Search

Changes in water quality can be shown in physical, chemical and biological indicators. The presence of phytoplankton can be used as a bioindicator to evaluate changes in water quality and fertility in a water. The purpose of this study was to determine the abundance and biological index of phytoplankton in the Ir.H. Djuanda Reservoir. The method used is a survey. Types of phytoplankton obtained in the results of the study consisted of 6 classes and 36 species. The average abundance of phytoplankton in the waters of the Ir. H. Djuanda ranged from 23809 – 98810 cells/l. The results of the analysis of diversity (H') = 1.78 – 2.53, uniformity index (E) = 0.62 – 0.8 and dominance index (C) = 0.12 – 0.28. These results indicate that the diversity of phytoplankton in the Ir. H. Djuanda has moderate diversity, high uniformity and no dominance. Based on the value of the diversity index, it shows that the reservoir is classified as lightly polluted. [ABSTRACT FROM AUTHOR]

The steel industries account for 6% of the world's CO2 emissions. The number of emissions will continue to increase as the steel industry in Indonesia grows. Generally, steel production uses blast furnaces which can produce large CO2 emissions. The blast furnace process emissions called blast furnace gas (BFG) contain 20.7% mol of CO2. The high CO2 content also causes the calorific value of the gas to be low, so the gas must be purified to increase its calorific value to be used for power generation. In addition, the steel industry also produces steel slag as waste with a high CaO content (45.2%) but with low economic value. To increase its economic value, CaO content can be used to absorb CO2 from BFG to produce Precipitated Calcium Carbonate (PCC). The use of PCC is very broad for various industrial needs, such as a filler in the paper industry which can increase paper brightness. Therefore, the "Precipitated Calcium Carbonate from Blast Furnace Gas and Steel Slag" plant is expected to be a solution to reduce CO2 emissions from the steel industry. BFG and steel slag as raw materials were obtained from PT. Krakatau Posco. The PCC production process consists of three main stages, namely: (1) Pre-Treatment Steel Slag; (2) Carbonation; and (3) Purification. In the pre-treatment stage, the pH-swing method was used to extract CaO with NH4Cl solvent using pH control. The use of NH4Cl solution is advantageous because it can be recycled. This process obtained a solution of CaCl2 and NH4OH, which was then reacted with CO2 from BFG in a bubble column reactor, resulting in a carbonation process. In the reactor, PCC (CaCO3) and several impurities are formed. The PCC solids formed will then be filtered, dried, and reduced in size so that the moisture content and size are under PCC specifications for the paper industry. Besides producing PCC, purified BFG will be recycled and used as fuel for power generation. The plant location is integrated with PT. Krakatau Posco in the industrial area, Cilegon, Banten, West Java, with a production capacity of 12,750 tons/year. From the results of the economic analysis, with the capital expenditure (capex) of about IDR 337 million and operational expenditure (OPEX) of about IDR 89 million: the payback period is about 6.35 years, and the break-even point (BEP) is 32.38%. [ABSTRACT FROM AUTHOR]

Institut Teknologi Bandung (ITB) - Jatinangor Campus is one of the higher educational institutions located at Jatinangor, Sumedang Regency, West Java Province. This campus has area for about 47 hectares. When this campus have fully active activity, it produces huge amount of compostable waste especially organic and leaves waste. Solving the compostable waste is a key to realize Zero Waste ITB-Jatinangor Campus. MASARO technology offers fast, reliable, and profitable composting method to overcome the compostable waste problem at ITB-Jatinangor Campus. This technology has been applied in several areas in Indonesia, such as Ciwastra, Babakan Sari Waste Processing Site (Bandung City), Sabah Balau Village (South Lampung Province), Institut Teknologi Sumatera (ITERA), Sukadana Village (Ciamis Regency), Gorontalo, and several other areas. It has waste processsing capacity up to 10 Tons/day. The MASARO technology not only produces solid and liquid compost with Standard Nasional Indonesia (SNI) quality, but also shortens the composting period (about 7-10 days). Compost composition at ITB-Jatinangor Campus have 50,8% C-Organic, 2,71% N-total, 0,33 P2O5-total, 1,96% K2O-total, and 18,75 of C/N ratio. In this paper, it will focus on explaining implementation of the MASARO technology starting with the installation of the MASARO Composting House – Rumah Kompos MASARO (RKM). It would describe also about composting process and lesson learned about how the MASARO technology could solve the problem of compostable waste at a big educational institution like ITB-Jatinangor Campus. [ABSTRACT FROM AUTHOR]

This paper aimed to evaluate the natural gas application as an alternative energy source that correlates with an environmental conservation issue. The government pursues the utilization of clean energy. The reduction of greenhouse gas emissions has implemented through the program of kerosene to LPG conversion in Indonesia. Through this program, emissions reduction by the use of LPG estimated to achieve 130,223,596 tons of CO2 (2020). The use of natural gas in the Garut district expected as a pilot plan to improve greenhouse gas emission reduction in the energy sector. The evaluation of energy demand in Garut district shows that the use of clean energy provides attractive benefit opportunities. The total energy demand in Garut district reaches 147,558 MMBTU/year to serve people as much as 2,548,723 inhabitants. It predicted that 30% of this amount could converted into cleaner energy, i.e., compressed natural gas (CNG) or liquefied (LNG). The use of energy from natural gas is considered more decent and more profitable. Gas distribution from the terminal carried out using pipeline or truck transportation. [ABSTRACT FROM AUTHOR]

The study area is located in Cihaur Village, Sukabumi, West Java, occupied by Jampang Formation which hosts numerous gold mineralization in West Java. This paper discusses the geology and ore characterization based on field mapping, thin section petrography, and X-Ray Diffraction (XRD) to define the rock and hydrothermal alteration, and ore microscopy to identify the type of ore minerals. The geology of the research area consists of tuff breccia, andesite, and dacite units, with three alteration zones, such as silicification, argillic, and propylitic. The alteration characterized by quartz as a dominant secondary mineral (silicification), clay minerals such as kaolinite and illite (argillic), chlorite, albite, calcite, and minor secondary quartz (propylitic), based on petrography and XRD analysis. The area mineralization is dominantly controlled by quartz vein with N 3300 E orientation, showing crustiform, comb, chalcedony, saccharoidal, acicular, cockade, and stockwork textures corresponding to the low sulfidation epithermal system. On surface (about 720 – 740 masl), mineralization is characterized by gold with quartz and oxide manifested as gangue mineral, while mineralization below the surface (about 640 – 680 masl) characterized by base metal with ore minerals such as galena and sphalerite, and supergene minerals such as covellite. [ABSTRACT FROM AUTHOR]

Polyphenols play a pivotal role as representative metabolites of tea. Their presence can also determine the quality of tea and provide valuable benefits for human health. Little attention, however, has been paid to studying polyphenols such as catechin and EGCG at various processes of green tea and limited information is available related to this study in Indonesia. This study was focused on the determination of polyphenols content, antioxidant and antibacterial activities from Indonesian green tea, Camellia sinensis extracts, obtained from Gambung, West Java. The samples used were fresh leaves, dried leaves, and green tea powder from three plant clones, namely GMB-1, GMB-3, and GMB-7. Metabolites of tea were extracted using a hot water method at a temperature of 80 °C and incubated for 60 min. Antioxidant activity was measured using a 2,2-diphenyl-1-pycrylhidrazyl (DPPH) radical scavenging assay, while antibacterial activity was examined using a paper disk diffusion assay. The content of catechin and EGCG was measured by using HPLC. All samples showed strong antioxidant activity against DPPH free radicals, and the highest activity was reached by powder extract from GMB-3 clones. Furthermore, all extracts inhibited the growth of Gram-positive Micrococcus luteus, Bacillus subtilis, and Staphylococcus aureus. However, the extracts had no activity against Gram-negative Pseudomonas aeruginosa, Mycobacterium smegmatis, and Escherichia coli. This study revealed that all samples from three clones of C. sinensis contributed to the potent antioxidant and antibacterial properties of Gram-positive bacteria. The content of catechin and EGCG was influenced by green tea processing steps, which consist of steaming, CTC (Crush, Tear, Curl), drying and grinding. In conclusion, Indonesian green tea can be potentially used as a functional beverage or additive in food applications intended to convey health benefits. [ABSTRACT FROM AUTHOR]

The occurrence of rapid slope movements is common in man-made slopes during heavy rainfall in West Java Province, Indonesia, and may pose a risk to transportation infrastructures such as railways and highways. Mitigation of such a landslide risk requires an understanding of the characterization of the hazard. The study presented in this paper aims to characterize a slope failure hazard at a railway section located between Sukatani and Ciganea stations in Purwakarta Regency. The objectives of this study were to determine the sliding surface within the man-made slope using Slope/W and PyBIMstab software and to predict the run-out distance and the velocity of the slope movement using the center of mass approach. Both slope stability software shows a good agreement in determining the slip surface location within the slope at critical safety factors. Based on the center of mass approach, the slope failure is characterized by a run-out distance of about 24.5 m and a movement of more than 6.3 m/s. Therefore, the combination of long run-out and extremely rapid movement indicators would suggest a high risk to the railway traffic. [ABSTRACT FROM AUTHOR]

Terminal cargoes are rapidly increasing due to economic growth. One of the ports in Indonesia, Tanjung Priok Port, has reached its capacity in storing cargoes incoming internationally. The government of Indonesia plans to build a new port, which is known as Patimban Port in Subang Regency, West Java. This study focuses on the breakwater to be analyzed regards to budget planning and working time duration. Breakwater particularly built on shores, facilitated in reduction the wave energy of the sea and the extreme wave, creating an area for port activities such as mooring ships, cargo loading operations, etc. The ground improvement methods for the breakwater construction are given in several alternatives. The chosen ground improvement method by utilizing bamboo piles is being implemented. In this paper, another method is being analyzed, which is by utilizing prefabricated vertical drains (PVD). The ground improvement methods for the breakwater construction are given in several alternatives. The chosen ground improvement method by utilizing bamboo piles is being implemented. The comparison of the budget plan using Microsoft Project shows that the soil improvement cost budget plan for breakwater using PVD is more economical than using Bamboo Piles. Based on the calculation using Microsoft Project, The Budget Plan using bamboo Piles is 13.6 % more expensive than compared to PVD. Similarly, the duration of time works using PVD is faster than using bamboo piles. [ABSTRACT FROM AUTHOR]

This paper presents the results of the research the analysis the effect of job satisfaction toward employees performance as an effort to human resources foundry industry development. The purpose of this research is to analyzed the relationship of job satisfaction and the effect to employees performance that was not yet as expected. The method of research using descriptive analysis toward the two variables studied with approximately 200 respondents. The samples are determined by Slovin formula and the sampling is conducted by proporsional cluster random sampling. Based on the results of survey to six foundry industries in West Java Indonesia. The dimensions of job satisfaction studied include: the job itself, compatibility between job and personality, co-workers, supervisor and boss, workplace. While the employees performance that are studied include: competence, effectiveness and efficiency, authority, discipline, and initiative. The result of this research in a descriptive studies show that the job satisfaction and employees performance is fair to good categories. Based on the statistical test, proved that there is significant influence between job satisfaction to employees performance because tcalculated (9,976) > ttable (1,972). The direct impact of the job satisfaction of toward employees of 65.45 and remainder 34.45%. This discussion is expected to be a reference to some dimensions and indicators that have not been optimal for human resource development in the National foundry industry. [ABSTRACT FROM AUTHOR]

Water and good sanitation are essential elements to support human health. Unfortunately, the fulfillment of clean water and sanitation needs has not been fully implemented in several parts of the world. Sanitation development in Indonesia refers to the Sustainable Development Goals, which in 2030 are targeted to ensure the availability and sustainable management of clean water and sanitation for all communities. The problem in this study is to determine community participation in its contribution to achieving SDGs (6) goals in the use of public toilet facilities built from local government budgets in a sustainable effort in the SANIMAS program in Bandung City West Java. The research results that have been carried out show that the use of shared toilet facilities requires participation from the community and the increasing number of residents in each urban area. Policies from the government can anticipate problems in the future, and there is a need for collaboration between the government, the private sector, and the community by paying attention to the environment both for the sustainability of water reserves from dug wells and the use of technology that can prevent river water pollution in the city, as well as the sustainability of the sanitation program for all public. [ABSTRACT FROM AUTHOR]

West Java is one of the largest citronella oil producers in Indonesia. Currently, several communities in West Java are still developing citronella grass with local varieties that have been passed down from generation to generation and have not been identified. This study aims to identify the potential of citronella grass in the Cikadu region as a local superior variety. The research was conducted in Cikadu District, Cianjur Regency, West Java Province in May-June 2021. The research methods involved survey techniques as well as laboratory tests. The survey was conducted to identify the morphology of citronella, the characteristics of habitat and its use by the local community, while laboratory tests were conducted to determine the yield and quality of citronella oil. The results showed five accessions of citronella have morphology differences in leaf width and leaf blade stiffness, especially in young leaves whose shoots grew from the middle of the clump weevil. The four accessions include Puncak Sirna (PS) 01, PS02, PS03 and PS04. Citronella grass habitat soil conditions are classified as infertile. This is indicated by several parameters of the soil, including soil pH levels classified as acidic to slightly acidic, C-organic content is classified as very low to very high, cation exchange capacity (CEC) levels are classified as very low to very high and Base Saturation (KB) is classified as very low to high. The analysis of citronella oil content shows that the quality of citronella was 39.05% – 49.01% with the highest citronella content in PS02 accession (49.01%). Meanwhile, the distillation results show a general yield value of 0.83% - 2.08% with the highest yield is obtained by PS04 accession (2.08%). Citronella oil refining is quite economical and is capable of empowering communities living around forest in research location. In general, the research indicates that citronella grass accessions in Cikadu have the potential to be cultivated and developed as superior local varieties of West Java. [ABSTRACT FROM AUTHOR]

The rapid growth of population, industrialization, and other activities increased with increase drinking water demands. Depok City, one of the most developing cities in West Java, require more drinking water to meet the needs of increased population. The purpose of this study is to evaluate the performance of the Legong Water Treatment at Plant by calculating and comparing the design parameters and criteria of each unit operation and processes. The research method used includes primary and secondary data collection such as field observation, measurements of unit dimensions, water quality sampling, interview, etc. The result of performance evaluation was: (i) effluent water quality analysis of surrogate parameters showed compliance upon regulation; (ii) Evaluation of each unit operation and processes vis-à-vis its design criteria indicated that flocculation and settling unit were not meet design criteria. (iii) Capacity of Legong WTP could be increased from 190 L/s up to 250 L/s; (iv) evaluation of sludge generation estimated 1763 kg/d of sludge was directly rejected to Ciliwung River without treatment. [ABSTRACT FROM AUTHOR]

Bacterial Leaf Blight (BLB) disease is a one-factor cause of decreasing rice production in Indonesia. This disease is caused by Xanthomonas oryzae pv oryzae (Xoo), which infects rice leaves to yellowish. Xoo isolates were obtained from three different locations, namely West Java, West Sumatera, and West Borneo. Each isolate was identified by using primer specifics in colony Polymerase Chain Reaction (PCR) techniques. Isogenic strains that contained resistance genes were infected and observed through pathogenicity tests. Based on the test results, Code variety holding Xa4-Xa7 gene had a high resistance level on Xoo infection from all locations compared to other isogenic and popular rice strains. In the meantime, IRBB5 holding Xa5 gene survived the attack of Xoo from West Java and West Borneo properly. The infection intensities on Code and IRBB5 consecutively were 1.62% and 3.55% for West Java isolates, 2.10% and 2.97% for West Sumatera Isolates, 2.17% and 4.45% for West Borneo isolates. [ABSTRACT FROM AUTHOR]

Proportional reasoning is fundamental for students as a part of higher-level mathematical reasoning. It is not only fundamental for students to learn mathematics but also important for teachers and pre-service mathematics teachers having a good capability in proportional reasoning because it can lead them to teach better mathematics. This study aims to analyze the implementation of Authentic Investigation Activity (AIA) model for enhancing proportional reasoning and beliefs of pre-service mathematics teachers. This is an experimental study with pre-test and post-test design. The population of this study are second year of pre-service mathematics teachers in mathematics education department of Garut District, West Java Province, Indonesia. Using random cluster sampling are 70 pre-service mathematics teachers as the sample of the study for both. The instrument in this study is a set of test that constructed for measuring the proportional reasoning of pre-service mathematics teachers and a set of the questioner for measuring mathematical beliefs of pre-service mathematics teachers. The proportional reasoning test consisted of six essay problems in the topic of ratio and proportion with three indicators: 1) differentiating proportional and non-proportional situation; 2) understanding the mathematical relationship in the proportional situation; and 3) solving the various problem in the proportional situation. The data were analyzed quantitative using a t-test and Mann-Whitney U test. The result of the study indicates that the AIA model can enhance the proportional reasoning of pre-service mathematics teachers especially in terms of differentiating proportional and non-proportional situation and understanding mathematical relationship in the proportional situation but not in solving the various problem in the proportional situation. However, the AIA model gives similar result for mathematical beliefs of pre-service mathematics teachers. [ABSTRACT FROM AUTHOR]

Phytochemistry screening on plants associated mangrove, especially in Indonesia silvofishery area has limited. This research was aimed to find out phytochemistry of plants associated mangrove and flavonoid content. Based on field survey there were two species of plants associated with mangrove, which were Pluchea indica and Sesuvium portuculastrum. Extraction was conducted through maceration using methanol for 48 hours. The results showed that the extract yield of P. indica was 8.92 g/80 g sample with total flavonoid of 4186.6 mg/kg. While S. portuculastrum showed the extract yield of 11.14 g/100 g with total flavonoid of 5571.2 mg/kg. The negative result of the qualitative test was shown by both species on the steroid test. Further research should be considered as these plants performed high flavonoid in order to develop the application of the compound in relevant studies. [ABSTRACT FROM AUTHOR]

The development of the industrial sector in Indonesia is growing rapidly. Based on data from the Central Bureau of Statistics (BPS) from 2014 to 2016, there was an increase in the number of large and medium manufacturing industries. However, industrial improvement can have an impact on the environment. This research was conducted in one of the surfactant factories in West Java. Where this factory is ISO 14001:2015 certified, environmental management system. The aims of this research are analysis and evaluation of material and energy consumption. Impact analysis is carried out with flow material analysis (FMA). The analysis is carried out starting from the stages of receiving raw materials, processing to the final product. Evaluation of material and energy consumption is done by comparing the program for several years and goals. The results show for five years, considering energy consumption, water consumption is not linear with optimum production volume. The results of this evaluation can be used as a basis for companies to develop and implement the life cycle perspective’s program according to the requirements of ISO 14001: 2015, environmental management system. [ABSTRACT FROM AUTHOR]

Papandayan volcano is an active volcano situated in Garut, West Java Indonesia. In 2002 eruption, it released pyroclastic volcanic material to the surface covering the 4 km2 area on the summit to the north part of the volcano and formed new craters on the summit. We have undertaken several geophysical measurements in period of 2008 - 2011 including magnetotelluric, gravity, magnetic and DC resistivity in order to delineate subsurface structure of the volcano. Magnetotelluric measurement was designed using a grid system with the 30 sites and interval station of approximately 250m covering the summit area. Frequency range from 320 Hz to 1 HZ were used in MT measurement by recording two components of electric and magnetic fields using phoenix MTU-5 system. Magnetic and gravity data were acquired in the summit area overlapping with the MT survey to determine basement of the volcano structure. The shallow resistivity structure was constrained by two lines DC resistivity survey that was carried out in east-west direction located in the center of the summit to confirm the thickness of pyroclastic distribution released from 2002 eruption. The MT result derived from 3D inversion shows that the resistive zone of deep structure with the circle-like shape exists in the middle of the model in coincidence with the location of new craters. A comparison of low total magnetic field appear to be consistent with the circle-like shaped resistive zone presumably related to high temperature distributed in center of the region. From gravity data, we have found the basement of the pyroclastic structure. [ABSTRACT FROM AUTHOR]

A one-dimensional (1-D) velocity model and station corrections for the West Java zone were computed by inverting P-wave arrival times recorded on a local seismic network of 14 stations. A total of 61 local events with a minimum of 6 P-phases, rms 0.56 s and a maximum gap of 299° were selected. Comparison with previous earthquake locations shows an improvement for the relocated earthquakes. Tests were carried out to verify the robustness of inversion results in order to corroborate the conclusions drawn out from our reasearch. The obtained minimum 1-D velocity model can be used to improve routine earthquake locations and represents a further step toward more detailed seismotectonic studies in this area of West Java. [ABSTRACT FROM AUTHOR]

In general contrast in the context of the first lunar crescent visibility or hilal is defined as ratio of two components, the illuminance of the lunar crescent and the brightness of the sky (Hoffman, 2003). We used theoretical model developed by Schaefer (1993) to estimate contrast at Pelabuhan Ratu, a famous place for young lunar crescent observation in west Java. The value of contrast is defined the different between brightness of the crescent and the sky divided by brightness of the sky. Some lunar crescent with FI (Fraction of illuminated area of the Moon) within 0.9% to 1.1% is assumed as hilal. Those hilal which appear in the same days of conjunction will be considered as threshold visible hilal. We calculate the contrast for the first lunar crescent visibility after conjunction for some hilal of VEG (Vernal Equinox Group) and AEG (Autumnal Equinox Group) (Sopwan, 2008) plotted in figure 1; PG and AG (Perihelion and Aphelion Groups) plotted in figure 2 and SSG (Summer Solstice Group) and WSG (Winter Solstice Group) plotted in figure 3. The three figures show systematically some different value of contrast for the appearance group of hilal. It indicates the different level of dificulties to find hilal, the higher value of contrast means less difficult to find hilal. [ABSTRACT FROM AUTHOR]