Efficiency evaluation of polishing ponds operating
as wastewater biological treatment process and
rearing fish tank in an Integrated Biosystems
Wastewater Treatment Plant
Fabrícia Fafá de Oliveira
Luiz Alberto Pinto Jr
Thiago Bollis Vieira
Maria Alice Moreno Marques
Samantha Santos
D. Alessandra Delazari-Barroso
NPA/FAESA – Environmental Research Group
Localização
Jacaraípe
Venda Nova do Imigrante
Meaípe
NPA/FAESA – Environmental Research Group
One of the major concerns in the
sanitary area is domestic
wastewater. The discharge of
unnatural wastewater in water
bodies may cause serious problems
to water quality resources and puts
in risk the domestic water supply
NPA/FAESA – Environmental Research Group
How to improve the health and the life quality of rural
communities to reduce rural exodus and the high
density of urban population?
What is the best appropriate technology for
wastewater treatment in rural communities?
NPA/FAESA – Environmental Research Group
CAXIXE PROJECT: Improvement of Life Quality in a Rural
Community: Sub-basin of the Caxixe Stream, ES
Coordination
Dr. José Luiz Helmer – Biólogo
Technical Team
Dr. Alessandra Delazari Barroso - Bióloga
M.Sc. Fabrícia Fafá de Oliveira – Eng. Civil
M.Sc. Jônio Ferreira de Souza – Eng. Civil
M.Sc. Maria Alice Moreno Marques - Química
M.Sc. Marcelo Simonelli - Biólogo
Realization
NPA/FAESA – Núcleo de Pesquisas Ambientais da FAESA
Sponsorship
Support
Prefeitura
Municipal
de Venda Nova do
Imigrante
NPA/FAESA – Environmental Research Group
Capacity: 1.000 inhabitants
Actual inhabitants= 302
Q = 0,58 l/s
CAXIXE WTP
Biossistemas Integrados - BSI
Final Effluent
Microphytes tank
Rearing fish tank
Algae tank
Constructed
wetland
Chinese
Biodigestor
Preliminary
treatment
Anaerobic
filter
NPA/FAESA – Environmental Research Group
Caxixe WWTP Location
Caxixe
WWTP
Dordenone Ville
9 Dordenone Village (Alto Caxixe – Venda Nova do Imigrante –
ES)
NPA/FAESA – Environmental Research Group
Rearing Fish Tank: Polishing Pond
Fishes : Oreochromis niloticus (tilápia)
Poecilia reticulate (barrigudinho)
0,70 m
Area = 750 m²
Depth = 0,70 m
HDT = 10,5 dias
NPA/FAESA – Environmental Research Group
Liquid Phases Samples: From October 2007 to May 2008
Samples collected between 9 to 11 AM
Analysed Parameters :
Input
- TSS
- Thermotolerant Coliform
Output
0,70 m
- BOD
- COD
- CODf
NPA/FAESA – Environmental Research Group
Phytoplanktonic Microalgae
¾ Mounthly samples
0,70 m
Collect point
¾ Samples without presentation: species observation
¾ Samples fixed with lugol: algae counting
NPA/FAESA – Environmental Research Group
Results and Discussion
Rearing fish tank Monitoring
Table 1 - Descriptive statistics of the effluent analysis results at input and output of
the tank
Average
Parameters
Unit
n
Input
TSS
mg/L
7
79
BOD5
mg O2/L
7
COD
mg O2/L
CODf
CT
SD
Output
Input
Output
94
68
48
54
39
23
17
7
144
146
45
45
mg O2/L
3
94
63
48
33
NMP/100mL
4
8,75 E+05
2,34 E+05
5,38 E+05
4,44 E+05
NPA/FAESA – Environmental Research Group
TSS
TSS
250
9 Maintenance
tank activities or
rain events prior
to the sampling.
TSS (mg/L)
200
150
100
50
0
14/11/07
input
24/12/07
02/02/08 13/03/08
Date
22/04/08
01/06/08
output
9 The suspended solids concentration was higher at the output of fish
tank, because of the large presence of phytoplanktonic, increasing
considerably the suspended particulate matter concentration in the
effluent.
NPA/FAESA – Environmental Research Group
BOD
BOD
100
90
Low efficiency in
the preceding unit
80
BOD (mgO2/L)
70
60
50
40
30
20
10
0
24/12/07
02/02/08
input
output
13/03/08
Date
22/04/08
01/06/08
9 The majority of the results presents lower values in the system
output due to the biodegradable fraction removal by microorganisms
and especially by fish, when feeding on microalgae and some particles
of organic material present in the water.
NPA/FAESA – Environmental Research Group
COD
COD filtered
300
300
250
250
COD filtered (mgO2/L)
COD (mgO2/L)
COD
200
150
100
50
0
24/12/07
02/02/08
input
output
13/03/08
Date
22/04/08
01/06/08
200
150
100
50
0
13/03/08
02/04/08
22/04/08
12/05/08
Date
input
output
¾ These results presented varianting values from the COD concentration, not maintaining a
declining standard to the removal of the Rearing Fish Tank, when compared to the input.
¾ In the tank output, the CODf had lower values than COD, indicating that most of the organic
material was found in microalgae.
NPA/FAESA – Environmental Research Group
Thermotolerant coliform
Thermotolerants coliforms
Thermotolerants coliforms (NMP/100mL)
1,00E+07
1,00E+06
¾ the reduction
of
thermotolerant
coliforms in the
output of the
rearing fish
tank, was 1 to
2 logarithmic
units
1,00E+05
1,00E+04
1,00E+03
1,00E+02
22/02/08
input
13/03/08
output
02/04/08
22/04/08
12/05/08
Date
¾The treatment process has not demonstrated an excellent performance in bacterial
removal. .
NPA/FAESA – Environmental Research Group
Efficiency:
Some results did not show a high percentage in
efficiency, since the Caxixe WWTP works as an integrated biosystems,
the rearing fish tank, which is the sixth stage of the treatment, will can
contribute with the removal of small concentrations of some of these
parameters, considering that its affluent comes with reduced values
Parameter
Efficiency (%)
TSS
- 35
BOD5
27
COD
-2
CODf
33
TC
73
Not satisfactory
because of the high
concentration of
microalgae found in
the rearing fish
tank, thereby
increasing the
concentration of
organic matter.
Increase at this
stage of the
treatment
system due to
the presence of
microalgae.
Interference in this system, as the presence of animals such as ducks and goose
may have contributed to its increase.
NPA/FAESA – Environmental Research Group
Phytoplankton: It was found 35 microalgae taxa of
phytoplanktonic Classes
Dry season
warmer months and with low rainfall
3,E+05
3,E+05
2,E+05
2,E+05
1,E+05
5,E+04
0,E+00
nov/07
dez
Chloro
jan/08
Cyano
Eugleno
mar
Zignema
abr
mai
Bacilla
Predominated Class
NPA/FAESA – Environmental Research Group
Phytoplankton: cyanobacteria registered as potentially toxic
in Brazil *
9 Aphanocapsa (hepatotoxic – microcistinas)
9 Synechocystis aquatilis (hepatotoxic – microcistinas)
9 Geitlerinema (unknow cianotoxine)
9 Synochococcus (unknow cianotoxine)
* Sant’Anna et al. 2008. Review of toxic species of Cyanobacteria in Brazil.
Algological Studies 126: 251-265.
NPA/FAESA – Environmental Research Group
Conclusions
¾ After analysis the monitoring results, can be emphasized that the reason to
a low organic material removal capacity is because it already has been
reduced sharply in previous stages of de WTP
¾Although the rearing fish tank has contributed to the BOD5 removal, there
was a significant suspended solids concentration increase due to the
presence of microalgae, also contributing to an increase in the COD
concentration, indicating a necessity of after-treatment tank of fish stages, to
attend the effluent discharge quality standards
¾The pathogens removal efficiency was not as expected, because the
removal of 1 to 2 logarithmic units does not contribute to disinfect the
effluent, requiring further treatment stages. It’s necessary to check the
influence of fish in the treatment efficiency of the polishing pond, by
counting them and performing genotoxic test
¾ The predominance of chlorophytes in the polishing pond indicates that it
is a favorable environment for the fish rearing, because it’s a source food.
Thus, the fish farming can be a gainful activity for the local people. The
occurrence of four genera of cyanobacteria already registered as toxic in
other parts of Brazil, reflects the contamination potential by cyanotoxins, in
the case of fish farm water use and also requires more detailed studies.
NPA/FAESA – Environmental Research Group
ACKNOWLEDGEMENTS
This research was supported
Petrobrás Environmental Program.
by
grant
from
The authors thanks
the Prefeitura Municipal de
Venda Nova do Imigrante - ES, for the support and
the FAESA, CEFETES, and OIA for the
partnership.
NPA/FAESA – Environmental Research Group
Thanks
[email protected]
NPA/FAESA – Environmental Research Group