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 (Studi Kasus: Industri Tahu X Kota Gorontalo)
Abstrak: Industri tahu X memiliki permasalahan pada kegiatan produksi, seperti inefisiensi penggunaan bahan baku, energi dan proses produksi menghasilkan limbah padat maupun cair. Penelitian ini bertujuan mengidentifikasi sumber terbentuknya limbah dan inefisiensi pada setiap proses produksi tahu, mengidentifikasi peluang penerapan produksi bersih, menganalisis kelayakannya serta memberikan rekomendasi peluang penerapan produksi bersih. Metode yang digunakan adalah mengidentifikasi kondisi umum industri, menganalisis tahapan proses produksi, menganalisis peluang penerapan produksi bersih, menganalisis kelayakan berdasarkan aspek teknis, aspek ekonomi dan aspek lingkungan, serta memberikan rekomendasi produksi bersih. Hasil penelitian mengidentifikasi permasalahan pada beberapa aspek, yaitu teknologi, proses produksi, tata laksana dan limbah. Alternatif yang direkomendasikan, mencakup pengadaan alat penyaring otomatis, penggunaan troli dorong untuk penanganan bahan, pencucian secara bertahap dan penyaringan kembali sisa air pencucian dan perendaman, penerapan Good Manufacturing Practice (GMP), pemanfaatan whey menjadi nata de soya dan pemanfaatan limbah cair menjadi pupuk organik cair. Penerapan produksi bersih dapat meningkatkan produksi tahu dari 5400 potong tahu menjadi 5481 potong tahu/100 kg kedelai, pengurangan limbah cair yang dihasilkan dan dibuang ke lingkungan berkurang dari 53,46 m3 /bulan menjadi 30,68 m3 /bulan energi listrik dari 11,16 MJ/100 kg menjadi 9,3 MJ/100 kg kedelai, total peningkatan keuntungan yang diperoleh industri sebesar Rp.5.266.320., Tofu X industry has problems in production activities, such as inefficiency in using raw materials and energy, and the production process produces solid and liquid waste. This study aims to identify sources of waste formation and inefficiency in each tofu production process, identify opportunities for implementing clean production, analyze their feasibility and provide recommendations for implementing clean production. The method used is to identify the general condition of the industry, analyze the stages of the production process, analyze opportunities for implementing clean production, analyze feasibility based on technical aspects, economic aspects, and environmental aspects, and provide recommendations for clean production. The study results identified problems in several aspects, namely technology, production processes, management, and waste. The recommended alternatives include the procurement of automatic filters, the use of push trolleys for material handling, gradual washing and re-filtration of the remaining washing and soaking water, the application of Good Manufacturing Practice (GMP), the use of whey into nata de soya and the utilization of liquid waste into liquid organic fertilizers. The application of clean production can increase the production of tofu from 5400 pieces of tofu to 5481 pieces of tofu/100 kg of soybeans. The reduction of liquid waste generated and discharged into the environment is reduced from 53.46 m3/month to 30.68 m3/month of electrical energy from 11.16 MJ/100 kg to 9.3 MJ/100 kg soybeans, the total increase in profits obtained by the industry is Rp. 5,266.320.
Keyword: clean production, feasibility analysis, tofu industry

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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