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: Desain Teknik Proses Co-composting Sludge dan Abu Ketel dan Dreg PT Tanjungenim Lestari Pulp and Paper dengan Metode Aerated Static Pile
Abstrak: PT Tanjungenim Lestari Pulp and Paper menghasilkan limbah padat yaitu sludge (30 ton/hari) dan abu ketel (33,3 ton/hari). Metode sanitary landfill yang digunakan saat ini sudah tidak efektif. Salah satu metode pemanfaatan limbah adalah 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 Aerated Static Pile (ASP) skala 500 kg dengan komposter berbahan kayu berdimensi panjang 100 cm, lebar 80 cm, dan tinggi 70 cm. Rasio C/N awal ditetapkan yaitu 30 sehingga berdasarkan formulasi, komposisi bahan senilai 2:1 (sludge 333 kg : 167 kg abu). Co-composting selama 32 hari mencapai fase termofilik dengan suhu 53?. Pemberian aerasi dilakukan melalui aerator selama 2 jam 6,4 menit/hari untuk meningkatkan laju degradasi oleh mikroorganisme. Karakteristik fisik kompos sesuai SNI-7847-2012 yaitu suhu kompos sama dengan ambien, berwarna hitam, beraroma seperti tanah, Kadar air 48,91%, pH 6, Rasio C/N 15,83. Kompos tidak mengandung Coliform fecal dan Salmonella sp.. Bobot akhir produk kompos sebesar 394 kg dengan rendemen 75%.
Keyword: Boiler ash, co-composting, sludge, Aerated Static Pile

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model