Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
HRSG merupakan peralatan yang berfungsi untuk mengubah air menjadi uap pada temperatur dan tekanan tertentu. Peralatan ini terdapat pada PLTGU yang menggunakan siklus kombinasi. Pada HRSG terdapat daerah LP evaporator, yang merupakan alat dengan fungsi untuk menaikkan temperatur air ke titik didih. Daerah LP evaporator ini terdiri dari susunan pipa-pipa yang bekerja pada temperatur dan tekanan yang cukup tinggi. Hal ini mengakibatkan seringnya terjadi kebocoran khususnya pada daerah elbow. Kebocoran ini dapat dianalisa dengan menggunakan simulasi CFD. Dari analisis didapatkan kesimpulan bahwa kebocoran tersebut disebabkan oleh kavitasi. Kavitasi menyebabkan terjadinya tumbukan oleh gelembung uap yang pecah pada daerah yang memiliki tekanan lebih besar daripada tekanan uap jenuh cairan. Tumbukan tersebut terjadi berulang-ulang dan mengakibatkan terbentuknya lubang-lubang kecil pada dinding elbow. ......HRSG is the component of combined cycle power plant which produces steam. The HRSG have low pressure evaporator area to increase water temperature until it reaches it’s boiling point. In low pressure evaporator, the tubes always work at a moderately high temperature and pressure. This condition causes leakage especially in the elbow area. The leakage can be analyzed with CFD simulation. Base on the analysis of the CFD simulation result, the leakage were caused by cavitation. Cavitation cause cnish at the tube wali by the breaking steam bubbles which have higher pressure than the pressure of vapor saturated fluid. The crush occurs continually and causes damage in elbow’s wali.

Abstrak :
[ABSTRAK
Fe-Cr adalah paduan yang memiliki ketahanan temperatur tinggi dan potensial digunakan sebagai interkonektor pada sel bakar (SOFC=solid oxide fuel cell). Sintesis paduan Fe-Cr terus dikembangkan untuk mendapatkan metode yang efektif, dan efisien. Metode sintesis paduan Fe-Cr yang ada sekarang ini adalah metode peleburan, metalurgi serbuk ataupun metode pemaduan mekanik. Metodemetode tersebut memiliki kelemahan misalnya paduan yang tidak homogen, terdapat oksida, proses panjang dan membutuhkan waktu lama. Untuk meminimumkan permasalahan ini, adalah penting untuk menghasilkan paduan mikro Fe-Cr yang memiliki kestabilan fasa dan sifat mekanis baik. Metode ultrasonik dapat dimanfaatkan untuk sintesis paduan mikro homogen melalui penggunaan gelombang suara ultrasonik. Gelombang suara ultrasonik menghasilkan gelembung-gelembung kavitasi, setiap runtuhan kavitasi dapat dianggap sebagai reaktor mikro yang mampu menghasilkan temperatur sekitar 4737 oC dan tekanan sekitar 1000 atm dan yang terbentuk dengan sangat cepat, serta menghasilkan gelombang kejut. Dengan demikian metode ultrasonik dapat dimanfaatkan dalam pembuatan paduan mikro Fe-Cr yang homogen serta tanpa oksida dan diharapkan bisa mengatasi kelemahan metode pembuatan paduan berbasis Fe saat ini. Pada penelitian ini telah dilakukan sintesis paduan mikro Fe- Cr dengan metode ultrasonik pada frekuensi 20 kHz dalam cairan toluene. Tahapan yang telah dilakukan adalah perlakuan ultrasonik sebagai variasi waktu terhadap partikel prekursor (Fe, Cr), kemudian terhadap campuran partikel precursor untuk mendapatkan paduan mikro Fe-Cr. Kemudian dilakukan pembuatan bongkah paduan Fe-Cr dari partikel hasil perlakuan ultrasonik melalui kompaksi tanpa lubrikan dan sintering dalam kapsul kaca kuarsa. Karakterisasi yang dilakukan adalah menggunakan Scanning Electron Microscopy (SEM) terhadap partikel precursor hasil rekayasa ultrasonic. Untuk partikel campuran prekursor Fe-Cr hasil perlakuan ultrasonik karakterisasi dilakukan menggunakan SEM-EDS (Energy Dispersive Spectroscopy), X-Ray Diffraction (XRD) disertai analisis dengan metode Rietveld, Transmission Electron Microscopy-Selected Area Electron Diffraction (TEM-SAED). Untuk bongkah Fe-Cr hasil konsolidasi dengan menggunakan SEM-EDS, XRD disertai analisis dengan metode Rietveld, pengukuran densitas sebenarnya, pengujian kekerasan Vickers. Efek perlakuan ultrasonik terhadap partikel Fe adalah pengurangan ukuran, penyatuan, dan aglomerasi. Setelah perlakuan ultrasonik 40 jam terjadi peningkatan ukuran partikel Fe (>2μm). Terhadap partikel Cr memberikan efek erosi permukaan, pengurangan ukuran dan pemecahan partikel aglomerasi. Partikel Cr aglomerasi terurai sepenuhnya menjadi partikel Cr kecil (< 2 m) setelah 63 jam. Terhadap campuran partikel Fe dan Cr dapat menyatukan partikel kohesif (Fe-Fe, Cr-Cr) dan adhesif (Fe-Cr), terbentuk paduan mikro Fe-Cr seutuhnya (setelah 20 jam) ataupun paduan mikro Fe-Cr sebagian (setelah 50 jam). Pembentukan paduan mikro Fe-Cr diawali pada ukuran partikel Fe ataupun Cr < 2m. Bongkah paduan mikro Fe-Cr yang diperoleh adalah homogen dan tanpa oksida, dengan karakteristik densitas melalui sintering dua tahap yaitu tipe O = 8.655 gr/cm3, tipe B=8.179 gr/cm3, dan tipe A=8.196 gr/cm3, dan melalui proses sintering satu tahap tipe O = 7.678 gr/cm3, tipe B=7.587gr/cm3, dan tipe A=7.092 gr/cm3. Kekerasan bongkah Fe-Cr terbesar melalui sintering satu tahap yaitu 88 VHN adalah tipe B, sementara terbesar dua tahap yaitu 81 VHN adalah tipe A. Proses perlakuan ultrasonik memberikan dampak positif baik dari sisi waktu proses maupun kualitas hasil paduan Fe-Cr. Dengan demikian metode ultrasonik bisa diandalkan sebagai alternatif dalam pembuatan paduan berbasis Fe untuk mengatasi kendala homogenisasi dan oksidasi yang dihadapi pada metode saat ini.;

---

ABSTRACT
Fe-Cr alloys have the potential for use as an interconnection material for solid oxide fuel cell (SOFC) due to its being resistance to high temperatures. Synthesis methods of Fe-Cr alloy continue to be developed in order to obtain a method that is both effective and efficient. Presently, the synthesis of Fe-Cr alloys include the casting, the powder metallurgy, and the mechanical alloying method. These methods have several drawbacks such as inhomogeneity in the resulting products, oxidation, and require a very time-consuming process to accomplish. In order to minimize this problem, it is important to produce Fe-Cr microalloys. Fe- Cr microalloys exhibit phase stability and good mechanical properties. Ultrasonic methods can be used in the synthesis of homogeneous microalloys by employing the ultrasonic sound waves. Ultrasonic sound waves will generate cavitation bubbles. Any cavitation collapse can be considered as a micro reactor in which a temperature of about 4737 oC and a pressure of about 1000 atm a very rapidly created, thereby generating a shock wave. Thus, the ultrasonic method can be used in producing homogeneous and free-oxide Fe-Cr microalloys and can be expected to overcome the limitations imposed by the current methods. In this work the formation of Fe-Cr microalloys by ultrasonic treatment at a frequency of 20 kHz in toluene liquid is presented. In the synthesis procedure, the procedure steps followed were: (1) the treatment of precursor particles (Fe, Cr) through ultrasonic method with a time-variation, followed by (2) the same time-varying ultrasonic treatment on the admixture of these specially prepared precursor particles in order to obtain the Fe-Cr microalloys, and (3) finally, the lubricantless compaction method was employed on these precursor particles admixture followed by sintering process inside quartz tubes to obtain a bulk of Fe-Cr alloy. Observations of the specially prepared precursor particles using ultrasonic technique were carried out by scanning electron microscopy (SEM) method. Observation of the precursor mixture of Fe-Cr particles mixture treated ultrasonically was performed using a SEM-EDS (energy-dispersive spectroscopy) apparatus, a X-Ray diffractometer and accompanied by the Rietveld analysis method, and transmission electron microscopy (TEM)-selected area electron diffraction (SAED) apparatus. The bulk of Fe-Cr alloy were observed using SEMEDS, XRD accompanied by analysis by the Rietveld method, true density measurement, and Vickers microhardness testing. Ultrasonic treatment has caused Fe particles to form agglomerations, an interparticles neck formation, and a fusing among the particles. The size of the Fe particles increased (>2μm) after 40 hours treatment. The agglomerated Cr particles experienced fragmentation, surface erosion, and reduction of particle size. The agglometrated Cr particles fully disintegrated into Cr microparticles (<2μm) after 63 hours treatment. The mixture of Fe-Cr forming cohesive (Fe-Fe, Cr-Cr) and adhesive (Fe-Cr) particles, forming completely (after ultrasonic treatment for 20 hours) and partially (after ultrasonic treatment for 50 hours) Fe-Cr microalloys. The complete formation of Fe-Cr microalloy was possible with an equal particle size of the precursor Fe and Cr (approximately <2 μm). The bulk of Fe-Cr alloy results are homogenous and oxide-free. For two-step sintering, its density (in gr/cm3 unit) is 8.655 for type O, is 8.179 for type B, and is 8.196 for type A, and for one-step sintering its density is 7.678 for type O, is 7.587 for type B, and is 7.092 for type A. The greatest microhardness number of 88 VHN is of type B (one-step sintering), and of 81 VHN is of type A (two-step sintering). The ultrasonic treatment process has a positive impact, with respect to both of quality and time-consumption to finish the Fe-Cr alloying process. Therefore the ultrasonic method can be relied upon as an alternative method in the production of Fe-based alloys to solve problems in homogenization and oxidation encountered in current methods;Fe-Cr alloys have the potential for use as an interconnection material for solid oxide fuel cell (SOFC) due to its being resistance to high temperatures. Synthesis methods of Fe-Cr alloy continue to be developed in order to obtain a method that is both effective and efficient. Presently, the synthesis of Fe-Cr alloys include the casting, the powder metallurgy, and the mechanical alloying method. These methods have several drawbacks such as inhomogeneity in the resulting products, oxidation, and require a very time-consuming process to accomplish. In order to minimize this problem, it is important to produce Fe-Cr microalloys. Fe- Cr microalloys exhibit phase stability and good mechanical properties. Ultrasonic methods can be used in the synthesis of homogeneous microalloys by employing the ultrasonic sound waves. Ultrasonic sound waves will generate cavitation bubbles. Any cavitation collapse can be considered as a micro reactor in which a temperature of about 4737 oC and a pressure of about 1000 atm a very rapidly created, thereby generating a shock wave. Thus, the ultrasonic method can be used in producing homogeneous and free-oxide Fe-Cr microalloys and can be expected to overcome the limitations imposed by the current methods. In this work the formation of Fe-Cr microalloys by ultrasonic treatment at a frequency of 20 kHz in toluene liquid is presented. In the synthesis procedure, the procedure steps followed were: (1) the treatment of precursor particles (Fe, Cr) through ultrasonic method with a time-variation, followed by (2) the same time-varying ultrasonic treatment on the admixture of these specially prepared precursor particles in order to obtain the Fe-Cr microalloys, and (3) finally, the lubricantless compaction method was employed on these precursor particles admixture followed by sintering process inside quartz tubes to obtain a bulk of Fe-Cr alloy. Observations of the specially prepared precursor particles using ultrasonic technique were carried out by scanning electron microscopy (SEM) method. Observation of the precursor mixture of Fe-Cr particles mixture treated ultrasonically was performed using a SEM-EDS (energy-dispersive spectroscopy) apparatus, a X-Ray diffractometer and accompanied by the Rietveld analysis method, and transmission electron microscopy (TEM)-selected area electron diffraction (SAED) apparatus. The bulk of Fe-Cr alloy were observed using SEMEDS, XRD accompanied by analysis by the Rietveld method, true density measurement, and Vickers microhardness testing. Ultrasonic treatment has caused Fe particles to form agglomerations, an interparticles neck formation, and a fusing among the particles. The size of the Fe particles increased (>2μm) after 40 hours treatment. The agglomerated Cr particles experienced fragmentation, surface erosion, and reduction of particle size. The agglometrated Cr particles fully disintegrated into Cr microparticles (<2μm) after 63 hours treatment. The mixture of Fe-Cr forming cohesive (Fe-Fe, Cr-Cr) and adhesive (Fe-Cr) particles, forming completely (after ultrasonic treatment for 20 hours) and partially (after ultrasonic treatment for 50 hours) Fe-Cr microalloys. The complete formation of Fe-Cr microalloy was possible with an equal particle size of the precursor Fe and Cr (approximately <2 μm). The bulk of Fe-Cr alloy results are homogenous and oxide-free. For two-step sintering, its density (in gr/cm3 unit) is 8.655 for type O, is 8.179 for type B, and is 8.196 for type A, and for one-step sintering its density is 7.678 for type O, is 7.587 for type B, and is 7.092 for type A. The greatest microhardness number of 88 VHN is of type B (one-step sintering), and of 81 VHN is of type A (two-step sintering). The ultrasonic treatment process has a positive impact, with respect to both of quality and time-consumption to finish the Fe-Cr alloying process. Therefore the ultrasonic method can be relied upon as an alternative method in the production of Fe-based alloys to solve problems in homogenization and oxidation encountered in current methods, Fe-Cr alloys have the potential for use as an interconnection material for solid oxide fuel cell (SOFC) due to its being resistance to high temperatures. Synthesis methods of Fe-Cr alloy continue to be developed in order to obtain a method that is both effective and efficient. Presently, the synthesis of Fe-Cr alloys include the casting, the powder metallurgy, and the mechanical alloying method. These methods have several drawbacks such as inhomogeneity in the resulting products, oxidation, and require a very time-consuming process to accomplish. In order to minimize this problem, it is important to produce Fe-Cr microalloys. Fe- Cr microalloys exhibit phase stability and good mechanical properties. Ultrasonic methods can be used in the synthesis of homogeneous microalloys by employing the ultrasonic sound waves. Ultrasonic sound waves will generate cavitation bubbles. Any cavitation collapse can be considered as a micro reactor in which a temperature of about 4737 oC and a pressure of about 1000 atm a very rapidly created, thereby generating a shock wave. Thus, the ultrasonic method can be used in producing homogeneous and free-oxide Fe-Cr microalloys and can be expected to overcome the limitations imposed by the current methods. In this work the formation of Fe-Cr microalloys by ultrasonic treatment at a frequency of 20 kHz in toluene liquid is presented. In the synthesis procedure, the procedure steps followed were: (1) the treatment of precursor particles (Fe, Cr) through ultrasonic method with a time-variation, followed by (2) the same time-varying ultrasonic treatment on the admixture of these specially prepared precursor particles in order to obtain the Fe-Cr microalloys, and (3) finally, the lubricantless compaction method was employed on these precursor particles admixture followed by sintering process inside quartz tubes to obtain a bulk of Fe-Cr alloy. Observations of the specially prepared precursor particles using ultrasonic technique were carried out by scanning electron microscopy (SEM) method. Observation of the precursor mixture of Fe-Cr particles mixture treated ultrasonically was performed using a SEM-EDS (energy-dispersive spectroscopy) apparatus, a X-Ray diffractometer and accompanied by the Rietveld analysis method, and transmission electron microscopy (TEM)-selected area electron diffraction (SAED) apparatus. The bulk of Fe-Cr alloy were observed using SEMEDS, XRD accompanied by analysis by the Rietveld method, true density measurement, and Vickers microhardness testing. Ultrasonic treatment has caused Fe particles to form agglomerations, an interparticles neck formation, and a fusing among the particles. The size of the Fe particles increased (>2μm) after 40 hours treatment. The agglomerated Cr particles experienced fragmentation, surface erosion, and reduction of particle size. The agglometrated Cr particles fully disintegrated into Cr microparticles (<2μm) after 63 hours treatment. The mixture of Fe-Cr forming cohesive (Fe-Fe, Cr-Cr) and adhesive (Fe-Cr) particles, forming completely (after ultrasonic treatment for 20 hours) and partially (after ultrasonic treatment for 50 hours) Fe-Cr microalloys. The complete formation of Fe-Cr microalloy was possible with an equal particle size of the precursor Fe and Cr (approximately <2 μm). The bulk of Fe-Cr alloy results are homogenous and oxide-free. For two-step sintering, its density (in gr/cm3 unit) is 8.655 for type O, is 8.179 for type B, and is 8.196 for type A, and for one-step sintering its density is 7.678 for type O, is 7.587 for type B, and is 7.092 for type A. The greatest microhardness number of 88 VHN is of type B (one-step sintering), and of 81 VHN is of type A (two-step sintering). The ultrasonic treatment process has a positive impact, with respect to both of quality and time-consumption to finish the Fe-Cr alloying process. Therefore the ultrasonic method can be relied upon as an alternative method in the production of Fe-based alloys to solve problems in homogenization and oxidation encountered in current methods]

Abstrak :
Pada penelitian ini, degradasi 100 ppm Blue KN-R dilakukan menggunakan ozonasi, kavitasi hidrodinamika, dan kombinasi keduanya dalam waktu 60 menit. Ketiga konfigurasi metode dioptimasi pada beberapa parameter seperti laju alir, pH awal, dan dosis ozon untuk mendapatkan degradasi maksimuum Blue KN-R. Proses ozonasi menghasilkan laju dekolorisasi sebesar 70,16 pada pH 11 dan 156,48 mg/jam dosis ozon, sementara proses kavitasi hidrodinamika menghasilkan laju dekolorisasi sebesar 1,79 pada pH 4. Dekolorisasi tertinggi dihasilkan oleh kombinasi ozonasi dan kavitasi hidrodinamika sebesar 79,39 pada pH 11 dan 156,48mg/jam dosis ozon. Penurunan TOC yang dihasilkan oleh metode ozonasi, kavitasi hidrodinamika, dan kombinasi keduanya adalah sebesar 14,81 ; 1,85 ; dan 19,9. Dengan menggunakan kondisi optimum, degradasi Blue KN-R dilakukan selama 120 menit dan menghasilkan dekolorisasi sebesar 92,63 dan penurunan TOC sebesar 24,54. Hasil dekolorisasi dan mineralisasi yang sinergis disebabkan oleh efek mekanis dan kimiawi dari kavitasi hirodinamika dalam meningkatkan kelarutan ozon dan produksi radikal hidroksil. Degradasi limbah batik dilakukan pada kondisi operasi optimum selama 120 menit. Hasil degradasi warna, COD, BOD, dan TSS adalah sebesar 69,82 ; 68,72 ; 66,54 ; dan 79,84. ......In the present work, degradation of 100 ppm Blue KN R has been investigated using ozonation, hydrodynamic cavitation, and their combination for 60 min. Three configuration methods were optimized in terms of different operating parameters such as flowrate, initial pH, and ozone dosage to get the maximum degradation of Blue KN R. It has been found that the decolorization rate at pH 11 and 156.48 mg h of ozone by ozonation was 70.16, while the decolorization rate at pH 4 by hydrodynamic cavitation was 1.79. The highest decolorization by their combination was observed at pH 11 and 156.48 mg h of ozone with 79.39 decolorization rate. The percentage of TOC removal by ozonation, hydrodynamic cavitation, and their combination has been investigated resulting 14.81, 1.85, and 19.9, respectively. Following the optimization of hybrid method, degradation of Blue KN R was conducted for 120 min resulted 92.63 decolorization rate and 24.52 of TOC removal. The synergetic decolorization and mineralization rate is due to the mechanical and chemical effect of hydrodynamic cavitation to enhance ozone solubility and hydroxyl radicals production. Degradation of batik effluent has been investigated by optimum operational condition for 120 min. The color, COD, BOD, and TSS removal were 69.82, 68.72, 66.54, and 79.84, respectively.

Abstrak :
ABSTRAK Limbah cair yang dihasilkan oleh industri batik masih mengandung zat warna serta bahan pencemar lain dalam konsentrasi yang sangat tinggi, sehingga dapat menurunkan kualitas ekosistem perairan jika langsung dibuang tanpa pengolahan. Oleh karena itu, pada penelitian ini, limbah cair batik diolah dengan menggunakan teknik kavitasi hidrodinamika, ozonasi, dan kombinasi keduanya. Oleh karena kandungan bahan pencemar pada limbah cair batik sangat tinggi, maka untuk meningkatkan efektivitas proses pengolahan limbah dilakukan pralakuan dengan menggunakan teknik koagulasi-flokulasi berbasiskan penggunaan koagulan PAC. Setelahnya proses pengolahan limbah utama dilakukan dengan melakukan variasi laju alir sirkulasi limbah pada 2 L/menit, 4 L/menit, dan 6 L/menit. Parameter pH awal limbah juga divariasikan menjadi 4, 7, dan 10 sebagai representasi kondisi asam, netral, dan basa. Hasil terbaik yang diperoleh dari penelitian ini, yaitu pada aplikasi teknik kombinasi kavitasi hidrodinamika dan ozonasi yang memberikan persentase penyisihan kadar TSS, COD, warna (Pt-Co), dan TOC sebesar 95,19%; 78,85%; 96,42%; dan 60,56% selama 60 menit.

Abstrak :
Penelitian ini bertujuan untuk mengevaluasi kinerja metode ozonasi, kavitasi hidrodinamika, dan kombinasi keduanya dalam mengolah limbah cair tahu. Variasi yang dilakukan adalah laju alir 2-4 LPM dan dosis ozon. Metode kombinasi kavitasi hidrodinamika dan ozonasi (laju alir 4 LPM dan dosis ozon 132,54 mg/jam) menghasilkan kinerja terbaik, yaitu menyisihkan 943 mg/L COD dan 293 mg/L TSS selama 180 menit. Hasil tersebut lebih baik dibandingkan metode kavitasi hidrodinamika laju alir 4 LPM dan ozonasi dengan dosis ozon 132,54 mg/jam secara terpisah, yang masing-masing hanya mampu menyisihkan 485 mg/L COD-288 mg/L TSS dan 136 mg/L COD-233 mg/L TSS selama 180 menit.

---

This research has purpose to evaluate the performance of ozonation, hydrodynamic cavitation, and combination of both in treating tofu wastewater. The variations being used are flowrate 2-4 LPM and dosage of ozone. Combination of hydrodynamic cavitation and ozonation (4 LPM flowrate and 132,54 mg/jam dosage of ozone) produces the best performance, with degradation of 943 mg/L COD and 293 mg/L TSS in 180 minutes. That result is far better than the 4 LPM hydrodynamic cavitation and 132,54 mg/jam dosage of ozone ozonation separately, which are 485 mg/L COD-288 mg/L TSS and 136 mg/L COD-233 mg/L TSS in 180 minutes accordingly.

Abstrak :
Pada penelitian ini, dilakukan evaluasi kinerja metode gabungan teknik ozonasi dan kavitasi hidrodinamika dengan menggunakan injektor venturi untuk mengolah limbah fenol sintetik. Fenol merupakan senyawa alkohol yang memiliki stabilitas tinggi. Hal tersebut diakibatkan oleh strukturnya yang memiliki cincin aromatis sehingga sulit disisihkan. Proses penyisihan fenol pada penelitian ini akan membandingkan penyisihan fenol untuk tiga kofigurasi proses, yaitu metode ozonasi, kavitasi venturi, dan gabungan dari kedua metode tersebut. Variasi untuk setiap konfigurasi proses yang dilakukan adalah variasi pH (4, 7, dan 11), Laju alir (2, 4, dan 6 L/menit) dan dosis ozon (63,77 mg/jam dan 118,48 mg/jam). Limbah Fenol yang digunakan pada penelitian ini adalah fenol sintetik dengan konsentrasi 10 ppm. Pada penelitian ini didapatkan penggunaan metode gabungan teknik ozonasi dan kavitasi menggunakan injektor venturi pada kondisi pH 11, laju alir 6 L/menit, dan dosis ozon 118,48 mg/jam akan menghasilkan presentase penyisihan fenol tertinggi dengan nilai sebesar 85% dibandingkan dengan penggunan hanya metode kavitasi hidrodinamika ataupun ozononasi.

---

n this research, performance evaluation of combination method of ozone technique and hydrodynamic cavitation with venturi injector to process syntethic phenol are done. Phenol is an alcoholic substance with high stability because of the aromatic ring that it has that makes it hard to be degraded. In this research, the performance of three process configuration, which are the ozonation technique, hydrodynamic cavitation with venturi injector, dan the combination of both method, are be compared to perform phenol degradation. Variation used in each process configuration are pH (4, 7, and 11), Flowrate (2, 4, and 6 L/min), and ozon dosage (63,77 mg/hr and 118,48 mg/hr). The phenol concentration used in this process is synthetic phenol with 10 ppm concentration. In this research it is found out that the combination method of ozonation technique and hydrodynamic with venturi injector in base condition (pH of 11), 6 L/min circulation flowrate, and 118,48 mg/hr ozone dosage will result in the highest phenol degradation rate (85% of phenol degradation rate and TOC removal of 4,5 mg/L) compared to doing the ozone technique and hydrodynamic cavitation with venturi injector separately.

Abstrak :
ABSTRAK
Baja ODS (Oxide Dispersion Strengthened) merupakan paduan dengan ketahanan temperatur dan korosi yang baik. Penggunaan metode iradiasi ultrasonik di dalam larutan toluene merupakan metode baru yang dapat memberikan keuntungan berupa ukuran butir yang halus, dapat membentuk microalloying di dalam serbuk, dan dapat meminimalisasi pembentukan fasa oksida. Penelitian ini mempelajari tentang pengaruh amplitudo terhadap reduksi ukuran partikel, homogenitas serbuk, dan pembentukan microalloying Fe-Cr pada preparasi serbuk Fe-15Cr-0.5Y2O3. Serbuk dibagi menjadi 4 sampel dengan perlakuan pencampuran mortar (sampel A), iradiasi ultrasonik dengan amplitudo 40% (sampel B), 50% (sampel C), dan 60% (sampel D) yang kemudian dikarakterisasi menggunakan SEM, EDS, dan XRD. Hasil dari penelitian ini adalah peningkatan amplitudo akan menurunkan ukuran butir dengan nilai sampel B>sampel C>sampel D adalah 4.63 μm>3.44 μm>3.09 μm. Sampel C menghasilkan partikel Fe-Cr sementara sampel B dan D terbentuk partikel paduan Fe-Cr-Y2O3. Nilai komposisi Fe-Cr terbesar dicapai pada amplitudo 40% dengan nilai sampel A:sampel B:sampel C: sampel D adalah 0.00%:20.5%:10.06%:5.2% tanpa pembentukan oksida dengan ukuran crystallite Fe-Cr sampel B:sampel C:sampel D berukuran 16.79 nm:30.13 nm: 55.69 nm. Nilai lattice strain sampel B:sampel C: sampel D adalah 0.0055:0.0030:0.0016.

---

ABSTRACT
ODS Steel (Oxide Dispersion Strengthened) is an alloy with good corrosion and high temperature resistance. The utilization of ultrasonic irradiation method in toluene solution is a new method giving benefits like producing fine grain-size, forming micro-alloying on powder, and minimizing the oxide phase formation. This research investigates the influence of amplitude on the reduction of the particle size, the homogeneity of the powder, and the formation of Fe-Cr microalloying on Fe-15Cr-0.5Y2O3 powder preparation. The powder was divided into 4 samples with various treatments such as mortar mixing (sample A) and ultrasonic irradiation with an amplitude of 40% (sample B), 50% (sample C) and 60% (sample D). After that, each sample was characterized by SEM, EDS and XRD. This research shows that increasing the amplitude will decrease the grain size with the value of sample B> sample C> sample D is 4.63 μm>μm 3:44> 3:09 μm. Sample C produced Fe-Cr particles meanwhile samples B and D formed Fe-Cr-Y2O3 alloy particle. The highest composition value of Fe-Cr is reached on the amplitude of 40% to the composition value of sample A: sample B: sample C: sample D is 0.00%: 20.5%: 10:06%: 5.2% without the oxide formation. The size of crystalline Fe-Cr sample B: sample C : sample D size of 16.79 nm: 30.13 nm: 55.69 nm. The lattice strain value of the sample B: the sample C: sample D was 0.0055: 0.0030: 0.0016. ;

Abstrak :
Penelitian ini bertujuan untuk menguji kinerja kombinasi metode ozonasi dan kavitasi hidrodinamika dengan pelat berlubang dalam proses desinfeksi bakteri E.coli. Pada penelitian ini, dilakukan variasi dosis ozon, laju alir sirkulasi, dan metode disinfeksi. Ozon diproduksi menggunakan ozonator komersial dengan dosis ozon 64,83 mg/jam, 108,18 mg/jam, dan 135,04 mg/jam sementara kavitasi dibangkitkan menggunakan pelat berlubang. Metode desinfeksi yang akan divariasikan pada percobaan ini adalah: kavitasi hidrodinamika, ozonasi, dan gabungan keduanya. Hasil terbaik pada masing-masing metode didapatkan pada menit ke-60 dan laju alir sirkulasi 7 L/menit. Metode gabungan kavitasi dan ozonasi mampu mendesinfeksi hingga 0 CFU/mL dari konsentrasi awal 2,10 x 105 CFU/mL. Metode ozonasi tunggal mampu mendesinfeksi bakteri E.coli hingga 0 CFU/mL dari konsentrasi awal 1,32 x 105 CFU/mL selama 60 menit. Metode kavitasi hidrodinamik memberikan hasil penyisihan paling sedikit, yaitu 5,20 x 104 CFU/mL dari konsentrasi awal 2,17 x 105 CFU/mL. Disimpulkan bahwa metode kombinasi menghasilkan desinfeksi bakteri E.coli yang lebih cepat dan lebih baik dibandingkan metode tunggalnya.

---

This research aims to evaluate the performance of hybrid method of ozonation and hydrodynamic cavitation with orifice plate on E.coli bacteria disinfection. Ozone dose, circulation flowrate, and disinfection method were varied. Ozone was produced by commercial ozonators with ozone dose of 64,83 mg hour, 108,18 mg hour, and 135,04 mg hour. Meanwhile, hydrodynamic cavitation was generated using an orifice plate. The disinfection methods compared in this research are hydrodynamic cavitation, ozonation, and the combination of both. The best result on each method was achieved on the 60th minutes and with a circulation flowrate of 7 L min. The hybrid method attained final concentration of 0 CFU mL from the initial concentration of 2,10 x 105 CFU mL. The ozonation method attained final concentration of 0 CFU mL from the initial concentration of 1,32 x 105 CFU mL. Cavitation method gives the least elimination with final concentration of 5,20 x 104 CFU mL from the initial concentration of 2,17 x 105 CFU mL. In conclusion, hybrid method gives a faster and better disinfection of E.coli than each method on its own.

Abstrak :
Penelitian ini mengkombinasikan metode ozonasi dan kavitasi hidrodinamikka dengan injektor venturi. Tujuan dari penelitian ini yaitu untuk mengetahui signifikansi kinerja dari penggabungan metode ozonasi dan kavitasi hidrodinamika terhadap proses desinfeksi bakteri Escherichia coli. Untuk mencapai tujuan tersebut dilakukan desinfeksi dengan metode ozonasi tunggal dan kavitasi tunggal sebagai pembanding. Variasi yang dilakukan adalah laju alir yaitu 3, 5 dan 7 L/menit dan dosis ozon 64,83, 108,18 dan 135,04 mg/jam. Metode kombinasi ozonasi dan kavitasi hidrodinamika laju alir 7 L/menit dan dosis ozon 135,04 mg/jam menghasilkan kinerja terbaik dengan konsentrasi awal sebesar 1,49 x 105 CFU/mL, semua bakteri dapat terdesinfeksi selama 45 menit. Hasil tersebut lebih baik dibandingkan metode kavitasi hidrodinamika tunggal laju alir 7 L/menit dengan bakteri tersisa sebesar 21 dan semua bakteri terdesinfeksi pada metode ozonasi tunggal dengan dosis ozon 135,04 mg/jam selama 60 menit.

---

This research combine ozonation and cavitation hydrodynamic methods with venturi injector. The purpose of this research is to observe significance of ozonation and hydrodynamic cavitation method to disinfection process of Escherichia coli bacteria. To achieve these objectives, disinfection process with single ozonation and single cavitation method was used as a comparison. The variations being used are flowrate 3, 5, 7 L min and dosage of ozone 64.83, 108.18 and 135.04 mg h. Combination of ozonation and hydrodynamic cavitation 7 LPM and 135.04 mg h dosage of ozone showed the best performance with initial concentration is 1.49 x 105 CFU mL, all bacteria were disinfected for 45 minutes. The results is better than the single hydrodynamic cavitation method 7 LPM which had 21 remaining of bacteria and all bacteria were disinfected on a single ozonation method 135.04 mg h dosage of ozone for 60 min.

Abstrak :
Erosi kavitasi menjadi satah satu moda kegagalan utama pada kepala silinder dump truck. Kegagalan tersebut terjadi akibat terdapat fluida dan fluktuasi tekanan pada ruang bakar yang memicu terbentuk dan meledaknya gelembung yang berasal dari cairan pendingin. Resistansi erosi kavitasi material meningkat ketika nilai kekerasan permukaan meningkt. Maka dari itu, untuk menanggulangi terjadinya erosi kavitasi, dilakukan rekayasa permukaan untuk meningkatkan nilai dengan melakukan pelapisan menggunakan proses wire arc spray yang dikenal sebagai proses pelapisan yang efisien secara energi dan tidak banyak mengubah sifat substrat. Proses pelapisan dilakukan dengan melakukan variasi pada voltase (26 V, 30 V, dan 32 V) dan variasi logam pengisi (baja paduan kromium dan baja karbon rendah) untuk mendapatkan parameter voltase dan logam pengisi yang optimal dalam meningkatkan resistansi erosi kavitasi. Penelitian ini menggunakan metode modified ultimate resilience dan composite modified resilience untuk menghitung nilai resistansi erosi kavitasi hasil pelapisan. Pengujian kekerasan dan komposisi juga dilakukan untuk menganalisis nilai resistansi kavitasi. Hasil menunjukkan bahwa baja paduan kromium memiliki nilai resistansi erosi kavitasi lebih baik dibandingkan baja karbon rendah karena memiliki kandungan kromium yang meningkatkan nilai kekerasan. Selain itu, didapatkan juga relasi bahwa semakin tinggi voltase (pada rentang 26 V- 32 V), maka semakin baik ketahanan erosi kavitasi.

---

Cavitation erosion is one of the main failure modes in the kepala silinder of a dump truck. The failure occurred due to fluid and fluctuations in pressure in the combustion chamber that triggered the formation and implosion of bubbles originating from the coolant. The cavitation erosion resistance of the material increases when the surface hardness value increases. Therefore, to enhance the materials' resistance of cavitation erosion, surface treatment is done to increase the value by coating using a wire arc spray process, the process that is known as an energy-efficient coating process. The coating process is done by varying the voltage ( 26 V, 30 V, and 32 V) and material types (chromium alloy steel and low carbon steel) to obtain optimal voltage and material parameters in order to increase cavitation erosion resistance. This study uses the modified ultimate resilience and composite modified resilience methods to calculate the cavitation erosion resistance value of the coating. Microvickers hardness and OES composition testing are also used to analyze the cavitation erosion resistance value. The results show that the chromium alloy steel material has a better cavitation erosion resistance value than low carbon steel because it has a chromium content that increases the hardness value. In addition, it was also found that the higher the voltage (in the range of 26 V-32 V), the better the cavitation erosion resistance.