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  • Piggery wastewater treatment by solar photo-Fenton coupled with microalgae production
    Publication . Ferreira, Alice; Attar, Solaima Belachqer-El; Villaro-Cos, Silvia; Ciardi, Martina; Soriano-Molina, Paula; López, Jose Luis Casas; Lafarga, Tomás; Santos, Cláudia Marques dos; Acién, F. Gabriel; Gouveia, Luisa
    ABSTRACT: Pig farming generates highly polluted wastewater that requires effective treatment to minimize environmental damage. Microalgae can recover nutrients from piggery wastewater (PWW), but excessive nutrient and turbidity levels inhibit their growth. Solar photo-Fenton (PF) offer a sustainable and cost-effective pretreatment to allow microalgal growth for further PWW treatment. This study optimized the concentrations of PF reagents to minimise water and nutrient inputs while maintaining microalgae-based treatment efficiency. PF trials were conducted in pilot-scale raceway ponds under solar radiation, testing different concentrations of FeSO4 (4.48 and 8.95 mM) and H2O2 (77, 154, and 309 mM). Following PF, Tetradesmus obliquus was used in a biological treatment of PWW to recover the remaining nutrients. PF achieved high removal efficiencies for turbidity (97.6-99.5 %), total organic carbon (59.2-77.1 %), and chemical oxygen demand (83.8-94.7 %), but ammonium was not significantly removed. Phosphorus was almost completely removed through iron precipitation during neutralisation. Lowering the H2O2 concentration from 309 to 77 mM did not compromise removal efficiency but reducing FeSO4 below 8.95 mM negatively affected the process. Consequently, 8.95 mM FeSO4 and 77 mM H2O2 were selected for microalgae production. The pretreated PWW could be recycled at least once for microalgal production, without nutrient supplementation, improving biomass productivity and PWW treatment, especially targeting ammonium. Phosphorus supplementation, however, did not significantly boost biomass productivity or treatment efficiency. Moreover, the iron sludge generated from PF pretreatment contained enough NPK to be repurposed as an organic fertilizer boosting sustainable agricultural practices. These findings encourage further investigation of this emerging combined technology towards wastewater treatment at large-scale.
    2025-03Journal article Open access Show more
  • A new species of Acitheca (Psaroniaceae, Marattiales) with exceptionally and three-dimensionally preserved sporangia from the Buçaco Carboniferous Basin, western central Portugal
    Publication . Correia, Pedro; Pereira, Sofia; Šimunek, Zbynek; Sá, Artur A.; Pereira, Zélia
    ABSTRACT: A new fern fossil-species Acitheca machadoi sp. nov. is erected under the family Psaroniaceae (Marattiales), based on adpression fossil remains of fertile foliage from the Monsarros Formation (upper Stephanian C, upper Gzhelian) of the Buçaco Carboniferous Basin, in western central Portugal. Acitheca machadoi comprises relatively narrow and long fertile pinnules bearing exceptionally and three-dimensionally preserved sporangia with in situ spores. These sporangia are elongate (fusiform) and one of the smallest documented for the genus, with a triangular pyramid-like shape in the upper part and rounded to hexagonal-like attachment base. Its occurrence within an assemblage dominated by mesophytes to hygrophytes, with fewer drought-tolerant forms, suggests a wetland environment with a seasonal climate, framed in the transition from humid to dry conditions in western Iberia during the Late Pennsylvanian–early Permian. This palaeobotanical finding provides new insights on the palaeoecology and species diversity of Acitheca, whose currently known fossil record is certainly underestimated.
    2025-03Journal article Open access Show more