Avaliação de estações de tratamento de água do tipo ciclo completo em função da ocorrência de cistos de Giardia e Oocistos de Cryptosporidium
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2020-01-23
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Universidade Federal de Goiás
Resumo
The protozoa Giardia spp. and Cryptosporidium spp. are etiological agents responsible for the
transmission of gastroenteritis mainly due to the consumption of contaminated water. The
(oo)cysts are resistant to harsh environmental conditions, as well as to most of the physicochemical
processes used at Water Treatment Plants (WTP). Thus, the objective of this work was to evaluate
the seasonal occurrence and removal of these protozoa in WTPs with complete cycle technology of
the State of Goiás. Among the 15 analyzed according to the variables: Escherichia coli in raw
water; filtered water turbidity and pasture area in the catchment area; The Cerrado Stream was
selected for the supply of Sanclerlândia (WTP I) and Santana Stream de São Luís de Montes Belos
(WTP II), managed by the Saneago delegate, since the predominance of pasture indicates a risk of
cryptosporidiosis outbreaks. These indicators (Cryptosporidium spp. and pasture area) showed a
positive correlation (p = 0.0461). Six samples of raw and filtered water were collected for
protozoan determination using the Membrane Filtration method and analysis of the physical
parameters turbidity and pH in accordance with the Standard Methods for the Examination of
Water and Wastewater. In the initial precision tests with ultrapure water, the tests met the USEPA
(2012) criteria for Giardia (78.13% ± 0%) and Cryptosporidium (60.63% ± 32.65%), however, in
raw water the recovery was lower due to turbidity. In the seasonal monitoring, the raw water from
the superficial water source presented pathogen concentrations with maximum values of 50 cysts /
L and 200 oocysts / L, and the maximum removal efficiency of Cryptosporidium was 99.69% and
98.75% in WTP I and II, respectively. The filter material of the quick filters of WTP I have well
graded particle size (Tef = 0.60mm; Cu = 2.15), which promoted better filter performance in
relation to the turbidity of the filtered effluent. WTP II quick filters made of uniform material (Tef
= 0.61mm; Cu = 1.623) presented average turbidity parameter concentration of 0.35 NTU and 0.33
NTU in the dry and rainy season, thus the filtered water with lower Turbidity aims to prevent the spread of disease and can improve the efficiency of pathogen removal. In the mass balance, the influence of the steps preceding the filtration process was analyzed in relation to the
physicochemical and microbiological parameters. The increase in raw water turbidity during the
rainy season did not affect the filtered water, and this parameter ranged from 0.34 - 0.93 NTU in
WTP I and 0.28 - 1.27 NTU in WTP II. The removal efficiency was higher than 99%, regarding
turbidity, total coliforms and E. coli parameters. It can be concluded that WTP I and II presented
pathogen removal efficiency below 99%, reported in the literature, which highlights the importance
of studying the distribution of protozoa in the aquatic environment of the State of Goiás and the
respective sources of contamination. , as well as the need to implement technologies to improve
water treatment and ensure protozoa inactivation.
Descrição
Palavras-chave
Giardia , Cryptosporidium , Água , Ciclo completo , Filtração , Giardia , Cryptosporidium , Water , Conventional treatment , Filtration
Citação
SILVA, D. P. Avaliação de estações de tratamento de água do tipo ciclo completo em função da ocorrência de cistos de Giardia e Oocistos de Cryptosporidium. 2020. 102 f. Dissertação (Mestrado em Engenharia Ambiental e Sanitária) - Universidade Federal de Goiás, Goiânia, 2020.