Judul: Penentuan Kriteria Variabel Operasional Unit Sedimentasi Limbah Cair Industri Kertas Berdasarkan Tipe Pengendapan Lumpur Aktif
Abstrak: Secondary sedimentation unit in activated sludge is often used due to high concentration of biomass as an effect from organic material degradation with biological process. The sedimentation process is divided into four types of, there are discrete particle settling, flocculant settling, hindered settling and compression settling. The study of sedimentation types is for determining operational variables criteria of secondary sedimentation unit and give a recommendation about unit capacity in the field scale. This study use three variation of HRT in order to know it’s impact to particles characteristic and settling velocity. The result of this study show that particles in paper mill wastewater has an ability to turn into floc naturally and increase the settling velocity, although flocullant and coagulant still needed to maximize TS reduction. In order to fulfill requirements of the optimum area, lowest cost instalation, and the optimum efficiency, then the operation of activated sludge secondary sedimentation was carried out with HRT of 6 hour, SLR limit of 102,46 kg/ m2.day, and an HLR of 42,16 m3/ m2.day., Unit sedimentasi sekunder di dalam lumpur aktif diperlukan karena tingginya konsentrasi biomassa akibat degradasi material organik limbah cair industri kertas secara biologis. Proses pengendapan di dalam sedimentasi sekunder terbagi menjadi empat tipe pengendapan, yaitu discrete particle settling, flocculant settling, hindered settling dan compression settling. Penelitian keempat tipe pengendapan bertujuan untuk menentukan kriteria variabel operasional unit sedimentasi sekunder dan memberi rekomendasi kapasitas pengolahan limbah cair untuk skala lapangan. Penelitian ini dilakukan dengan menerapkan 3 variasi HRT, yaitu HRT 6 jam, 8 jam, dan 12 jam untuk mengetahui pengaruh perubahan HRT terhadap karakteristik partikel dan kecepatan pengendapan. Hasil penelitian menunjukkan bahwa partikel limbah cair industri kertas memiliki kecenderungan untuk membentuk flok secara alami dan meningkatkan kecepatan pengendapan, meskipun pembubuhan flokulan dan koagulan tetap dibutuhkan untuk memaksimalkan reduksi TS. Sebagai upaya memenuhi kebutuhan luas area optimum, biaya instalasi terendah, dan efisiensi unit terbaik, maka operasional unit sedimentasi sekunder lumpur aktif dijalankan dengan HRT 6 jam, SLR 102,46 kg/m2.hari, dan HLR sebesar 42,16 m3/m2.hari.
Keyword: compression settling, discrete particle settling, flocculant settling, hindered settling

Judul: Determination of Sedimentation Unit Design Parameters Based on the Settling Type Model of Coagulation-Flocculation Process Results in Paper Industry Wastewater
Abstrak: Teknologi pengolahan koagulasi-flokulasi merupakan opsi teknologi yang sering digunakan untuk pengolahan limbah kertas. Unit koagulasi dan flokulasi membutuhkan unit sedimentasi untuk mengendapkan flok berupa padatan tersuspensi dan material organik. Parameter yang diamati pada penelitian ini adalah Total Solid (TS) dan Chemical Oxygen Demand (COD). Dalam perancangan unit sedimentasi, empat tipe pengendapan digunakan untuk analisis sedimentasi, yakni tipe discrete settling, tipe flocculant settling, tipe hindered settling, dan tipe compression settling. Analisis empat tipe pengendapan akan menghasilkan parameter desain unit sedimentasi seperti surface overflow rate (SOR), kecepatan pengendapan, solid loading rate dan waktu detensi. Pada hasil analisis, nilai efisiensi penyisihan partikel TS pada setiap sampel berkisar antara 35-80%. Nilai SOR pada bak pengendapan diketahui berkisar antara 3-11 m3/m2∙hari. Kecepatan pengendapan berkisar antara 0,002-0,006 m/menit dan waktu detensi menghasilkan nilai sebesar 22-69 menit. Nilai parameter tersebut kemudian akan dianalisis menjadi nilai dimensi unit sedimentasi berdasarkan sampel yang memiliki nilai penyisihan TS paling besar., The coagulation-flocculation treatment is a technology that often used for paper and pulp wastewater treatment. The coagulation and flocculation unit requires a sedimentation unit to precipitate the floc in form of suspended solids and organic matter. Observed parameters in this study were Total Solid (TS) and Chemical Oxygen Demand (COD). It is necessary to analyze the four types of sedimentation, such as discrete settling, flocculant settling, hindered settling, and compression settling. The analysis of settling types will be resulting in parameters of the sedimentation unit design such as surface overflow rate, settling velocity, solid loading rate and detention time. In the analysis results, it is known that the efficiency of TS particle removal in each sample ranges from 35-80%. For the surface overflow rate in the settling basin ranges from 3-11 m3 /m2 ∙day. Settling velocity values ranged from 0,002-0,006 m/min and detention time parameter produces a value of 22-69 minutes. These parameter values will be analyzed into the design values in form of sedimentation unit design based on the sample with the largest TS removal value.
Keyword: coagulation, flocculation, particle, sedimentation, settling

Judul: Mitochondrial DNA Gene Organization and Phylogenetic Relationship of Naja siamensis
Abstrak: Naja siamensis is one of Asiatic cobra in the Family of Elapidae, known as a cryptic snake. It has many morphological variations that lead to misidentification. Misidentification can cause the wrong concept in developing antivenom types due to high snakebite cases occur in Thailand. Thus, an accurate species identification using a molecular approach is crucially required. Mitochondrial DNA has been used widely in snake molecular studies. These studies were aimed to determine the arrangement of the N. siamensis partial mitochondrial genes using reptile-oriented primers and to reveal the phylogenetic relationship among other species of Asian cobra. DNA extraction was carried out based on the standard DNA salting-out protocol and was conducted by bioinformatics analysis using BLASTn and MEGA 6 software. Gene annotation was performed against N. kaouthia complete genome. A total of 3121 bp of N. siamensis mtDNA genes were sequenced consisting of partial of six regions: 16S rRNA, ND1, tRNA-Ile, CRII region, tRNA-Leu, tRNA-Gln, and COI genes. The mtDNA gene organization of N. siamensis was predicted to has a similar pattern with the common Elapidae mtDNA gene organization. This study showed that there is a monophyletic form in Naja genus and N. kaouthia is the closest species with N. siamensis based on partial 16S rRNA and ND1 gene.
Keyword: 16S rRNA, Elapidae, ND1, phylogenetic relationship