Applied Research in Science and Technology

Characterization of Fly Ash from Coal-fired Steam Power Plant Tarahan, Lampung, and Its Potential as a Soil Amendment

Adiksa Insan Mutaqin — 2025-10-06

Background: Fly ash, a byproduct of coal combustion in steam power plants, has significant potential for utilization, particularly as a soil amendment. However, in Indonesia, including at the Tarahan coal-fired steam power plant (PLTU Tarahan), most fly ash remains underutilized and is primarily disposed of in landfills.
Aims: This study aimed to analyze the characteristics of fly ash produced at PLTU Tarahan and evaluate its potential for recycling through three utilization pathways: biosilica production, application as a soil-stabilizing agent, and incorporation into compost mixtures.
Methods: Samples were collected from three distinct locations and analyzed at a certified laboratory using standardized procedures. The resulting data were subsequently compared with values reported in existing literature and interpreted using a descriptive analytical approach.
Result: Characterization results indicated that the fly ash belongs to Class F, with high silica (SiO₂) content and low calcium oxide (CaO), making it pozzolanic but non-cementitious. Each reuse pathway was assessed in terms of technical compatibility, infrastructure readiness, pretreatment requirements, market potential, and environmental risk mitigation. The findings showed that biosilica production offers high added value but requires advanced chemical extraction technology. Soil stabilization using fly ash and lime is technically feasible for internal infrastructure and land reclamation projects, offering immediate benefits with minimal pretreatment. When mixed with organic materials such as press mud or combined with garbage enzyme, fly ash also enhances compost maturity, nutrient content, and enzymatic activity. Based on these results, a phased implementation strategy is recommended, beginning with applications that are low-risk and compatible with existing infrastructure. These findings contribute to the development of more adaptive and sustainable fly ash management strategies within coal-fired power plants. To support practical implementation, further laboratory- and field-scale studies are needed to validate long-term performance. Additionally, future research should incorporate multicriteria decision-making approaches, such as the Analytic Network Process (ANP), to comprehensively evaluate technical, environmental, social, and economic factors in selecting the most appropriate utilization pathway.

Sub-Watershed Prioritization for Sustainable Sediment Management in the Upper Cisokan Hydropower Catchment Using SWAT+

Laella Pusparinda — 2025-10-07

Background: Sedimentation poses a critical threat to hydropower sustainability, particularly in pumped storage systems such as the Upper Cisokan Pumped Storage (UCPS) plant in West Java, Indonesia.
Aims and Methods: This study assesses the spatio-temporal dynamics of sediment yield in the Cisokan Watershed using the SWAT+ model, incorporating historical simulations (2013 and 2023) and a 2038 projection under a Business-As-Usual (BAU) scenario developed through supervised classification in Google Earth Engine (GEE).
Result: Model calibration based on observed discharge data yielded satisfactory results (NSE = 0.80 in 2013, 0.65 in 2023), validating its suitability for sediment analysis. Results reveal a nearly fourfold increase in average sediment yield from 0.61 to 2.25 tons/ha/year between 2013 and 2023, with a projected rise to 5.57 tons/ha/year by 2038. A composite prioritization index, integrating current sediment output, decadal change, and sub-watershed area, identified SW-23, SW-16, and SW-5 as the highest priority areas for erosion mitigation. These findings were validated against future projections, confirming their persistent erosion risk. The study emphasizes the importance of scenario-based watershed planning in safeguarding hydropower infrastructure. By integrating sediment modeling with scenario-based land use projection via supervised classification in Google Earth Engine (GEE), this study provides a replicable framework for proactive watershed management and hydropower sustainability planning.

Quality and Resilience of Subsidized Housing for Low-Income Communities in Disaster Prone Zone of Padang City: An Analysis of Residents' Perceptions

Yuni Purnama Syafri — 2025-10-10

Background: Subsidized housing for Low-Income Communities (LIC) in Indonesia continues to encounter significant quality challenges, particularly in disaster-prone regions. These challenges are primarily associated with the limited enforcement of technical standards, insufficient infrastructure provision, and inadequate policy support, which collectively undermine the resilience and habitability of such housing.
Aims and Methods: This study analyzes the quality and resilience of subsidized housing for LIC in Padang City, which are in disaster-prone zones. Using questionnaire survey methods and factor analysis, this study identified technical and non-technical variables that affect the feasibility of housing. The KMO-Bartlett test, validity, and reliability ensured the instrument's feasibility, resulting in 18 valid variables grouped into four main factors: the quality of infrastructure, facilities, and public utilities (IFP), housing development policies and support, technical quality and housing standards, and residential accessibility.
Result: The study results show that basic infrastructure, regulatory support, implementation of technical standards, and strategic location have a significant role in the quality of subsidized housing. These findings confirm the importance of synergy between technical and policy aspects in improving the quality and resilience of subsidized housing, especially in disaster-risk areas.

Evaluation and Ranking of Urban Drainage Systems Using SAW, TOPSIS, and VIKOR Methods: A Case Study in Bantul Regency

Muhamad Arifin — 2025-10-12

Background: Urban flooding and waterlogging in Bantul Regency stem from inadequate drainage systems, exacerbated by rapid urbanization, land use changes, poor infrastructure planning, and intensified rainfall due to climate change. Therefore, an integrated risk management approach compassing both structural and non-structural solutions—is crucial for improving urban drainage resilience. Conversely, the comprehensive evaluation of drainage system performance continues to pose considerable challenges. Assessments that concentrate solely on hydraulic or technical parameters while neglecting environmental, social, and economic factors—often result in suboptimal or misdirected decisions. As such, adopting a more integrative approach through multi-criteria decision-making methods, such as Multi-Attribute Decision Making (MADM), emerges as a pertinent alternative.
Aims and Methods: The methods employed for MADM analysis in this study include the Simple Additive Weighting (SAW), the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), and the Vlse Kriterijumska Optimizacija I Kompromisno Resenje (VIKOR). Each of these approaches is designed to accommodate different data characteristics, levels of analytical complexity required, degrees of uncertainty involved, computational load, and the decision maker’s experience or expertise in applying the respective method.
Results: The analysis results indicate that, based on the SAW method, location A11 obtained the highest score (0.8637), signifying the poorest drainage system performance and thus requiring top-priority intervention, whereas location A77 achieved the lowest score (0.3132), indicating a well-functioning drainage condition. Using TOPSIS, location A9 ranked first with a preference value (Vi) of 0.7498, reflecting significant proximity to the ideal solution, while A6 recorded the lowest score (0.2152). Meanwhile, the VIKOR method identified location A99 as the top-ranked alternative with a VIKOR index of 16.5321, while A1 emerged as the lowest-ranked alternative with a VIKOR index of 0.0188.