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Abstrak :
Hydrodynamic charactersitic for the mixing of gas-solid-liquid in membrane bioreactor submerged (MBRs) and its influence on mass transfer was studied computationally at various solid concentration, incoming gas rate and the befle distance......

Abstrak :
Mathemathical simulations on dam break or failure using BOSS DAMBRK hydrodynamic flood routing dam break model were carried out to determine the extent of flooding downstream,flood travel times flood water velocities and impacts on downstream affected residences, properties and environmental sensitive areas due to floodwaters released by failure or them dam structure....

Abstrak :
Pada penelitian ini, kavitasi (hidrodinamika dan ultrasonik) dimanfaatkan untuk mengatasi kelemahan ozonasi, yaitu kelarutan dan stabilitas yang rendah di dalam air serta selektivitasnya. Peran kavitasi dikaji dalam memperbaiki perpindahan massa ozon dari fasa gas ke fasa cair, meningkatkan jumlah radikal OH melalui dekomposisi ozon dan kinerjanya dalam mengolah senyawa fenol. Dalam rentang kondisi yang diterapkan dalam penelitian ini, hasil penelitian menunjukkan bahwa koefisien perpindahan massa (kLa) ozon meningkat sekitar 3,5 kali, 7,5 kali dan 20 kali dari kLa ozonasi tunggal karena efek total kavitasi masing-masing untuk penggunaan kavitasi hidrodinamika (HD), kavitasi ultrasonik (US) dan keduanya (HD + US) simultan; dimana efek kimiawi lebih signifikan perannya dalam peningkatan nilai kLa. Laju dekomposisi ozon meningkat 20%-40% dengan penggunaan kavitasi. Yield radikal OH meningkat 3,3 kali, 3,8 kali dan 4,4 kali dari hasil proses ozonasi tunggal masing-masing dengan pemakaian kavitasi HD, kavitasi US dan kavitasi HD + US. Yield fenol tidak mengalami perubahan berarti dengan penggunaan kavitasi. Namun, tingkat mineralisasi meningkat hingga sekitar 2 kali dengan penggunaan kavitasi tunggal, dan 3,3 kali dengan penggunaan kavitasi secara simultan. Kavitasi meningkatkan utilisasi ozon, dimana kavitasi HD menunjukkan utilisasi tertinggi yaitu 4,45 mg/menit. Selain menghasilkan produk-produk oksidasi yang bersifat asam ? dibuktikan dengan penurunan pH ? proses ozonasi dan gabungannya dengan kavitasi menghasilkan senyawa-senyawa rantai panjang.

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This research utilized ultrasonic and hydrodynamic cavitations to overcome the the drawbacks of ozonation process, which are low solubility and stability of ozone in water and its selectivity. The role of cavitations was assessed in enhancing ozone mass transfer, increasing radical production from ozone decomposition and improving the performance of phenol removal. In the range of conditions limited in this research, the results shows that ozone mass transfer coefficient (kLa) enhanced about 3.5, 7.5 and 20 times of kLa of single ozonation due to total effects of cavitations respectively for utilization of hydrodynamic (HD), ultrasonic (US) and both kinds (HD + US) of cavitations simultaneously. The role of chemical effect was more significant than mechanical effect in enhancing kLa . Cavitations increased ozone decomposition rate by 20%-40%. The yield of OH radicals increased 3.3, 3.8 and 4.4 times of it was from single ozonation respectively for utilization of HD, US and (HD + US) cavitations. The yield of phenol was not changed significantly by utilization of cavitations. However, mineralization ability improved about 2 times for utilization of only one kind of cavitation, and about 3.3 times for utilization both kinds of cavitation simultaneously. Cavitations improved ozone utilization, where application of HD cavitation was the highest by 4.45 mg/menit. Ozonation of phenol and its combinations with cavitations produced acidic intermediate compounds which was indicated by pH reduction along the process. And they also produced higher (long-chained) compounds.

Abstrak :
Hidrodinamika merupakan sifat dasar dari sistem yang diperlukan untuk mengklasifikasikan sistem unggun terfluidisasi tiga fasa. Parameter-parameter yang termasuk di dalamnya adalah waktu tinggal, hold up dan koefisien dispersi aksial, dimana nilainya diperoleh dari serangkaian percobaan dengan menggunakan metode tracer untuk penentuan waktu tinggal, metode penangkapan gas dan cairan secara simultan untuk penentuan hold up, sedangkan koefisien dispersi aksial diperoleh dari hubungan antara bilangan Peclet dan hold up fasa cair.

Teknik untuk menentukan harga waktu tinggal dari kolom fluidisasi G-C-P yaitu dengan cara menginjeksikan bahan kimia yang bersifat inert, yang disebut sebagai tracer, ke dalam kolom pada waktu t = 0 kemudian konsentrasinya diukur pada aliran keluar sebagai timgsi waktu. Metode ini disebut sebagai metode tracer.

Sedangkan penelitian dengan menggunakan metode penangkapan gas dan cairan secara simultan melibatkan penutupan katup aliran gas dan cairan yang masuk ke dalam kolom secara serentak, kemudian diukur ketinggian kolom yang terisi oleh tiap fasa Metode ini dilakukan untuk sistem gas-cair-padat dan sistem gas-cair.

Dari hasil percobaan diketahui bahwa kecepatan air dan udara serta ukuran diameter partikel mempengaruhi waktu tinggal, hold :gp tiap fasa dan tingkat dispersi dalam aliran. Semakin besar lcecepatan fluida cair maupun gas, maka harga waktu tinggal semakin kecil, dan semakin kecil diameter partikel harga walctu tinggal akan semakin besar_ Kecepatan air yang semakin besar akan menyebabkan hold up cairan meningkat, sedangkan hold :go gas dan padatan akan menunm. Semakin besar kecepatan udara maka hold :go gas dan padatan akan meningkat, sedangkzm hold iq; cairan akan menurun Sedangkan pengaruh diameter partikel rnemherikan hasil semakin besar ukuran diameter partikel maka hold up gas dan cairan akan menumn, sedangkan hold up padatan meningkat. Intensitas dispersi akan meningkat dengan bertambahnya kecepatan udara dan ukuran diameter partikel serta dengan berkurangnya kecepatan cairan.

Abstrak :
Pada Standar Nasional Indonesia (SNI) Jembatan dan ACSE-24 mengenai Flood Resistant Design Construction disebutkan bahwa adanya pengaruh scouring terhadap desain jembatan, namun belum ada langkah-langkah yang jelas untuk menghitungnya. Penelitian ini akan membahas mengenai langkah perhitungan scouring yang terjadi di sekitar pondasi menggunakan metode California State University (CSU) dan bagaimana pengaruhnya terhadap beban hidrodinamika yang terjadi pada pondasi menggunakan persamaan hukum kekekalan momentum dan hukum kekekalan massa. Penelitian ini menggunakan alat bantu aplikasi SAP2000 untuk mengetahui besarnya defleksi yang terjadi serta dibandingkan dengan defleksi izin agar tidak terjadi kegagalan struktur pondasi jembatan. Variabel yang diuji coba pada penelitian ini diantaranya massa jenis, curve number, periode ulang, durasi terjadinya hujan, koefisien Manning, dan tinggi inflow. Data variabel tersebut divariasikan untuk mengetahui variabel mana yang paling sensitif terhadap scouring dan defleksi yang terjadi dengan melakukan sensitivity analysis menggunakan metode korelasi Pearson. Hasil penelitian menunjukkan adanya pembesaran luas kontak gaya yang bekerja sehingga perlu diperhitungkan debit kritis yang menghasilkan defleksi maksimum yang terjadi pada pondasi. ......In the Standar Nasional Indonesia (SNI) for Bridge and ACSE-24 about Flood Resistant Design Construction, it is mentioned that there is a scouring effect on the bridge design, but there are no clear steps to calculate it. This study will discuss the steps of scouring calculation that occur around the foundation using the California State University (CSU) method and how they affect the hydrodynamic load that occurs on the foundation using the law of conservation of momentum and the law of conservation of mass. This study uses SAP2000 application tools to determine the magnitude of the deflection that occurred and compared with permit deflection so that the bridge foundation structure doesn’t fail. The variables tested in this study include density, curve number, return period, duration of rainfall, Manning coefficient, and inflow height. The variable data is varied to find out which variable is most sensitive to scouring and deflection that occurs by conducting sensitivity analysis using the Pearson correlation method. The results showed an enlargement of the area of ​​contact force that worked so it was necessary to calculate the critical discharge which produced the maximum deflection that occurred at the foundation.

Abstrak :
Telah dilaporkan bahwa kinerja pengolahan di kolam fakultatif di Instalasi Pengolahan Air Kotor (IPAK) Bojongsoang adalah tidak stabil. Salah satu penyebabnya adalah karakteristik hidrodinamika yang tidak sesuai dengan criteria. Yang termasuk dalam karakteristik hidrodinamika yang tidak tepat antara lain kehadiran daerah mati, aliran pendek, dan turbulensi oleh arus eddy. Penelitian ini bertujuan untuk menganalisa pengaruh variasi debit influen terhadap karakteristik hidrodinamika menggunakan model matematis. Model hidrodinamika dua dimensi dibangun dari dua persamaan hidrodinamika, yaitu persamaan kontinuitas dan persamaan momentum. Kedua persamaan diselesaikan dengan metoda numerik beda hingga semi implisit (Crank-Nicolson). Dari hasil simulasi, dianalisa nilai bilangan Froude aliran serta waktu tinggal efektif dan luas efektif kolam fakultatif untuk melihat kehadiran daerah mati. Hasil simulasi menunjukkan bahwa daerah mati terdapat di tengah kolam. Apabila debit influen semakin besar, waktu tinggal efektif dan luas efektif semakin besar. Selain itu, distribusi nilai bilangan Froude menunjukkan bahwa nilai 10-10 semakin berkurang bila debit influen semakin besar. Dapat dikatakan bahwa daerah mati akan berkurang pada debit influen yang lebih besar. Dengan demikian debit influen yang semakin besar akan memperbaiki karakteristik hidrodinamika di kolam fakultatif.

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The Effects of Influent Debit on Hydrodynamic Characteristic of Bojongsoang Facultative Pond: Without Wind Effects. The performance of facultative pond in Bojongsoang WWTP have reported to be unstable. One of the cause of the unstable performance is the hydrodynamic characteristics that not met the criterion. The improper hydrodynamic characteristics are included the existence of dead-zone, the short-circuiting, and the turbulence due to eddy current. The study was to analyze the effect of the influent debit variation on the hydrodynamic characteristics of the pond using mathematical model. The two-dimensional hydrodynamic model was built from two hydrodynamic equations which are continuity and momentum equations. The equations were solved by finite-difference numerical method of semi-implicit (Crank-Nicolson). From the simulation results, the Froude number of the water flow was analyzed. Beside that, the effective residence time and the effective area were calculated. All of them were done to analyzed the existence of the dead-zone in the pond. The simulation results show that the dead-zone was exist in the center of the pond. when the influent debit was larger, the effective residence time and the effective area become larger. The distribution of the Froude number value shows that the area with the value of 10-10 become reduced in the larger influent debit. The existence of the dead-zone was reduced since the influent debit become larger. It can be said that the larger influent debit can improve the hydrodynamic characteristics of the pond.

Abstrak :
ABSTRAK
The study assumes that Srinagarind Dam of Kanchanaburi province will be collapsed by overtopping with a final breach of trapezoidal shape due to heavy rainstorm. Subsequently, various forms of demolitions and dynamic flooding are identified using Dam Break and Hydrodynamic models of MIKE 11 by applying the principle of the Probable Maximum Flood (PMF). Srinagarind dam is a rock fill dam with it is crest at +185.00 m. from Mean Sea Level (MSL) and store a maximum volume of 17,745 million m3 of water at the beginning of the break. For dynamic flooding prediction, the maximum breach outflow discharge was 11,307 m3/s with a velocity of 5.39 m/s at 62.29 hours after the break. In addition, the maximum discharge, water level and flood duration at cross sections of main rivers are also extracted for flood zone identification into 4 zones which include: at Ban Phu Thong Maeo, Wang Dong Sub-district, Mueang Kanchanaburi district, the discharge is 14,231 m3/s, the maximum water level is +56.56 m. (MSL.) at 68.28 hr. after dam failure. At Ban Nuea, Ban Nuea Sub-district, Mueang Kanchanaburi district, the discharge is 14,081 m3/s and the maximum water level is +41.59 m. (MSL.) at 83.21 hr. after dam failure. At Ban Wang Khanai, Wang Khanai Sub-district, Tha Muang district, the discharge is 13,244 m3/s and the maximum water level is +37.671 m. (MSL.) at 93.24 hr. after dam failure. At Ban Luk Kae, Ban Don Khamin Sub-district, Tha Maka District, the discharge was 12,047 m3/s, the maximum water level is +18.92 m. (MSL.) at 107.26 hours after dam failure. Land use land cover (LULC) types are affected by the flood after the dam-break which would cover an area of 1,172.21 sq.km. (1) Urban and built-up area (City, town, and commercial areas), (2) Paddy field, (3) Field crop, (4) Orchard, (5) Horticulture, (6) Pasture and farm house, (7) Evergreen forest, (8) Deciduous forest, (9) Natural water bodies (10) Reservoir (11) Rangeland, and (12) Mine and pits are included. The most affected LULC is paddy field that covers an area of 331.88 sq.km. (28.32%). The second and third largest affected LULC are rangeland and field crop areas that covered an area of 285.66 sq.km. (24.37%) and 267.02 sq.km. (22.78%). The least affected LULC is a deciduous forest that covers area of 15.49 sq.km. (1.32%).

Abstrak :
ABSTRAK
The study assumes that Srinagarind Dam of Kanchanaburi province will be collapsed by overtopping with a final breach of trapezoidal shape due to heavy rainstorm. Subsequently, various forms of demolitions and dynamic flooding are identified using Dam Break and Hydrodynamic models of MIKE 11 by applying the principle of the Probable Maximum Flood (PMF). Srinagarind dam is a rock fill dam with it is crest at +185.00 m. from Mean Sea Level (MSL) and store a maximum volume of 17,745 million m3 of water at the beginning of the break. For dynamic flooding prediction, the maximum breach outflow discharge was 11,307 m3/s with a velocity of 5.39 m/s at 62.29 hours after the break. In addition, the maximum discharge, water level and flood duration at cross sections of main rivers are also extracted for flood zone identification into 4 zones which include: at Ban Phu Thong Maeo, Wang Dong Sub-district, Mueang Kanchanaburi district, the discharge is 14,231 m3/s, the maximum water level is +56.56 m. (MSL.) at 68.28 hr. after dam failure. At Ban Nuea, Ban Nuea Sub-district, Mueang Kanchanaburi district, the discharge is 14,081 m3/s and the maximum water level is +41.59 m. (MSL.) at 83.21 hr. after dam failure. At Ban Wang Khanai, Wang Khanai Sub-district, Tha Muang district, the discharge is 13,244 m3/s and the maximum water level is +37.671 m. (MSL.) at 93.24 hr. after dam failure. At Ban Luk Kae, Ban Don Khamin Sub-district, Tha Maka District, the discharge was 12,047 m3/s, the maximum water level is +18.92 m. (MSL.) at 107.26 hours after dam failure. Land use land cover (LULC) types are affected by the flood after the dam-break which would cover an area of 1,172.21 sq.km. (1) Urban and built-up area (City, town, and commercial areas), (2) Paddy field, (3) Field crop, (4) Orchard, (5) Horticulture, (6) Pasture and farm house, (7) Evergreen forest, (8) Deciduous forest, (9) Natural water bodies (10) Reservoir (11) Rangeland, and (12) Mine and pits are included. The most affected LULC is paddy field that covers an area of 331.88 sq.km. (28.32%). The second and third largest affected LULC are rangeland and field crop areas that covered an area of 285.66 sq.km. (24.37%) and 267.02 sq.km. (22.78%). The least affected LULC is a deciduous forest that covers area of 15.49 sq.km. (1.32%).

Abstrak :
ABSTRAK
Pada penelitian ini disimulasikan fermentor bioetanol untuk produksi skala besar. Fermentor yang digunakan adalah tangki berpengaduk. Pengaduk yang digunakan adalah propeler kapal bersudu tiga yang dipasang dari samping bawah tangki. Dalam simulasi ini divariasikan kecepatan rotasi dan geometri propeler yang dapat mempengaruhi yield dan konversi. Simulasi dilakukan berdasarkan konsep dinamika fluida komputasional (CFD) dengan mempertimbangkan neraca momentum aliran turbulen k-ε, neraca massa, dan kinetika reaksi. Hasil dari simulasi model menunjukkan kesesuaian yang baik dengan data produksi di pabrik bioetanol PT. Xyz untuk waktu fermentasi selama 40 jam. Kecepatan alir fluida mempengaruhi laju pertumbuhan yeast, yang pada akhirnya mempengaruhi konversi glukosa dan yield bioetanol. Konversi glukosa tertinggi adalah 51,37% dan yield bioetanol tertinggi adalah 90,28% yang diperoleh pada diameter propeler 1000 mm, kecepatan rotasi propeler 500 rpm, jarak antar propeler 90o dan sudut pemasangan shaft terhadap bidang horisontal 0o.

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ABSTRACT
In this research, the large-scale fermentor for bioethanol production was simulated. Configuration of fermentor is a stirred tank. Configuration of impeller is side-entry three-bladed marine propeller that mounted on the bottom of the tank. This simulation varying rotation speed and geometry of propeller that all of these are known to affects yield and conversion. The simulation was performed based on the concept of computational fluid dynamics (CFD) by considering momentum balances of turbulent flow k-ε, mass balances, and reaction kinetics. The results from the model?s simulations shows good agreement with the production data in a bioethanol plant PT. Xyz for 40 hours fermentation. Fluid velocity affects yeast growth rate, which in turn affects glucose conversion and bioethanol yield. The highest glucose conversion is 51.37% and the highest yield is 90.28% which obtained with diameter of propeller 1000 mm, rotation speed 500 rpm, spacing between the propellers 90o and mounting angle of shaft against horizontal plane 0o.