Browsing by Author "Espirito Santo, Daiana Rocha do"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Aqueous chlorination of herbicide metribuzin : Identification and elucidation of new disinfection by-products, degradation pathway and toxicity evaluation.
    (2021) Barros, André Luis Corrêa de; Rodrigues, Daniel Aparecido da Silva; Cunha, Camila Cristina Rodrigues Ferreira da; Chagas, Igor Aparecido Santana das; Espirito Santo, Daiana Rocha do; Silva, Silvana de Queiroz; Afonso, Robson José de Cássia Franco
    A widely used herbicide, metribuzin, was evaluated for degradation, mineralization and disinfection byproducts (DBPs) formation during aqueous chlorination. In addition, to assess the toxicity effects of chlorination on metribuzin solution the following tests were performed: acute toxicity using Artemia salina nauplii; cell viability using MTT assay; estrogenicity using a re-engineered Bioluminescent Yeast Estrogen Screen (BLYES) and a constitutively bioluminescent strain (BLYR); mutagenicity and developmental toxicity using Q(SAR) methodology. Metribuzin at 10 mg·L−1 was degraded by chlorination, achieving 93% of removal at 30 min of reaction. TOC analysis showed that the herbicide does not suffer complete mineralization, even after 24 h of contact with free chlorine. Seventeen DBPs were detected and their structural formulae were elucidated by high resolution mass spectrometry. Toxicity effects for chlorinated solutions increased when compared to the unreacted metribuzin solution. DBPs were more toxic to Artemia salina nauplii, increasing around 20% on nauplii mortality. It was also observed high estrogenicity to human receptors in BLYES assays and mutagenic and developmental toxicant effects to animals and humans in Q(SAR) methodology, suggesting that DBPs are potentially more toxic than the precursor metribuzin. Metribuzin solutions at 10 mg·L−1 showed equivalent 17-β-estradiol values ranged from 0.061 to 6.71 μg·L−1 after to be chlorinated at different reaction times.
  • No Thumbnail Available
    Item
    Removal of cephalexin and erythromycin antibiotics, and their resistance genes, by microalgae-bacteria consortium from wastewater treatment plant secondary effluents.
    (2021) Rodrigues, Daniel Aparecido da Silva; Cunha, Camila Cristina Rodrigues Ferreira da; Espirito Santo, Daiana Rocha do; Barros, André Luis Corrêa de; Pereira, Andressa Rezende; Silva, Silvana de Queiroz; Santiago, Aníbal da Fonseca; Afonso, Robson José de Cássia Franco
    Antibiotics have become a concern in the aquatic environments owing to the potential development of bacterial resistances. Thus, this study evaluated the removal of cephalexin (CEP) and erythromycin (ERY) from a local wastewater treatment plant (WWTP) effluent, mediated by microalgae-bacteria consortium. Likewise, the removal of correlated antibiotics resistance genes blaTEM and ermB was also assessed. The incubation results showed that the added concentrations of selected antibiotics did not restrain the consortium growth. Moreover, CEP and ERY were almost completely removed after the cultivation period, reaching total removals of 96.54% and 92.38%, respectively. The symbiotic interaction between microalgae and bacteria plays a role in the kinetics removal of CEP and ERY. The abundance of blaTEM and ermB was reduced by 0.56 and 1.75 logs, respectively. Lastly, our results suggest that technology based on natural microalgae-bacteria consortium could be a potential alternative to improve the quality of WWTP effluents.