Judul: Co-Composting Process Engineering Design of Sludge, Boiler Ash, and Dregs at PT Tanjungenim Lestari Pulp and Paper using Aerated Static Pile Method
Abstrak: PT Tanjungenim Lestari Pulp and Paper menghasilkan limbah padat berupa sludge (30 ton/hari), abu ketel (33,7 ton/hari), dan dregs (3 ton/hari). Limbah yang dihasilkan ini belum diolah dengan baik. Sanitary landfill yang menjadi penanganan limbah saat ini tidak tepat untuk diterapkan ke depannya. Cocomposting dapat menjadi solusi terbaik untuk mereduksi limbah dalam jumlah besar berdasarkan kandungan organik pada bahan dan mengubahnya menjadi produk bernilai tambah. Penelitian ini bertujuan untuk merancang proses co-composting berupa campuran sludge:abu:dregs (2:1:1) dengan metode Aerated Static Pile (ASP). Pengomposan dilakukan pada skala 500 kg dengan menggunakan laju aerasi 0,4 L/menit.kg bahan. Kualitas produk kompos yang dihasilkan lalu dibandingkan dengan baku mutu pada SNI-7847:2012. Dari pengomposan yang telah dilakukan selama 32 hari, diperoleh produk kompos dengan suhu 28?, pH 5,75, kadar air 44,12%, dan rasio C/N sebesar 17,43. Berdasarkan parameter fisik, produk kompos memiliki warna dan bau khas dregs. Berdasarkan parameter kimia, produk kompos kurang memenuhi baku mutu pH dan c-organik. Produk kompos memenuhi baku mutu parameter biologi dan logam berat. Produk kompos yang dihasilkan belum memenuhi baku mutu warna, bau, dan pH, sehingga desain proses pengomposan yang dilakukan belum bisa menjadi acuan untuk peningkatan skala pengomposan., PT Tanjungenim Lestari Pulp and Paper produces solid waste such as sludge (30 tons/day), boiler ash (33.7 tons/day), and dregs (3 tons/day). These wastes are currently not well managed. The sanitary landfill currently used for waste disposal is not suitable for future application. Co-composting could provide the best solution to reduce large quantities of waste based on the organic content of the materials and convert them into value-added products. This research aims to design a cocomposting process using a mixture of sludge:ash:dregs (2:1:1) with the Aerated Static Pile (ASP) method. Composting was conducted on a 500 kg scale with aeration flow rate of 0.4 L/minute.kg of material. The compost product quality was compared to quality standards of SNI-7847:2012. After 32 days of composting, the compost product had a temperature of 28?, pH of 5.75, moisture content of 44.12%, and C/N ratio of 17.43. Based on physical parameters, the compost product had the characteristic color and odor of dregs. Based on chemical parameters, the compost product didn’t meet the quality standards for pH and c-organic. Compost product met quality standards of biology and heavy metal parameters. The compost product did not accord the quality standards for color, odor, and pH, indicating that the composting process design conducted cannot yet serve as a reference for scaling up composting operations.
Keyword: Boiler ash, co-composting, sludge, dregs, process design

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: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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