Judul: Co-composting Process Engineering Design of Sludge and Boiler Ash PT Tanjungenim Lestari Pulp and Paper using Windrow Composting Method.
Abstrak: PT Tanjungenim Lestari Pulp and Paper menghasilkan limbah sludge (30 ton/hari) dan abu ketel (33,3 ton/hari). Penanganan limbah saat ini menggunakan metode sanitary landfill. Salah satu alternatif pemanfaatan limbah adalah melalui proses co-composting. Penelitian ini bertujuan untuk menganalisis karakteristik sludge dan abu ketel, mendesain teknik proses co-composting dan menganalisis mutu produk kompos berdasarkan SNI-7847:2012. Penelitian ini merupakan penelitian faktor tunggal dengan metode windrow composting berskala 500 kg dan menggunakan komposter kayu berukuran panjang 100 cm, lebar 80 cm, dan tinggi 70 cm. Rasio C/N awal ditetapkan senilai 30, komposisi bahan senilai 2:1 (sludge 333 kg : 167 kg abu). Co-composting dilakukan selama 32 hari dengan pembalikan setiap 3 hari sekali. Fase termofilik tercapai dengan suhu 51 oC. Karakter fisik kompos sesuai dengan SNI-7847:2012, dengan warna hitam dan aroma seperti tanah. Kadar air akhir kompos adalah 46,31%, pH kompos 6, dan rasio C/N produk kompos 15,64. Kompos tidak mengandung Coliform fecal dan Salmonella sp. Kandungan logam berat kompos berada dibawah baku mutu. Bobot akhir produk kompos sebesar 365,5 kg dengan rendemen 69,5%., PT Tanjungenim Lestari Pulp and Paper produced sludge waste (30 tons/day) and boiler ash (33.3 tons/day). The current waste management method used sanitary landfill. One alternative for waste utilization was through the co-composting process. This study aimed to analyze the characteristics of sludge and ash, design co-composting process engineering, and analyze the quality of compost product based on SNI-7847:2012. This study was a single-factor research using the windrow composting method on a scale of 500 kg and used a wooden box composter with dimensions of length 100 cm, widht 80 cm, height 70 cm. The initial C/N ratio was set at 30, the material composition of 2:1 (sludge 333 kg : 167 kg ash). Co-composting was carried out for 32 days with turning every 3 days. The thermophilic phase was reached at a temperature of 51 oC. The physical characteristics of the compost complied with SNI-7847:2012. With a black color and soil-like aroma. The final moisture content of the compost was 46.31%, the pH was 6, and the C/N ratio of the compost product was 15.64. The compost did not contain Coliform fecal and Salmonella sp. The heavy metal content of the compost was comply to the quality standards. The final weight of the compost product was 365.5 kg with a yield of 69.5%.
Keyword: abu ketel, co-composting, sludge, windrow

Judul: Desain Teknik Proses Co-composting Sludge, Abu Ketel dan Dregs PT Tanjungenim Lestari Pulp and Paper dengan Metode Windrow Composting
Abstrak: PT Tanjungenim Lestari Pulp and Paper menghasilkan limbah padat dalam jumlah besar diantaranya sludge 30 ton/hari, abu ketel 33,7 ton/hari dan dregs 3 ton/hari. Limbah ditangani dengan ditimbun langsung di sanitary landfill, diperlukan pemanfaatan lain agar bisa meminimalisir dampak limbah terhadap lingkungan dan menciptakan produk bernilai tambah. Limbah mengandung bahan organik yang dapat digunakan sebagai bahan baku co-composting. Co-composting merupakan metode pamanfaatan limbah dengan mencampurkan dua bahan atau lebih dengan bantuan mikroorganisme untuk mendekomposisi bahan. Penelitian dilakukan untuk mengetahui karakteristik limbah padat, merancang desain proses co-composting sludge, abu ketel dan dregs serta menganalisis mutu produk kompos sesuai dengan SNI-7847-2012. Co-composting dilakukan dengan menggunakan komposter berdimensi (100×80×70) cm untuk panjang, lebar dan tingginya. Berdasarkan nilai rasio C/N bahan didapatkan formulasi komposisi bahan untuk pengomposan adalah 2:1:1 dengan nilai rasio C/N awal yang ditetapkan 30. Co-composting dilakukan selama 32 hari dengan pemberian aerasi setiap 3 hari sekali. Produk kompos yang dihasilkan memiliki nilai rasio C/N sebesar 19,58. Nilai pH yang dihasilkan pada produk kompos adalah sebesar 5,75 dengan kadar air akhir 41,88%. Rendemen yang dihasilkan sebesar 75,1% dengan penyusutan 24,9%. Kompos yang dihasilkan memiliki warna kehitaman khas dregs dengan bau khas dregs pula. Kompos tidak mengandung bakteri pathogen Coliform fecal dan Salmonella sp., PT Tanjungenim Lestari Pulp and Paper produces a large amount of solid waste including sludge 30 tons/day, boiler ash 33.7 tons/day and dregs 3 tons/day. Waste is handled by being dumped directly in sanitary landfills, other utilization is needed in order to minimize the impact of waste on the environment and create value-added products. Waste contains organic matter that can be used as raw material for co-composting. Co-composting is a method of utilizing waste by mixing two or more materials using the help of microorganisms to decompose the material. The research was conducted to determine the characteristics of solid waste produced, design the process of co-composting sludge, boiler ash and dregs and analyze the quality of compost products in accordance with SNI-7847-2012. Co-composting was carried out using a composter with dimensions of 100 cm for length, 80 cm for width and 70 cm for height. Based on the C/N ratio value of the material, the material composition formulation for composting was 2:1:1 with the initial C/N ratio value set at 30. Co-composting was carried out for 32 days with aeration every 3 days. The resulting compost product has a C/N ratio value of 19.58. The pH value produced in the compost product was 5.75 with a final moisture content of 41.88%. The resulting yield was 75.1% with 24.9% shrinkage. The compost produced has a blackish color typical of dregs with a distinctive smell of dregs as well. The compost does not contain pathogenic bacteria Coliform fecal and Salmonella sp.
Keyword: abu ketel, co-composting, dregs, sludge, windrow

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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