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Flocculation using natural plant-based biopolymers from Moringa oleifera seeds and Acacia mearnsii flocculant as Tanfloc® (TSG) has emerged as an efficient strategy for microalgae biomass harvesting. This study optimized the recovery process of Nannochloropsis oculata by varying flocculant concentration, sedimentation time, and culture pH. Results revealed that 1.2 mg.L−1 of TSG at pH 8.9 achieved optimal conditions, although TSG proved effective across different pH ranges. Alkaline flocculation (ALK) also enhanced microalgae harvesting, yielding a high harvesting efficiency (>96%) within 30 minutes of sedimentation. Both methods achieved a concentration factor exceeding 20. However, the use of ALK resulted in reduced lipid and carbohydrate content compared to the control condition. Carotenoid levels showed no significant difference. TSG influenced lipid extraction but not fatty acid quality or carbohydrate extraction. Importantly, the residual medium from TSG flocculation could sustain subsequent cultivation cycles without nutrient supplementation, presenting a cost-effective solution for microalgae cultivation and harvesting. [ABSTRACT FROM AUTHOR]

Ethidium Bromide (EtBr) is an organic compound used in molecular biology investigations. EtBr ability of intercalating in the DNA molecule makes it a toxic substance. The objective was to evaluate the phycoremediation potentials of Chlorella vulgaris, Desmodesmus subspicatus and Raphidocelis subcapitata tested separately and in a mixture (Mix) for EtBr removal from the aqueous medium. Experiments were conducted using an initial algae biomass of 106 cell/mL, exposed to 500 µg/L of EtBr. The removal efficiency (µg EtBr L−1) after 3 h in each treatment were: Mix (72.8 µg.L−1) >D. subspicatus (48.4 µg.L−1) >R. subcapitata (24.6 µg.L−1) >C. vulgaris (19.9 µg.L−1). However, when EtBr mass reduction per microalgae density is considered (ng.algae−1), the efficiency ranking changes to: D. subspicatus (1.9 × 10−5 ng.algae−1) >C. vulgaris (1.4 × 10−5 ng.algae−1) >Mix (9.8 × 10−6 ng.algae−1) >R. subcapitata (2.8 × 10−6 ng.algae−1). The results suggest that initial algal population density is a determinant factor for efficient EtBr removal by microalgae species in short term treatments. In order to obtain 100% of EtBr removal, it should be necessary 1010, 1010 and 1011 algae.mL−1 of C. vulgaris, D. subspicatus and R. subcapitata, respectively. The results strongly suggest phycoremediation can be explored as an alternative method for EtBr removal. [ABSTRACT FROM AUTHOR]

To assess natural attenuation and the efficiency of remediation actions after more than two years a large accident with gasoline spill contaminated a wetland in a tropical region, an Ecological Risk Assessment based on the Dutch Triad was applied. In total, eight surface water-sampling points were distributed randomly in the affected area and on reference area upstream the contaminated site, with similar ecological characteristics. Risks based on chemical, ecotoxicological, and ecological lines of evidence (LoE) were calculated to integrate the environmental risk indexes. The chemical risk was derived from toxic pressure coefficients based on the total BTEX and naphthalene concentrations. Ecotoxicological LoE based on acute toxicity withDaphnia similisandAliivibrio fischeribioassays and chronic toxicity withDesmodesmus subspicatusbioassay contributed to raise uncertainty due to low sensitivity of acute assays. Genotoxicity and endocrine disruption biomarkers ofOreochromis niloticuswere used to calculate the Biomarker Stress Index (BSI) assumed as Ecological Risk Index. The integration of the Chemical Risk Index with BSI to estimate the Biological Vulnerability Index allowed a meaningful analysis of the threats to the aquatic ecosystem, thereby supporting managers and decision-makers. [ABSTRACT FROM PUBLISHER]

Owing thatOreochromis niloticusis resistant to different aquatic environments, four contaminated sites were selected: decentralized engineered ecosystem (DEE) and conventional wastewater treatment plants (WWTP); urban lagoon; and gasoline-contaminated marshland. Endocrine disruption was assessed by alkali-labile phosphate (ALP) quantification, genotoxicity by micronuclei frequency, and morphological changes by hepatosomatic and gonadosomatic indexes. The ALP baseline of non-exposedO. niloticusmales was low, compared with other fish species in the literature. Endocrine disruption was observed in fish exposed to raw wastewater of WWTP and DEE, discharge point of channeled river in the urban lagoon, and water from gasoline-contaminated marshland. After treatment in the DEE, the endocrine disruption effect was removed. The micronuclei frequency corroborated with the ALP results in most cases and proved to be a useful tool to assess genotoxicity in fish. The exposure time of 15 days was not enough to provoke morphological effects in most samples. However, in all gasoline-contaminated samples, the fishes showed an increase in the hepatosomatic index followed by a decrease in the gonadosomatic index. The tested biomarkers showed feasibility, sensibility, reproducibility, and were complementary in the assessment of chronic ecotoxicity; therefore, we recommend them to compose a suitable protocol for aquatic monitoring programs. [ABSTRACT FROM PUBLISHER]

Vitellogenin protein (Vtg) inOreochromis niloticusplasma has been indirectly quantified through protein-bound phosphate groups also known as alkali-labile phosphates (ALP) using a recently modified method. Such method as described in the literature was originally applied to Crucian carp and resulted in lower detection limits (3.2 μg PO43–per mL). In this study,O. niloticusmales were exposed to intermittent doses of oestrogens for 15 days using different concentrations (converted to loads) of 17α-ethinyloestradiol (EE2) (two different aquarium volumes), oestrone (E1) and 17β-oestradiol (E2) individually and in combination (1:1:1). The induction of physiologic and genotoxic effects in erythrocytes was investigated. For the tested oestrogen (EE2), load proved to be more relevant than concentration in determining the oestrogenicity.O. niloticusmales proved to have lower ALP baseline (4.11 µg PO43−/mL plasma, IQ25 = 3.38; IQ75 = 5.18) than other fish species, including Crucian carp, which makes it suitable for oestrogenicity detection in water. Exposure to E2, EE2 separately and in combination (1:1:1) all induced significant increases in the ALP levels at loads ≥ 0.72 μg/fish. This load was three times lower than the E1 load required to increase ALP (≥ 2.2 μg/fish). All oestrogens with loads ≥ 0.072 μg/fish caused significant increase in micronucleus frequency (≥ 2‰) compared with the control (0.1 ± 0.4‰). The study highlighted the importance of taking into account not only concentration and dose regime but also the mass load and therefore, the volume used in the experimental units, which is rarely addressed in ecotoxicity assays. Considering the good sensitivity ofO. niloticusexposed to relatively low concentrations of oestrogens, the combination of the ALP method with auxiliary biomarkers (particularly micronucleus) can be used as a protocol for oestrogenicity and genotoxicity detection in different contaminated waters as part of water environmental monitoring programmes. [ABSTRACT FROM PUBLISHER]

There is a worldwide demand for decentralized wastewater treatment options. An on-site engineered ecosystem (EE) treatment plant was designed with a multistage approach for small wastewater generators in tropical areas. The array of treatment units included a septic tank, a submersed aerated filter, and a secondary decanter followed by three vegetated tanks containing aquatic macrophytes intercalated with one tank of algae. During 11 months of operation with a flow rate of 52 L h-1, the system removed on average 93.2% and 92.9% of the chemical oxygen demand (COD) and volatile suspended solids (VSS) reaching final concentrations of 36.3±12.7 and 13.7±4.2 mg L-1, respectively. Regarding ammonia-N (NH4-N) and total phosphorus (TP), the system removed on average 69.8% and 54.5% with final concentrations of 18.8±9.3 and 14.0±2.5 mg L-1, respectively. The tanks with algae and macrophytes together contributed to the overall nutrient removal with 33.6% for NH4-N and 26.4% for TP. The final concentrations for all parameters except TP met the discharge threshold limits established by Brazilian and EU legislation. The EE was considered appropriate for the purpose for which it was created. [ABSTRACT FROM AUTHOR]

This study consists of an ecotoxicological assessment related to one the most important environmental Brazilian disasters: the failure of an iron mining dam of the Vale S.A. in Brumadinho (Minas Gerais State, Brazil). Tailing samples (mixed with many other materials) were collected in three areas: (i) Zona Quente (n = 9) – close to the dam collapse; (ii) Parque das Cachoeiras (n = 3) – downstream of the Zona Quente; and (iii) Alberto Flores (n = 3), closer to Paraopeba river (an important tributary of one of the most important Brazilian watersheds). Acute ecotoxicological tests with Eisenia andrei and Daphnia similis and chronic reproduction tests with Folsomia candida and Chlorella vulgaris were performed. The bioassays with aquatic organisms were carried out with elutriates of the samples. Metal concentrations and physical, chemical and mineralogical properties of the samples were determined to support the interpretation of the ecotoxicological data. The increase of the particle density values (significantly correlated to an anomalous iron-enrichment and positive ΔpH values) seem to play a relevant role in the toxicity. As a result of iron-enrichment, the reduction of organic matter contents and water holding capacity were also crucial in the toxicity. Metal-enrichment factors showed abnormally high values, especially for Fe, Mn and Ni, while toxic metals concentrations exceeded the limits established by Brazilian law. Reproduction chronic effects were more intense than the acute ones, for both aquatic and soil organisms. Such extremely low reproduction levels of F. candida and C. vulgaris should be highlighted, since such organisms have a key ecological relevance. The samples collected in the Zona Quente were significantly different from the samples collected in downstream areas — fact that might be related to a high energy and turbulent flux of tailings in zones closer to dam, and the reduction of its energy in downstream areas. • First evaluation integrating toxic effects on soil and aquatic biota in Brumadinho • Toxic metals contents exceeded the limits defined by Brazilian law. • The iron contents played a crucial role in the terrestrial and aquatic toxicity. • Chronic ecotoxicological effects were more severe compared to the acute ones. • Materials deposited in areas closer to the dam are different from downstream ones. [ABSTRACT FROM AUTHOR]

The variety of available technologies and the low investment power in sanitation services, especially in regions with low and emerging economies, makes the selection of an optimal wastewater treatment system design an even more complex task for decision-makers. Thus, this study aimed to develop a multi-criteria analysis-based tool to support decision-making on the optimal wastewater treatment technology for the needs and priorities of each region, the Most Appropriate Treatment Technology Index (MATTI). The methodology to apply the MATTI comprises five steps: select suitable technologies; determine the effluent quality parameters; define the most relevant variables for design; normalize and define the weighting criteria; and calculate the level of compliance (0-1, on an increasing scale of suitability). To validate the tool, two different scenarios and seven variables for the Brazilian context were simulated. Different sets of technologies scored above 0.75, and were classified as highly recommended, according to the weight criteria attributed to each scenario. MATTI not only contributed to improving the decision-making process, but also with a more global vision of the parameters to be considered in the selection of technologies to meet the needs and priorities.