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: 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: Lejeuneaceae Subfamily Ptychanthoideae (Hepaticae) in  West Java
Abstrak: Subfamily Ptychanthoideae of the family Lejeuneaceae (Hepaticae) in West Java is still poorly known. Publications on this subfamily are out of dated and written in the 19th or early of 20th century. The last taxonomic treatment of Ptychanthoideae of West Java was in 1933, many species names have changed since then. Studies on Ptychanthoideae of West Java are urgently needed. Studies on the Ptychanthoideae were based on the specimens collected from West Java. A total number of 361 of specimens deposited in the Herbarium Bogoriense (BO), Herbarium Biotrop (BIOT), Gottingen Herbarium (GOET) and Bangi Herbarium (UKMB) were examined, those are old and several recent specimens collected in West Java. Recent collections were made from Telaga Warna, Ciater, Gunung Halimun Salak National Park, Cibodas Botanical Garden, Bodogol Education Center and Conservation (Gunung Gede Pangrango National Park), University of Indonesia Campus Depok, including several collections from Banten Province. Twenty four species of Lejeuneaceae subfamily Ptychanthoideae are known from West Java, belonging to 8 genera namely Acrolejeunea (Spruce) Schiffn. (2 species), Archilejeunea (Spruce) Schiffn. (1 species), Lopholejeunea (Spruce) Schiffn. (10 species), Mastigolejeunea (Spruce) Schiffn. (3 species), Ptychanthus Nees (1 species), Schiffneriolejeunea Verd. (1 species), Spruceanthus Verd. (2 species) and Thysananthus Lindenb. (4 species). Two new records of Ptychanthoideae: Mastigolejeunea indica Steph. and Thysananthus minor Verdoorn are reported for Java. A determination key to the species is presented including their descriptions and illustrations.
Keyword: