Avaliação da fécula de mandioca como floculante auxiliar nas etapas de coagulação/floculação e flotação por ar dissolvido para o tratamento de água
This work deals with the use of natural flocculants as coadjuvants in the combined coagulation/flocculation process, followed by the dissolved air flotation stage, in which the ferric chloride acts as the main flocculant and the cassava starch as auxiliary flocculant. The use of natural flocculants...
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| Formato: | bachelorThesis |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/38897 |
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| Resumo: | This work deals with the use of natural flocculants as coadjuvants in the combined coagulation/flocculation process, followed by the dissolved air flotation stage, in which the ferric chloride acts as the main flocculant and the cassava starch as auxiliary flocculant. The use of natural flocculants is an interesting alternative due to its biodegradability and less aggression to the environment. The purpose of this study was to verify if cassava starch, acting as a coagulation/flocculation aid, contributes to the removal of turbidity from the water, as well as influencing parameters: turbidity, pH and electric conductivity. The raw water to be treated comes from a reservoir located in Santa Maria, a municipality belonging to the state of Rio Grande do Norte. The steps of coagulation/flocculation and flotation were performed on a bench scale equipment called Flotateste, adopting the time from 3 minutes for the rapid mixing step and 5 minutes for the slow mixing step, while for flotation the time to perform the analyzes of the parameters were 3 and 10 minutes. The assays were done in duplicates on two columns operating simultaneously. The total concentration of flocculant injected into the column was defined as 105 mg/L. Several experiments were carried out with different concentrations of auxiliary flocculant and main flocculant, at each test, 25% of the cassava starch concentration was increased, at the same time as the concentration of ferric chloride in the same proportion was decreased, starting at 0% of starch and 100% chloride until a combination of 100% starch and 0% chloride was reached. At the end of the flotation, the highest removal efficiency was 69.05% for the experiment without the presence of manioc starch. It was verified that as the starch concentration was increased, the percentage of turbidity removal was lower, and an increase of this parameter occurred for the test in which the cassava starch acted alone as a flocculant, increasing the turbidity of the treated water in 3.81% more than the value initially obtained for raw water. For conductivity, the values varied, but there was no predictable, increasing or decreasing trend, while increasing the concentration of the starch. For the pH, during the joint action of the flocculants, the values remained between 6 and 7, being smaller than the initial value. For the test in which the starch was the only flocculant in the process, the pH value was alkaline and higher than the initial one. At the end, it is possible to conclude that manioc starch did not contribute as a coagulation/flocculation aid to a process with ferric chloride as the main flocculant for the treatment of water. |
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