Experimental study on chitosan composite flocculant for treating papermaking wastewater
In this paper, the flocculation effect of a novel composite flocculant for treating papermaking wastewater was studied and discussed. Results indicated that it achieved the best flocculation effect when this composite flocculant consisting of 60 mg/L of polymerized ferrous sulfate, 2 mg/L of polyacr...
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Інститут колоїдної хімії та хімії води ім. А.В. Думанського НАН України
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irk-123456789-1306912018-02-20T03:02:50Z Experimental study on chitosan composite flocculant for treating papermaking wastewater Zeng, D. Hu, D. Cheng, J. Технология водоподготовки и деминерализация вод In this paper, the flocculation effect of a novel composite flocculant for treating papermaking wastewater was studied and discussed. Results indicated that it achieved the best flocculation effect when this composite flocculant consisting of 60 mg/L of polymerized ferrous sulfate, 2 mg/L of polyacrylamide and 0.4 mg/L of chitosan, and pH value of wastewater was adjusted to 7.5. It also observed that the removal rate of chemical oxygen demand (COD) and solid substances (SS) with this novel composite flocculant reached 72.5% and 98.5% respectively. Compared with the conventional flocculant such as polyacrylamide/ polyaluminium chloride, the percentage of removing COD and SS using this composite flocculant were increased by 15.2 and 6.4% respectively, moreover, its input cost was cut down 18.4%. So this composite flocculant has significantly environmental and economic benefits. Изучен коагулирующий эффект новой смеси флокулянтов при очистке сточных вод бумажного производства. Результаты исследований показали, что наибольший коагулирующий эффект достигался при следующем составе смеси коагулянтов: 60 мг/дм³ полимеризованного сульфата железа, 2 мг/дм³ полиакриламида, 0,4 мг/дм³ хитозана и значении pH сточных вод 7,5. Также установлено, что ХПК и степень извлечения взвешенных веществ новой смесью флокулянтов составляли соответственно 72,5 и 98,5%. По сравнению с традиционными флокулянтами, такими, как полиакриламид/полиалюминий хлорид ХПК и степень извлечения взвешенных веществ с помощью этой смеси флокулянтов повысились соответственно на 15,2 и 6,4%. Кроме того, ее стоимость по сравнению с традиционными флокулянтами была ниже на 18,4%. Таким образом новая смесь флокулянтов имеет значительные экологические преимущества и экономически эффективна. Вивчено коагулюючий ефект нової суміші флокулянтів при очищенні стічних вод паперового виробництва. Результати досліджень показали, що найбільший коагулюючий ефект досягався при такому складі суміші коагулянтів: 60 мг/дм³ полімеризованого сульфату заліза, 2 мг/дм³ полі-акріламіда, 0, 4 мг/дм³ хитозана і значенні pH стічних вод 7,5. Також встановлено, що ХПК і ступінь вилучення зважених речовин нової сумішшю флокулянтів становили відповідно 72,5 і 98,5%. У порівнянні з традиційними флокулянтами, такими, як поліакриламід/поліалюміній хлорид, ХПК і ступінь вилучення зважених речовин за допомогою цієї суміші флокулянтів підвищилася відповідно на 15,2 і 6,4%. Крім того, її вартість в порівнянні з традиційними флокулянтами була нижчою на 18,4%. Таким чином, нова суміш флокулянтів має значні екологічні переваги та економічно ефективна. 2012 Article Experimental study on chitosan composite flocculant for treating papermaking wastewater / D. Zeng, D. Hu, J. Cheng // Химия и технология воды. — 2012. — Т. 34, № 1. — С. 55-65. — Бібліогр.: 18 назв. — англ. 0204-3556 http://dspace.nbuv.gov.ua/handle/123456789/130691 en Химия и технология воды Інститут колоїдної хімії та хімії води ім. А.В. Думанського НАН України |
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Технология водоподготовки и деминерализация вод Технология водоподготовки и деминерализация вод |
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Технология водоподготовки и деминерализация вод Технология водоподготовки и деминерализация вод Zeng, D. Hu, D. Cheng, J. Experimental study on chitosan composite flocculant for treating papermaking wastewater Химия и технология воды |
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In this paper, the flocculation effect of a novel composite flocculant for treating papermaking wastewater was studied and discussed. Results indicated that it achieved the best flocculation effect when this composite flocculant consisting of 60 mg/L of polymerized ferrous sulfate, 2 mg/L of polyacrylamide and 0.4 mg/L of chitosan, and pH value of wastewater was adjusted to 7.5. It also observed that the removal rate of chemical oxygen demand (COD) and solid substances (SS) with this novel composite flocculant reached 72.5% and 98.5% respectively. Compared with the conventional flocculant such as polyacrylamide/ polyaluminium chloride, the percentage of removing COD and SS using this composite flocculant were increased by 15.2 and 6.4% respectively, moreover, its input cost was cut down 18.4%. So this composite flocculant has significantly environmental and economic benefits. |
| format |
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| author |
Zeng, D. Hu, D. Cheng, J. |
| author_facet |
Zeng, D. Hu, D. Cheng, J. |
| author_sort |
Zeng, D. |
| title |
Experimental study on chitosan composite flocculant for treating papermaking wastewater |
| title_short |
Experimental study on chitosan composite flocculant for treating papermaking wastewater |
| title_full |
Experimental study on chitosan composite flocculant for treating papermaking wastewater |
| title_fullStr |
Experimental study on chitosan composite flocculant for treating papermaking wastewater |
| title_full_unstemmed |
Experimental study on chitosan composite flocculant for treating papermaking wastewater |
| title_sort |
experimental study on chitosan composite flocculant for treating papermaking wastewater |
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Інститут колоїдної хімії та хімії води ім. А.В. Думанського НАН України |
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2012 |
| topic_facet |
Технология водоподготовки и деминерализация вод |
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http://dspace.nbuv.gov.ua/handle/123456789/130691 |
| citation_txt |
Experimental study on chitosan composite flocculant for treating papermaking wastewater / D. Zeng, D. Hu, J. Cheng // Химия и технология воды. — 2012. — Т. 34, № 1. — С. 55-65. — Бібліогр.: 18 назв. — англ. |
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Химия и технология воды |
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2025-07-09T14:04:40Z |
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2025-07-09T14:04:40Z |
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| fulltext |
ISSN 0204–3556. Химия и технология воды, 2012, т. 34, № 1 55
D.F. ZENG, D. HU, J. CHENG, 2012
ТЕХНОЛОГИЯ ВОДОПОДГОТОВКИ И ДЕМИНЕРАЛИЗАЦИЯ ВОД
EXPERIMENTAL STUDY ON CHITOSAN COMPOSITE
FLOCCULANT FOR TREATING PAPERMAKING
WASTEWATER
D. Zeng, D. Hu, J. Cheng
School of Resource and Environmental Engineering, Wuhan University
of Technology, P.R. China
Recieved 04.03.2011
In this paper, the flocculation effect of a novel composite flocculant for treating
papermaking wastewater was studied and discussed. Results indicated that it achieved
the best flocculation effect when this composite flocculant consisting of 60 mg/L of
polymerized ferrous sulfate, 2 mg/L of polyacrylamide and 0.4 mg/L of chitosan, and
pH value of wastewater was adjusted to 7.5. It also observed that the removal rate of
chemical oxygen demand (COD) and solid substances (SS) with this novel composite
flocculant reached 72.5% and 98.5% respectively. Compared with the conventional
flocculant such as polyacrylamide/ polyaluminium chloride, the percentage of removing
COD and SS using this composite flocculant were increased by 15.2 and 6.4%
respectively, moreover, its input cost was cut down 18.4%. So this composite flocculant
has significantly environmental and economic benefits.
Keywords: composite flocculant, flocculation, papermaking wastewater.
Introduction
Papermaking industry is one of six industrial pollution sources in the world.
Papermaking wastewater has a large amount of discharge, high concentration
of pollutants, poor biodegradation and strong toxicity [1 – 3]. And it contains
the massive phenol, halogenated hydrocarbon and many other kinds of persistent
organic pollutants in papermaking wastewater. So, to solve the pollution
problem of papermaking wastewater has aroused the concern from the whole
society.
As a physical chemical method, flocculation is widely used to treat
papermaking wastewater because of its simple technology, upstanding effect in
persistent organic pollutants, some fine particles, chromaticity and turbidity, low
cost as well [4, 5]. Current flocculants are generally classified into three categories,
inorganic, organic and composite flocculants. The obvious disadvantages of
inorganic flocculants, like polyaluminium chloride, are its large applied dosage
56 ISSN 0204–3556. Химия и технология воды, 2012, т. 34, №1
and high cost for single use [6, 7]. For organic flocculants with good water
purification property, such as polyacrylamide, hard degradability and toxic
residual monomer are two main constrains of organic flocculants for
industrialized applications. For composite flocculants including
polyacrylamide / polyaluminium chloride, although it has excellent treatment
effect, there are still negative factors like residual poisonous chemicals and
high price [8 – 10]. Thus, a novel composite flocculant consisting of
polymerized ferrous sulfate, polyacrylamide and chitosan was prepared to treat
papermaking wastewater in this research. Compared with the conventional
flocculant such as polyacrylamide/polyaluminium chloride, the percentage of
removing COD and SS in the treated water using this novel composite flocculant
were enhanced by 15.2% and 6.4% respectively, and the input cost was
decreased by 18.4%, showing significant application values and market
prospects in papermaking wastewater treatment fields.
Materials and methods
Materials. Polymerized ferrous sulfate (PFS) was obtained from Nanjing
Fine Chemical Company of P.R.China. Polyacrylamide (PAM) was purchased
from Daqing Fine Chemical Company of P.R.China. Chitosan (CTS) was obtained
from Qingdao Biochemical Company of P.R.China. Polyaluminum chloride
(PAC) was obtained from Nanjing Fine Chemical Company of P.R.China. All
chemicals are analysis pure.
Raw water. The raw water from Chenming Paper Mill in Wuhan of
P.R. China, COD=1270 mg/L, turbidity value =18889 NTU, SS=1790 mg/L,
pH 7.5, water temperature about 35°C. The raw water within a lot of fiber and
suspended solids is cloudy and dark brown.
Flocculation experiment. Composite flocculants with PFS/PAM/CTS of
different dosage were designed as 1#- 6#. After treating 300 ml raw water with
flocculation test mixing apparatus (Model TA6-2, Hengling Science and
Technology Co. Ltd., Wuhan, P.R. China) under the same conditions, kept the
wastewater resting for a while, then the upper fluid was used to measure the
concentrations of COD and SS in the treated water samples so as to determine
the removal rate of COD and SS.
Experimental and analytic methods
Comparative experiment of composite flocculant with six designed
formulations was conducted to select formula with highest removal rate of COD
and SS. By investigating the influence of pH value, reaction temperature, stirring
speed and mixing time on coagulating effect, the optimal formula and process
could be determined. After comparing the composite flocculant with the best
ISSN 0204–3556. Химия и технология воды, 2012, т. 34, № 1 57
formulas to the traditional flocculant on performance-price ratio, the
characteristics and properties of the composite flocculant was achieved last.
In each experiment, raw water with 300 ml were dispensed into six beakers,
after stirring at a certain velocity for a few minutes on a coagulation test mixing
apparatus, kept the wastewater resting for a while, then the upper fluid was used
to measure the concentrations of COD and SS in the treated water samples. The
COD and SS determination were done by means of COD digestion device
(Model XJ-1, Environmental Protection Apparatus and Equipments Plant,
Guangdong, P.R.China) and scattering-type optoelectronic turbidity meter
(Model WGZ-100, Jinziguang Apparatus Corp., Beijing, P.R. China)
respectively. The concentrations of COD and SS were measured according to
the Water Quality Suspension Measuring Method(GB-11901-89) and
Hydrochemistry Oxygen Requirement Measuring Method (GB-11914-89).
Results and discussion
Confirming the optimal dosage of composite flocculant. To determine
the effect on COD and SS removal using composite flocculant, we initially
conducted tests to determine the optimal dosage of composite flocculant. We
prepared six kinds of composite flocculant (Table 1). And the optimal one was
determined. The results indicated that the optimal dosage was 4# composite
flocculant (Table 2). And the optimal dosage of composite flocculant was 60 mg/L
of polymerized ferrous sulfate, 2 mg/L of polyacrylamide and 0.4 mg/L of chitosan.
The removal rate of COD and SS were enhanced with the increased dosage of
composite flocculant. And the removal rate of COD and SS reached the highest
level when treated by 4# flocculant formula. The optimal removal efficiency of
COD and SS were 62.1% and 88.7% respectively.
Table 1. Dosage of 6 kinds of composite flocculant
Dosage of PFS
Dosage of PAM Dosage of CTS
No. of flocculant
mg/L
1# 10 0.5 0.1
2# 20 1.0 0.2
3# 40 1.5 0.3
4# 60 2.0 0.4
5# 80 2.5 0.5
6# 100 3.0 0.6
58 ISSN 0204–3556. Химия и технология воды, 2012, т. 34, №1
Table 2. Comparison of the flocculation effect of 6 kinds of composite flocculant
No.
No. of flocculant Removal rate of
COD (%)
Removal rate of
SS (%)
1 1# 56.7 73.3
2 2# 56.2 82.5
3 3# 60.5 84.9
4 4# 62.1 88.7
5 5# 60.7 88.0
6 6# 60.2 86.6
Confirming the optimal treatment conditions of composition flocculant.
Optimization experiments of the composite flocculant based on 4# flocculant
formulas was conducted with the following effect factors to determine the
appropriate treatment conditions that led to the best removal rate of COD and
SS.
Confirming the optimal pH value. pH value plays a critical role in
flocculation effect. A series of tests were conducted to study the flocculation
effectiveness of composite flocculant under various pH value conditions. Fig. 1
showed that the optimal flocculation effect of composite flocculant at pH value
7.5. And the removal rate of COD and SS varied with pH value that followed
a curve. The removal rate of COD and SS reached the highest level in the
range of pH 6.5 to 8.5. We attribute it to that chitosan would be dissolved
when pH value was less than 6.5 and it affected the flocculation effect. Besides,
alkaline substance would polymerize and subside with PFS in raw water and
led to the removal rate of COD and SS was reduced when pH value exceeded
6.5 [11].
50
70
90
4 5 6 7 8 9 10
pH
R
em
o
v
al
r
at
e(
%
)
Removal rate of COD Removal rate of SS
Fig. 1. Influence of pH value on removing COD and SS.
ISSN 0204–3556. Химия и технология воды, 2012, т. 34, № 1 59
Confirming the optimal reaction temperature. Temperature has a direct
influence on flocculation effect. It is a disadvantage to flocculation effectiveness
when the temperature is too high or too low. The water temperature is too high
would accelerate the chemical reaction, product fine flocs and increase the
hydration of flocs. But it will consume a lot of energy and rise cost when the
water heats up. Nevertheless, the water temperature is too low would increase
the hydrolysis time of some flocculant. It affects the flocculation effectiveness
without prolonging the time. We conducted the tests to determine the optimal
reaction temperature of composite flocculant (Fig. 2). The results of the
experiment showed that the removal rate of COD was enhanced when the
reaction temperature in the range from 20°C to 35°C, however, the removal
rate of SS had not a obvious change when the temperature was between 20°C
and 45°C. And the removal rate of COD and SS reached the highest level
when the temperature was 35°C. So, we selected 35°C as the optimal reaction
temperature. As the temperature of the papermaking wastewater was 35°C,
there was no need to adjust the temperature.
50
70
90
15 20 25 30 35 40 45 50
T,
o
C
R
em
o
v
al
r
at
e(
%
)
Removal rate of COD Removal rate of SS
Fig. 2. Influence of reaction temperature on removing COD and SS.
Confirming the optimal stirring speed. The hydraulic condition has a great
influence on forming flocs. The stirring speed can change the hydraulic condition
so that it will affect the flocculation effect. The flocculation process can be
divided into two stages: mixing and reaction. The stirring speed was critical to
the formation of flocs in the two stages. A series of tests were conducted to study
the flocculation effectiveness of composite flocculant under various stirring speed.
Fig. 3 showed that the optimal flocculation effect of composite flocculant at the
rapid stirring speed of 100 r/min. And the removal rate of COD and SS were
70.5% and 96.8% respectively that reached the highest level. Fig. 4 showed that
the optimal coagulation effect of composite flocculant at the slow stirring speed
of 50 r/min. And the removal rate of COD and SS were 71.3% and 97.2%
respectively. The reasons could be explained by the mechanism of flocculation,
60 ISSN 0204–3556. Химия и технология воды, 2012, т. 34, №1
on one hand, composite flocculant reacted with substance which consumed
oxygen directly and formed flocs. On the other hand, composite flocculant
adsorbed the substance in the raw water by the function of bridging and net-
capture [12]. Therefore, macromolecule flocs would be broken up when the
mixing speed was too fast, and led to reducing the removal rate of COD and SS.
60
80
100
55 75 95 115 135 155
Rapid stirring speed (r/min)
R
em
o
v
al
r
at
e(
%
)
Removal rate of COD Removal rate of SS
Fig. 3. Influence of rapid stirring speed on removing COD and SS.
60
80
100
15 25 35 45 55 65 75
Slow stirring speed (r/min)
R
em
o
va
l
ra
te
(%
)
Removal rate of COD Removal rate of SS
Fig. 4. Influence of slow stirring speed on removing COD and SS.
Confirming the optimal mixing time. To determine the influence of mixing
time to flocculation effect, we conducted tests under various mixing time. Fig.
5 showed that the optimal flocculation effect of composite flocculant at the
rapid mixing time for 2 min. And the removal rate of COD and SS reached the
highest level which was 72.0% and 97.9% respectively. Fig. 6 showed that the
optimal flocculation effect of composite flocculant at the slow mixing time for
8 min. And the removal rate of COD and SS reached the highest level which
was 72.5% and 98.5% respectively. It was because that the mixing stage should
at the rapid stirring speed in the flocculation process so that flocculant would
ISSN 0204–3556. Химия и технология воды, 2012, т. 34, № 1 61
spread into the water rapidly and evenly and made colloid particles to
coagulation. As the formation of fine aggregate was completed in a few minutes,
it would break up the formed fine aggregate and affected interpretive
flocculation if the mixing time was too long [13]. In addition, it needed slow
stirring the water for a while when reaction stage made the particles to forming
large flocs. The mixing time could not last too long as it could be bad for the
formation of the flocs.
Fig. 5. Influence of rapid mixing time on removing COD and SS.
50
60
70
80
90
100
3 6 9 12 15
Slow mixing time (min)
R
em
o
va
l
ra
te
(%
)
Removal rate of COD Removal rate of SS
Fig. 6. Influence of slow mixing time on removing COD and SS.
Confirming the optimal dosage of traditional flocculant PAM/PAC. To
determine the effect on COD and SS removal using traditional flocculant PAM/
PAC, we initially conducted tests to determine the optimal dosage of traditional
flocculant. We prepared six kinds of traditional flocculant (Table 3). And the
optimal one was determined. The results indicated that the optimal dosage
was 4# traditional flocculant (Table 4). The optimal dosage of traditional
flocculant was 8 mg/L polyacrylamide and 200 mg/L polyaluminum chloride.
60
80
100
0,25 0,85 1,45 2,05 2,65 3,25
Rapid mixing time (min)
R
em
ov
al
r
at
e(
%
)
Removal rate of COD Removal rate of SS
62 ISSN 0204–3556. Химия и технология воды, 2012, т. 34, №1
And the removal rate of COD and SS reached the highest level when treated
by 4# traditional flocculant formula. The optimal removal efficiencies for COD
and SS were 57.3% and 92.1% respectively.
Table 3. Dosage of 6 kinds of traditional flocculant
Dosage of PAM Dosage of PAC
No.of flocculant
mg/L
1# 2.0 50
2# 4.0 100
3# 6.0 150
4# 8.0 200
5# 10.0 250
6# 12.0 300
Table 4. Comparison of the coagulating effect of 6 kinds of traditional flocculant
Removal rate of COD Removal rate of SS
No. No.of flocculant
%
1 1# 50.7 86.3
2 2# 52.2 88.5
3 3# 55.4 90.9
4 4# 57.3 92.1
5 5# 54.7 89.8
6 6# 51.9 87.6
Comparison of flocculation effect and cost between composite flocculant
and traditional flocculant. To achieve the advantages of composite flocculant,
we treated the raw water with composite flocculant and traditional flocculant
respectively and calculated the cost of treating 1 ton of papermaking wastewater.
Table 5 showed that compared with the traditional flocculant PAM/PAC, the
removal rate of COD and SS with composite flocculant was increased by 15.2%
and 6.4% respectively, and the cost was decreased by 18.4%. The advantage of
cost-performance ratio was so obvious. So this composite flocculant has a
significant application values and market prospects in papermaking wastewater
treatment fields.
ISSN 0204–3556. Химия и технология воды, 2012, т. 34, № 1 63
Table 5. Comparison of flocculation effect and cost
Removal rate of COD Removal rate of SS Flocculant’s
category
%
Cost of treating 1 ton
of wastewater ($)
PFS/PAM/CTS 72.5 98.5 0.047
PAM/PAC 57.3 92.1 0.057
The mechanism of flocculation analyses. According to the adsorption
theory of flocculant [14, 15], flocculation effect of composite flocculants is
generally better than that of single used flocculants, and "inorganic/organic"
composite flocculants is superior to "inorganic/inorganic" and "organic/
organic", since inorganic flocculants’ function to adsorb colloid is better than
that of organic, but its chelating and bridging function is inferior to that of
organic macromolecule flocculants. Organic macromolecule flocculants make
it easier to turn off stability and initiate flocculation with the existence of several
inorganic flocculants such as electrolyte salts. Moreover, organic
macromolecule flocculants plays a positive role in neutralizing and reducing
the surface charge of colloid, compressing double electrode layer of colloid
and making them easier to destabilize, flocculation and sediment via middle
bridges activity [16]. Therefore, the combined use of inorganic and organic
flocculants has complementary advantages and synergism to improve the
flocculation and settling performance. With the application of PFS with
adsorption effect and PAM /CTS with bridge activity, the composite flocculant
can flocculate small colloid into bigger flocs and increase the degree of
polymerization and cohesive force of the flocs, which can significantly promote
depositing velocity and adsorption rate [17]. Above all make it is characterized
by super quality and competitive price.
In addition, there are many hydroxyl groups (– OH) on the molecular chain
in chitosan’s molecular structure, it can form hydrogen bond with the substances
contained – NH
2
and – COOH groups such as amino acid in water, which is
able to adsorb and precipitate the substances so as to remove the organics and
improve the removal rate of COD [18].
Above two factors and mechanisms jointly contributes to the higher removal
rate of COD and SS with the novel composite flocculant than that of traditional
flocculant.
64 ISSN 0204–3556. Химия и технология воды, 2012, т. 34, №1
Conclusions
A new composite flocculant made by ourselves for treating papermaking
wastewater has higher cost-performance ratio than traditional flocculant. In
the process of preparation, 60 mg/L of PFS, 2 mg/L of PAM and 0.4 mg/L of
CTS are the optimal dosage, and the optimal pH value is adjusted to 7.5, the
optimal rapid stirring speed and slow stirring speed are 100 r/min and 50 r/min
respectively, rapid mixing time and slow mixing time are 2 min and 8 min
respectively. Under the conditions, compared with the conventional flocculant
PAC/PAM, the removal rate of COD and SS with this novel composite
flocculant were increased by 15.2% and 6.4% respectively, its input cost was
decreased by 18.4%. So this composite flocculant has obviously environmental
and economic benefits and has a significant application values and market
prospects in papermaking wastewater treatment areas.
Acknowledgements
This project was supported through ministry of science and technology in
P.R. China of SME technology innovation foundation and department of science
and technology in Hubei province, P.R.China of science and technology research
foundation, which we thank together in this.
Резюме. Изучен коагулирующий эффект новой смеси флокулянтов
при очистке сточных вод бумажного производства. Результаты исследо-
ваний показали, что наибольший коагулирующий эффект достигался при
следующем составе смеси коагулянтов: 60 мг/дм3 полимеризованного
сульфата железа, 2 мг/дм3 полиакриламида, 0,4 мг/дм3 хитозана и значе-
нии pH сточных вод 7,5. Также установлено, что ХПК и степень извлече-
ния взвешенных веществ новой смесью флокулянтов составляли соот-
ветственно 72,5 и 98,5%. По сравнению с традиционными флокулянтами,
такими, как полиакриламид/полиалюминий хлорид ХПК и степень из-
влечения взвешенных веществ с помощью этой смеси флокулянтов по-
высились соответственно на 15,2 и 6,4%. Кроме того, ее стоимость по
сравнению с традиционными флокулянтами была ниже на 18,4%. Таким
образом новая смесь флокулянтов имеет значительные экологические пре-
имущества и экономически эффективна.
Резюме. Вивчено коагулюючий ефект нової суміші флокулянтів при
очищенні стічних вод паперового виробництва. Результати досліджень
показали, що найбільший коагулюючий ефект досягався при такому складі
ISSN 0204–3556. Химия и технология воды, 2012, т. 34, № 1 65
суміші коагулянтів: 60 мг/дм3 полімеризованого сульфату заліза, 2 мг/дм3
полі-акріламіда, 0, 4 мг/дм3 хитозана і значенні pH стічних вод 7,5. Та-
кож встановлено, що ХПК і ступінь вилучення зважених речовин нової
сумішшю флокулянтів становили відповідно 72,5 і 98,5%. У порівнянні з
традиційними флокулянтами, такими, як поліакриламід/поліалюміній
хлорид, ХПК і ступінь вилучення зважених речовин за допомогою цієї
суміші флокулянтів підвищилася відповідно на 15,2 і 6,4%. Крім того, її
вартість в порівнянні з традиційними флокулянтами була нижчою на
18,4%. Таким чином, нова суміш флокулянтів має значні екологічні пере-
ваги та економічно ефективна.
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