Tropical Environment, Biology, and Technology

Sustainable Concrete Production through Partial Cement Replacement Using Fly Ash and Rice Husk Ash

Thu, 29 Jan 2026 00:00:00 +0000

This study explores the utilization of fly ash and rice husk ash as supplementary cementitious materials to partially replace ordinary Portland cement (OPC) in concrete production. The increasing environmental impact of cement manufacturing, particularly its contribution to carbon dioxide emissions, has driven the search for alternative materials that promote sustainability without compromising performance. Fly ash and rice husk ash, both industrial and agricultural by-products, possess pozzolanic properties that enhance the mechanical and durability characteristics of concrete when properly incorporated. This paper reviews their chemical composition, particle morphology, and the effects of replacement levels on compressive strength, workability, and long-term durability. Additionally, the study discusses challenges such as variability in ash quality, optimal replacement percentages, and curing conditions that influence performance outcomes. By integrating these waste materials into concrete, significant environmental and economic benefits can be achieved, including reduced landfill disposal, conservation of natural resources, and lower greenhouse gas emissions. The findings highlight the potential of fly ash and rice husk ash as sustainable cement substitutes, supporting the development of eco-friendly construction materials aligned with green building standards and circular economy principles. This research contributes to advancing sustainable practices in the construction industry and provides insights for future studies focused on optimizing mix design, performance enhancement, and large-scale application of alternative cementitious materials.

Comparison of Piggery Wastewater Treatment after the Biogas Process by Cyperus alternifolius and Ipomoea aquatica in a Vertical Subsurface Flow Constructed Wetland System in Vietnam

Bui Thi Van Nga, Chao Rong — Wed, 25 Feb 2026 00:00:00 +0000

Vertical subsurface flow constructed wetlands (VSF CWs) have been widely applied as an eco-friendly solution for treating livestock wastewater. This study compared the treatment performance of Cyperus alternifolius and Ipomoea aquatica planted in VSF CWs treating piggery wastewater after biogas digestion. Two laboratory-scale VSF CW systems (50 × 50 × 50 cm) with identical media configuration and operational conditions were operated in an intermittent mode with a hydraulic retention time of 3 days over 20 treatment cycles. The VSF CW planted with C. alternifolius consistently exhibited higher removal efficiencies for all monitored parameters compared with the system planted with I. aquatica (p < 0.05). The average removal efficiencies of the papyrus-based system reached 74.2 ± 3.1% for COD, 85.8 ± 3.4% for TSS, 70.9 ± 4.1% for TN, 75.1 ± 5.5% for NH₄⁺–N, and 64.7 ± 7.9% for TP, with most effluent concentrations complying with the Vietnamese discharge standard QCVN 62:2025/BTNMT (Column B). In contrast, the VSF CW planted with water spinach achieved lower treatment efficiencies, with average removal rates of 53.9 ± 2.6% for COD, 80.5 ± 5.6% for TSS, 54.6 ± 5.6% for TN, 57.0 ± 8.6% for NH₄⁺–N, and 44.5 ± 13.1% for TP, and did not consistently meet discharge limits for nitrogen and phosphorus.

Epiphytic Biomass And Chlorophyll-a Concentration – Relations In Seagrass Leaves Enhalus acoroides In Sanur Waters, Bali

Mon, 20 Apr 2026 00:00:00 +0000

Seagrass beds are important coastal ecosystems that functioned as primary producers and habitats for various marine biota; however, their persistence was vulnerable to environmental pressures. One of these pressures was the increase in epiphytic biomass on seagrass leaves, which had the potential to inhibit photosynthesis. This study aimed to assess the condition of Enhalus acoroides seagrass cover and to analyze the relationship between epiphyte biomass and chlorophyll-a concentration in seagrass leaves in the waters of Sanur, Bali. This study was based on seagrass ecological theory, the role of epiphytes, and chlorophyll-a as an indicator of seagrass physiology and productivity. The research methods included field observations using line transects and quadrats, measurement of seagrass cover, analysis of chlorophyll-a in seagrass leaves using spectrophotometric methods, and calculation of epiphyte biomass using gravimetric methods. The results showed that Enhalus acoroides seagrass cover in Sanur waters was classified as moderate to dense, with water quality conditions that still supported seagrass growth. The relationship between epiphyte biomass and chlorophyll-a concentration indicated a weak negative correlation, in which an increase in epiphyte biomass tended to be followed by a decrease in chlorophyll-a. The findings of this study indicated that epiphytes had the potential to reduce the photosynthetic efficiency of seagrass, although their influence was also affected by local environmental factors.