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CHEMICAL ENGINEERING TRANSACTIONS

VOL. 43, 2015

A publication of

The Italian Association
of Chemical Engineering
Online at www.aidic.it/cet

Chief Editors: Sauro Pierucci, Jiří J. Klemeš
Copyright © 2015, AIDIC Servizi S.r.l.,
ISBN 978-88-95608-34-1; ISSN 2283-9216

Application of Coagulation/Flocculation Process of Dairy
Wastewater from Conventional Treatment Using Natural

Coagulant for Reuse

Gabriele Wolf*, Roselene Maria Schneider, Milene Carvalho Bongiovani, Eduardo
Morgan Uliana, Adriana Garcia do Amaral

Mato Grosso Federal University. 1200 Alexandre Ferronato, Avenue, Industrial Secto 78.557-267. Sinop, Mato Grosso,
Brazil.
wolf_gabriele@yahoo.com.br

The objective of this study was to evaluate the applicability of tannins natural coagulants, Tanfloc SG and SH,
in coagulation / flocculation process for clarification, as post-treatment of effluent from a dairy industry aiming
its reuse. Determined pH and optimal dosage of coagulant activity through jar test, in dosages ranging from 10
- 60 mg.L-1 and pH range 3 – 9. The optimum conditions defined by statistical analysis of the values of
turbidity removal were, for Tanfloc SG dosage of 20 mg.L-1 and pH 6 and the Tanfloc SH dosage of 20 mg.L-1
and pH 5. According to the parameters defined in technical standard for wastewater reuse, both treated
effluent have the potential for reuse in irrigation of orchards, pastures, among others, by runoff or irrigation
system off, and the treated effluent with Tanfloc SH has potential also discharges for reuse in toilets.

1. Introduction

The dairy industry consumes considerable amount of water for its production processes (Lolei et al., 2014),
generating large volumes of effluents with high load pollution (Parmar et al., 2011), which if not properly
disposed or treated, can cause serious problems of environmental contamination. The increase in catchment,
water and effluent treatment costs and the imposition of environmental regulations have driven the industry to
implement reuse systems (Sarkar et al., 2006). Wastewater reuse is a significant resource; however, its
quality must be suitable for reuse (Bastos et al., 2005).
In this context, coagulation and flocculation processes has been widely used both in treatment of drinking
water (Bongiovani et al., 2010) as industrial waste (Sarkar et al., 2006). The coagulation and flocculation
process enables the reduction of color (Verma et al., 2014) and turbidity (Teh and Wu, 2014) parameters by
suspension, colloidal particulate, some dissolved substances removal (Vaz et al., 2010) and cyanotoxins
(Camacho et al., 2013), besides the reduction of organic matter content, which contributes to reduction of
COD in the effluent (Lolei et al., 2014).
The most commonly used coagulants in water and wastewater treatment are the inorganics that are trivalent
aluminum and iron salts. Despite the performance and cost-effectiveness of these coagulants proven, there is
still a certain amount of residual aluminum content after treatment. It has recently been the subject of
discussion, due to be evidence that Alzheimer's disease may be linked to aluminum present in water intended
for human consumption. Moreover, aluminum is not biodegradable and can cause problems of disposal and
treatment of the large amount of sludge generated (Sahu and Chaudhari, 2013).
In this context, natural coagulants (polymers), derived from certain kinds of plants and animal life, are
workable alternatives to synthetic coagulants.
Tannins are mostly vegetal water-soluble polyphenolic compounds. Their molecular weight is ranged between
500 and some thousands Daltons. Trees such as Schinopsis balansae (Quebracho), Castanea sativa
(Chestnut) or Acacia mearnsii de Wild (Blackwattle) are traditional tannin sources. Previous studies found at
tannins a coagulant activity in water treatment (Beltrán-Heredia et al., 2011). The main aim of the present

DOI: 10.3303/CET1543341

Please cite this article as: Wolf G., Schneider R.M., Bongiovani M.C., Morgan Uliana E., Garcia Do Amaral A., 2015, Application of
coagulation/flocculation process of dairy wastewater from conventional treatment using natural coagulant for reuse, Chemical Engineering
Transactions, 43, 2041-2046 DOI: 10.3303/CET1543341

DOI: 10.3303/CET1543341

2041

investigation is to evaluate the applicability of tannin, TANFLOC SG and SH, in coagulation/flocculation
process as post-treatment of dairy effluent aiming their reuse.

2. Material and methods

The experiments were conducted in the Waste Treatment Laboratory of Agricultural and Environmental
Sciences Institute, Federal University of Mato Grosso, Campus of Sinop, Sinop (MT). The effluents for
coagulation/flocculation tests were collected from a dairy plant at Sinop, MT. Samples were collected at the
end of dairy effluents treatment from a facultative lagoon, through simple sampling, whereas complete mixing
and homogenization of the lagoon effluent. The agroindustry treatment system is only for stabilization lagoons.
The coagulants used for the tests were a tannin-based product called Tanfloc (Tanfloc SG and Tanfloc SH) a
trademark that belongs to TANAC (Montenegro, Brazil). This product, supplied as a solid, is modified by a
physic-chemical process from Acacia mearnsii de Wild. This tree is very common in Brazil and it has a high
concentration of tannins with high flocculant power. Standard solutions of both coagulants were prepared in
concentrations of 1,000 mg.L-1.
The experiment was divided into two steps. The first step involved the determination of the optimal pH and
dosage of coagulants that takes the most significant turbidity removal of the samples in
coagulation/flocculation process. The dosage range investigated during the tests was 10 to 60 mg.L-1 and pH
3-9. NaOH (1.0 M) and concentrated HCl were used to the pH adjustment according to the natural pH of the
effluent.
In the second step, it was performed the coagulation/flocculation tests with the coagulants optimal dosage. For
this the raw and clarified effluent were evaluated for the parameters turbidity, total solids, total and fecal
coliforms, chemical oxygen demand (COD) and sludge volume.
The pH was determined by Multiparameter quality meter U-20XD Water - Horiba and turbidity by turbidimeter
AP 2000 - Policontrol in nephelometric turbidity units (NTU). To assess the amount of sludge generated its
volume was measured after each test by Imhoff cone. The other parameters were determined following the
procedures described by the Standard Methods (APHA, 1995).
Experimental tests were conducted in jar-test equipment FlocControl IV – Policontrol with six samples of
effluent simultaneously. For the step of optimal pH and dosage determination, 250 mL of effluent was used in
the tests, and in the second step, 1,000 mL of effluent was used, due to the larger number of parameters to be
determined.
After the coagulant was added to jars, rapid mix was done for 2.5 min at 120 rpm and the slow stirring for 20
min at 20 rpm. Twenty minutes were allowed for the settling of the flocs (Bongiovani et al., 2010).
At the end of the first phase of each test sample supernatant (clarified liquid) were collected and the turbidity
analysis was performed. The combination of pH and dosage showed the best results, considering smaller
amount of reagents and high turbidity removal, confirmed by the statistical analysis was defined as optimal
condition which were applied in the second step of the experiment.

2.1 Statistical analysis
For turbidity removal after coagulation/flocculation process in the first step, design of experiments was carried
out using complete factorial design in factorial arrangement 7x6, which factors: pH levels (3, 4, 5, 6, 7, 8 and
9) and six different dosages (10, 20, 30, 40, 50 and 60 mg.L-1), with three replications, comprising a total of 42
experiments. This was performed to verify the effect of pH on each dosage and dosage in each pH, and the
effects of interactions between it.
The STATISTICA 6.0 software was used for all statistical analysis. All statistical significance was considered
when p< 0.05. Analysis of variance (ANOVA), with Tukey’s test was carried out to verify the significance of
differences among the means.
As ANOVA testing only indicates which response variables are significantly affected by different factors but
provides no insight into trends (i.e. how the response variables are affected), Tukey’s test was chosen for this
study, all samples are compared pairwise to determine which sets of samples vary significantly from each
other. To identify the optimal region of coagulants action in the coagulation/flocculation process, it was used
response surface analysis. In the second stage of determining the parameters turbidity, total solids, total and
fecal coliforms, chemical oxygen demand (COD) and sludge volume, it was used descriptive statistics to
analyze the variations in data replicas.

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3. Results and discussions

3.1 Dosage and pH optimum determination
The effluent collected from the dairy industry for the tests of the first step showed a natural pH of 6.8 and a
natural turbidity value of 109 NTU. Figure 1 shows the response surface analysis for varying turbidity using
coagulants Tanfloc SG and SH, respectively, depending on the dosage of the coagulant and the pH of the
effluent.

Response Surface - pH x Dosage

T urbidity
Removal (%)

100
80
60
40
20
0 0 10 20 30 40 50 60 70

Dosage (mg.L-1)

p
H

Response Surface - pH x Dos age

T urbidity
Removal (%)

100
80
60
40
20
0

0 10 20 30 40 50 60 70

Dosage (mg.L-1)

p
H

Figure 1: Response variable area for turbidity as a function of pH variation and dosage of coagulant (1)
Tanfloc SG and (2) Tanfloc SH

It is observed that most of the experiments showed turbidity removal values higher than 80 %. In the
experiments conducted at pH 9, turbidity removal values were below 80 % at all dosages tested for both
coagulants. Low values of turbidity removal were also observed for the dosage of 10 mg.L-1 for both the
coagulants at pH values above 5.
In general, for both coagulants, high removals of turbidity (> 90 %) was observed for dosages of 30, 40, 50
and 60 mg.L-1 at pH 3 to 8, wherein the pH 4 both coagulants showed turbidity higher than 90% for all the
dosages tested, i.e., smaller dosages associated with pH values close to the natural pH of the effluent achieve
satisfactory turbidity removal (80 – 100 %).
Analysis of variance (ANOVA) showed a significant difference between the means at 5 % significance in the
characteristic evaluated turbidity for both coagulants Tanfloc SG and SH, i.e. both dosage and pH influenced
the variable turbidity and there was interaction between dosage and pH (p <0.05).
Based on these results, we defined the dosage of 20 mg.L-1 for both optimum dosage as coagulants, since at
pH values near the effluent turbidity values provides satisfactory removal. Figure 2 shows the turbidity removal
efficiency for the dosage of 20 mg.L-1 to SG Tanfloc coagulants (1) and SH Tanfloc Coagulant (2) at different
pH values tested.

Figure 2: Turbidity removal in coagulation/flocculation tests using coagulants Tanfloc SG (1) and Tanfloc SH
(2) the optimal dosage of 20 mg.L-1 at different pH levels. Letters (a, b, c etc.) to identify different statistical
graphs groups (Tukey test, p < 0.05)

d d d
d

100

3 4 5 6 7 8 9

T
u
rb

id
it
y

R
e

m
o

va
l
(%

)

d d d

c c
b

100

3 4 5 6 7 8 9

T
u
rb

id
it
y

R
e

m
o

va
l
(%

)

(1) (2)

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Based on these results, it was established to Tanfloc SG coagulant dosage of 20 mg.L-1 and pH 6, as to the
dosage of 20 mg.L-1, there is no statistically significant difference for pH levels 3 to 6 according Tukey test at
5% probability. In addition, for Tanfloc SH, coagulant settled dosage conditions of 20 mg.L-1 and pH 5, as by
Tukey test at 5% probability there is no significant difference turbidity removal statistically for dosing 20 mg.L-1
levels between pH 3 to 5.
These conditions were established by first considering the pH and dosage that promotes greater turbidity, and,
with respect to pH values that approximate the natural pH of the effluent, in order to reduce the use of acidic
or basic solution for pH adjustment, and with respect to dosage, low dosage values in order to reduce the use
of concentrated coagulant.

3.2 Comparison of coagulants in optimum conditions of dosage and pH
The characterization of the effluent for testing in pH and dosage optimal of each coagulant are shown in Table
1. The collection of the effluent was accomplished by simply sampling and on different days, hence the
original characteristics of the effluent for testing each coagulant were different.

Table 1: Characterization of the raw sewage used in the process of coagulation/flocculation

Parameters Tanfloc SG Tanfloc SH

Turbidity (NTU) 31.95 47.95

COD (mg.L-1) 338.3 123.3

Total solids (mg.L-1) 0.44 0.47

Total coliform (NPM.100 mL-1) 4 4

Termotolerant coliform (NPM.100 mL-1) 0 15

Table 2 shows the results after jar test experiment: turbidity, COD removal, total solids, total and fecal
coliforms and volume of sludge generated for coagulants Tanfloc SG and SH, which will be used to evaluate
the quality of effluent for reuse.

Table 2: Results obtained with coagulation/flocculation tests of the effluent for each coagulant

Parameters Tanfloc SG Tanfloc SH

Turbidity (% uptake) 71.2 65.6

COD (% uptake) 77.28 44.14

Total solids (mg.L-1) 0.48 0.43

Sludge volume (mL.L-1) 27.3 41.1

Total coliform (% uptake) 100.0 69.0

Thermotolerant coliform (% uptake ) - 91.1

It is found that the turbidity was less than the removal obtained in the first stage of the experiment for both
coagulants. Possible causes of these results are the largest volume of wastewater used for
coagulation/flocculation used in jar test, which may have changed the mixing ratio in relation to the mixing
blade of the equipment. Another important factor is the lowest value of the initial turbidity presented by the
effluent collected in the second step, due to variability that normally occurs in agro-industrial effluents,
because for higher baseline turbidity coagulant removal efficiency is higher.
Regarding the removal of COD, it appears that for Tanfloc SG coagulant, COD removal was 77.28 %, and for
Tanfloc SH was 44.14 %. In terms of total solids can be seen that the data obtained for both coagulants,
treatment did not give significant results, given that the effluent has already had reasonably clarified.
The sludge volume generated for the treated effluent with Tanfloc SH was 41.17 mL.L-1 and the treated
effluent with Tanfloc SG was 27.33 mL.L-1. Cruz et al. (2005) evaluated Tanfloc coagulant in the process of
coagulation / flocculation in the primary treatment of industrial laundry wastewater and the parameters
removal were 95.82 % for turbidity, 84.12 % for COD and sludge volume of 130 mL.L-1.
Pedroso (2012) evaluated the treatment of landfill leachate by process of coagulation/flocculation with Tanfloc
SG and obtained significant reductions mainly for color and turbidity of the leachate from the landfill. Vaz et al.
(2010) to assess the color and turbidity removal efficiency of electroplating effluent with the use of coagulants
Tanfloc SG, obtained turbidity removal up to 99.13 %.

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For total coliforms analysis it was obtained for Tanfloc SG coagulant, removal of 100 %. Regarding
thermotolerant coliforms were not completely removed, since the effluent before the clarification process had
no thermotolerant coliforms. For Tanfloc SH coagulant, fecal coliform removal was 91.1 % and 69 % of total
coliforms. There are few studies in the literature for wastewater treatment dairies using
coagulation/flocculation with natural coagulants. The studies cited in literature are in the primary treatment
stage or pre-treatment effluents using Moringa oleifera seed (Schmitt, 2010) and Moringa oleifera seed and
tanino (Ferreira, 2012). In this study, the process of coagulation/flocculation with natural coagulant was used
in the post-treatment of the effluent aiming its reuse.
Table 3 shows the quality standards for wastewater classification potential for non-potable reuse determined
by Brazilian normative NBR-13.696 (1997) compared with the turbidity values, total solids and thermotolerant
coliforms obtained by coagulation/flocculation.

Table 3: Quality standards for direct reuse non-potable water

Parameter Coagulants Water reuse classes *

Tanfloc SG Tanfloc SH Class 1 Class 2 Class 3 Class 4

Turbidity (NTU) 9.20 16.5 < 5 < 5 < 10 -

Total solids (mg.L-1) 0.482 0.433 < 200 - - -

Thermotolerant
coliform**

- 1.34 < 200 < 500 < 500 < 5000

According to the results, it can be seen that the effluent treated with Tanfloc SH does not have reuse potential
for applications in Classes 1, 2 and 3 since the residual turbidity value exceeds the threshold for such classes,
presenting potential for reuse for class 4 applications - irrigation orchards, cereal, forage, pasture for cattle
and other crops through runoff or from point irrigation system. The treated effluent with Tanfloc SG has
potential reuse for applications in Class 3 - discharges in toilets and class 4, as the residual turbidity value is
above the limit established for classes 1 and 2. For the remaining parameters, clarified effluent with both
coagulants are adequate for all the reuse of classes, since the residual values of total solids and
thermotolerant coliforms are below the maximum allowed values.
It is noted that, if the removal of turbidity values observed in the first phase of the experiment had been
obtained also in the second phase, i.e. the phase of the first turbidity removal efficiency was also found in the
second stage, the effluent had reached the quality required for classification in relation to its reuse potential for
applications proposed by NBR 13.969 (1997), showing the importance of coagulation / flocculation assays for
determining dosage and optimal pH of action of the coagulant for the conditions of the effluent.
Also worth mentioning that, for the use of wastewater for irrigation should be analyzed other parameters than
those shown above and suggested by NBR, as salt content (Na, Ca, Mg, Fe), sodium adsorption ratio (SAR),
conductivity, concentration and nature of suspended solids, oils, nutrients - nitrate, ammonium, phosphate,
potassium, among others, as the misapplication of effluents in the soil can interfere with physical and chemical
characteristics of the soil, causing problems such as salinization, clay dispersion, tightness of the deeper
layers of soil and toxicity to plants, affecting soil productivity and causing losses in production and the
environment, in addition to technical problems such as physical obstruction of irrigation systems, such as
pipes and emitters of systems and localized wear of pumps and hoses (Ucker et al., 2013).

4. Conclusions

In the study of the coagulation/flocculation with coagulants Tanfloc SG and Tanfloc SH, it was possible to
verify that, due to the effluent variables and reaction mechanisms of pH and coagulant dosage used, it is often
necessary to determine the treatment conditions to choice the ideal coagulant in economical and efficient
dosage, and for the Tanfloc SG optimal conditions, defined by statistical analysis, were dosage of 20 mg.L-1
and pH 6 and the Tanfloc SH coagulant dosage 20 mg.L-1 and pH 5. The response surface analysis allowed
the identification of the optimal processing performance ranges of dosages for each pH level allowing the
agroindustry from this identification can adjust the amount of coagulant to the effluent to be incorporated
according to the present effluent pH since the characteristics of the effluent vary without, however, need to
adjust the pH of the effluent.
The process of coagulation / flocculation with coagulants Tanfloc SG and SH pH and optimal dosages defined
previously allowed satisfactory reductions in COD and turbidity. With regard to the reuse of clarified effluent,
effluent treated with coagulants Tanfloc SG and SH have potential to be reused according to NBR 13.969
(1997), in irrigation orchards, cereal, forage, pasture for cattle and other crops by runoff or from point irrigation

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system, however more parameters must be analyzed to ensure that the quality required for the use of
wastewater in irrigation was reached, as the physico-chemical characteristics, soil characteristics, tolerance of
crops be used, the local climate, water management and drainage, so as not to cause damage to soil and
crops. The treated effluent with Tanfloc SH also has potential for reuse in toilets discharges.

References

APHA – American Public Health Association. Standard methods for the examination for water and
wastewater. 19 ed. Washington, D.C., USA, 1995.

Bastos, R. K. X.; Bevilacqua, P. D.; Silva, C. A. B.; Dornelas, F. L.; Assunçăo, F. A. L. de; Rios, E. N.; Silva, A.
F. S.; Freitas, A. S.; Costa, G. S. Treatment of sewage effluent and multiple uses. Journal of Agricultural
and Environmental Engineering, 9 (Supplement) 164-170, 2005.

Beltrán-Heredia, J., Sánchez-Martín, J., Dávila-Acedo, M.A. Optimization of the synthesis of a new coagulant
from a tannin extract, Journal of Hazardous Materials, 6, 1704-1712, 2011.

Bongiovani, M. C.; Konradt-Moraes, L. C.; Begamasco, R.; Lourenço, B. S. S.; Tavares, C. R. G. The benefits
of using natural coagulants for obtaining potable water. Acta Scientiarum Technology, Maringá, PR, 32 (2)
167-170, 2010.

Brazilian Association of Technical Standards (ABNT). NBR 13.969: Septic tanks - complementary treatment
plants and final disposal of wastewater - Design, construction and operation. Rio de Janeiro, Brazil, ABNT,
1997. 60p.

Camacho, F. P.; Bongiovani, M. C.; Arakawa, F. S.; Shimabuku, Q. L.; Shimabuku, Q. L.; Vieira, A. M. S.;
Bergamasco, R. . Advanced Processes of Cyanobacteria and Cyanotoxins Removal in Supply Water
Treatment. Chemical Engineering Transactions, 32, 421-426, 2013.

Cruz, J. G.; Menezes, J. C. S. S.; Rubio, J.; Schneider, I. A. H. Vegetable coagulant Application tannin-based
treatment by coagulation / flocculation and adsorption / coagulation / flocculation of the effluent of an
industrial laundry . In: 23 Brazilian Congress of Sanitary and Environmental Engineering. Annals... Campo
Grande, MS, Brazil, 2005.

Ferreira, R. P. Use of natural coagulants such pre-treatment dairy effluent. 2012. 75 f. Working graduation
(Degree in Chemical Engineering) - Lorena Engineering School, University of São Paulo, São Paulo, 2012.

Loloei, M.; Alidadi, H.; Nekonam,G.; Kor, Y. Study of the coagulation process in wastewater treatment of dairy
industries. International Journal of Environmental Health Engineering, 3 (1) 17-21, 2014.

Parmar, Kokila A.; Prajapati, S.; Patell, R.; Dabhi, Y. Effective use of ferrous sulfate and alum as a coagulant
in treatment of dairy industry wastewater. ARPN Journal of Engineering and Applied Sciences, 6 (9) 42-45,
2011.

Pedroso, K.; Tavares, C. R. G.; Janeiro, V.; Silva, T. L.; Dias, P. Z. Leachate treatment evaluation of landfill
Maringá, Paraná, by process of coagulation / flocculation with Tanfloc SG®. Journal of Engineering and
Technology, 4 (2) 87-98, 2012.

Sahu, O. P.; Chaudhari, P. K. Review on Chemical treatment of Industrial Waste Water. Journal of Applied
Sciences and Environmental Management, 17, 241-257, 2013.

Sarkar, B.; Chakrabarti, P. P.; Vijaykumar, A.; Kale, V. Wastewater treatment in dairy industries — possibility
of reuse. Desalination, 195 (1) 141-152, 2006.

Schmitt, D. M. F.; Klen, M. R. F., Veit, M. T.;Bergamasco, R. Wastewater treatment of the dairy industry by
coagulation process / flocculation using the Moringa oleifera seed. In: National Meeting of Moringa. 2010.
Aracaju, Sergipe. Annals... UFSE, 1, 1-3, Sergipe, 2010.

Teh, C. Y.; Wu, T. Y. The Potential Use of Natural Coagulants and Flocculants in the Treatment of Urban
Waters, Chemical Engineering Transactions, 39, 1603-1608, 2014.

Ucker, F. E.; Lima, P. B. S. O.; Camargo, M. F.; Pena, D. S.; Cardoso, C. F.; Evangelista, A. W. P. Interfering
elements in the quality of water for irrigation. Electronic Journal of Management, Education and
Environmental Technology, 10 (10) 2102-2111, 2013.

Vaz, L. G. L.; Klen, M. R. F.; Veit, M. T.; Silva, E. A.; Barbiero, T. A.; Bergamasco, R. Efficiency evaluation of
different coagulants in the removal of color and turbidity in the effluent electroplating. Eclectic Chemistry.
[online], 35 (4) 45-54, 2010.

Verma, A. K.; Bhunia, P.; Dash, R. R. Reclamation of Wastewater Using Composite Coagulants: a
Sustainable Solution to the Textile Industries. Chemical Engineering Transactions, 42, 175-180, 2014.

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