Judul: Opportunities for Application of Cleaner Production in the Tofu Industry in Dairi Regency
Abstrak: Industri tahu merupakan salah satu industri kecil yang dapat menyebabkan pencemaran lingkungan karena adanya limbah dan loss pada proses produksi sehingga dilakukan peluang penerapan produksi bersih pada industri tahu. Penelitian ini bertujuan mengidentifikasi limbah dan peluang produksi bersih, menganalisis kelayakan dan menentukan prioritas peluang produksi bersih yang dihasilkan. Tahap penelitian yang digunakan adalah tahap quick scan, identifikasi masalah, dan penentuan peluang produksi bersih, melakukan analisis kelayakan secara teknis, lingkungan dan ekonomi (B/C Ratio dan PBP), dan menentukan prioritas penerapan produksi bersih melalui Metode Perbandingan Eksponensial. Proses pembuatan tahu terdiri dari beberapa tahap yaitu perendaman, pencucian, penggilingan dan penyaringan, pemasakan, penggumpalan, penyaringan, pencetakan, pengepresan dan pemotongan. Limbah yang terbentuk diakibatkan oleh adanya ceceran kedelai dan ceceran air selama proses produksi berlangsung. Alternatif produksi bersih adalah (1) menerapkan Good Manufacturing Practice (PBP 0,2 tahun, B/C 3,6) (2) memanfaatkan whey tahu menjadi nata de soya (PBP 0,37 tahun, B/C 3,9) (3) Recycle air pencucian dan perendaman (PBP 0,49 tahun, B/C 2,49 (4) pemanfaatan limbah cair menjadi biogas (PBP 0,28 tahun, B/C 6,48). Prioritas utama sebagai penerapan peluang produksi bersih adalah penerapan GMP, karena dianggap mudah untuk diterapkan dibandingkan dengan alternative lainnya. Kata kunci: MPE, produksi bersih, periode pengembalian modal, B/C ratio, tahu, The tofu industry is one of the small industries that can cause environmental pollution due to waste and loss in the production process, so a opportunities for clean production in the tofu industry is carried out. This study aims to identify waste and clean production opportunities, analyze the feasibility and determine the priority of the resulting clean production opportunities. The research phase used is a quick scan, problem identification, and determination of clean production opportunities, conducting technical, environmental and economic feasibility analysis (B/C Ratio and PBP), and determining priorities for implementing clean production through the Exponential Comparison Method. Making tofu consists of several stages, namely soaking, washing, grinding and filtering, cooking, clumping, filtering, printing, pressing and cutting. The waste formed is caused by the spilt soybeans and water spills during the production process. Alternatives for cleaner production are (1) applying Good Manufacturing Practices (PBP 0.2 years, B/C 3.6) (2) utilizing tofu whey into nata de soya (PBP 0.37 years, B/C 3.9) ( 3) Recycle washing and soaking water (PBP 0.49 years, B/C 2.49 (4) utilization of liquid waste into biogas (PBP 0.28 years, B/C 6.48). The main priority for clean production opportunities is the use of whey into nata de soya, because it is considered easy to implement compared to other alternatives. Keywords: B/C ratio, MPE, net production, payback period, tofu.
Keyword: B/C ratio, MPE, net production, payback period, tofu, The tofu industry is one of the small industries that can cause environmental pollution due to waste and loss in the production process, so a opportunities for clean production in the tofu industry is carried out. This study aims to identify waste and clean production opportunities, analyze the feasibility and determine the priority of the resulting clean production opportunities. The research phase used is a quick scan, problem identification, and determination of clean production opportunities, conducting technical, environmental and economic feasibility analysis (B/C Ratio and PBP), and determining priorities for implementing clean production through the Exponential Comparison Method. Making tofu consists of several stages, namely soaking, washing, grinding and filtering, cooking, clumping, filtering, printing, pressing and cutting. The waste formed is caused by the spilt soybeans and water spills during the production process. Alternatives for cleaner production are (1) applying Good Manufacturing Practices (PBP 0.2 years, B/C 3.6) (2) utilizing tofu whey into nata de soya (PBP 0.37 years, B/C 3.9) ( 3) Recycle washing and soaking water (PBP 0.49 years, B/C 2.49 (4) utilization of liquid waste into biogas (PBP 0.28 years, B/C 6.48). The main priority for clean production opportunities is the use of whey into nata de soya, because it is considered easy to implement compared to other alternatives. Keywords: B/C ratio, MPE, net production, payback period, tofu.

Judul: Kajian Peluang Penerapan Produksi Bersih Pada Industri Tahu Bandung (Studi Kasus di Industri Tahu PD XYZ Kota Serang)
Abstrak: Penelitian ini bertujuan untuk mengidentifikasi potensi efisiensi produksi dengan menganalisa penerapan produksi bersih pada proses produksi tahu. Metode yang digunakan diantaranya tahap wawancara atau quick scan, identifikasi limbah dan inefisiensi (loss), identifikasi peluang produksi bersih, dan analisis kelayakan dari aspek teknis, lingkungan, dan ekonomi, serta penentuan prioritas penerapan produksi bersih. Tahapan proses pembuatan tahu yaitu perendaman, pencucian, penggilingan, pemasakan, penyaringan dan pengepresan, penggumpalan, penyaringan, pencetakan, pengepresan dan pemotongan, serta pewarnaan. Limbah yang terbentuk pada proses pembuatan tahu adalah limbah padat dan limbah cair yangdihasilkan selama proses produksi berlangsung. Konsumsi energi pada bagian produksi sebesar 41,509 MJ/kg kedelai dan bagian non produksi sebesar 0,0313 MJ/kg kedelai. Alternatif produksi bersih yang direkomendasikan yaitu (1) pencucian kedelai secara bertahap dengan nilai PBP 0,13 tahun dan B/C ratio 4,7 (2) penerapan Good Manufacturing Practice dengan nilai PBP 0,12 tahun dan B/C ratio 5,28 (3) penggunaan boiler untuk pemasakan sistem uap dengan nilai PBP 0,13 tahun dan B/C ratio 4,2 (4) pembuatan pupuk organik cair dari whey dengan nilai PBP 0,01 tahun dan B/C ratio 4,3 (5) pemanfaatan limbah cair menjadi biogas dengan nilai PBP 0,29 tahun dan B/C ratio 3,6. Berdasarkan hasil dari pemilihan prioritas peluang produksi bersih yang dilakukan didapatkan prioritas pertama yaitu pembuatan pupuk organik cair dari whey, This research aims to identify the potential of production efficiency by analyzing the application of cleaner production to the tofu production process. The methods used include the interview or quick scan stage, identification of waste and inefficiency (loss), identification of cleaner production opportunities, and feasibility analysis of technical, environmental, and economic aspects, as well as prioritizing the implementation of cleaner production. The stages of tofu manufacturing process are soaking, washing, grinding, cooking, filtering and pressing, clumping, filtering, printing, pressing and cutting, and coloring. The waste formed in the tofu manufacturing process is solid waste and liquid waste produced during the production process. Energy consumption in the production section amounted to 41,509 MJ / kg ofsoybeans andnon-production parts of 0.0313 MJ / kg ofsoybeans. Recommended net production alternatives are (1) gradual soy washing with a PBP value of 0.13 years and B /C ratio of 4.7 (2) the application of Good Manufacturing Practicewith a PBP value of0.12 years anda B/C ratio of 5.28 (3) the use of boilers for steam system cooking with a PBP value of 0.13 years and a B/C ratio of 4.2 (4) making liquid organic fertilizer from whey with a PBP value of 0.01 years and B/C ratio of 4.3 (5) utilization of liquid waste into biogas with a PBP value of 0.29 years and a B/C ratio of 3.6. Based on the results of the selection of priority of cleaner production opportunities carried out, the first priority is the manufacture ofliquid organic fertilizer from whey.
Keyword: Cleaner Production, B/C ratio, Industry Tofu

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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