investigation0nphysico-chemical parameters of tannery effluent in bangladesh

Investigation of physico-chemical parameters of tannery effluent in Bangladesh

Md. Farhad Ali1 , Umme Habiba Bodrun Naher2 , Md. Mahamudul Hasan3

Institute of Leather Engineering and Technology, University of Dhaka, Bangladesh

1. [email protected] 2. [email protected] 3. [email protected]

Abstract

This study was conducted to determine the quality of tannery effluent with the analysis of physico-

chemical parameters of effluents discharged by different tanneries in Dhaka, Bangladesh .The samples

of effluent were taken from Nine tanneries and three points of Hazaribagh , Dhaka. Different physical

and chemical properties like Temperature, Color , Odor, The PH, Electrical Conductivity( EC), total

Dissolved Solids( TDS), Dissolved Oxygen(DO), Chemical Oxygen Demand(COD),Biological Oxygen

Demand(BOD5), Suspended Solid(SS), Chloride, Nitrate, Sulphate, Phosphorous, etc. were measured and

compared. The value range of the observed parameters are 1072-3833 mg/L for TSS, 1251-6240 mg/L

for COD, 3.2-10.43 for pH, 2375-4385 mg/L for TDS, 200-1257 mg/L for BOD5, 7.81-13.85 mg/L for

phosphorous, 2100-9745.8 μs/cm for EC, 684-1020.2 mg/L for alkalinity, 2.85-22.34 mg/L Cr3+ ,8-26

mg/L for NO3 - ,484-1928 mg/L for Cl-, 0.68-2.8 mg/L for NO2- and 124-512 mg/L for SO4

2-.

Index Terms : Tannery Effluent, Chemical Oxygen Demand, Biological Oxygen Demand. Electrical

Conductivity, Alkalinity, Total Dissolved Solid , Suspended Solid, Dissolved Oxygen.

Introduction

Tannery industries are one of the oldest industries in Bangladesh. About 95% of the tanneries of the

country are situated in the area of Hazaribagh, Dhaka.The total area of Hazaribagh and also the whole

capital are being largely polluted with the untreated effluent discharged by different tanneries. Specially

the water of the river Buriganga situated by the area of Hazaribagh is being polluted significantly.

Recently Hazaribagh area has been included at the list of top 10 most polluted places of the world [11].

The river of Buriganga in Bangladesh is considered as one of the most polluted rivers in the world. The

tanneries of Hazaribagh are discharging the solid waste and effluent containing putrid rotten flesh, fat,

blood and skin. Toxic chemicals, dissolved lime, chromium sulfate, alkali, hydrogen sulfide , sulfuric acid,

bleach, dyes , oils formic acid, heavy metal, suspended solids , organic matt etc. Which are generally

flown to the river of Buriganga without any treatment[2]

15800m3/day of waste water with a BOD load of 17600 kg/day and high chromium concentration is

discharged from the tanneries at Hazaribagh [3].The heavy metals can cause cancer brain or kidney

damage. Here one of the greatest environmental problems in the tannery industries is the disposal of

chromium contents sludge created as a by product. Tannery effluent largely affects the ecosystem of

river and decreases seeds germination in extensively cultivable crops[4].

mailto:[email protected]



Materials and Methods

In the present study, Effluents were collected from nine tanneries and three final discharged points

from Hazaribagh and other areas near it.

Table I. Identification of Samples

Collected Samples ID Name of the Tannery/points

A Apex Tannery Ltd

B F.K Leather Complex Ltd

C Bangla Tannery

D R M M Leather Industry Ltd.

E H B Tannery Ltd.

F Fancy Leather Ltd.

G Beri Badh point -1

H Rayerbazar point -2

I Hazaribagh Bazar Point-3

J Ruma tannery

K Chowdhury tannery

L Madina tannery

Effluent Collection

The samples were collected in plastic bottles and some parameters were analyzed within four hours.

Most of the samples were analyzed at the analytical chemistry Lab ( ISO 17025 accredited ) at the

Institute of Leather Engineering and Technology, University Of Dhaka . Some tests were done at Center

for Advanced Research and Sciences, University Of Dhaka and Bangladesh Council of Scientific and

Industrial Research, Dhaka.

Table II. Analysis Of Physico-chemical Parameters

Parameters Method of Analysis / Instruments

pH pH meter

Electrical Conductivity ( EC) Digital conductivity meter

Total Dissolved Solid( TDS) Gravimetric Method

Dissolved Oxygen(DO) Titrimetric Method

Chemical Oxygen Demand( COD) Titrimetric Method

Biological Oxygen Demand(BOD5) Microbiological titration method

Suspended Solid(SS) Gravimetric Method

Chloride (Cl-) Colorimetric method

Nitrite ( No2-) Colorimetric Method

Sulphate (So4--) UV- visible Spectrophotometer

Phoisphorous (Po4--- ) Molybdo-vanado phoshphoric acid method

Alkalinity Titrimetric Method

Color and Odor Visual Observation

Temperature Thermometer

Chromium Colorimetric method

Nitrate( No3- ) Colorimetric Method

Results and Discussion

After collecting the samples the physical condition like as color and odor were assessed by visual

observations and the temperature of the samples were determined by thermometer.

Table III. The physical parameters of the samples are shown below

ID of Samples Temperature(0C) Color Odor

A 31.80 Blackish blue High pungent

B 30.20 Blackish blue High pungent

C 28.25 Brown High pungent

D 29.75 Dark violet Pungent

E 33.10 Reddish violet Pungent

F 27.65 Blackish blue High pungent

G 26.15 Black Pungent

H 29.40 Almost brown Less pungent

I 31.00 Dark violet Pungent

J 28.30 Black Pungent

K 28.00 Dark violet Less pungent

L 32.85 Blue Pungent

The above table shows different physical characteristics like the temperature, color and odor of

samples . The observed temperature of the samples are less than the standard temperature. For tannery

effluent in Bangladesh. 400 C is considered the standard temperature for tannery effluent in

Bangladesh.

pH and TDS

The study determines the average value of pH of the effluent sample as 6.56. Here the highest value

of pH 10.43 is found for sample- L and lowest 3.2 for sample- G. Most of the samples were either high

acidic or high basic. Almost all the observed values are deviated from the standard pH value 6-9,

according to the department of environment. This ensures that the pH measurements remain in worse

condition which can bring about a very unstable condition of water for the survival of aquatic lives.

TDS fulfilled in water is a quantity for salinity. In this research, the TDS values of the tannery effluent

are higher than the standard one (2100 mg/L). The highest value of TDS was found as 4385 mg/L for

sample D and lowest 2375 mg/L for sample H. High amount of dissolved solid elements hampers the

density of water. Thus, it creates impact on osmoregulation of water and also lessens solubility of gasses

[9].

COD and TSS

Chemical oxygen demand (COD) is the amount of oxygen in milligrams consumed by the oxidisable

substance having in one litre of sample. The result of the present study expressed that COD levels of

tannery effluent are significantly higher than the standard level 200 mg/L(for inland surface) -

400mg/L(irrigation land). The average COD value of observation is 2776.83mg/L. Here, the highest value

is found for sample- E and lowest for sample- L. This ensures the incompatibility for the existence of the

aquatic organism.

0

2

4

6

8

10

12

A B C D E F G H I J K L

PH

Val

ue

Collected Sample ID

0

500

1000

1500

2000

2500

3000

3500

4000

4500


Tota

l Su

spe

nd

ed

So

lid(m

g/L)

Collected Sample ID

The result of the study expresses the higher level of TSS of the effluent. It exceeds the permissible

TSS level of 150-500 mg/L. High level of TSS present in the effluent could be attributed to the increase at

the time of processing of finished leather. Presence of total suspended solid in water results poor

photosynthetic process in the aquatic process and hampers respiratory system of fishes a lot.

BOD5 and EC

BOD5 is one of the most common processes of determining for pollutant organic material in water. It

is the rate of discharge of oxygen by microorganism in aerobic decline of the dissolved organic

substance in water. The experimental average BOD5 value is 754.15 mg/L for effluent which is extremely

higher than the permissible limit of 50(inland surface)-250(irrigation land) mg/L. The sample sample- E,

shows the highest BOD5 value of 1257 mg/L and sample- A of 200 mg/L as lowest.

0

1000

2000

3000

4000

5000

6000

7000


Ch

em

ical

Oxy

gen

De

man

d(m

g\L)

Collected Sample ID

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000


Tota

l Dis

solv

ed

So

lids(

mg\

L)

Collected Sample ID

The experimented average EC value is 5610.46 μs/cm for the observed tannery effluent is significantly

higher than the standard value 1200 μs/cm. The highest EC value of the samples 9745.8 μs/cm was

found for the sample- K and lowest 2100 μs/cm for sample- A which is very large in amount. Augment in

EC values shows higher concentration of ions [1].

Alkalinity and Phosphorus

Alkalinity of water is the capability of neutralization of acid. The study reveals the alkalinity among

the observed effluent samples 1420.2 mg/L as highest and 684 mg/L as lowest. The average value of

alkalinity of the experiment is 1018.08 mg/L. This study found large amount of it. Reasons of large

portion of it is having hydroxides, carbonates and bicarbonates [8].

0

200

400

600

800

1000

1200

1400


Bio

logi

cal O

xyge

n D

em

and

(mg\

L)

Collected Sample ID

0

2000

4000

6000

8000

10000

12000


Ele

ctri

cal C

on

du

ctiv

ity(μ

s\cm

)

Collected Sample ID

The experimental average phosphorus value is 10.35 mg/L. The highest observed value of it is 13.78

mg/L for sample L and 7.81 mg/L for sample- E as lowest. The observed results are larger than the

standard value of 8 mg/L for municipal process. Increased concentration of phosphorus accelerates the

growth of water plants and modifies the water feature.

Sulfate and DO

The average sulfate substance of the tannery effluent is found as 300.75 mg/L The highest value of

sulfate was found 412 mg/L for sample- E and 158 mg/L for sample- A as lowest. Sulfates in tannery

effluent are originated from the use of sulfuric acid or creation with a high sodium sulfate content [7].

0

200

400

600

800

1000

1200

1400

1600


Alk

alin

ity(

mg/

L)

Collected Sample ID

0

2

4

6

8

10

12

14

16


Ph

osp

ho

rou

s(m

g/L)

Collected Sample ID

DO, the most important factor of water quality [1] was found in a very low amount for the collected

effluent. For the samples of D, G and H DO was found nil. The highest amount was found as 3.8 mg/L

for sample -A. This absence of Oxygen is a great threat for the aquatic creatures.

Cr3+ and NO2-

Chromium, an essential element of chrome tanning process, is toxic carcinogenic at high

concentration. It exists in oxidation states of +2,+3 and +6. The chromium(+3) is a compulsory element

for mammals needed in extent amount. But Cr(VI) is a widespread contaminant can be created by the

tannery effluent easily soluble with water with great danger. This is created by untreated process of

effluent with great amount. This observation expresses the average chromium value of 1.95 mg/L which

is significantly higher than the standard (0.5-10) mg/L range.

Again, the sample sample- G expresses the highest amount of 2.79 mg/L and sample -A for 0.68 mg/L

as lowest. The average observed amount is 1.47 mg/L.

0

100

200

300

400

500

600


Sulp

hat

e(m

g/L)

Collected Sample ID

Cl- and NO3-

The observed average value of chloride is 1333.67 mg/L and the highest Chloride value 1928 mg/L for

sample- E and the lowest 484 mg/L for sample- L. The increased amount of chloride enhances the

acridity of water [6].

Nitrate was recorded 26 mg/L for sample- E and 8 mg/L for sample- F. The average nitrate value of

the observation is 15.83 mg/L. The amount of the nitrate is higher than the standard 10 mg/L almost all

observations. High concentration of nitrate can create health problem if it is used for the purpose of

cultivation and thirst quenching.

0

5

10

15

20

25


Ch

rom

ium

(mg/

L)

COllected Sample ID

0

0.5

1

1.5

2

2.5

3


NIt

rite

(mg/

L)

Collected Sample ID

0

500

1000

1500

2000

2500


Ch

lori

de

(mg/

L)

Collected Sample ID

0

5

10

15

20

25

30


Nit

rate

(m

g/L)

Collected Sample ID

Table IV. Experimental average values with standard values

Sl. No.

Parameters Values of experiments Standard value

1 pH value 6.56 6-9

2 TSS (mg/L) 2048.42 150-500

3 COD (mg/L) 2776.83 200 -400

4 TDS (mg/L) 3516.5 2100

5 BOD (mg/L) 754.5 50-250

6 EC (μs/cm) 5409.50 1200

7 Alkalinity (mg/L) 1018.08 500

8 Phosphorous (mg/L) 10.35 8-15

9 Chlorides (mg/L) 1333.67 600

10 Nitrite (mg/L) 1.47 -

11 DO (mg/L) 1.58 4.5-8

12 Sulfate (mg/L) 300.75 -

13 Nitrate (mg/L) 15.83 10

14 Chromium (mg/L) 12.95 0.5-1.0

Conclusion

Conclusively, this paper reported that the values of the parameters of the effluent are extensively

deviated from the standards. For examples, the average value of BOD5 is about seven times than it’s

standard value and chromium is about twelve times. Again other parameters remain in worst condition.

Because of lacking of proper effluent treatment plants, the untreated effluent get mixed with the river

of Buriganga and other areas devastatingly which affect human lives, plants, aquatic creatures and also

total environment adversely. The ensuring of special treatment plants and other necessary steps must

be taken as soon as possible for protecting the environment from being spoilt.

References

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