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In the plasma electrolysis process, hydrogen generation around the cathode is affected by the amount of evaporation energy. Utilizing a veil, minimizing the cooling in the liquid phase, and maximizing the cooling in the gas phase become important parameters to improve the process efficiency of hydrogen production. This research aims to obtain an optimum high-efficiency electrolysis plasma reactor based on decreased energy consumption and increased hydrogen gas production. The research method varied the NaOH concentration, voltage, veil length, cathode depth, and the volume of the methanol additive. In characterizing the current and voltage, as the concentration increases, the voltage needed to form the plasma will decrease. As the concentration and voltage increase, the rate of production, hydrogen content percentage, and the hydrogen ratio also increase, while the energy consumption decreases. The optimum condition, based on variations of veil length, is 5 cm when the depth of the cathode is 1 cm below the surface of the solution. Improving the efficiency of the hydrogen production process can be done by adding methanol. The best result was achieved using 15% volumes of methanol additive in 0.01 M NaOH, and higher hydrogen-ratio plasma-electrolysis results were found in comparison with Faraday electrolysis: the hydrogen ratio was 151.88 mol/mol, the lowest energy consumption was 0.89 kJ/mmol, and the highest hydrogen production rate was 31.45 mmol/min. The results show that this method can produce hydrogen 152 times more than Faraday electrolysis.

Innovation has a central role in technology development. It is produced everywhere and enriched by local wisdom for problem solving in particular regions to further increase human wellbeing. Technology development thus becomes a dynamic system of relationships among various stakeholders, and it requires a collaborative and mutual partnership.Technology partnerships become a network model that is formed by stakeholders who share linked knowledge, activities, and resources, which lead to future strategic options and alternative product solutions that are efficient, effective, and sustainable. Technology results from inventors and researchers in various laboratories and companies translating ideas into prototypes, which can then serve various needs and purposes through transformation into value added products and/or projects. Technology transfer is conducted firstly via provider collaboration and secondly to customers. Both the governments and private investors that provide financial support to fund technology development and transfer make significant contributions by supporting development strategies and policies as well as creating sufficient market incentives.

The adsorption process has been successfully used as a technique for water and wastewater treatment over the past 40–50 years, but it is not without drawbacks as the treatment method for heavy metal removals. One of the main issues of the process is the posttreatment requirement to separate nanoparticles from the water sources. This chapter provides a review on the development of adsorptive ultrafiltration (UF) membranes composed of organic polymer and inorganic nanomaterial for elimination of heavy metal ions in a relatively simple way. The roles of different types of nanomaterials embedded in the membranes, including metal oxides (e.g., zirconium oxide, iron oxide, and titanium dioxide), carbon-based nanomaterials (e.g., carbon nanotubes and graphene oxide) and other nanomaterials (e.g., natural clays and waste) are assessed for their selectivity toward heavy metal ion adsorption. In most of the published research work, the adsorptive membranes exhibited promising results with respect to adsorption capacity and water permeability. However, more research is needed to address the possible leaching of nanomaterials from the membrane during operation and the potential of membrane degradation upon exposure to strong acid/alkali solutions during the desorption process.

Iron fortification program relates to iron delivery through daily foods, which have a potential impact on many people. In this study, chitosan microparticle loaded with ferrous gluconate was used as fortificant, while gummy candies were selected as food vehicles. This work aimed to assess the effect of iron microparticles addition on basic nutrient composition, textural, and microstructural characteristics. The properties of iron microparticles obtained from the spray drying method were also discussed in this article. The iron fortification was carried out by adding the iron microparticles into the candies solution. This solution was then molded and cooled at room temperature before the analysis. The yield, iron loading, efficiency encapsulation, mean diameter, and SPAN factor of iron microparticles were 49%, 3.5 mg Fe/100 mg dried microparticles, 48%, 17 µm, and 1.7. The iron microparticle had a spherical shape with the wrinkles structure on the surface. Therefore, the fortified gummy candies had wavy structures with the prominent spheres. The protein and fat content of our gummy candies were higher than the commercial gummy candies. However, gummy candies’ hardness and gumminess value had changed significantly, while the cohesiveness and springiness properties were not significantly different during the storage.

The current need to reduce dependence on non-renewable fuels has contributed a lot to the rapid growth of renewable energy systems and electric vehicles. One of the exciting sources of energy storage is the battery. The development of lithium-based batteries is an exciting trend and is continuously being developed for long life and high-level battery quality. Batteries are considered a primary energy storage source. They are essential materials for many applications such as vehicles and electronic devices, including laptops, mobile phones, watches, etc. With the increasing demand and use of batteries globally for many applications, much research on advanced batteries has been interested in improving their performance, significantly to extend their safety and prolong their service life. The type of batteries and some external parameters, including voltage, current, and temperature, are essential to further exploration. Research on how to minimize the pollution from after-used batteries is also needed since electronic waste cannot be disposed into nature without prior treatment. This is important in preventing environmental destruction and supporting environmental sustainability, in addition to the economic impact of reusing certain technologies. Furthermore, with the advancement of civilization and technology, everything related to engineering and sciences can be developed according to its functions and humans' need. To address the above issues, the 5th International Tropical Renewable Energy Conference (i-TREC) was held on October 29-30, 2020, via online conference. The i-TREC is an annual event organized by the Tropical Research Energy Center, Faculty of Engineering Universitas Indonesia (TREC FTUI). The theme of this conference is the role of renewableand clean energy in supporting sustainable development goals. From the papers presented there, 18 paper have been selected for publication in IJTech. These 18 papers are summarized below.

This work demonstrates the feasibility of employing direct contact membrane distillation (DCMD) for treating industrial textile wastewater for clean water production. Experimental results showed that the in-house fabricated polyvinylidene fluoride-Cloisite 15A polymer–inorganic nanocomposite membrane is robust and able to treat the industrial effluent by reducing at least 89% of the initial values of the water quality parameters measured. However, the membrane permeate flux was reported to decline almost 50% in the first few hours of the 40-h treatment process before reaching water flux of 13–22 kg/m2 h. It is believed that the initial flux decline is mainly caused by the foulants accumulated on the membrane outer surface that increases mass transfer resistance of water molecules and reduces water productivity. With respect to separation characteristics, the DCMD process has shown better performance for COD and color removal in comparison to the other commonly used pressure-driven membrane processes. Further improvement on the membrane surface properties is necessary to reduce fouling propensity and pore wetting caused by the surfactants and other foulants in the textile wastewater. This is of particular importance for long-term operation of DCMD process.

This research mainly aims to simulate compressed natural gas (CNG) combustion to create a valid reaction mechanism that can be used to determine the effects of temperature, pressure, equivalent ratio, diluents composition, and CNG composition on the ignition delay time profile in a combustion reaction. The combustion reaction involves many elementary reactions; therefore, in this study, the stages of important reactions were identified by sensitivity and rate of production analyses. In this study, CNG was represented by three components, namely, methane, ethane and propane (CH4/C2H6/C3H8). The model is arranged according to the literature and validates the experimental data for CH4/C2H6/C3H8/O2/N2 mixture in the temperature (T) range of 1039–1553 K, initial pressure (P) range of 1.1–40.0 atm, and equivalent ratio (ɸ) = 0.5, 1.0, and 2.0 using a shock tube. The software used in this study is Chemkin 3.7.1. The ignition delay time profile for CNG combustion has been successfully reproduced by the kinetic model. The slowest ignition delay time for the composition of 88% CH4/8% C2H6/4% C3H8 with an initial temperature range of 1100–1500 K is 37.2 ms (P=2 atm, T=1100 K, and ɸ=2.0) and the fastest IDT is 0.033 ms (P=30 atm, T=1500 K, and ɸ=0.5). For constant ethane or propane composition, the increase in methane composition will cause slower ignition.

This study aims to evaluate the effectiveness of a polypropylene hollow fiber membrane contactor in removing dissolved ammonia in wastewater using sulfuric acid solution as an absorbent. In the ammonia removal experiments, wastewater and absorbent solutions flowed through the shell side and the lumen side of the contactor, respectively. The pH of wastewater, rate of circulation and ammonia initial concentration were operating variables which influenced the efficiency of the removal process. The efficiency of ammonia removal increases with the wastewater pH level when it is at the same circulation rate and time. In addition, the increase in the circulation rate of the wastewater will increase the efficiency of ammonia removal and the overall mass transfer coefficient. Meanwhile, the efficiency of ammonia removal and the overall mass transfer coefficient decreased with initial ammonia concentration in the wastewater solution.

Transport behaviour of thin film composite (TFC) reverse osmosis (RO) membrane is highly dependent on the physicochemical property of the uppermost polyamide (PA) layer. In this work, we provide a comprehensive understanding of the impacts of post interfacial polymerization (IP) rinsing using either organic solvents (i.e., hexane, cyclohexane and isoparaffin-G) or aqueous solution on the structure and chemistry of PA layer and correlate the properties change to membrane performance. Evidently, the desalination performance of the aqueous-rinsed membrane is better than the organic solvents-rinsed membrane. Compared to the un-rinsed membrane, the aqueous-rinsed membrane also showed 28% higher pure water flux and 13% lower water contact angle (i.e., greater hydrophilicity) with least compromised NaCl rejection (97.70%). This is possibly caused by its reduced PA cross-linking degree and/or hydrolysis of acyl chloride monomers that alter the membrane surface chemistry. It is also found that the introduction of air-drying prior to the rinsing process could improve the membrane reproducibility as a result of extensive polymerization. The findings from this experimental work confirmed that aqueous solution is the best rinsing solution for TFC RO membrane fabrication, improving both physicochemical properties and water permeability of membrane.

As a type of gas that contributes to air pollution, nitrogen oxide (NOx) has harmful effects on humans and the environment. Among several types of NOx, nitric oxide (NO) and nitrogen dioxide (NO2) are most commonly found in air. The utilization of membranes as reactors is a system that combines chemical reactions with the separation process through membranes to increase the conversion of the reaction. This study investigated the absorption process by utilizing a hollow fiber membrane module (polysulfone) as a bubble reactor with H2O2 (0.5 wt. %) and HNO3 (0.5M) as the absorbent. NOx feed gas was flown into the tube side of the membrane; the shell side was filled with static H2O2 and HNO3 and the shell input and the tube output flow were closed to create gas bubbles. The experimental results showed that the absorption efficiency increased, but the mass transfer coefficient and flux decreased as the number of fibers in the membrane module increased at the same feed gas flow rate. The NOx loading is relatively constant as the amount of fiber in the membrane module increased at the same feed gas flow rate. The experimental results also showed that the mass transfer coefficient, flux, and NOx loading increased with increasing feed gas flow rate, but the absorption efficiency decreased when using the same number of fibers in the membrane module. The maximum NOx absorption efficiency achieved in this study was 94.6% at the feed gas flow rate of 0.1 L/min, using a membrane module with 48 fibers.

Ascorbic acid and folic acid are very important vitamins which have some crucial roles in human body’s metabolism, including enhancing iron absorption. Regardless of its roles, these vitamins are also known to be unstable and easily degraded in the processing by oxygen, pH, temperature, and UV light. Nowadays, microencapsulation may be a proper technique to overcome some of these shortcomings. However, there is a possibility of the changes in vitamin stability during encapsulation processes, particularly while using chitosan and acetic acid as wall material and solvent, respectively. In this study, cyclic voltammetry method was carried out for investigating the electrochemical properties of ascorbic acid and folic acid under acidic medium. The effect of scan rate (0.1; 0.2; 0.3 V/s) on the observed current was also studied. Furthermore, vitamin-aquadest solutions were also studied as a referred sample. Cyclic voltammetry was conducted using a three electrodes configuration connected to an electrochemical analyser. Platinum wire, graphite, and Ag/AgCl were employed as the working, auxiliary and reference electrodes, respectively. All the solutions were maintained for free oxygen by the degassing process. In general, the recorded currents of all solutions were increased while using a higher scan rate. Cyclic voltammogram also showed that ascorbic acid had two anodic peaks and two cathodic peaks which indicated that ascorbic acid undergoes reversible reaction. However, folic acid only had one anodic peak in water which represented an oxidation reaction. Furthermore, the electrochemical properties of ascorbic acid have a similar profile with folic acid while were in acidic solutions. Both vitamins have more positives anodic peak; hence depicted that acid could suspend the oxidation reaction.

Batik is a cultural heritage which was handed down to her craftsmen in Indonesia, even now it is recognized by UNESCO as one of the world heritages. However, the batik industry is also known as an industry that discharges a lot of wastewater so that the processing of batik waste becomes very important to prevent surface water pollution from batik wastewater. Therefore, this study aims to examine the performance of polypropylene (PP) fibers-based membrane module in wastewater treatment from the batik industry. The batik wastewater was prior treated through a combination of ozonation (O3) and flocculation, and then ultra-filtered by a PP membrane module at various trans membrane pressures (TMP). Conductivity, total suspended solids (TSS), chemical oxygen demand (COD) and color (Pt/Co) were the observed variables to examine the performance of the batik wastewater treatment process. The experimental results show that TSS, COD and Pt/Co can be reduced by about 99.8%, 24% and 57%, respectively. Meanwhile, the permeate fluxes from the membrane module were 141.3, 182.0, 243.9, 264.7 and 290.88 L.m−2.h−1 at TMP of 3, 5, 7, 9 and 11 bars, respectively.

Selecting a proper material is the first key step for determining suitable membrane application. Hence, the comparison of membrane properties is urgently required to be conducted. This work aimed to compare two common materials of polymer flat sheet membranes, i.e poly(vinylidene) fluoride (PVDF) and polysulfone (PSf), from preparation to characterization. Phase inversion method was applied for both materials using different solvent. PVDF was dissolved in N, N, dimethyl acetamide (DMAc) whereas PSf was dissolved in N-methyl pyrrolidone (NMP) with the same composition ratio of polymer and solvent. The properties of membranes were investigated by FTIR, FE-SEM, water contact angle, and Universal pull machine. FE-SEM result indicates that PSf membrane has larger pores than PVDF membrane. Meanwhile, water contact angle analysis describes that PVDF membrane is more hydrophilic than PSf membrane.

There are many oil and gas fields in Indonesia which contain high CO2 that need to be treated. The Acid Gas Removal Unit (AGRU) is installed to remove the CO2. The AGRU will release the CO2 gas from the regeneration column. It still contains a high concentration of CO2 (higher than 80%). The accumulation of CO2 emission to the atmosphere will impact the environment. To promote environment-friendly technology, the process can be improved with conversion of CO2 into methanol. It will provide a relatively closed loop of the carbon cycle and as a renewable energy alternative. This study aims to provide packed bed reactor design which can be implemented in the small-scale methanol production plant utilizing high CO2 feed gas. The reactor temperature was varied from 200°C to 250°C and pressure were operated in the range of 40 Bar up to 75 Bar. These variations were used to analyze the effects of methanol production. The simulation results showed that peak methanol production rate was achieved at the temperature around 230°C. As the conclusion, the reactor showed better performance at the higher pressure and higher temperature although the reaction is exothermic including the recycling process can reduce the cost of hydrogen.

Methane Number (MN) is one of quality requirement of gas as fuel for gas engine, which indicates fuel capability to avoid knocking in the engine. Higher MN provides better quality of gas for gas engine. Natural gas with higher methane (CH4) and fewer higher hydrocarbon, tends to have higher MN score. This study aims to obtain heating methods of LNG to produce vapor that has appropriate MN as a fuel gas supply to gas engine. The simulation for LNG regasification prepared is an approach to the design of the existing regasification facility of the power plant in Bali. The temperature ranges for LNG heating simulation were obtained based on saturated temperatures of LNG phase envelopes. In the simulation. to obtain a certain MN value can be conducted by adjusting the temperatures at two different values i.e. above -110 ° and below - 80 °. To produce LNG vapor that has MN of 80 either through higher temperature of heating (HT heating) or lower temperature of heating (LT heating) requires more energy than direct heating without MN improvement. Heat loading for LT heating is higher than HT heating due to more temperature defference between LT and heating fluid temperatures. The ability of engine to produce power decreased with decreasing fuel gas MN. The power increment increases for lower MN gas if MN improvement is conducted.

Hollow fiber membrane modules have been extensively used as gas-liquid contactor devices to provide a high surface area within a small volume. Hollow fiber membrane contactors have been demonstrated in a wide range of application such as in gas stripping and gas absorption. In this study the performance of sealed end hydrophobic microporous hollow fiber membranes contactors were evaluated to remove dissolved oxygen from water via vacuum degassing process. Hollow fibers membranes used in the experiment were hydrophobic microporous polypropylene of 650 μm in outer diameter, 130 μm wall thickness and nominal pore size of 0.2 μm. Based on the experimentalresult the sealed end membrane contactor can remove oxygen from water as high as 3.4-gram oxygen per square meter of membrane area per hour. The oxygen flux decreases with increasing module-packing density for the same water velocity. The same effect also occurred for the mass transfer coefficient of the membrane contactors. The mass transfer coefficients were independent of fiber length within the range of study. Hydrodynamics analysis of the contactors showed that at the same Reynolds number pressure drops increase with increasing packing density due to an increase in friction between fibers and water.

Dietary modification, supplementation and food fortification are common strategies to alleviate iron deficiencies. Fortification of food is an effective long-term approach to improve iron status of populations. Fortification by adding iron directly to food will cause sensory problems and decrease its bioavailability. The purpose of iron encapsulation is: (1) to improve iron bioavailability, by preventing oxidation and contact with inhibitors and competitors; and (2) to disguise the rancid aroma and flavor of iron. A microcapsule formulation of two suitable iron compounds (iron II fumarate and iron II gluconate) using chitosan as a biodegradable polymer will be very important. Freeze dryer was also used for completing the iron microencapsulation process. The main objective of the present study was to prepare and characterize the iron-chitosan microcapsules. Physical characterization, i.e. encapsulation efficiency, iron loading capacity, and SEM, were also discussed in this paper. The stability of microenca...

Wastewater from tofu industries contain many parameters such as total suspended solid (TSS), total dissolved solid (TDS), turbidity, and chemical oxygen demand (COD). These parameters are present in high amount and can endanger the aquatic environment and also decrease water quality. Several studies have been conducted to reduce these parameters, but still require a longer time which is around 12 to 78 days. This study aims to discuss the processes and methods to reduce TSS, TDS, turbidity, and COD parameters from tofu wastewater. The processes discussed in this study include a combined process of coagulation-flocculation and ultrafiltration (UF). The results of the study show that TSS, turbidity and COD reduced to 60%, 60% and 20%, respectively, in the coagulation-flocculation process, but TDS increased to around 90% because of the neutralization process using Sodium Hydroxide (NaOH) solution. Furthermore, it was shown that the combined process of coagulation-flocculation and UF was able to reduce TSS, turbidity, COD and TDS up to 99%, 99%, 75% and 50%, respectively. All the parameters contained in the water produced from the combined process of coagulation-flocculation and UF was in line with the National Environmental Quality Standard requirements, excluding COD due to the COD content in fresh tofu wastewater is very high.

Chlor-alkali is one of the most important processes in chemical industry. This process produces chlorine and caustic soda that becomes the main feedstock of daily needs products. In this study, the process condition on chlorine gas production by electrolysis plasma is examined. Plasma electrolysis can increase the chlorine gas production up to 24 times in single compartment reactor and can reach up to 59 times in double compartment reactor compared to electrolysis process. In reactor with single compartment, high voltage results high current then cause high-energy consumption. The highest chlorine gas production is at 0.5 M and 300 V that results 4.63 mmol within 15 minutes. On the other hand, using double compartment reactor, current is lower due to its higher distance between two electrodes that makes the higher resistance. In this case, the highest chlorine gas production is at 0.5 M NaCl and 700 V that results 11.25 mmol within 15 minutes. The use of ion selective membrane can keep the movement of charge from one electrode to other. Ion selective membrane can separate side product of NaOH, but side reaction of chlorine ion still exists. NaCl, will be decomposed in the solvent and form ions in the solution. Positive discharge electrode is called anode and the negative one is cathode. Each electrode bonds ions which have different discharge, so that ions with negative discharge will go to anode and the positive ions will go to cathode. Nevertheless, electrolysis of NaCl solution (brine electrolysis) used in chlor-alkali production has significant weaknesses, those are low conversion resulted by the electrolysis process and the use of high electric current when the electrolysis process occur (4). Hence, it is needed to observe other possible technologies that can be applied in the production of chlor-alkali to reduce the energy consumption. One of the technologies that can reduce the energy consumption is plasma electrolysis. The plasma electrolysis process is similar with electrolysis process, but it is done with high enough voltage until the electric spark is formed producing the plasma on the electrolyte solution. The plasma will produce reactive species such as radicals on large amount which are accelerated by the sharp potential gradient and have enough kinetic energy to induce unique chemical changes in aqueous solutions, so it is able to increase the formation of products in solution several more times than the Faraday electrolysis process (5), (6). Using this technology may reduce the energy consumption several times than conventional electrolysis so the productivity is more effective (6).

Ammonia in waste water is a major pollutant produced in industrial and agricultural waste water. Ammonia is often removed by conventional technologies such as pack tower aeration, biological treatment or adsorption as ammonium ion onto zeolites. In many cases, conventional methods are very costly and inefficient, and therefore, there is a need for an alternative separation technique for more efficient removal of ammonia from waste waters. The aim of this study is to investigate the performance of the combination of ozonation and absorption through membrane processes to remove ammonia from wastewater using natural hot spring water (NHSW) as absorbent. Experimental results show that operating variables such as time and pH of absorbent solution are found to remarkably influence the removal process efficiency. Based on experimental results ozonation can improve ammonia removal efficiency through the hollow fiber membrane contactor. Ammonia removal efficiencies and overall mass transfer coefficients increase with decreasing pH of absorbent solution. Keywords: ammonia, mass transfer, membrane, ozonation, removal efficiency Abstrak Amonia di dalam air limbah merupakan polutan utama yang berasal dari air limbah industri dan pertanian. Amonia kebanyak disisihkan dengan teknologi konvensional seperti aerasi di menara isian, pengolahan secara biologi atau penyerapan sebagai ion amonium pada zeolit. Dalam banyak hal, metode konvensional sangat mahal dan kurang efisien, sehingga diperlukan teknik separasi alternatif untuk proses penyisihan amonia dari air limbah yang lebih efisien. Tujuan dari studi ini adalah untuk menyelidiki kinerja kombinasi proses ozonasi dan proses absorbsi melalui membran untuk menyisihkan amonia dari air limbah menggunakan absorben berbahan dasar air dari sumber air panas. Hasil eksperimen memperlihatkan bahwa variabel operasi, seperti waktu dan pH larutan penyerap, sangat mempengaruhi efisiensi proses penyisihan amonia. Berdasarkan hasil eksperimen, ozonasi dapat meningkatkan efisiensi penyisihan ammonia melalui kontaktor membran serat berlubang. Efisiensi penyisihan amonia dan koefisien perpindahan massa keseluruhan naik dengan turunnya pH larutan penyerap. Kata kunci: amonia, perpindahan massa, membran, ozonasi, efisiensi penyisihan

Hollow fiber membrane contactors have been widely used as gas-liquid contactors recently such as in the CO2absorption process from gas stream. This research aims to evaluate the effectiveness of hollow fiber membranecontactor to absorb CO2 from its mixture with CH4 or N2 using water through mass transfer and hydrodynamic tests.There are 3 membrane modules used in this research with shell diameter of 1.9 cm, length of 40 cm, outer fiberdiameter of 2.7 mm and fiber number in the contactors of 10, 15 and 20. Liquid flow rates in the hollow fiber membranecontactors are varied in this research. Research results show that mass transfer coefficients in the membrane contactorincrease with increasing liquid flow rate and decrease with increasing fiber number in the contactor. Flux of CO2 intowater can achieve 1.4x10-9 mol CO2 /m2.s and mass transfer coefficients can achieve 1.23 x 10-7 m/s. Meanwhile,hydrodynamic test results show that water pressure drop in the membrane contactors increase with increasing fibernumber in the contactors.

Wastewater generated from the tofu industry usually still contains high organic pollutants that can contaminate the surface water. Therefore, it should be treated properly before it can be disposed to the environment. This study aims to evaluate the combination of coagulationflocculation and ultrafiltration methods in treating the wastewater from tofu industry. Based on the preliminary tests, the wastewater from tofu industry have pH, total dissolved solid (TDS), total suspended solid (TSS), turbidity and chemical oxygen demand (COD) of 3.4, 870 - 1080 mg/L, 370 mg/L, 446 FAU and 7954 mg/L, respectively. The coagulant and membrane used in this study were Poly aluminum chloride (PAC) and the ceramic membrane, respectively. Experimental results showed that the best pH for coagulation-flocculation process is at pH of 7.0, and this pH was then used for ultrafiltration process. The flux of the ultrafiltration membrane increased with increasing the trans membrane pressure due to increasing driving force. The observed parameters such as TSS and turbidity of wastewater decreased drastically after experiencing ultrafiltration process and met the National Environmental Quality Standard. However, the COD of water produced in the ultrafiltration process was still high and did not meet the National Environmental Quality Standard.

The tofu industry is generally a household-scale industry so that the efficiency of water used and wastewater treatment are mistreated. Wastewater from tofu industry is very hazardous when discharged directly into the aquatic environment as it contains high organic pollutants which is indicated by high concentrations of BOD (biological oxygen demand), COD (chemical oxygen demand), TSS (total suspended solid), TDS (total dissolved solid) and turbidity. The optimization of wastewater treatment process is needed to meet the quality standards set by the government and also needed to obtain more effective and efficient effluent treatment. The aim of this study is to evaluate the performance of combination coagulation-flocculation and ultrafiltration processes for tofu industry wastewater treatment. The process of pretreatment coagulation and flocculation using poly aluminum chloride (PAC) was conducted to extend the life of the ultrafiltration membrane and improve the performance of ultrafiltration membrane separation. The experimental results showed that TSS and turbidity decreased with precipitation time whereas COD did not significantly change. TDS after coagulation-flocculation has increased due to the addition of PAC. The TSS, TDS, COD and turbidity of wastewater were drastically reduced after experiencing ultrafiltration process. After the ultrafiltration process, the TSS, Turbidity, COD and TDS rejection were 98.8%, 98.1%, 71.0% and 50.6%, respectively.

Wastewater from tofu industry is one of water pollution sources that still require more effective treatment. This study aim to treat wastewater from tofu industry through a combination of coagulation-flocculation and ultrafiltration processes. Coagulation-flocculation is conducted prior to ultrafiltration process to minimize the effect of fouling on membrane and to improve the performance of ultrafiltration process. Poly aluminum chloride (PAC) was used as coagulant with doses of 100, 200, 300, 400 and 500 ppm. The wastewater feed have pH, total dissolved solid (TDS), total suspended solids (TSS), turbidity and chemical oxygen demand in the ranges of 3.8 - 4, 850 - 880 mg /L, 380 - 420 mg /L, 450-530 FAU and 5600 - 6600 mg /L, respectively. Experimental results showed that the effectiveness of coagulation increased with the addition of coagulant dose until the optimum dose is reached. After coagulation-flocculation process, COD, TSS, and turbidity decreased, whereas TDS increased. The optimum dose of the coagulationflocculation process was then used for a combination of coagulation-flocculation and ultrafiltration processes. The result of this combination process showed a decrease in COD, BOD, TSS, and turbidity.

NOx is produced from the reaction between nitrogen, oxygen and even hydrocarbons (during combustion), especially at high temperatures. Nitrogen oxide compounds are one of the harmful emissions that can result from fuel combustion. This research aims to find out the performance of super hydrophobic membrane contactors in the absorption process of N2O from its mixture with air using acid solution and hydrogen peroxide. N2O gas must be reduced from the exhaust gas especially to meet the regulations applicable to the environment due to the hazardous nature of the N2O gases. The experimental results showed that the amount of NOx absorbed and the absorption efficiency increased with increasing absorbent flow rate in the membrane contactor. Meanwhile, the concentration of NOX in the outlet gas decreased with increasing absorbent flow rate.

Cryogenic Power Generation or commonly called Cryopower is the generation of electricity by utilizing cold energy which one is produced at the LNG (liquefied natural gas) Regasification Terminal. Cold energy utilization has been applied in several countries, especially in Japan. In Indonesia, the regasification terminal has been built few, but in the future according to the Government of Indonesia's plan, some natural gas/LNG power plants will be built to meet the national electricity needs. It requires gas infrastructure, one of which is the regasification terminal. The aim of this study is to evaluate the effects of LNG flowrate on working fluid and cooling water flowrates as well as power needed and produced in the combine direct expansion and Rankine cycle processes. The flowrates and power calculations were conducted using UNISIM R390.1. Simulation results showed that the working fluid and cooling water flowrates increase with increasing LNG flowrate. The increased in the working fluid and cooling water flowrates also increased the power needed by the pumps and power produced by the turbines. Overall, the net power produced from the combine cycle increased with increasing the LNG flowrate.

The 15th International Conference on Quality in Research (QiR) was held in Nusa Dua, Bali, Indonesia on July 24–27, 2017. The main theme was “Science, Technology and Innovation for Sustainable World.” This third book of special edition of International Journal of Technology (IJTech) present 18 papers in the research areas of chemical and metallurgy & materials engineering. The International Symposium on Chemical Engineering, QiR, covered various topics such as renewable energy business and economics, biomass conversion technologies, modeling and simulation, advanced thermal and chemical processes, waste to energy, advanced biofuel technology, catalysts, composites, photocatalysis, and adsorption. We have selected 10 papers from the 80 submitted for publication in the IJTech. The International Symposium on Materials and Metallurgy, QiR, covered topics such as carbon, graphene, oxides, nanocomposites, mesostructured materials, advanced superconducting, electrochemical water splitting, extraction, hydrometallurgy, and energy storage devices. We selected 8 papers from the 111 fullpapers for publication in the IJTech. The eighteen papers, from both symposia, are summarized below.

This study uses DEA solution to absorb CO2 from the gas flow through the hollow fiber membrane contactors. Thisstudy aims to evaluate the performance of hollow fiber membrane contactors to absorb CO2 gas using DEA solution assolvent through mass transfer and hydrodynamics studies. The use of DEA solution is to reduce the mass transferresistance in the liquid phase, and on the other side, the large contact area of the membrane surface can cover thedisadvantage of membrane contactors; additional mass transfer resistance in the membrane phase. During experiments,CO2 feed flows through the fiber lumens, while the 0.01 M DEA solution flows in the shell side of membranecontactors. Experimental results show that the mass transfer coefficients and fluxes of CO2 increase with an increase inboth water and DEA solution flow rates. Increasing the amount of fibers in the contactors will decrease the masstransfer and fluxes at the same DEA solution flow rate. Mass transfer coefficients and CO2 fluxes using DEA solutioncan achieve 28,000 and 7.6 million times greater than using water as solvent, respectively. Hydrodynamics studiesshow that the liquid pressure drops in the contactors increase with increasing liquid flow rate and number of fibers inthe contactors. The friction between water and the fibers in the contactor was more pronounced at lower velocities, andtherefore, the value of the friction factor is also higher at lower velocities.