Tropical Aquatic and Soil Pollution

Synergistic Effect of Banana Corm-Based Microbial Organic Liquid and Cyperus papyrus on Lead Removal in a Subsurface Flow Constructed Wetland System

2026-06-08T00:21:06+00:00

Laboratory wastewater often contains hazardous heavy metals such as lead (Pb). A previous study found that laboratory wastewater contained Pb at a concentration of 3.52 mg/l, exceeding the Indonesian quality standard (1 mg/l; Minister of Environment Regulation No. 5/2014). In that study, laboratory wastewater was treated using a subsurface flow constructed wetland (SSF-CW) with Cyperus papyrus, which successfully reduced Pb concentration from 3.52 mg/l to 0.75 mg/l within 9 days. While effective, this setup required a long retention time and large space. To improve treatment efficiency, this study combined Cyperus papyrus with banana corm-based microbial organic liquid (MOL) containing indigenous microorganisms. A batch SSF-CW reactor (soil and gravel media) treated 1.2 l of artificial wastewater (initial Pb concentration: 3.33 mg/l) using 10% (v/v) banana corm MOL and four Cyperus papyrus plants. Pb concentration, pH, and plant morphology were monitored for nine days. The results showed that Pb concentration met the quality standard by day 2 (0.283 mg/l; 91.50% removal) and reached maximum removal on day 4, with Pb concentration < 0.0002 mg/l and 99.99% removal efficiency. Thus, combining Cyperus papyrus with banana corm MOL proved more effective in reducing Pb concentration than using Cyperus papyrus alone, achieving comparable results in only two days instead of nine.

Eco-Friendly Wood Preservation Using Nano Urea to Prevent Fungal Degradation and Improve Material Durability

2026-06-08T00:21:04+00:00

Wood is widely used in construction due to its renewability and favorable mechanical properties; however, it is highly susceptible to fungal degradation, which reduces durability and structural performance. Conventional wood preservatives are effective but often raise environmental and health concerns because of their toxic chemical content. This study investigates the use of nano-urea as an eco-friendly wood preservative for sengon wood (Falcataria moluccana), representing one of the first studies exploring nano-urea specifically for antifungal wood protection and durability enhancement. Sengon wood samples were treated with nano-urea at concentrations of 2%, 3%, and 5%, alongside untreated control samples. Antifungal performance was evaluated through weight loss measurements, fungal growth observations, and assessment of the infected area after 12 weeks of exposure, while mechanical performance was assessed using tensile strength testing and microstructural analysis. The results demonstrated that increasing nano-urea concentration significantly reduced fungal degradation, with the 5% treatment completely inhibiting visible fungal growth. In addition, nano-urea treatment slightly improved tensile performance and produced a denser wood microstructure with reduced pore size, indicating enhanced structural compactness. These findings confirm that nano-urea is a promising sustainable alternative to conventional preservatives, offering effective biological protection while maintaining mechanical integrity. The proposed treatment also shows strong potential for scalable and environmentally responsible applications in sustainable construction and wood-based material industries.

Optimisation of Photocatalytic Degradation for Enhancing Bathroom Greywater Quality Using 2,4,6-Trinitrotoluene/Zeolite Photocatalyst

2026-03-14T05:22:56+00:00

This experimental study investigated the solar photocatalytic degradation process for improving bathroom greywater quality using titanium dioxide nanotubes modified 2,4,6-trinitrotoluene with zeolite (TNTs/zeolite) and sought to optimize it. Organic pollutants, suspended solids, and personal care products remained in total household greywater at a proportion of 43–70% from bathroom sources. The optimization method applied was Central Composite Design (CCD) under Response Surface Methodology (RSM), in which three independent variables were considered: pH within a range of 3–10; catalyst loading expressed as the exposed surface area of 1 or 2 cm²; and irradiation time between thirty and one hundred eighty minutes under natural sunlight conditions with average irradiance values between six hundred twenty and seven hundred eighty watts per square meter. Twenty runs were carried out in triplicate. The responses tested were Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), turbidity, pH, and Dissolved Oxygen (DO). The optimum condition predicted by RSM had a pH of 6.25, an irradiation time of 180 minutes, and a catalyst loading of 1 × 1 cm². Experimental validation at this optimum condition confirmed the adequacy of the model, with removals greater than 50% for COD, BOD, TSS, and turbidity. ANOVA showed that the models were statistically significant (p < 0.0001) and highly predictively reliable (R² > 0.90 for most responses). The study demonstrated that TNTs/zeolite under natural sunlight represented a potential low-energy alternative for bathroom greywater treatment with practical possibilities for decentralized reuse applications.

Environmental Implications of Liquid Natural Rubber Latex as a Sustainable Additive in Concrete: Effects on Mechanical Performance and Water–Cement Interaction

2026-06-08T00:21:01+00:00

Increasing demand for ecologically friendly construction materials has promoted the use of renewable additives in concrete systems. This study investigates the influence of liquid natural rubber latex on the mechanical properties and water–cement interaction of conventional concrete with a focus on the environmental impact. Concrete mixtures were made using 0%, 5%, 7.5%, and 10% by volume of latex. Compressive and flexural strength tests were performed at 28 days to evaluate structural performance. The results show that increasing the latex content consistently decreases mechanical characteristics. Compressive strength dropped by roughly 10%, 18% and 26% and flexural strength reduced by 8%, 14% and 20% with 5%, 7.5% and 10% latex additions accordingly. This behavior is related to the involvement of latex as an extra fluid phase which affects the effective water–cement ratio, modifies hydration and leads to increased porosity and weaker bonding within the concrete matrix. From an environmental perspective, natural rubber latex provides advantages as a renewable and biodegradable resource that can lessen dependence on synthetic admixtures. However, the decline in mechanical performance suggests potential trade-offs, including reduced durability and greater material demand over the service life. The results imply that the latex application in concrete should be carefully regulated or supplemented with stabilizing materials to attain the best results. In conclusion, this study emphasizes the necessity to reconcile environmental benefits and engineering needs in the development of bio-based construction materials, especially in tropical settings.

Phytoremediation of Coal Mine Acid Drainage Using the Invasive Weed Cyperus rotundus and Typha angustifolia: Optimizing Biomass Density in a Substrate-Free Batch System

2026-06-08T00:21:03+00:00

Acid mine drainage (AMD) presents a persistent environmental challenge, particularly in tropical mining regions. This study evaluated the phytoremediation potential of the zero-cost invasive weed Cyperus rotundus against the established hyperaccumulator Typha angustifolia in a substrate-free batch system. Utilizing extreme raw AMD (pH 2.69; Fe 6.40 ppm; TDS 1,390 ppm), the experiment encompassed a baseline comparison (9 clumps), density optimization (6–15 clumps), and a synergistic mixed-culture evaluation over 15 days. Baseline results indicated that T. angustifolia intrinsically outperformed C. rotundus in iron (Fe) removal (89.10% vs. 82.22%) by day 10. However, optimizing C. rotundus to a 15-clump saturation threshold successfully overcame this deficit, achieving 91.20% Fe attenuation (0.56 ppm). Crucially, extended hydraulic retention (15 days) in high-density configurations induced a severe secondary pollution event, catastrophically increasing Total Dissolved Solids (TDS) to 2,300 ppm because of biomass carrying capacity limits and necrosis. The mixed-culture configuration exhibited the highest overall efficacy, maximizing Fe removal (92.63%), buffering pH to 3.27, and moderating late-stage TDS spikes. The findings demonstrated that while C. rotundus was a highly viable bioremediator, engineering designs needed to cap biomass at the saturation threshold and strictly enforce a 6- to 10-day retention window to prevent secondary decay pollution.