masterThesis
Ensaios de tratabilidade aplicados a determinação de parâmetros para dimensionamento de processos de tratamento de água de manancial eutrofizado
Fecha
2010-12-17Registro en:
EUSTÁQUIO, Hugo Mozer Barros. Ensaios de tratabilidade aplicados a determinação de parâmetros para dimensionamento de processos de tratamento de água de manancial eutrofizado. 2010. 144 f. Dissertação (Mestrado em Saneamento Ambiental; Meio Ambiente; Recursos Hídricos e Hidráulica) - Universidade Federal do Rio Grande do Norte, Natal, 2010.
Autor
Eustáquio, Hugo Mozer Barros
Resumen
Eutrophication is a growing process present in the water sources located in the
northeast of Brazil. Among the main consequences of these changes in trophic levels
of a water source, stands out adding complexity to the treatment to achieve water
standards. By these considerations, this study aimed to define, on a laboratory scale,
products and operational conditions to be applied in the processing steps using raw
water from Gargalheiras dam, RN, Brazil. The dam mentioned shows a high number
of cyanobacteria, with a concentration of cells / ml higher than that established by
Decree No. 518/04 MS. The same source was also considered by the state
environmental agency in 2009 as hypereutrophic. The static tests developed in this
research simulated direct filtration (laboratory filters) and pre-oxidation with chlorine
and powdered activated carbon adsorption. The research included the evaluation of
the coagulants aluminum hydrochloride (HCA) and alum (SA). The development of
the research investigated the conditions for rapid mixing, the dosages of coagulants
and pHs of coagulation by the drawing of diagrams. The interference of filtration rate
and particle size of filtering means were evaluated as samples and the time of
contact were tested with chlorine and activated carbon. By the results of the
characterization of the raw water source it was possible to identify the presence of a
high pH (7.34). The true color was significant (29 uH) in relation to the apparent color
and turbidity (66 uH and 13.60 NTU), reflecting in the measurement of organic
matter: MON (8.41 mg.L-1) and Abs254 (0.065 cm-1). The optimization of quick mix
set time of 17", the speed gradient of 700 s-1 in the coagulation with HCA and the
time of 20" with speed gradient of 800 s-1 for SA. The smaller particle sizes of sand
filtering means helped the treatment and the variation in filtration rate did not affect
significantly the efficiency of the process. The evaluation of the processing steps
found adjustment in standard color and turbidity of the Decree nº 518/04 MS, taking
in consideration the average values found in raw water. In the treatment using the
HCA for direct filtration the palatable pattern based on the apparent color can be
achieved with a dose of 25 mg L-1. With the addition of pre-oxidation step, the
standard result was achieved with a reduced dose for 12 mgHCA.L-1. The turbidity
standard for water was obtained by direct filtration when the dose exceeds 25 mg L-1
of HCA. With pre-oxidation step there is the possibility of reducing the dose to 20 mg
L-1.The addition of CAP adsorption, promoted drinking water for both parameters,
with even lower dosage, 13 mg L-1 of HCA. With coagulation using SA removal
required for the parameter of apparent color it was achieved with pre-oxidation and
22 mgSA.L-1. Despite the satisfactory results of treatment with the alum, it was not
possible to provide water with turbidity less than 1.00 NTU even with the use of all
stages of treatment