CO2 gas injection is one of the recommended enhanced oil recovery (EOR) methods by injecting CO2 through reservoir pores after the residual saturation is reached, since CO2 dissolves easily in oil phase as confirmed by many other researchers in pertaining field studies. An integrated system is urgently required for assessing CO2-EOR study, covering multi-disciplinary aspects as follows: geology, geophysics, reservoir, production, process and economic. Hence, those systems must be reliable in suggesting final decision for feasibility of CO2-EOR operation program, applicable either for pilot scale or for full scale. This paper is proposing an integrated system evaluation, which has the following features: (1) estimate fraction of dissolved CO2, (2) estimate viscosity reduction, (3) estimate future oil productivity index resulted, (4) forecast incremental oil production, (5) estimate surface facilities equipment design, (6) evaluate economical aspects and (7) generate final decision for feasibility of CO2-EOR operation program. Finally, as the main objective of this program, those systems will present a picture of essential reason why we need to promote or reject CO2-EOR plan program, and also some recommendations will be presented in case the CO2-EOR plan does not perform as expected.

Limbah laundry dapat menjadi masalah serius bagi lingkungan jika dibuang tanpa pengolahan. Masalah yang timbul diantaranya nilai Chemical Oxygen Demand (COD), fosfat, dan kekeruhan yang tinggi. Tujuan penelitian yaitu mempelajari pengaruh laju alir terhadap efisiensi penurunan kadar kekeruhan, COD, dan TSS, serta menentukan kondisi optimalnya dengan alat elektrokoagulasi kontinyu berpengaduk. Reaktornya adalah reaktor berkapasitas 10 L dilengkapi pengaduk 180 rpm, pompa peristaltik, rectifier dan 3 pasang elektroda Alumunium dengan ketebalan 0,3x15x15cm yang disusun secara monopolar. Percobaan variasi laju alir (115mL/menit, 170 mL/menit, 340mL/menit) dilakukan dengan rapat arus tetap (70 A/m2), dengan waktu operasi 60 menit untuk setiap variasi. Hasilnya menunjukkan bahwa pada laju tinggi (340 mL/menit) dan laju rendah (115 mL/menit) menghasilkan efisiensi penurunan pengotor yang rendah dan laju alir terbaik ditunjukkan pada 170 mL/menit. Kondisi optimal terjadi pada laju alir 170 mL/menit pada rapat 70 A/m2 menghasilkan efisiensi penurunan kekeruhan, COD, dan TSS berturut-turut 89,35%, 73,33%, dan 99,26%. Laundry waste can be a serious problem for the environment if it is disposed of without treatment. Problems that arise include the value of Chemical Oxygen Demand (COD), phosphate, and high turbidity. The aims of the research were to study the effect of flow rate and current density on the efficiency of reducing turbidity, COD, and TSS levels, and to determine the optimal conditions using a continuous stirred electrocoagulation device. The reaktor used is a reaktor with a capacity of 10 L equipped with a 180 rpm stirrer, a peristaltic pump, a rectifier and 3 pairs of aluminum electrodes with a thickness of 0.3x15x15cm arranged in a monopolar manner. The flow rate variation experiment was carried out with a constant current density (70 A/m2), and the current density variation experiment was carried out with a fixed flow rate (170 ml/minute) with an operating time of 60 minutes for each variation. The results of the flow rate variation showed that at a high rate (340 ml/min) and a low rate (115 ml/min) resulted in a low impurity reduction efficiency, the best flow rate was shown at 170 ml/min. The results of the current density variation show that the increase in impurity reduction efficiency occurs as the current density increases, the best results occur at a current density of 70 A/m2. Optimal conditions occurred at a flow rate of 170 ml/min at a rate of 70 A/m2 resulting in the efficiency of reducing turbidity, COD, and TSS respectively 89.35%, 73.33%, and 99.26%.

<p class="E-JOURNALAbstractBodyEnglish">One of the issues in urban areas such as DI Yogyakarta province is air pollution. The pollution level is high, as shown by the quality index value of about 85.25 in 2019. Vehicle emissions are the most significant source of this pollution in urban areas and can be decreased by using fuel with minimum carbon emission. Compressed Natural Gas (CNG) is an environmentally friendly fuel. However, a safety study is required because CNG is stored under high pressure. Therefore, this research aims to analyze the risk of using CNG in the Trans Jogja bus. The research method collects secondary data and then processes them using FTA, ETA, ALOHA software, and a risk matrix. The result shows that the risk value for CNG usage in the Trans Jogja bus is low to a moderate level or acceptable.</p>

In recent years Low Salinity Waterflood (LSW) had been supposed as trusty method to improve oil recovery and the most essential aspect is a alteration of divalent ion concentration in reservoir pore volume as a respon LSW. The objective of this paper are to find divalent diffusivity constant (Ca2+ and Mg2+) in berea sandstone by ionsmass conservation equation along with Atomic Absorption Spectroscopy (AAS) as validation. The study was conducted at 2 berea core having porosity : 0.235 and 0.230 and permeability : 661 mD and 550 mD, we use synthetic formation water accordance to "LN" field property. Experiment was treated by by diluting Ca2+ up to 79% from its original value and  by diluting Mg2+ up to 95% from its original value while other ion were maintained fit to their original value. As a result we got difusion constant 0.0620 cm2.min-1 and 0.2667 cm2.min-1for Ca2+ and Mg2+, respectively.

Salah satu upaya untuk mengatasi penggunaan plastik yang tidak dapat terurai di alam adalah dengan bioplastik yang terbuat dari biodegradable film. Pada penelitian ini dilakukan karakterisasi biodegradable film berbahan dasar pati garut yang dibuat dengan metode casting. Gliserol ditambahkan sebagai plastisicizer dan asam sitrat sebagai crosslinker. Dari hasil penelitian yang telah dilakukan menunjukkan bahwa biodegradable film yang dihasilkan memiliki warna putih bening dimana semakin banyak pati maka warna akan semakin keruh. Hasil uji kuat tarik pun menunjukkan bahwa semakin banyak pati yang digunakan maka kuat tarik dari biodegradable film akan semakin kuat namun % elongation at breaknya akan semakin kecil atau sifat nya menjadi kurang elastis. Sebaliknya, penambahan asam sitrat menunjukkan bahwa kuat tariknya menjadi semakin lemah yang dikarenakan adanya hidrolisis ikatan glikosida pada pati. Kata Kunci: pati; garut; gliserol; asam sitrat; biodegradable film; bioplastik ABSTRACT: The biodegradable film is an attempt to reduce the use of plastics that cannot be decomposed by nature. This study described biodegradable films produced from arrowroot starch using the casting method. As a plasticizer and crosslinker, glycerol and citric acid are added. The investigation results indicate that the biodegradable film has a clear white color; the greater the amount of starch, the more opaque the color. The tensile strength test results also indicate that the biodegradable film's tensile strength will be greater the more starch is used, but its percent elongation at break will decrease, or its characteristics will become less elastic. In contrast, adding citric acid demonstrates that the tensile strength decreases due to the hydrolysis of glycosidic linkages in starch.