Judul: Utilization of Biodiesel Transesterification Waste as an  Additive to Improve the Quality of Biopellets
Abstrak: Energi alternatif yang potensial untuk dikembangkan salah satunya yaitu energi berbahan dasar limbah, seperti limbah biodiesel, sampah daun kering, dan kertas bekas dengan mengolahnya menjadi biopelet. Pengoptimalan pemanfaatan limbah biodiesel sebagai aditif merupakan upaya yang dapat dilakukan untuk meningkatkan mutu, terutama nilai kalor biopelet. Penelitian ini bertujuan membuat, melakukan pegujian mutu dan analisis karakteristik biopelet sebagai energi bahan bakar alternatif yang ramah lingkungan. Perbandingan formulasi bahan yang digunakan yaitu A1 sebagai kontrol (100% daun kering), A2 (70% daun kering : 20% limbah biodiesel : 10% kertas), A3 (65% daun kering : 25% limbah biodiesel : 10% kertas), A4 (60% daun kering : 30% limbah biodiesel : 10% kertas), A5 (55% daun kering : 35% limbah biodiesel : 10% kertas), dan A6 (50% daun kering : 40% limbah biodiesel : 10% kertas). Parameter nilai mutu biopelet mengacu pada SNI 8675:2018. Formulasi terbaik diperoleh pada perlakuan A6 dengan nilai kerapatan 0,7 g/cm3, kadar air 13,1%, ketahanan 97,6%, kadar zat terbang 58,3%, kadar abu 7,6%, karbon terikat 34,1%, nilai kalor 17,8 MJ/kg, laju pembakaran 1,42 kg/jam, dan rasio energi sebesar 3,577 yang menunjukkan energi hasil produk biopelet lebih tinggi dari keperluan energi untuk proses produksinya (energi listrik dan manusia). Penambahan limbah biodiesel hasil samping transesterifikasi berpengaruh positif dalam meningkatkan mutu biopelet, terutama pada nilai kalor, karbon terikat, kerapatan dan ketahanan., One of the potential alternative energies to be developed is waste-based energy, such as biodiesel waste, dry leaf waste, and used paper by processing them into biopellets. Optimizing the utilization of biodiesel waste as an additive is an effort that can be made to improve quality, especially the calorific value of biopellets. This study aims to manufacture, conduct quality testing and analyze the characteristics of biopellets as an alternative fuel energy that is environmentally friendly. Comparison of the formulation of the ingredients used, namely A1 as a control (100% dry leaves), A2 (70% dry leaves: 20% biodiesel waste: 10% paper), A3 (65% dry leaves: 25% biodiesel waste: 10% paper), A4 (60% dry leaves : 30% biodiesel waste : 10% paper), A5 (55% dry leaves : 35% biodiesel waste : 10% paper), and A6 (50% dry leaves : 40% biodiesel waste : 10% paper ). The parameters for the quality value of biopellets refer to SNI 8675:2018. The best formulation was obtained in A6 treatment with a density value of 0.7 g/cm3, moisture content 13.1%, durability 97.6%, volatile matter content 58.3%, ash content 7.6%, bound carbon 34.1%, calorific value 17.8 MJ/kg, combustion rate 1.42 kg/hour, and an energy ratio of 3.577 which indicates that the energy produced by the biopellet product is higher than the energy required for pelletizing process (electrical and human energy). The addition of biodiesel waste as a by-product of transesterification has a positive effect on improving the quality of biopellets, especially on calorific value, bound carbon, density and durability.
Keyword: biomassa, biopelet, daun kering, kertas bekas, limbah biodiesel

Judul: Study of Tea Dregs Biopellet with Biodiesel Transesterification Waste as Additive to Improve Quality
Abstrak: The production of packaged tea drinks produces tea dregs which can be used as fuel in the form of biopellets as an environmentally friendly alternative energy. The process of making biodiesel using the transesterification method produces a by-product in the form of a mixture of glycerol, methanol, and a catalyst (KOH). The by-product waste has the potential to be reused, one of which is as an additive in the manufacture of biopellets. This study aims to analyze and characterize tea dregs biopellets with biodiesel waste as an additive to increase the quality value and find out the best formulation for each treatment. Comparison of the formulations used, namely A0 as control (90% tea dregs: 10% adhesive), A1 (85% tea dregs: 5% biodiesel waste: 10% adhesive), A2 (80% tea dregs: 10% biodiesel waste: adhesive 10%), A3 (75% tea dregs: 15% biodiesel waste: 10% adhesive), A4 (70% tea dregs: 20% biodiesel waste: 10% adhesive), and A5 (65% tea dregs: 25% biodiesel waste : adhesive 10%). The parameter value of the quality of the biopellet refers to the SNI 8675:2018 standard. The best formulation was obtained in treatment A2 with a density value of 0.91 g/cm3 , 98.08% resistance, 6.96% moisture content, 73.37% volatile matter content, 6% ash content, with calorific value of 15.05 MJ/kg. The addition of biodiesel waste up to 10% as an additive was proven to be able to improve the quality of tea dregs biopellet., Produksi minuman teh kemasan menghasilkan limbah ampas teh yang dapat dimanfaatkan sebagai bahan bakar berupa biopelet sebagai energi alternatif yang ramah lingkungan. Proses pembuatan biodiesel dengan metode transesterifikasi menghasilkan hasil samping berupa campuran gliserol, metanol, dan katalis (KOH). Limbah hasil samping tersebut memiliki potensi untuk dimanfaatkan kembali, salah satunya sebagai aditif dalam pembuatan biopelet. Penelitian ini bertujuan untuk melakukan analisis dan karakterisasi biopelet ampas teh dengan limbah biodiesel sebagai aditif untuk meningkatkan nilai mutu serta mengetahui formulasi terbaik dari setiap perlakuan. Perbandingan formulasi bahan yang digunakan yaitu A0 sebagai kontrol (ampas teh 90% : perekat 10%), A1 (ampas teh 85% : limbah biodiesel 5% : perekat 10%), A2 (ampas teh 80% : limbah biodiesel 10% : perekat 10%), A3 (ampas teh 75% : limbah biodiesel 15% : perekat 10%), A4 (ampas teh 70% : limbah biodiesel 20% : perekat 10%), dan A5 (ampas teh 65% : limbah biodiesel 25% : perekat 10%). Parameter nilai mutu biopelet mengacu kepada standar SNI 8675:2018. Formulasi terbaik diperoleh pada perlakuan A2 dengan nilai kerapatan 0,91 g/cm3 , ketahanan 98,08%, kadar air 6,96%, kadar zat terbang 73,37%, kadar abu 6%, dengan nilai kalor yaitu 15,05 MJ/kg. Penambahan limbah biodiesel hingga 10% sebagai aditif, terbukti mampu meningkatkan mutu biopelet ampas teh.
Keyword: additive, biodiesel waste, biopellet, tea dregs

Judul: Implementation of Spatio-Temporal Change Query in Relational Database.
Abstrak: Geographic object changes in various views. Object changes are recorded using a model of static storage. No historical connection between old version data and new version data has been built. For that, a storage model of spatio-temporal queries that can analyze spatio-temporal changes has been developed. The object changes the geometry are grouped according to the taxonomy of Spatio-Temporal Pattern Change. This research has been able to apply the query patterns change including born, expand, merge, contract, split, normal and die. This query based on geometric (area) changes. The implementation of spatio-temporal change queries represents an object changes continuously with easy, change detection is done by comparing two versions of data. Keyword: spatio-temporal change query, spatio-temporal change pattern.
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