bluuebunny/crossref_metadata_2025 huggingface dataset:
Coordinated Control Strategy of Emulated Inertia and Damping for Grid-Forming Energy Storage Considering Capacity Characteristics
Authors: Li Ting , Tang Quan , Zhu Ke , Du Xinwei , Li Bo , Liu Fang , Zhen Tianwen
Published: January 2022

The grid-forming control method of the emulated synchronous generator can enhance the response capability of the electricity frequency and enhance the anti-interference capability of the new energy system. But the system frequency regulation ignores the fact that the active power of multiple energy storage is not proportional allocation, which can decrease the stability of the system. To solve this problem, a grid-forming control method of emulated rotational inertia and damping characteristics for multiple energy storage considering capacity characteristics is proposed. First, the control construction of the grid-forming inverter is presented, and the mathematical model of the grid-forming control of the emulated synchronous generator is established. Secondly, the frequency change and frequency deviation are introduced into the grid-forming control, and the grid-forming control method of emulated inertia and damping coefficient is designed. Each energy storage obtains the emulated rotational inertia and damping value through the real-time state of charge, which adjusts the frequency response of the power grid and active power of the distributed electricity storage system. And this method can realize proportional allocation according to the capacity of electricity storage system. Finally, the simulation analysis results of Matlab/Simulink simulation model is carried out to verify the effectiveness and feasibility of the proposed grid-forming control method.
Overview of High-voltage Large-capacity DC Transformer
Authors: Chen Meng , Li Yan , Bai Jinyang , Feng Gang , Peng Yujin , Guo Jiangzhen
Published: January 2022

DC transformer is the core equipment to realize the convergence and transmission of new energy such as solar energy, wind energy, etc. It also plays a key role in the construction of large-scale DC power grid in the future. Therefore, DC transformer has a broad application prospects in the future energy Internet era. This paper briefly summarizes the current research on DC transformer at home and abroad, and also summarizes the current research on DC transformer in the future. On the basis of the basic principle of decomposing DC transformers, the characteristics and applications of common DC transformers are classified and the problems to be solved are summarized.
Fault Diagnosis of Transmission Lines Based on High Frequency Electromagnetic Spectrum Distribution Characteristics
Authors: Miu Zhongling , Wu Nian , Yao Junwen , Ke Xianbin , Liu Pingyuan , Bie Shiguang
Published: January 2022

According to the recognition of the fault of the transmission line, the traditional methods of manual detection, image recognition and infrared observation can not distinguish the defects, but the line produces the electromagnetic interference level change is its produces the flaw the important characteristic. Therefore, the electromagnetic interference (EMI) can be used as a parameter in the inspection of high-voltage transmission line. this paper studies the correlation between the fault of the transmission line and the distribution of the high frequency electromagnetic spectrum, by analyzing the level change of the electromagnetic interference between the normal wire and the broken wire, the defects such as the old wire, the broken wire and the serious corrosion, which can not be distinguished by image, are detected, it provides a strong technical support for the condition assessment of transmission line conductors.
Research on Cloud-edge Interaction Technology of Power Internet of Things Based on MQTT Protocol
Authors: Liu Qing , Hou Jixin , Yan Yu , Wang Xiaochao , Liu Xiaohu
Published: January 2022

Under the development trend of power industry with energy Internet as the core, with the update of information technologies such as intelligent devices, mobile communication technology and cloud computing, the application of Internet of things (IOT) in power industry has developed from the concept of specific link service to the application of large-scale market. The core of the next power Internet of things construction is to build an open IOT management platform to realize the ubiquitous access of massive devices, the deep sharing of cross-professional data, business integration, and the provision of precise user services. Based on this, an industrial alliance will be formed and a power industry ecosystem with power grid enterprises as the core will be established. At present, the application of power Internet of things in China is still in the primary stage of research and application. The research on what the IOT management platform should manage and the interaction technology between the IOT management platform and edge agents is still in the stage of exploration and pilot. This paper mainly studies the cloud-edge interaction technology, including the interaction object, process and message format. Then it formulates a set of cloud-edge format specifications to meet the requirements of the platform’s own management and business system message transmission, so as to provide reference for the cloud-edge interaction of power Internet of things.
Short-term Load Prediction Based on the Combination of K-means and Random Forest
Authors: Chai Weiwei , Qin Lei , Dong Haiying , Sun Chunshan , Shen Wei , Qiao Shiyun
Published: January 2022

Aiming at the problem that the power supply and distribution system runs at low load rate for a long time and wastes capacity due to the expansion of the power supply and distribution system, a short-term load forecasting method combining K-means and random forest is proposed. The proposed method divides power users into four categories based on electricity behavior, based on which the corresponding category load data is selected as the input sample of the random forest model to obtain short-term load prediction results. Example analysis shows that this method can ensure the rapid clustering accuracy, and effectively realize the short-term prediction of power load based on the random forest, to achieve the purpose of improving the load rate.
A Real-time Detection Framework for Abnormal Devices in the Power Internet of Things
Authors: Miu Weiwei , Zhang Zhen , Wang Xiaochao , Hou Jixin , Sun Yunan , Liu Qing , Zeng Zeng
Published: January 2022

Power Internet of Things [1] is the application of Internet of Things in smart grid. By effectively integrating power system and communication infrastructure resources, the information level of power system and the utilization rate of existing resources are improved. Thus, important technical support is provided for power grid generation, transmission, transformation, distribution and electricity consumption. The Power Internet of Things contains a large number of terminal equipment, which involves the data interaction frequency of 100 million levels per second. Therefore, how to avoid the access of invalid data is an important topic in the construction process of power Internet of Things. In response to the detection requirements of abnormal devices, this paper, based on existing Intelligent IoT System architecture, designs a real-time detection framework that integrates a two-level control mechanism, which is universal, extensible, and supports multiple protocols, using the data interaction specifications formulated by the State Grid Corporation as the basic detection basis. As a result, the framework realizes the effective interception of abnormal devices in power Internet of Things.
Research on the Detection Technology of Audible Noise Sources of UHVDC Transmission Lines
Authors: Lv Jianxun , Zhao Penghui , Yuan Haiwen , Liu Xinyu
Published: January 2022

In order to directly and deeply study the law and characteristics of audible noise sources of UHVDC transmission lines, a method of detecting the sound intensity vector at the source position in the bundle conductor is proposed. First, the structure of the sound intensity detection device is designed, and the method for calculating the sound intensity vector is deduced based on this prototype. Then, the simulation of the electric field distribution on the surface of the device in the UHV extreme electric field environment is carried out. The change of the maximum electric field intensity and the influencing factors are obtained, which proves that the proposed detection device has the adaptability of the UHV electric field environment. Finally, the measurement error of the proposed detection device is analyzed. The results show that in the frequency range of 100∼5000Hz, the theoretical error of the sound intensity vector components and the total sound intensity level obtained by the measurement device in three directions are less than 2dB, which can meet requirements of sound intensity detection at the sound source.
Development and Application of Downhole Chokes with Pressure and Temperature Monitoring Function
Authors: Chen Jiaxiao , Tan Jinfeng , Yu Fan , Chen Ke , Jiang Mi
Published: January 2022

For wells employing downhole choking technology, the traditional well testing methods no longer accommodate the requirements for dynamic monitoring of production performance due to the existence of downhole chokes. On one hand, the wellhead pressure data of gas wells with downhole chokes can neither truly reflect the actual situation of gas wells nor directly provide effective data for the dynamic gas well performance analysis. On the other hand, because of the calculation error with the nozzle flow pressure drop in the calculation method, the calculation error of wellbore pressure is significant, resulting in failure of the annulus liquid level method to carry out monitoring as most wells are installed with packers. In this regard, the downhole choke with pressure and temperature monitoring function has been independently developed by combining the production features of the wells with downhole choking technology. Under the condition of no change of tubing string, no use of cable running and no impact on gas well production, the steel wire operation was implemented, achieving the downhole choking production of gas wells and the monitoring of pressure and temperature prior to the choking operation, thus to establish a wellbore pipe flow prediction model and a nozzle flow model. Through the field application and evaluation, the error between the calculation results of the flow model and the field measured data is controlled within 5%, which provides a theoretical calculation basis for the accurate pressure prediction of wells using choking technology as well as technical support for the dynamic analysis of downhole choking gas wells.
Improved Anomaly Detection Based on Image Reconstruction and Global Template Features for Industrial Products
Authors: Tang Huixiong , Hu Guanghua , He Wenliang , Tu Qianxi
Published: January 2022

Anomaly detection in industry applications is a challenging problem when negative (defective) samples are unavailable, especially in the case where there are missing parts or foreign objects occupied a relatively large region. Conventional reconstruction-based approaches cannot guarantee the restored image being a normal one, leading to poor segmentation results. In this work, we propose an unsupervised anomaly detection approach to tackle the problem of large-area anomaly detection by incorporating global template features into an Auto-Encoder like reconstruction model. In particular, our model infers the value of each pixel based on both the surrounding local-neighborhood information and the global information encoded at the same pixel position. During the reconstruction phase, any abnormal features are then replaced with normal ones, avoiding over-reconstruction of large-area abnormalities. The experimental results in comparison with other methods demonstrate its effectiveness for industrial anomaly detection.
4H-silicon carbide as particle detector for high-intensity ion beams
Authors: Christanell M. , Tomaschek M. , Bergauer T.
Published: January 2022

In ion cancer therapy, high-intensity ion beams are used to treat tumors by taking advantage of the Bragg-peak. Typical ion therapy centers use particle rates up to 1010 ions/second for treatment. On the other hand, such intensities are often too high when using these beamlines for particle physics experiments or as a test-beam environment in general. The project presented here aims to develop a beam position and intensity monitor, to cover a wide intensity range from a few Hz up to GHz rates, as used in clinical settings. Silicon carbide (SiC) is an attractive detector material for this application because it combines potential high radiation hardness with high thermal conductivity to avoid cooling. Moreover, its high electron saturation velocity allows very fast signals to mitigate pile-ups. However, some special properties of the material like different crystal polytypes have to be considered. In this paper, measurements on both a pad and a micro-strip SiC sensor prototype of 4H lattice geometry are shown. The sensors were tested in the laboratory using radioactive sources and with a proton beam in a wide intensity range (kHz–GHz) and with different energies (60–800 MeV) available at MedAustron, an ion cancer therapy center located in Austria. The measurements show that MIP particles cannot be detected reliably with the used discrete electronics setup in combination with the single-channel sensor. However, the strip sensor combined with an ASIC-based readout electronics from the CMS/Belle-II experiments allows to recover a certain part of the signal. This makes it possible to determine the ionization energy and average number of electron/hole pairs generated in the studied sensor samples.
Advance of glucose conversion to 5-hydroxymethylfurfural using ionic liquid: mini review
Authors: Zunita M , Yuan D M , Laksono A S
Published: January 2022

Biomass has been used as a raw material to replace fossil fuel due to its abundance and renewability in recent years. The majority of biomass consists of carbohydrates such as glucose and fructose. The conversion of glucose into its derivative (i.e., 5-hydroxymethylfurfural (HMF)) opens several spaces to be studied. However, the yield of HMF is still low due to its ease of degradation into by-products and the difficulty of product separation. Therefore, ionic liquid (IL) is used as a solvent or media to avoid HMF degradation, which has high thermal stability, low toxicity, an un-flammable, wide range of solubility, physical and chemical stability. In addition, IL is recyclable, has good performance at dissolving biomass, and can act as a catalyst. Many important aspects of glucose conversion into HMF in IL as a media and catalyst can be deeply developed and investigated regarding conversion yield, which is affected by different ILs used, and conversion time. This review paper will discuss a detailed summary of the development of glucose conversion into HMF using IL.
Impact of surfactant-aided subcritical water pretreatment process conditions on the reducing sugar production from oil palm empty fruit bunch
Authors: Rachmah A N L , Fatmawati A , Widjaja A
Published: January 2022

Oil palm empty fruit bunch (OPEFB), waste produced from the palm oil mills, has not been intensely utilized while its abundant availability in tropical countries such as Indonesia. It is one of the potential lignocellulosic material sources which can be utilized to produce sugar. The subcritical water process has been known as a promising lignocellulose-to-sugar conversion process. This study examined the effects of temperature, surfactant types, and concentrations on the sugar yield from OPEFB through the subcritical water process. In this research, the subcritical water process was conducted at a varied temperature of 140-180 °C, constant pressure and time of 60 bar, and 60 minutes, respectively. The types of surfactants studied were non-ionic, anionic, and cationic (Tween 80, SDS, and CTAB). Reducing sugar concentration analyses and solid characterizations using SEM, XRD, FTIR, and TGA were carried out in this research to evaluate the impact of the subcritical water process variables. The experiments showed that Tween 80 addition to the subcritical water process produced significant sugar yields at temperature 140 °C. The addition of CTAB to the subcritical water process shows adverse effects, while that of SDS showed support in the sugar production yields. This may be caused by hydrophobic and hydrophilic interactions between functional groups of the lignin unit and the hydrophobic and ionic groups of the surfactants. The subcritical water process run at a temperature of 180 °C assisted by SDS is the best scenario to produce the highest reducing sugar yield of 4.034%.
Analysis of biogas production from palm oil mill effluent at different feed flow rates in biogas plant Sei Pagar Riau
Authors: Wulandari W , Senda S P
Published: January 2022

Indonesia’s palm oil industry is considered one of the biggest in the world. Palm Oil Mill Effluent (POME) has the potential for further processing, which can be used as a substitute for boiler fuel (co-firing). Research on converting POME to biogas for boiler fuel (co-firing) in the oil palm plantation Sei Pagar Riau has been carried out. This study aimed to investigate and analyze the biogas production from Palm Oil Mill Effluent at different feed flow rates in Biogas Plant Sei Pagar Riau. Experiments were carried out using the Continuous Stirred-Tank Reactor (CSTR). The reactor capacity was 2000 m3. The reactor was equipped with one unit of vertical agitator and three units of horizontal agitators. POME was distributed from the fat pit unit to the pretreatment unit using the fat pit transfer pump. From the pretreatment unit, then POME proceeds to the reactor using the reactor feed pump started from 2.4 m3/h then gradually increase to 6.3 m3/h as the highest feed flow rate. Biogas was produced in the anaerobic reactor at mesophilic temperature. This study showed that an increase in the POME feed flow rate into the reactor also increases the production of biogas generated in the reactor. The biogas production began to increase every day, with the highest average biogas production of 167 m3/h. The methane concentration was also measured and showed that the highest methane concentration was on day 6, with a value of 70%. And then, the methane concentration trend decreased. However, it was relatively stable in the range of 62.1%-66.7% on day 18 to day 53. Based on this research, it was found that the optimal biogas production of the Biogas Plant in Sei Pagar Riau was generated when the POME feed flow rate was gradually increased and reached the maximum capacity according to its design.
Influence of fenton pretreatment on anaerobic digestion of sugarcane vinasse: effect of H2O2 dosage
Authors: Hakika D C , Sarto S , Mindaryani A , Hidayat M
Published: January 2022

Sugarcane vinasse is one of the resources with a high potential for biogas production. However, its high value of COD (>100 g/L) and poor biodegradability could present substrate inhibition during anaerobic digestion. Thus, pretreatment techniques seem necessary for improving the process efficiency and enhancing biogas yield from sugarcane vinasse. In this study, the pretreatment process has been carried out using Fenton reagent, which utilizes the hydroxyl radical produced from the catalyzing reaction between hydrogen peroxide and Fe2+ or Fe3+. Sugarcane vinasse as substrate was pretreated using Fenton reaction at different doses of 30% H2O2 within the range of 15 to 80 g/L. Through Fenton pretreatment, the biodegradability of sugarcane vinasse and biogas production was markedly increased. The optimum dose of H2O2 for Fenton pretreatment of biogas production from sugarcane vinasse was 60 g/L. At this pretreatment condition, the cumulative biogas yield was 124.39 mL/g sCOD, and the methane content was 52.6%. The methane content of biogas from Fenton-pretreated vinasse increased approximately four times higher (from 11.3% to 52.6%) compared to the untreated sugarcane vinasse as control. These results indicate that Fenton pretreatment can be applied to improve substrate biodegradability and enhance biogas production from sugarcane vinasse.
Modeling the synthetic gas fermentation for bioethanol production
Authors: Krista G M , Kresnowati M T A P
Published: January 2022

The productivity of bioethanol from the synthetic gas anaerobic fermentation by Clostridium jungdahlii is still very low when compared to other bioethanol fermentation methods. The low mass transfer rate of CO, CO2, and H2 gases to the liquid fermentation broth has been considered a major bottleneck in the overall process. Another possible bottleneck is the low concentration of biomass as the real catalyst for bioethanol production. A repeated batch fermentation configuration is proposed to solve the biomass concentration problem. This paper presents the evaluation of the repeated batch configuration for syngas anaerobic fermentation. A model for syngas fermentation has been developed and was used to simulate the effects of repeated batch configurations on bioethanol productivity. The results indicated more than a 50% increase in bioethanol productivity can be achieved by running this fermentation configuration.
A review of sugarcane bagasse pretreatment for bioethanol production
Authors: Nasution M H , Lelinasari S , Kelana M G S
Published: January 2022

Bioethanol is a new and renewable energy source. The second-generation bioethanol production process from lignocellulosic materials has development opportunities. This is because the first generation of bioethanol raw materials is generally a food source. Diversification of raw materials for the bioethanol production process can be developed through the use of non-food or waste sources. The process of developing bioethanol from local non-food resources or waste can increase energy security and the added value of these sources. One of the potential sources is sugarcane bagasse. The production process of bioethanol from sugarcane bagasse consists of: (i) pretreatment; (ii) enzymatic hydrolysis; (iii) fermentation; (iv) distillation; and (v) dehydration. The major composition of sugarcane bagasse consists of cellulose, hemicellulose, and lignin. Sugarcane bagasse requires a pretreatment process to separate lignin and hemicellulose from cellulose, reduce the crystallinity of cellulose and facilitate the hydrolysis of cellulose. This review focuses on sugarcane bagasse pretreatment for bioethanol production. There are several types of pretreatment processes, including (i) physical pretreatment; (ii) acid pretreatment; (iii) alkaline pretreatment; (iv) organosolv pretreatment; (v) steam explosion; and (vi) wet oxidation. Physical pretreatment is the process of physically changing the size of the sugarcane bagasse to be smaller. Chemical pretreatment is the separation process of lignin and hemicellulose from cellulose using acid compounds. Alkaline pretreatment is the separation process of lignin and hemicellulose from cellulose using alkali compounds. Organosolv pretreatment is lignocellulosic pretreatment using organic solvents. Steam explosion is the process of disrupting the complicated structure of sugarcane bagasse using steam. Wet oxidation is the process of biomass treatment with water, oxygen, or air. Steam explosion is superior to other processes in terms of hemicellulose solubilization, reaction time and no toxic substances.
Myco-briquettes from sugar palm dregs fibre, cassava dregs and coconut shell charcoal with solid substrate fermentation technology
Authors: Agustina W , Aditiawati P , Kusumah S S
Published: January 2022

Abstratct. Myco-briquettes from sugar palm dregs fibre (SPDF), cassava dregs (CD), and coconut shell charcoal (CSC) have been prepared by the solid substrate fermentation method using Ganoderma lucidum. The purpose of this study was to determine the best formula and characteristics of the myco-briquette product. The myco-riquette were prepared by varying the composition ratios of the SPDF and CD i.e. 65:35; 50:50; and 35: 65% w/w) and then optimized by adding CSC to the selected formula with varying of CSC concentration such as 10%, 15%, and 20% of total solid weight. The stages of myco-briquette production include preparation of inoculum, material mixing, sterilization, inoculation, fermentation, pressing, drying, cutting, and packaging. The products of myco-briquette are then compared with the Indonesian Standard of wood pellets (Indonesian National Sandard (SNI): 8021: 2014). Based on the test results, the fermentation time is around 11-12 days. The best formula for myco-briquette products is 35: 65% w/w of composition ratio between SPDF and CD with the addition of 20% CSC. The optimum myco-briquette had a moisture content (7.55%), an ash content (3.06%), a heating value (4522.56 cal/g), a density (0.51g/cm3), volatile matter (61.64%) and fixed carbon (26.90%) fulfilled SNI 8021-2014 for wood pellet. However, the density and ash content of Myco-briquette did not satisfy SNI 8021-2014.
Effect of solid loading and dipping time on microstructure and shear strength of hydroxyapatite coatings deposited via dip coating technique
Authors: Fadli A , Mulya N , Pane K B , Pratama A
Published: January 2022

Stainless steel (SS) 316L has been used in the biomedical field, especially as a bone plate. Although SS 316L provides high mechanical and corrosion resistance, the low biocompatibility of SS 316L hampers its application for permanent bone implants. This research investigates the effect of hydroxyapatite loading and dipping time on microstructure and shear strength of hydroxyapatite layer coated on SS 316L surface. Hydroxyapatite powder and aquadest were mixed with sago starch to form suspension with stirring rate at 150 rpm for 20 hours. Subsequently, the stainless steel plate was dipped into the suspension and put into the oven at 110°C for 10 minutes, followed by sintering at 800°C for 1 hour. The coating process was carried out with variations in the hydroxyapatite addition of 8, 10, and 12 grams and dipping time variations of 2, 6, and 10 seconds. Then, the microstructure of stainless steel coated hydroxyapatite was analyzed with X-ray diffraction, scanning electron microscopy, and autograph. The result shows that the increase in hydroxyapatite and the dipping time increase the hydroxyapatite layer on stainless steel. The hydroxyapatite with the thickest layer is 65 µm for 12 gr hydroxyapatite addition and dipping time of 10 seconds. Moreover, shear strength of the layer increase with hydroxyapatite addition and dipping time. The maximum shear strength obtained in this study is 244 kPa.
Production of bone implant filaments from blue crab shells (Portunus pelagicus) in various synthesis conditions and blending ratios of hydroxyapatite (HAp)-polycaprolactone (PCL)
Authors: Ningrum E O , Pratiwi E L , Shaffitri I L , Putra A F P , Karisma A D , Suprapto S
Published: January 2022

The effect of calcination temperatures and KH2PO4concentrations on filament properties using the precipitation method was investigated. Moreover, the effect of optimum hydroxyapatite-polycaprolactone ratios was also elucidated. In this study, blue crab shells (Portunus pelagicus) waste was used to synthesis hydroxyapatite. The modification of composite production was done by adding polymer as filler to obtain stronger composites with suitable mechanical properties for a stronger bone implant. The filament production consists of several steps, i.e., raw material pretreatment, synthesis of hydroxyapatite using a precursor of KH2PO4with precipitation method, and synthesis of hydroxyapatite-polycaprolactone composites, and hydroxyapatite-polycaprolactone filament formation process using an extruder. It was found that the hydroxyapatite has been successfully synthesized from raw material of blue crab (Portunus Pelagicus) shells by calcination temperatures of 950°C and 1000°C. The highest calcium concentration in the raw material calcined from rajungan shells obtained from the XRF analysis was 94.96% at a temperature of 950°C. The FTIR analysis results showed a PO43-group indicating hydroxyapatite content in the crab shells.
The effect of silica filler quartz sand from tailing processing of mining material on mechanical properties, thermal aging and morphology rubber compound
Authors: Prasetya H A , Marlina P , Rahmaniar  , Sugiyono B , Danimasthari F , Subari  , Faizal M
Published: January 2022

Tailings as waste from mining material processing contain constituents that have the potential to be exploited economically. Tailings deposits derived from tin mines include quartz sand with a SiO2 content of 98.03%, which can function as a filler for rubber products. This research studied silica quartz sand as a mineral filler in natural rubber (NR) on rubber’s mechanical and thermal aging characteristics. The effect of reinforced filled in NR was observed by varying 0, 10, 20, 30, 40, and 50 phr of the filler. The thermal aging test is carried out at 70 °C and 100 °C for a storage period of 72 hours. SEM micrographs were used to examine morphology. The results showed that using silica quartz sand as a filler improved various properties, including tensile strength, tear strength, elongation at break, hardness, and abrasion resistance. The higher the grinding temperature, the higher the hardness and tensile strength, but the lower the elongation at break. Morphological analysis using SEM micrographs revealed the system’s strengths and weaknesses. The silica particles are homogeneously mixed with natural rubber, according to SEM analysis. According to the findings of this study, the silica of quartz sand from tin mining processing industrial waste can be used as a cost-effective alternative filler in NR compounding.
Preparation of magnesium oxide confined in activated carbon synthesized from palm kernel shell and its application for hydrogen sulfide removal
Authors: Abriyani D , Ariyanto T , Prasetyo I
Published: January 2022

In this study, magnesium oxide (MgO) confined in porous carbon was synthesized and the efficacy of this material was analyzed for hydrogen sulfide removal. The palm kernel shell was carbonated to obtain the porous carbon material (labelled as AC-TKS). The confinement of magnesium oxide was carried out by the incipient wetness impregnation process of a metal oxide precursor followed by calcination. The MgO content in porous carbon was optimized to maintain a 5 wt. % total content of oxide (MgO-5%/AC-TKS). Materials were characterized using N2-sorption analysis, X-ray diffraction (XRD) and scanning electron microscopy-EDX (SEM-EDX). AC-TKS has a high specific surface area (SSA) of 708 m2/g. Meanwhile, the specific surface area decreased by up to 50% (ca. 248 m2/g) for MgO-5%/AC-TKS caused by the blocking of the MgO content. The successful confinement process was proven by X-ray diffraction analysis which revealed that MgO was formed by the appearance of MgO peaks. This is supported by the results of SEM-EDX mapping, which showed the presence of Mg and O elements on the carbon surface. The higher H2S removal was shown by MgO-5%/AC-TKS which could reduce H2S up to 98.6% and showed a better performance compared to only porous carbon.
High cell density submerged membrane photobioreactor (SMPBR) for microalgae cultivation
Authors: Steven S , Friatnasary D L , Wardani A K , Khoiruddin K , Suantika G , Wenten I G
Published: January 2022

Microalgae have been extensively studied as a potentially sustainable biomass resource. However, its cultivating and harvesting system faces many challenges due to the low cell density of microalgae. Recently, membrane technology in microalgae cultivation is believed to improve the CO2 gas-liquid mass transfer. It could generate more uniform microbubbles to prolong the gas retention time in the culture solution. This study used a submerged membrane photobioreactor (SMPBR) based on a hydrophobic polypropylene membrane as a CO2 diffuser for producing high cell density microalgae. The SMPBR performance during Chaetoceros calcitrans batch cultivation in a modified f/2 (Guillard) medium was investigated. Results show that Chaetoceros calcitrans growth follows a sigmoid mode without a lag phase until it reaches the stationary and death phase. Cultivation using SMPBR also intensified the biomass concentration, initially from 7.0 x 106 cells/mL up to 4.8 x 108 cells/mL. In 7 days of cultivation under 3% of CO2 and 1.8 L/min of inlet gas flow rate, a maximum biomass concentration of 2.1 g/L was achieved with a maximum specific growth rate of 2.1 day1. Results show that the SMPBR configuration effectively supplies CO2 to a microalgae culture due to the high CO2 transfer in the medium. Moreover, it has the potential application for producing high cell density microalgae.
The effect of temperatures and monomer ratios on the characteristic of anionic and cationic gel-based adsorbents
Authors: Ningrum E O , Safitri Z M , Dzaky M A , Suprapto S , Karisma A D , Ni’mah H
Published: January 2022

Industrial development has caused the metal concentration in the environment to increase. This is a serious issue considering that heavy metals are stable and cannot naturally decompose. Therefore, wastewater should be processed before being disposed to the environment. Several technologies have been developed for removing heavy metal content in industrial liquid wastes. The adsorption method using solid adsorbent is a simple and effective method for separating heavy metal ions from electroplating wastes since they are eco-friendly and efficient. However, they produce secondary wastes and require high operational costs. The blending of cationic gel NIPAM-co-Chitosan and anionic gel NIPAM-co-Acrylic Acid is a potential candidate as a new alternative adsorbent. By this method, the secondary wastes can be eliminated, adsorbed ions simultaneously, and adsorb-desorb ions reversibly. NIPAM-co-Chi and NIPAM-co-Acrylic Acid are synthesized from a polymerization reaction using N, N, N’, N’-tetramethylethylenediamine (TEMED) and sodium sulfite as accelerators, ammonium peroxodisulfate (APS) as an initiator, and N, N’-methylene bisacrylamide (MBAA) as a cross-linker. The gel was synthesized in a three-neck round flask for 6 hours. The product crush gel was then used for the adsorption and swelling degree test. The swelling degree test was performed by measuring the swelling gel volume before and after being soaked for 24 hours in target solutions. The gel obtained from the adsorption test was separated from the solution to be analyzed with Atomic Absorption Spectrophotometry (AAS). Based on the FTIR analysis of NIPAM-co-Chi and NIPAM-co-Acrylic Acid gels, there is no peak indicating the presence of vinyl C=C bonds. It can be concluded that the gel copolymer synthesis that was carried out was successful. The optimum results were obtained from the swelling degree analysis on electroplating waste at a concentration of 8:2.
The role of C/N ratio on anaerobic decomposition of industrial tempeh wastewater for optimizing methane production
Authors: Fransiscus Y , Simangunsong T L
Published: January 2022

Considering its high organic contents, A biological process, in particular anaerobically decomposition is considered to be the most suitable treatment for industrial tempeh wastewater. Among the important parameters that determine the success level of the process, C/N ratio was mentioned to play a significant role. Thus, this study was carried out to investigate the effects of different C/N ratios (10; 20; 30 and 40) on the decomposition process to produce methane gas. The experiment was conducted using 1L batch reactors with sludge from active cow manure biogas digester as inoculum. Several parameters such as pH, COD, BOD, VFAs and methane gas were monitored during the process to understand the mechanism. The experimental results confirmed that the C/N ratio significantly affected the anaerobic decomposition of tempeh wastewater, giving the best achievement for C/N = 30, with organic removal as high as 89% (COD) and total methane produced as much as 1240 mL in 14 days of observation. The balanced composition between carbon and nitrogen is important for the anaerobic process, higher organic loading (C/N = 40) will potentially lead to VFAs accumulation, meanwhile higher nitrogen concentration (C/N = 10) will stimulate complex transition, mainly denitrification and free ammonia formation. Both conditions will block the methanogenesis stage, resulting in a nonoptimal decomposition process and minimum methane production.
The effect of pH, initial concentration, and salinity on the biosorption process of chromium (VI) ions using microalgae Chlorella sp.
Authors: Wanta K C , Saptoaji D , Miryanti Y I P A , Kristijarti A P
Published: January 2022

The chromium (VII) (Cr6+) ions are carcinogenic substances, and thus the presence of these substances in water is hazardous for the environment and humans. Therefore, removing Cr6+ ions in water is required before the water is utilized or discharged into the environment. One of the processes that can be used is the biosorption process which involves microalgae as biosorbents. In this study, a synthetic solution of potassium dichromate (K2Cr2O7) and living microalgae Chlorella sp. was applied in this experiment. The study focused on studying pH, initial solution concentration, and salinity level on removing Cr6+ ions from the solution. The pH of the solution was varied at 2–6; the initial concentration of the solution was varied at 10-30 ppm; while the salinity level was varied at 2,000–16,000 ppm. The biosorption process was carried out in a batch reactor for 48 hours using white light. Samples were taken and analyzed periodically using a UV-Vis spectrophotometer to determine the decrease of Cr6+ ions in the solution and a haemocytometer to calculate the number of microalgae in the system. The results showed that 91.79% of Cr6+ ions could be removed from the solution.
Potential of natural sunlight for microalgae cultivation in Yogyakarta
Authors: Habibah E , Suyono E A , Koerniawan M D , Suwanti L T , Siregar U J , Budiman A
Published: January 2022

The study of microalgae is widely developed on a laboratory scale. The large-scale applications of microalgae such as large photo-bioreactors or commercial ponds are not well established due to some obstacles. The high cost of artificial lighting in microalgae cultivation is one of the obstacles. Markedly, the natural sunlight intensity is high every month for a whole year in Indonesia. This natural sunlight may serve as a low-cost lighting source for microalgae cultivation in a tropical country such as Indonesia. However, the basic knowledge of whether the natural sunlight in Indonesia is sufficient or not for microalgae cultivation is poorly understood. This study was performed to investigate whether sunlight in Indonesia, particularly in Yogyakarta, is sufficient or not for microalgae cultivation in the absence of artificial lighting. The sun lighting period data from January 2019 to June 2020 were collected from BMKG (Badan Meteorologi Klimatologi dan Geofisika) website. The sun lighting period data were converted into solar radiation data. The Liliefors test was performed to evaluate the distribution of the solar radiation data. To confirm whether the sun lighting in Yogyakarta is sufficient for microalgae cultivation or not, the parametric statistical test namely single sample T-test was used in this study. The Liliefors test showed that solar radiation in Yogyakarta (January 2019 to June 2020) was normally distributed. The calculated Liliefors value (0.14) was less than Liliefors table value (2.00). The T-test results revealed that the solar radiation in Yogyakarta is equal to or higher than the sufficient solar radiation (reference) for microalgae cultivation (795 kWh/m2). The calculated t value (0.65) was higher than the t table value (-1.74). When taken together, our findings suggest that natural sunlight in Yogyakarta is sufficient as a lighting source for microalgae cultivation.
The extraction and purification of squalene from Nyamplung (Calophyllum Inophyllum L) leaves
Authors: Ardhyni D H , Aparamarta H W , Widjaja A , Ibrahim R , Gunawan S
Published: January 2022

Squalene is a natural organic compound that is primarily found in shark liver oil. It can act as a skin moisturizing, anticancer, antivirus, and drug delivery agent. The advantages of people consuming healthy oil which contains squalene can lower the risk of heart disease. Due to the high market demand for squalene, it becomes a severe threat to shark existence. Therefore, investigation to find a new source of squalene is deemed necessary. Squalene is present in the leaves of nyamplung (Calophyllum inophyllum), a species of mangrove plant commonly found along Indonesia’s coast. This study aims to extract and purify squalene from nyamplung leaves. First, nyamplung leaves were crushed and extracted with n-hexane. The extract was designated as a crude extract of nyamplung leaves. After that, squalene was purified from the crude extract by the multistage adsorption-desorption method at 3°C. The crude extract was dissolved in hexane, and silica gel was then added at 30 min. The mass ratios of silica gel to crude extract were varied at 1:1, 2:1 and 4:1 (g/g). N-hexane fraction was separated from silica gel by filtration paper. N-hexane fraction was designated as a non-polar fraction (NPF), while silica gel fraction was designated as a polar fraction (PF). The dark-colored of PF was employed for the desorption process using methanol until its color became colorless. Meanwhile, NPF was extracted with fresh silica gel until it reached the 10th stage of extraction. NPF and PF were then quantitatively and qualitatively analyzed using TLC and GC, respectively. The best result was obtained from silica gel to crude extract mass ratio of 1:1 (g/g) at the 5th stage with squalene purity of 35.96% (45.82% recovery).
The effect of ultrasonic extraction methods on extract quality from Strobilanthes crispus L.
Authors: Arbianti R , Ningsih H , Utami T S , Muharam Y , Slamet
Published: January 2022

Strobilanthes crispus L. leaves are known to have many health benefits that have been proven both traditionally and in scientific research. To achieve more benefits from the leaves of Strobilanthes crispus L., the ultrasonic extraction (53 kHz) method was carried out using various ways. The variations of the ultrasonic method being carried out are UAE (Ultrasound-Assisted Extraction), UAEE (Ultrasound-Assisted Enzymatic Extraction), UAE-ATPE (Ultrasound-Assisted Enzymatic Aqueous Two-Phase Extraction) sequence and simultaneously. Extraction was carried out at 27 °C for 1hour, enzymatic hydrolysis reaction for 2 hours with a cellulose concentration of 7% w/w dry leaves, and the ATP (Aqueous Two-Phase) system of ethanol-ammonium sulfate of 33-14% w/w. The extract parameters measured were the yield, TPC (Total Phenolic Content), and TFC (Total Flavonoid Content) values. The highest yield was obtained by the Hydrolysis/UAE-ATPE method simultaneously, namely 80.94% w/w dry biomass. The highest TPC and TFC values were obtained from the extraction using the Hydrolysis/UAE-ATPS method simultaneously, i.e. 5.517 and 3.332 mg/g dry biomass respectively. Thus, it can be concluded that the simultaneous use of hydrolysis enzymatic with the cellulase enzyme and the ATP system in the ultrasonic extraction method can increase the quantity and quality of Strobilanthes crispus L. leaves extract.
Glucose production from oil palm empty fruit bunch (OPEFB) using microwave and fungal treatment method
Authors: Juliastuti S R , Hendrianie N , Sabar K R , Anggita S
Published: January 2022

Palm oil is one of the plants that can be used to produce cooking oil, industrial oil, and fuel. Indonesia itself was one of the largest palm oil-producing countries in the world. OPEFB includes lignocellulose biomass, whose main content is 46.5% cellulose, 33.8% hemicellulose, and 32.5% lignin. This research method used 3 stages, namely microwave pretreatment, Fungal Treatment 1 (FT 1), and Fungal Treatment 2 (FT 2). The raw materials used are OPEFB, while the fungi used are Phanaerochaete chrysosporium, Tricodherma harzianum, Aspergillus niger, and Tricodherma viride. The first step to be prepared in this study was to prepare OPEFB powder measuring 20 mesh. OPEFB powder was then put in the microwave for 20, 40, and 60 minutes. OPEFB that had been heated in the microwave was then converted into a slurry with the addition of water with a ratio of 3:5 (w/w). The second and third phases were Fungal Treatment for ±10 days. The parameters analyzed were the introduction of OPEFB, product of microwave pretreatment, product of fungal treatment 1, and product of fungal treatment 2. The content to be analyzed were lignin, cellulose, hemicellulose, and glucose. The result of pretreatment revealed that microwave-based pretreatment with the addition of alkaline solution could eliminate lignin by 83.45% and increase holocellulose levels by up to 41.907% at 300 W power and 60 minutes. As for the result for fungal treatment, the best treatment for FT 1 was treatment ratio TH:PC 1:2, which could eliminate lignin for 47.55% and FT 2 with treatment ratio TV:AN 1:2 that could increase glucose up to 84.9%.
Characteristic of oil palm empty fruit bunch after ethanol-organosolv pretreatment catalyzed by acid
Authors: Mondylaksita K , Budhijanto W , Taherzadeh M J , Millati R
Published: January 2022

The increasing growth of palm oil industry results in an increase in the accumulation of waste generated from the industry, such as oil palm empty fruit bunches (OPEFB). OPEFB is a good source of renewable raw materials if a pretreatment process can overcome the recalcitrance of OPEFB and allows the fractionation of all carbohydrates and lignin. In this work, the effectiveness of organosolv pretreatment to deconstruct OPEFB and to recover high purity of lignin and glucan was studied. The pretreatment experiments were carried out at 210 °C for 90 minutes with a solid to liquid ratio of 1/10. Ethanol 50% (v/v) was used as solvent. The effect of H2SO4 0.07% (w/w) as catalyst was also studied. The results showed that organosolv pretreatment with the addition of acid increased the purity of glucan and lignin by 36 and 5%, respectively. A total of 65% lignin was recovered, which was 3.6 times higher than lignin from pretreatment without acid catalyst. After organosolv pretreatment with an acid catalyst, the crystallinity index (CRI) decreased by 54%, while the decrease in CRI was only 14.4% after pretreatment without an acid catalyst. The water retention value of the pretreated OPEFB with acid catalyst increased by 8%. It can be concluded that organosolv pretreatment using ethanol as a solvent with the addition of acid catalyst succeeded in fractionating OPEFB with high purity and reducing recalcitrant OPEFB.