Banca de DEFESA: GEISA FREITAS DO MONTE SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : GEISA FREITAS DO MONTE SILVA
DATE: 29/08/2025
TIME: 09:00
LOCAL: meet.google.com/fjo-dgok-yoj
TITLE:

PROTECTIVE EFFECT OF FOLIC ACID AGAINST FETAL INTOXICATION BY WATER TREATMENT PLANT SLUDGE IN A ZEBRAFISH (DANIO RERIO) MODEL

KEY WORDS:

Aquatic animals; Ecotoxicity; Fish; Solid waste.

PAGES: 108
BIG AREA: Engenharias
AREA: Engenharia Sanitária
SUMMARY:

The water potabilization process generates solid waste, primarily during the decantation stage, due to the chemical products added during the coagulation step. The final disposal of this solid waste (sludge) without prior treatment into water bodies is a significant concern, as the sludge contains metals. This action can induce toxicity to aquatic organisms, compromisse water quality, and affect human health, especially when high concentrations of metals are present in the sludge. Therefore, it is necessary to assess parameters that reflect the true magnitude of ecotoxicological impacts. The use of animal models, such as zebrafish, can serve as sensitive tools for detecting potential environmental risks caused by Chemical compounds. Furthermore, zebrafish can also be used as a model for human fetal intoxication, as the first 24 hours of development in this animal correspond to the first trimester of human fetal development. In this context, the present study aims to evaluate the protective effect of folic acid against fetal intoxication by water treatment plant sludge using the zebrafish (Danio rerio) model. The mapping of scientific production regarding the use of zebrafish in the embryonic and larval stages revealed its relevance as an animal model for toxicological analysis of effluents and waste. A total of 88 documents were found over a ten-year horizon (2013 - 2023). China led in the number of published articles (15 papers). The studies indicated a trend in relation to the main effluents and solid waste (pharmaceutical, tannery, hospital, petroleum, and textile dyes). Regarding sludge, solubilization was performed and the elutriate was obtained. The physicochemical characterization of the sludge and elutriate was then studied, with the following parameters assessed: pH, turbidity, electrical conductivity, color, solids series, chemical oxygen demand (COD), chloride content, and metals. After exposure to individual dilutions of the elutriate based on NBR 15088 (ABNT, 2016) and mixtures of folic acid and elutriate, the toxic effects were evaluated using the zebrafish fetal intoxication model in relation to epiboly at 8 hours post-fertilization (hpf) and affected animals (mortality and teratogenic effects – at 24 hpf). Considering the toxicity assessment at 8 hpf and 24 hpf, the elutriate dilutions were not found to be potentially toxic. Regarding the evaluation of the protective effect of folic acid, folic acid (FA) alone increased the percentagem of epiboly in the embryos – FA 75 μM (79.89%) and FA 100 μM (84.07%). However, when combined with the water treatment plant (WTP) elutriate, there was a reduction in the percentage of epiboly – FA 50 μM + ELU 100% (60.31%); FA 75 μM + ELU 100% (58.77%); FA 100 μM + ELU 100% (62.94%). We conclude that the WTP elutriate was not toxic for the parameters evaluated in this study, confirming NBR 10.004 (ABNT, 2004), which classifies sludge as a class II non-hazardous waste. However, when combined with folic acid, toxicity was observed in the evaluated parameters, demonstrating the complexity of studying interactions with real samples in animal models.

COMMITTEE MEMBERS:
Presidente - ROSANGELA GOMES TAVARES
Externa à Instituição - SÂMARA DA SILVA GOMES - UFPE
Interno - VALMIR CRISTIANO MARQUES DE ARRUDA