos yang dihasilkan sebesar 39°C dan suhu akhir sebesar 30°C. Skala hedonisme kebauan kompos pada pengukuran hari ke-30 sebesar 0 dengan warna kompos kehitaman. Penggunaan beton pracetak sebagai bak pengomposan memiliki keunggulan berdasarkan faktor biaya, tenaga kerja, dan waktu. Namun masih terlalu lemah terhadap guncangan, sehingga rentan mengalami keretakan., Increased economic growth has an impact on the high amount of urban waste. Most of the waste comes from households, with a larger composition of organic waste. A simple method of processing organic waste is composting with various containers. This research aims to design and build a composting bin made of concrete, which is then tested for its performance. The design is based on the human body ergonomics, removal and installation of composting bin, the mechanism for entry and exit of the black soldier flies, and leachate drainage. The dimensions of the precast concrete composting bin are 60 cm x 50 cm x 50 cm. The performance test of the precast concrete composting bin refers to SNI 19-7030-2004 based on the parameters of temperature, colour, and odour emission of compost. The maximum temperature of the compost produced was 39°C and the final temperature was 30°C. The compost odour emission scale on the 30th day of measurement was 0 with black colour. The use of precast concrete as a composting bin has advantages based on cost, labour, and time factors. However, it is still too weak against shocks, so it is prone to cracking.
Keyword: Black soldier fly (BSF), composting bin, organic waste, precast concrete, Bak pengomposan, Beton Pracetak, Sampah organik, Black Soldier Fly (BSF)

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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