Combination of Constructed Vertical flow Wetlands, Microalgae Photobioreactor and Microbial Fuel Cell (KIT) for wastewater treatment in small pig production farms

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Application of green technology to extract clean and safe bioactive compounds from tetradesmus obliquus biomass grown in poultry wastewater

Publication . Vladić, Jelena; Jazić, Jelena Molnar; Ferreira, Alice; Maletić, Snežana; Cvetković, Dragoljub; Agbaba, Jasmina; Vidović, Senka; Gouveia, Luisa

Microalgae are capable of assimilating nutrients from wastewater (WW), producing clean water and biomass rich in bioactive compounds that need to be recovered from inside the microalgal cell. This work investigated subcritical water (SW) extraction to collect high-value compounds from the microalga Tetradesmus obliquus after treating poultry WW. The treatment efficiency was evaluated in terms of total Kjeldahl nitrogen (TKN), phosphate, chemical oxygen demand (COD) and metals. T. obliquus was able to remove 77% TKN, 50% phosphate, 84% COD, and metals (48-89%) within legislation values. SW extraction was performed at 170 degrees C and 30 bar for 10 min. SW allowed the extraction of total phenols (1.073 mg GAE/mL extract) and total flavonoids (0.111 mg CAT/mL extract) with high antioxidant activity (IC50 value, 7.18 mu g/mL). The microalga was shown to be a source of organic compounds of commercial value (e.g., squalene). Finally, the SW conditions allowed the removal of pathogens and metals in the extracts and residues to values in accordance with legislation, assuring their safety for feed or agriculture applications.

2023Journal article

Open access

Unlocking the potential of Euglena gracilis cultivated in piggery wastewater: biomass production, nutrient removal, and biostimulant potential in lettuce and tomato plants

Publication . Butzke, Valéria Louzada Leal; Ferreira, Alice; Oliveira Corrêa, Diego de; Furlan, Júnior Mendes; Gouveia, Luisa; Schneider, Rosana de Cássia de Souza; Corbellini, Valeriano Antonio

Microalgae are increasingly recognized as a valuable resource for bolstering sustainability in agriculture. However, current research and patents primarily focus on Chlorella spp., Scenedesmus spp., and Spirulina spp., thus leaving the vast diversity of microalgae relatively unexplored for agricultural applications. Euglena gracilis (Euglenophyta) is a microalga renowned for its resilience to diverse environmental stressors and capability to produce a variety of bioactive metabolites. This study investigated the potential of cultivating E. gracilis in piggery wastewater for nutrient recycling and as a source of beneficial biomolecules, particularly for biostimulant use. Utilizing raw wastewater diluted to 25% (P25) and pre-treated wastewater with photo-Fenton (PF), the research found that E. gracilis exhibited elevated cell density, biomass concentration, and overall cell health in both wastewaters compared to a synthetic medium (BG11-NPK). This was due to its efficient removal of nutrients, especially ammoniacal-nitrogen and phosphate, resulting in a biomass rich in polyunsaturated fatty acids, amino acids, and paramylon content.

2024-06-19Journal article

Restricted access

Innovative approach in sustainable agriculture: harnessing microalgae potential via subcritical water extraction

Publication . Ferreira, Alice; Vladić, Jelena; Corrêa, Diego de Oliveira; Butzke, Valéria Louzada Leal; Martins, Pedro L.; Ribeiro, Belina; Marques-dos-Santos, Cláudia; Acién, F. Gabriel; Gouveia, Luisa

Microalgae can contribute to sustainable agriculture and wastewater treatment. This study investigated Tetradesmus obliquus, , grown in piggery wastewater (To-PWW), as a biostimulant/ biofertilizer compared to biomass grown in synthetic medium (To-B). Subcritical water extraction was tested for disruption/hydrolysis of wet biomass, at three temperatures (120, 170, and 220 degrees C) and two biomass loads (1:10 and 1:80 (g dry biomass/mL water)). Extracts were evaluated for germination, and root formation/expansion. Residues were quantified for nutrient composition to assess their biofertilizer potential and tested for their affinity to oil compounds for bioremediation. The best germination was achieved by To-B extracts at 170 degrees C (1:10: 148% at 0.2 g/L, 1:80: 145% at 0.5 g/L). Only To-PWW extracts at 0.2 g/L had a significant germination effect (120 degrees C: 120-123 % for both loads; 170 degrees C: 115% for 1:80). To-PWW extract at 120 degrees C and 1:10 significantly affected cucumber and mung bean root formation (224 and 268%, respectively). Most extracts significantly enhanced root expansion, with all To-B extracts at 1:10 showing the best results (139-181 %). The residues contained essential nutrients (NPK), indicating their biofertilizer potential, helping decrease synthetic fertilizers demands. To-B residues had high affinity to toluene and diesel but lower to used cooking and car oils. To-PWW showed very low affinity to all oil compounds. Finally, all residues were only able to form stable emulsions with the used car oil. This study fully exploits the use of microalgal biomass in sustainable agriculture, producing biostimulant extracts, and residues for biofertilizer and bioremediation, from a low-cost wastewater source.

2024-11Journal article

Open access

Piggery wastewater treatment by solar photo-Fenton coupled with microalgae production

Publication . Ferreira, Alice; Belachqer-El Attar, Solaima; Villaró-Cos, Silvia; Ciardi, Martina; Soriano-Molina, Paula; López, José Luis Casas; Lafarga, Tomás; Marques-dos-Santos, Cláudia; Acién, Gabriel; Gouveia, Luisa

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

Restricted access