Name: Graciele Zavarize Belisário Gobetti
Type: MSc dissertation
Publication date: 24/09/2018
Advisor:
Name |
Role |
|---|---|
| Ricardo Franci Gonçalves | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Ricardo Franci Gonçalves | Advisor * |
Summary: Concerns about the presence of pathogenic microorganisms in reuse waters are one
of the impediments to the greater acceptability of this practice in urban
centers. Therefore, many parameters of water quality are monitored to ensure the
quality required for reuse, and turbidity is one of the most used. Thus, this study
sought to analyze the relationships between the quality of the reuse water produced
from gray water and its perception by the users. Through a statistical correlation
analysis with data from several studies, this research showed that between gray
water and sewage samples, there is a moderate correlation between the turbidity
values with the presence of Escherichia coli. (E. coli). Therefore, in statistical terms,
there is no strong and significant correlation between turbidity and E. coli in
wastewater, concluding that not always high turbidity values must necessarily
represent a higher value of indicator microorganisms. In terms of characterization of
the samples, the gray water quality was very similar to those reported in the
literature. Here, a COD / BOD ratio in the raw gray water (ACB) of 1;1, was obtained,
which indicates a high biodegradability of this effluent. The treated gray water quality
(ACT) is in compliance with the parameters presented in the standard "Alternative
sources of non-potable water in buildings" released for public consultation by ABNT.
In addition, this study showed that there are possibilities of E. coli regrowth in ACB
and ACT under different concentrations of residual chlorine. There was up to 2 logs
regrowth of E. coli at the time that the residual chlorine was above 2 mg Cl2/L. This
result can be explained by the fortification of samples with nitrogen and phosphorus
and inoculation of microorganisms, large chlorine consuming agents. Finally,
organoleptic tests for the perception of the quality of gray water with different levels
of turbidity showed that the samples with lower turbidity were more naturally
accepted. However, among the samples with higher levels (8 NTU and 10 NTU),
there was no difference. However, for non-potable purposes, considering 3 NTU gray
water samples as a comparative basis, the judges were only able to perceive the
difference when the comparison was made with a sample of 10 NTU.
