Tropical peat water contains high levels of dissolved organic matter, particularly humic substances (HS), which degrade water quality and are difficult to remove. Moringa oleifera seed powder is an attractive natural coagulant, but its practical use is limited by incomplete removal of dissolved organic matter and by the leaching of soluble organic constituents from the raw seeds. Combining the raw seed powder with magnetite Fe3O4 nanoparticles could overcome these limitations, but the performance of such a directly mixed hybrid has not been sufficiently investigated. This study therefore evaluated M. oleifera seed powder, alone and as a magnetic hybrid with Fe3O4 nanoparticles, as a sustainable bio-coagulant for removing HS from tropical peat water. The coagulant was prepared by drying and grinding M. oleifera seeds into a fine powder, which was then physically mixed with Fe3O4 at a 1:1 w/w ratio. Using Response Surface Methodology (RSM) with a Box-Behnken Design, the coagulation process was optimized at a dosage of 0.30 g/100 mL, pH 8, and a 150-min contact time. Under these conditions, M. oleifera achieved 96.2
Evidence that land-use change degrades surface water comes almost entirely from single-jurisdiction studies, which cannot ask whether the same land-system pressure is associated with the same water-quality outcome elsewhere. This study combines 41 years of annual MapBiomas land-cover data for six monitored water-management units (UGRHIs) in São Paulo State, Brazil, with a harmonised land-cover and water-quality panel for 179 European NUTS2 regions (LUCAS, cross-checked against Corine Land Cover for 2018, r=0.92 ). A within/between panel decomposition shows that within-unit increases in artificial land share are associated with lower nitrate (NO3–N) in São Paulo ( β =-0.210 standard deviations per percentage point, mixed-model p<0.001 ) and essentially unrelated to nitrate in Europe ( β =0.004 , 95 -0.026 to 0.034). The São Paulo estimate is stable across data-handling choices and precipitation adjustment, but it is not significant under cluster-robust or wild-cluster-bootstrap inference with six clusters ( p=0.23 and 0.43) or under a time-series-preserving permutation test ( p=0.30 ); it disappears when one unit is omitted, when unit-specific trends are allowed, and when land cover is measured over each station’s upstream drainage area ( β =-0.027 ). Biochemical oxygen demand and total phosphorus show no reliable within-unit differences, turbidity is associated with land use only in an exploratory model and not under few-cluster inference, and lead was excluded because its decline coincides with Brazil’s leaded-gasoline phase-out. The associations therefore differ across these monitored samples at the scale of management units, but their robustness and causes remain uncertain; differences in wastewater treatment are a plausible but untested explanation.
Freshwater scarcity and the rising demand for clean energy standout as two ofthe most pressing global challenges, particularly in arid and semi-arid regions. To tackle these interconnected issues, this study explores an innovative approach utilizing a solar-powered Air Gap Membrane Distillation (AGMD) system integrated with a Proton Exchange Membrane (PEM) electrolyzer.This hybrid system is designed for the simultaneousproduction of freshwater and green hydrogen. The AGMD unit, driven by solar thermal power, generates high-purity distilled water suitable for both human consumption and use as feedwater in the PEM electrolyzer,which is powered by photovoltaic-generated electricity. An experimental setup,supported by a semi-empirical numerical model, was developed to evaluate how key operating factors—such as feedwater temperature, solar irradiation levels, membrane porosity, and air-gap thickness—affectthe system’s performance. The results reveal a strong correspondence between experimental observations and model predictions, validating the reliability of the proposed approach. Underpeak solar irradiation conditions, the system demonstrated the capacity to produce freshwater at rates of 4–5 litersperhour and generate hydrogen at a rate of approximately 0.04–0.06 Nm3 h⁻1 under peak operating conditions. Sensitivity analysis highlights that feedwater temperature, membrane porosity, and air-gap thickness are critical parameters influencing vapor flux and overall system efficiency. Additionally, the combinedprocesses of desalination and hydrogen production enhance the utilization of renewable solar energy while ensuring consistent water quality and stable hydrogen output. In summary, this AGMD–PEM hybrid system offers substantialpromise as a sustainable solution for decentralized water and energy generation in regions with amplesolar resources but limited water availability.
Polycyclic aromatic hydrocarbons (PAHs) are persistent emerging contaminants found frequently in wastewater streams. Their recalcitrant nature makes them challenging to remove. Constructed wetland-microbial fuel cell (CW-MFC) systems have recently emerged as promising advancements over conventional CWs. Yet, studies investigating their effectiveness for PAH removal remain scarce. This study investigated the removal of eight commonly occurring PAHs ̶ naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene. Real domestic sewage was treated using CW-MFC and compared to a conventional CW and an unplanted control. The influent was spiked with a total PAH concentration of 248.88 µg L⁻¹ (∑8PAHs). The CW-MFC system achieved the highest removal efficiency of 92.48
The growing scarcity of freshwater necessitates sustainable alternatives, such as the use of aquaculture effluent to irrigate drought-resistant crops like Opuntia cochenillifera (Nopalea cochenillifera). This study aimed to evaluate the morphometric and productive variables of forage cactus under fertigation with aquaculture effluent in the Brazilian semiarid region. The experiment was conducted at the Universidade Federal Rural do Semi-Árido, Mossoró, Rio Grande do Norte, Brazil, using a randomized complete block design with five replications in a split-plot-in-time arrangement. The main plots comprised five aquaculture effluent proportions (0, 25, 50, 75, and 100
