Judul: Pencirian dan Pengolahan Fine Coal dengan Poliakrilamida sebagai Flokulan
Abstrak: Fine coal merupakan hasil samping proses produksi batu bara yang tidak dimanfaatkan dan tertimbun sebagai limbah. Sebelum dapat dimanfaatkan, fine coal perlu dicirikan dan diolah terlebih dulu. Penelitian ini menggunakan 2 sampel fine coal dari kolam penampungan yang sama, di 2 titik lokasi yang berbeda. Sampel memiliki kadar abu 33% dan 32% serta zat terbang 64% dan 68%. Tidak terdeteksi logam berat Cr dan Cd, serta ditemukan gugus fungsi yang serupa dengan batu bara (rantai alifatik, cincin aromatik, dan karboksilat). Poliakrilamida (PAM) digunakan sebagai flokulan. Polimer ini dipilih karena bersifat hidrofilik, sehingga mudah larut dalam fase koloid fine coal. PAM nonionik dan anionik dibandingkan untuk mengetahui interaksi amonium aluminium sulfat (tawas) sebagai koagulan dengan kedua jenis PAM tersebut. Kekeruhan fine coal setelah koagulasi dan flokulasi diukur secara turbidimetri. Kekeruhan terendah ialah 128 NTU, yang diperoleh dengan konsentrasi tawas 250 mg/L dan PAM nonionik 25 mg/L. Nilai tersebut lebih rendah dibandingkan dengan batas maksimum kekeruhan yang ditetapkan Keputusan Menteri Negara Lingkungan Hidup No 113/2003, yaitu 400 NTU.
Keyword: fine coal, flokulasi, poliakrilamida

Judul: Pengolahan Fine Coal dan Aplikasinya sebagai Briket
Abstrak: Fine coal is a by-product of coal washing, which is not utilized and nearly 2 billion tons per year of fine coal is waste. The objectives of the research are to treatment fine coal using centrifugation and coagulation-flocculation and use it to produce briquette. The fine coal was treated using centrifugation in laboratory scale. Coagulation-flocculation steps used alum as coagulant with starch (nonionic polymer) and sulfate starch (anionic polymer) as flocculants. Coagulationflocculation using alum-starch was more effective than that of using centrifugation and alum-starch sulfate based on the highest turbidity reduction efectiveness of 99.96%. The results of this test showed that particles of fine coal thought to be negatively charged. The fine coal was then applied to produce briquette using tapioca flour as binding material at concentration of 3%, 5%, and 10%. Characterization of the fine coal briquette showed that the volatile matter and ash content did not meet the coal briquette standard, as stipulated in Permen ESDM No 47/2006
Keyword: Bogor Agricultural University (IPB), starch, flocculation, fine coal, coagulation, briquette

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