Evaluation of some environmental impact indicators of tannery wastewaterin Tuul river, Ulaanbaatar, Mongolia
ODGEREL Dalkhjav1
Graduate School of Life and Environmental Sciences, University of TSUKUBA

1. BackgroundDue to Ulaanbaatar city’s nowadays population growth and some other reason,
Ulaanbaatar citizen’s basic drinking water source Tuul river’s water quality is decreasing year
by year. Namely, Tuul river’s water quality sharply polluting just after passed throughUlaanbaatar city [1].
In recent 10 years Tuul river’s pollution is increasing due to industrialization,
urbanization and lack of the old aged technology of waste water treatment plants. The self
purification coefficient of the Tuul river was 6.57 until first pollution point, but thatcoefficient is decreased till 0.98 at the waste water joining point from the Central waste water
treatment plant (CWWTP) [2].
Nowadays research result shows that efficiency of the CWWTP is around 60-70%,
because of the lack of technology; it means that 10-20% untreated waste water pouring to the
Tuul river and it shows negative effect to river water quality [3].
Except waste water treatment technology innovation and instrument capacity, one of
the reasons which couldn’t fully treat waste water from the central sewage water treatment
plant is about 30 tanning industries which are located in Ulaanbaatar city area. Also,
municipal treatment plant has a responsibility to treat tanneries waste water which contains
highly amount of toxic elements and transfer to CWWTP, due to out of date technology can
not treat tanneries waste water.
Mongolia has a large number (in Ulaanbaatar city 34 tanning industries) of smallleather tanneries which process some 30 000 skins per day, for a total output of about 8
million units per year. The tanneries produce wastewater, solid waste and sludge that containsignificant amounts of chromium (Cr) and other chemical pollutants.
Particularities of tanneries are their activity is not regular, maximum number ofleathers manufactured in autumn season, not much considers about waste management, safety
and technology innovation. Due to these factors the chemical properties of the rivers and thedrinking water source have been changed, and may impact further on human health andecosystems in the future. That is why we need to improve monitoring of the waste water
discharge to river and do assessment on the chemicals usage and impact on the environment.
2. Material and methods
For the purpose to evaluate Tuul river’s pollution, 11 sampling points chosen along
the main branch Tuul river from Uu bulan of Terelj till Altanbulag of Tuv aimag, 2 times inyear from May 2012 to October 2013. The tanneries and waste water treatment plants arelocated in Khan-Uul, Songinokhairkhan district of Ulaanbaatar city.
In water samples, pH, dissolved oxygen (DO), biochemical oxygen demand (BOD),
oxidity, color, nitrogen, some cations and anions, and heavy metals (lead, cadmium, copper,
iron, cobalt, chromium) determined in laboratory of Metropolitan Inspection Agency by using
Mongolian National and International standard method .
River water quality assessment was done by 142-352th arrangement “Surface water
quality grade” of Ministry of Nature and Environment and Ministry of Health (MOH) in
1997.

1

3. Result and Discussion
Tuul river water quality assessment by chemical and microbiological parameters
For the purpose to evaluate Tuul river’s water quality, 11 sampling points chosen
along the Tuul river from Uu bulan of Terelj till Altanbulag of Tuv aimag and was done
chemical, microbiological and heavy metal analysis, respectively two times between 20122013.
There are 2 basic
indicators of surface
water quality, DO andBOD analysis shows that
Tuul river water quality isfrom Uu bulan until
Yarmag bridge belongs to
class
2,
from
the
Sonsgolon bridge waterpollution is increasing andthat pollution is getting
maximum level at theSongino point, belongs toclass 5.

BOD, ppm

60
40
20
0

Figure1. BOD concentration in Tuul river water

Pollution level

In 2012, by microbiological parameters Tuul river water quality belongs 2 class fromUu bulan to Bayanzurkh bridge, but in 2013 at the second point (Nalaikh waste water joining
point) sharply increased and transferred to class 4 (contaminated water).
Thatcontinues
constantly till Yarmag
5
bridge. At the Songino
4
bridge point observed
3
maximum contamination2
level 5 (heavily polluted)
and further points Tuul1
tosgon belongs to class 40(moderately
polluted),around Altanbulag point
belongs to 3 class(slightly polluted).
Figure 2. Tuul river pollution level by microbiological parameters

Generally, Tuul river’s water quality belongs to class 2 (pure) at the points from Uubulan till Marshal bridge, belongs to class 3 (slightly polluted) from Zaisan bridge till
Sonsgolon bridge, at the Songino point belongs to maximum pollution level, class 5 (heavily
polluted), Tuul tosgon and Altanbulag points belongs to 4 (moderately polluted), 3 (slightly
polluted) class respectively.

2

Pollutionlevel

Altanbulag

TuultosgonSonginoSonsgolon

Yarmag

ZaisanMarshalBayanzurkhNalaikhTereljUu bulanYear

SeasonTable 1 . Tuul river pollution level

2012

SpringAutumn2013 Spring
AutumnAverage

2
2
2
2
2

2
2
2
2
2

2
2
2
2
2

2
2
2
2
2

2
2
2
3
2.2

3
2
3
3
2.8

3
3
3
3
3

3
3
3
4
3.3

4
4
4
5
5.3

3
3
4
4
3.5

2
3
4
4
3.3

2.5
2.7
2.8
3.1

Tuul river’s pollution level is measured at the first point after discharge from CWWTP
enters to the river. At the further points the pollution level little bit decreases, but river selfpurification process still insufficient.
Heavy metal analysis in river water and sediment
The heavy metal analysis in river water and sediments shows that compare to
Mongolian National Standard MNS 4586:1998, not exceeded from the permissible level ofchemical variables.
Table 2. Heavy metal concentration in Tuul river, ppm
PointsUu bulanNalaikh
Bayanzurkh
ZaisanSonsgolon
Bio
Tuul tosgon
Altanbulag

Pb
<2
<2
<2
<2
<2
<2
<2
<2

Cd
<0.3
<0.3
<0.3
<0.3
<0.3
<0.3
<0.3
<0.3

Cr
<2.5
<2.5
<2.5
<2.5
<2.5
<2.5
<2.5
<2.5

Fe
30±0.3536±0.3230±0.34
50±0.1282±0.22190±0.43
90±0.1780±0.09Zn
150±0.18148±0.12152±0.11
208±0.08
250±0.34
1054±0.76
470±0.33
390±0.43

Note: Detection limit of determination of heavy metals by AAS, ppm Pb <2; Cd <0,3; Cr <2,5; Fe <6; Zn <1

However, heavy metal analysis in river sediment shows that in the sampling point indownstream, after the discharge from the CWWTP enters the river contaminated by Cr (39.4
ppm) and Cd (0.43 ppm) (Table 2).
Table 3 . Heavy metal concentration in the Tuul river and sediment
Elements
Zn
Pb
Fe
Cd
Cr

Tuul river water,
ppm
0.352±0.030<0.0020.074±0.008<0.0003<0.0025

Tuul
river
sediment, ppm
40.70±0.06
36.50±0.26
6.40±0.10
0.43±0.02
39.40±0.32

Heavy metal analysis shows that in
Tuul river water not contaminated by toxic
heavy metals but river sediment contains

heavy metals such as Cr and Cd whichindicates originating from the tanneries
waste water. It can be expected thatchanges from reducing to oxidizing
conditions which involve transformationsof sulfides that from tannery waste waterand shift to more acid conditions wereincreased the mobility of Cd and Cr [11].

Analysis of tanneries waste water
The main quantity of pH, SS, COD, BOD and Cr of 52 samples of 13 delegations of
13 tanneries were selected on 2012-2013 and were investigated two times. The 15 factories
were operated on March 2012 but total 23 factories were operated on 2013.

Parameters, ppm

9000
6000
3000
0
рН

SS

BOD

COD

Cr

SulfideMPL-max permissible level

Figure 3. Comparison of tanneries waste water
quality to MPL

The requirements ofwaste water of leather factories in
Mongolia have been released
standard about following as“Waterquality.
Technical
requirement for tannery effluent
to municipal treatment plant.
MNS 5582:2006”. It was shown
our results studied 52 samples ofwaste water of tanneries that the
35 samples (67 %) are the highest
values above the permitted level.

For the evaluate tannery waste water quality particularly, we were investigated 3
samples from tanneries, 1 sample from municipal treatment plant and have done heavy metals
analysis using ICP-MS (Inductively coupled plasma mass spectrometry) in Hokkaido
University, Japan. The analysis result shown in Table 4.
Table 4. Quality of heavy metals in waste water oftreatment plant and tanneries
SamplesCr
2632
Treatment plant
28816
Mon ireedui Co., Ltd
231
Belon Co., Ltd
75.9
Arildii Co., Ltd
ND: not detected

Heavy metal concentrations, ppb
Cu
As
Cd
ND
ND
2.63
ND
ND
5.55
ND
ND
ND
ND
ND
0.09

Fe
619
361
68.2
78.4

Pb
25.2
130
4.66
5.04

Hg
1.99
8.19
7.74
1.72

The permitted level of these heavy metals in waste water of tanneries in standard ofMongolia is not included, therefore we could not discuss about. However, detection of toxic
heavy metals such as Cr, As and Hg in tannery waste water is very interesting in the future
research and discussion.
Analysis of waste water after purified in treatment plant
The main quantity of pH, SS, BOD, COD, sulfide and Cr of each 8 samples from
sulfide and chromium lines of “Municipal treatment plant” of operating tanneries in Khan-Uul
district of Ulaanbaatar city which interflows into CWWTP of water purification and 4
samples of entrance, 8 samples of exit at CWWTP for qualification of waste water were
investigated.

Parameters, ppm

Municipal treatment plant

Permissible level

6000
4000

3968.42261.4

2000
0

407

11.4
8.5
рН

SS

974.5
400
BOD

800

COD

12.9
5
Cr

Figure 4. Comparison of Municipal treatment plant’s waste waterwith maximum permissible level

The results ofwaste water of treatment
plant shows that theamount of COD is 4
times, BOD is 2 times,
weighing component is 10
times, pH is two times

Efficiency, %higher than maximum permissible level. In Mongolia, municipal treatment plant’s waste
water contamination managed by regulation named by “Requirement of the highest level of
waste
water
of
factories
toCentraltreatment
plant”.
The waste water at exit from CWWTP must be lower than the requirement for level of
toxic components of Mongolian National Standard “Purified waste water interflows to nature.
Technical requirement MNS 4943:201” but in waste water at exit from treatment plant, theamount of BOD is 9, COD is 6 times, SS is 11 times, nitrogen of ammonium is 3 times higher
than standard level and the amount of Cr (VI) is 3.9 ppm which is not approved in purified
waste water.
After
the
80
71 69
67
64
evaluated
the
force
of
62
58
purification of CWWTP
60
for BOD, COD, SS and
36
40
Cr, the average efficiency
23
were calculated as 66.8 %20
on 2012 but 49.8% on
2013
which
was
0
decreased by 17 %.
BOD
COD
SS
Cr
Figure 5. Efficiency of CWWTP

Results of correlation analysis
Based on correlation analysis it was clearly showed that, on autumn and spring data ofTuul river water, the following parameters such as [BODspring = f (BODautumn)], [DOspring = f(DOautumn)], [рНspring= f (рНautumn)], [Colorspring= f (Colorautumn)] are correlated strongly.
Calculation of them is shown on the table 5.
Table 5.Seasonal correlation of parameters characterizing river water
quality of Tuul river
Parameters

SeasonAnalyze

BOD

spring-autumn

rxy =0.811

tab=0.423

PositiveDO

spring-autumn

rxy =0.518

tab=0.423

PositiveрН

spring-autumn

rxy =0.823

tab=0.423

PositiveColor

spring-autumn

rxy =0.705

tab=0.423

Positive

Correlation

For tanneries waste water the correlation is formulated as between [COD= f (pH)],[COD = f (SS)] which means DO strongly correlated to SS.
However, elements and parameters of waste water from treatment plants are correlated
strongly, [Cr = f (SS)] for water from the “Municipal treatment plant” and [BOD = f (SS)],[Cr = f (SS)], for the water waste pouring directly to Tuul river from CWWTP.
Table 6. Correlation between CWTTP’s waste water parameter
BOD

COD

рН

SS

Аmmonia

BOD

1

COD
SS

0.597
0.709

0.580

1

рН

-0.3870.298-0.4951

Аmmonia

0.045

0.027

0.290

1

Cr

0.574

0.383

-0.1160.720-0.229

0.483

Cr

1

rxy (α, f)→0.707
Strong correlated

14. Conclusion
The following conclusions are made based on the survey of Tuul river pollution fromthe tanneries which are located in Khan-Uul district of Ulaanbaatar city: The assessment on Tuul river quality by chemical and microbiological characteristics
indicates that, the section from Uu-bulan to Marshal’s bridge has the second level of pollution(pure), the section from Zaisan bridge to Sonsgolon has third level of pollution (small
contamination), the section near the Songino has fifth level of pollution (high contaminated)and pollution is decreasing according to the location how far from Ulaanbaatar, as an
example, water pollution in Tuul village is fourth (contaminated) and Altanbulag of Tuv
aimag is third level.
 In 2012, when 15 factories were operating near Tuul river, data result shows Tuulriver had 2 level of pollution in average. However, in 2013, when number of tanneries had
been increased up to 23, average pollution is also increased to the 3 level. Water quality ofTuul river becomes poor in autumns, which overlaps with intensive operating period ofleather factories. From the other hand, efficiency of the CWWTP had been decreased 66.8%
in 2012 to 49.8% in 2013 by 17 percents.
 Analysis of Cr in river water not detected, however our study shows that Crconcentrated and mobilized in river sediment. That indicates tannery waste water withchromium contamination is polluting the environment.
 Based on the correlation analysis on autumn and spring data of Tuul river water, thefollowing parameters such as [BODspring= f (BODautumn)], [DOspring= f (DOautumn)],[рНspring=f(рНautumn)], [Colourspring= f (Colourautumn)] are correlated directly and moderately
and for water waste of leather factories [COD= f (pH)], [COD= f (SS)], which means they arecorrelated directly. However, elements and parameters of treatment plant’s waste water are
correlated strongly [Cr= f (SS)], [BOD= f (SS)], [Cr= f (SS)], respectively.

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