Avaliação da codisposição de resíduos de fossa e tanque sépticos em sistema de tratamento de esgoto composto por lagoas anaeróbias, facultativas e de maturação
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2013-07-17
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Universidade Federal de Goiás
Resumo
The deficiency displayed by public basic sanitation systems in Brazil forces a major part of
the population to seek individual alternatives to the final treatment and disposal of domestic
septage such as septic tanks and rudimentary cesspools. Waste coming from such individual
systems are, for the most part, discharged into Waste Water Treatment Plants (WWTPs),
which are not designed to such end. Hence, we observe a decrease in the efficiency of
sanitary waste treatment by WWTPs, which, in turn, leads to the pollution of water
resources. Thus, the present study aimed to assess the impacts caused by waste discharge
from cesspools and septic tanks into an anaerobic lagoon, followed by a facultative and
maturation lagoons. Barro Preto WWTP has two modules of stabilizing lagoons (A and B).
Module A was utilized as evidence. In other words, it did not receive cesspool and septic
tank waste discharge. Module B rate was 0.20%. In order to force the system, the WWTP
total flow was deviated to module B and the volumetric flow rate yielded was 0.05%. To
characterize sludge yield in the Trindade-GO municipality, composite samples from six
septage haulers were collected. Parameter analyses were: PH, Biological Oxygen Demand
(BOD), Chemical Oxygen Demand (COD), solid series (TSS,VSS, FSS,TS,TVS,TFS), oils
and grease, total Kjedhal nitrogen, amonniacal nitrogen, phosphorus and Escherichia coli.
Sludge deposit bathymetry was conducted in the anaerobic lagoons and surface scum bulk
was collected and quantified. To assess the interference of co-treatment in the performance
of stabilizing lagoons simple samples were collected from the anaerobic, facultative and
maturation lagoons. Parameters analyzed were: PH, BOD, COD, settleable solids ,total
suspended solids, amonniacal nitrogen, phosphorus, oils and grease, total coliforms and E.
coli. For the independent samples the t- Student test was applied in order to compare the
values obtained from the lagoon effluents. In addition, results from maturation lagoons were
compared with the Conama Resolution 430/2011 and the State Decree
1,745/1979.Statistically, no significant interference was observed in the co-treatment of
cesspool and septic tank septage in the Barro Preto WWTP, except for settleable solids in
the anaerobic lagoon effluents. Maturation lagoon effluents were in accordance with the
Conama Resolution 430/2011 and State Decree 1,745/1979 requirements for analyzed
parameters, with the exception of BOD, with yielded higher values in both modules over
some periods of the study. The wastes from cesspool and septic tanks have characteristics
similar to concentrated sewage pH raging between 5.3 and 8.4. COD/BOD ratio found was
3.92 mg.L-1, indicating that these residues are not found industries. The amount of scum
collected from anaerobic lagoons was similar displaying an increase of 8% in sludge
formation in the receiving lagoon. Hence, we concluded that Barro Preto WWTP is fit for
the co-treatment of cesspool and septic tank septage disposal produced by the municipality
of Trindade-GO. Furthermore, results show that anaerobic systems followed by facultative
and maturation lagoons conforming to the same standards practiced by Barro Preto WWTP
are fit to co-treat cesspool and septic tank septage.
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HADDAD, Katia Bittar. Avaliação da codisposição de resíduos de fossa e tanque sépticos em sistema de tratamento de esgoto composto por lagoas anaeróbias, facultativas e de maturação. 2013. 125 f. Dissertação (Mestrado em Engenharia do Meio Ambiente) - Universidade Federal de Goiás, Goiânia.