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: 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: Pengaruh vaksinasi terhadap dinamika populasi pada model SIR (Susceptible-Infected-Recovered)
Abstrak: SIR model can be used to model the spread of diseases in a closed population based on certain assumptions. In this research, the SIR model is formulated by including the factor of vaccination. As the result, the model has been shown to have two equilibrium points, i.e. disease free and endemic equilibrium. A simulation study is carried out to illustrate the model. The results show that some equilibrium points are asymptotically stable. Moreover, a minimum level of vaccination has been defined. For the vaccination level less than the minimum level, increase in the vaccination level results in decrease of the proportion of infected individuals in the corresponding equilibrium point. On the other hand, for the vaccination level greater than the minimum level, increase in the vaccination level results in decrease the proportion of susceptible individuals in the corresponding equilibrium point. Furthermore, when vaccination level is greater than the minimum level, it is found that the time needed for the disease to extinct is shorter.
Keyword: