physico-chemical parameters of coir industry...

Chapter -III

Physico-Chemical Parameters of Coir Industry Effluents

3.1 Introduction

The coir industry in India is one of the major agro-based industries

which continues to play a prominent role in the national economy and also

contributes notable job opportunities to the rural communities. Coir is a natural

organic hard fibre derived from a renewable resource namely, coconut husk.

Coir fibre is used commercially for the manufacture of wide range of coir yarn,

and products like ropes, brushes mat and mattings etc. Only 36 per cent of

available coconut husks in India are used for extraction of coir (Kasthuri et al.,

2011). Therefore, there is enough scope to enhance its application.

Dyeing of coir fibre is essential for improving the marketability of coir

products and satisfying the requirements of consumers. These dyes are applied

to the materials from their solution in water with the aid of chemicals like acetic

acid, sulphuric acid, formic acid, common salt etc. Thus coir industries consume

voluminous quantities of water and diverse chemicals, ranging from inorganic

to organic compounds, for wet processing of fibre (Banat et al., 1996). This

makes the effluents coloured, highly acidic, high in BOD, COD, total suspended

solids (TSS) and contain nitrogen, phosphates, toxic chemicals, dyes and

pigments, oils and grease etc. Out of these chemicals, dyes are the most

important pollutant to be treated since it may affect not only the aquatic flora

and fauna but also may cause serious harmful changes in the entire food web.

68 Chapter 3Chapter 3Chapter 3Chapter 3

In this chapter, an attempt has been made to find the physico-chemical

properties of the waste water from a coir industry in Kerala, South India.

3.2 Materials and Methods

3.2.1 Sample collection

Alleppy, the leading coir industrial cluster in Kerala, South India (Lat.9⁰

30’ N, Long. 76⁰ 23’ E) was chosen for effluent sample collection. The coir dye

effluent samples were collected from the Dye house of a coir industry on

January, 2009 and carried out during dyeing and washing operations. Standard

procedures (Spot and Grab) were followed during sampling and the samples

were taken from three sites spanning a distance of 500 m. The first sample (S1)

was collected from source (outlet of finishing unit), second sample (S2) from

the effluent treatment plant and third sample (S3) from nearby water body

(pond). All the samples of the effluents were collected in sterile, dry and

properly stopper polypropylene bottles.

3.2.2 Sample Preservation and Analysis

Water samples may undergo change with regard to their chemical,

physical and biological quality during transportation and storing. To preserve

the integrity of the samples after collection, the samples were refrigerated at

4⁰C. The samples for the determination of Dissolved oxygen were siphoned into

the DO bottles without giving any chance for aeration. The pH and temperature

of the effluents were determined at the spots, whereas, the rest of

physicochemical and microbiological parameters determined instantly after

bringing the samples to the laboratory. The samples were transported to

laboratory at 4⁰C as in accordance with the standard methods (APHA, 1998).

Physico-chemical analysis of the effluent such as pH, Temperature, Dissolved

PhysicoPhysicoPhysicoPhysico----Chemical Parameters of Coir Industry EffluentsChemical Parameters of Coir Industry EffluentsChemical Parameters of Coir Industry EffluentsChemical Parameters of Coir Industry Effluents 69

Oxygen (DO), Biological Oxygen Demand (BOD), Chemical Oxygen Demand

(COD), Total Hardness, Electrical conductivity, Chloride content and Total

Suspended Solids (TSS) was carried out according to standard methods of

American Public Health Association (APHA, 1998).

3.2.3 Chemicals and Glass wares

The chemicals, reagents and standards used in the present study were of

analytical grade purchased from HiMedia Industries, Mumbai and Sisco

Research Laboratories, India. Distilled and de-ionized water was used for all

analytical work and for preparing stock solutions. Acid and alkali resistant

borosilicate glass wares manufactured by M/S Borosil, India were used.

3.2.4 Determination of pH

pH is a measure of acidity or alkalinity of a solution and measures the

concentration of hydrogen ions in water. The pH of the sample was measured

using a pH meter (Systronics digital pH meter 335). The pH meter was

standardized by immersing the electrode in buffer solution of known pH of 4

and 9.2. And then the electrode was immersed in the sample till a stable reading

was obtained.

3.2.5 Determination of Temperature

Temperature is a measure of heat in terms of a standardized unit. It is an

important ecological factor which greatly affects vital activities like

metabolism, behaviour, reproduction and development of aquatic organisms.

Temperature was noted at the site prior to its collection with a thermometer.


3.2.6 Determination of Dissolved Oxygen (Winkler’s Method)

In natural and wastewater, Dissolved Oxygen (DO) levels depend on the

physical, chemical and biological activities of the water. The analysis of DO

plays a key role in water pollution control activities and waste treatment process

control.

When Manganous sulphate is added to the sample containing alkaline

Potassium iodide, manganous hydroxide, Mn(OH)2 is formed, which is oxidised

by the DO of the sample to give a brown precipitate of manganic hydroxide,

MnO(OH)2. Upon acidification with H2SO4, the manganic hydroxide forms

manganic sulphate which acts as an oxidizing agent to release free iodine from

potassium iodide. The released iodine is stochiometrically equivalent to that of

dissolved oxygen (DO) originally present in the sample and is then titrated with

a standard solution of sodium thiosulphate using starch as the indicator.

Reagents

1. Alkaline iodide - sodium azide solution:- 50 gm NaOH and 15 gm KI was

dissolved in distilled water and diluted to 100 ml followed by the addition

of 1g NaN3.

2. MnSO4. H2O solution:- Dissolved 36.4 gm MnSO4. H2O in water and diluted to 100 ml.

3. Stock Sodium thiosulphate solution (0.1 N):- Dissolved 25 gm Na2S2O3.

7H2O and 0.1 gm Na2CO3 in distilled water and made up to 1000 ml.

4. Standard Sodium thiosulphate solution (0.025 N):- Dilute 250 ml stock

sodium thiosulphate solution to 1000 ml with freshly boiled and cooled

distilled water.


5. K2Cr2O7 standard solution (0.1 N):- Dissolved 1.23 g K2Cr2O7 in distilled

water and made up to 250 ml.

6. Starch solution:- A paste of 2gm of soluble starch powder and 0.2gm

salicylic acid as preservative was prepared in distilled water and added to

100 ml boiling distilled water. Boiling was continued for a few minutes and

was used after cooling.

A glass stopper DO bottle of 250 ml volume was taken and filled it with

sample avoiding any bubbling. No air was trapped in the bottle after the stopper

was placed. 1 ml of MnS04 solution (Winkler-A) was added followed by 1 ml of

alkaline iodide - azide solution with the help of separate pipettes. The bottle was

stoppered carefully and inverted 2-3 times to allow mixing of reagent. Presence

of brown precipitate indicated dissolved oxygen.

1 ml of concentrated H2SO4 was added and the solution was mixed until

the precipitate gets dissolved. 201 ml of this solution was taken in a conical

flask and titrated against 0.025 N Na2S2O3 using starch (2ml) as indicator. The

end point was the colour change from blue to colourless. The titrations were

repeated to get concordant values.

Calculation

Where V = Volume of Thiosulphate

N = Normality of Thiosulphate

VI = Volume of sample bottle after placing the stopper

V2 = Volume of MnSO4 and KI added


3.2.7 Determination of Biochemical Oxygen Demand (BOD)

BOD is the measure of degradable organic material present in a water

sample. It can be defined as the amount of oxygen required by the micro

organisms in destroying the biologically degradable organic matter under

aerobic conditions. Here the living organisms serve as the medium for oxidation

of the organic matter CO2 and H2O.

Microbes C6H12O6 + 6O2 ----------------> CO2 + H2O+ New microbes

On the basis of the above relationship, it is possible to interpret BOD

data in terms of organic matter as well as the amount of oxygen used during its

oxidation.

Reagents

All reagents listed in DO estimation were used for BOD. In addition

following reagents were required:

1. Phosphate buffer: Dissolved 8.5gm KH2PO

4, 21.75gm K

2HPO

4, 33.5gm

Na2HPO

4.7H

2O and 1.7gm NH

4C; in distilled water and diluted to 1000mL.

The pH was made to 7.2 without further adjustment

2. Magnesium sulphate: Dissolved 22.5gm MgSO4.7H

2O in about 700mL of

distilled water and diluted to 1 Litre.

3. Calcium chloride: Dissolved 27.5gm anhydrous CaCl2

in about 700mL of

distilled water and diluted to 1 Litre.

4. Ferric chloride: Dissolved 0.25gm FeCl3.6H

2O in about 700mL of distilled

water and diluted to 1 L.


5. Acid and Alkali solutions 1N: Prepared 1N H2SO

4 and 1N NaOH or

neutralization of caustic or acidic sample

Preparation of dilution water: For the dilution of sample, one litre of distilled

water was taken and aerated by clean filtered compressed air until DO

saturation attained at 20°C. To this, 1 ml each of phosphate buffer, magnesium

sulphate, calcium chloride and ferric chloride was added and mixed well.

(Samples S1 and S2 were diluted 1% whereas S3 was diluted 5%).

Procedure: The sample was taken in three labelled BOD bottles and stopper

immediately. Dissolved oxygen of one of the BOD bottles was analysed

immediately and the other two was incubated for 5 days at 20°C. A blank was

prepared using plain dilution water siphoned in a BOD bottle in order to

measure the oxygen consumption by dilution water. After 5 days, the DO of the

water sample in the incubated BOD bottle was calculated by Winkler method.

Calculation

[Do-D5] x 100BOD at 20°C as O2, mg/L =

% dilution

where Do is the DO of the sample immediately after preparation and D5

is the DO of the sample after 5 days.

3.2.8 Determination of Total Hardness of the Sample

Water hardness is a traditional measure of the capacity of water to

precipitate soap. Total hardness is defined as the sum of the calcium and

magnesium concentration, both expressed as CaCO3, in mg/L. The

determination of the total hardness of water is based on a complexometric

titration of calcium and magnesium with an aqueous solution of the disodium

salt of EDTA at pH value of 10. If an indicator dye like Eriochrome Black T


(EBT), when added to solution containing calcium and magnesium ions, the

colour of the solution turned to wine red. The titrant, EDTA complexes with

magnesium and calcium ions and removes them from the association of the

indicator and thus changed the colour. When completely complexed with

EDTA, the solution becomes blue, which is the end point of the titration.

Reagents

1. Buffer solution:- 16.9 gm NH4C1 was dissolved in 143 ml concentrated

NH4OH and to this 1.179 gm Sodium EDTA. 2H2O followed by 0.78 gm

MgSO4. 7H20 were added and made up to 250 ml using distilled water in a

volumetric flask. The pH was adjusted to 10.1 ± 0.1.

2. Standard EDTA solution (0.1M) - Dissolved 9.306 gm Sodium EDTA. 2H2O

in 250 ml distilled water in a volumetric flask.

3. Standard MgSO4 solution:- 0.6162 gm MgSO4 in 250 ml water.

4. Eriochrome black T indicator- Dissolved 0.2 gm of Eriochrome Black T

indicator in 15 ml of concentrated ammonia solution and 5 ml absolute

alcohol. Do not store more than two days before use.

25 ml of well mixed sample was taken in a 250 ml conical flask and

2 ml of buffer solution was added to give a pH of 10.0 followed by 3 drops of

EBT indicator solution. It was then titrated against standard EDTA solution

taken in the burette until wine red colour changes to blue and the volume of

EDTA required (A) was noted. A reagent blank was conducted and the volume

of EDTA taken (B) was noted. The volume of EDTA required by the sample

was calculated as C= (A-B). Titrations were repeated to get concordant values.


Calculation

C D 1000 Total Hardness as CaCO3 mg/L=

V

× ×

Where C= volume of EDTA required by sample,

V = Volume of water sample,

D = mg CaCO3 equivalent to 1 ml EDTA titrant

3.2.9 Determination of Electrical Conductivity

Conductivity is the capacity of water to carry an electrical current and

varies both with number and types of ions in the solutions, which in turn is

related to the concentration of ionized substances in the water. Most dissolved

inorganic substances in water are in the ionized form and hence contribute to

conductance.

Reagents

Standard KCl solution - 3.727 gm KCl was weighed out and made up to

500 ml. The solution has a concentration of 0.1 N and conductivity of 14.13

mmho/cm.

The conductivity meter (Systronics direct Reading Conductivity Meter-

303) was calibrated using 0.1 N KCl solution. The electrode was washed with

distilled water and wiped with tissue paper. The conductivity of the standard

was set on the display by adjusting the calibration control. Then the

conductivity of the water sample was determined.


3.2.10 Determination of Chemical Oxygen Demand

Chemical Oxygen Demand (COD) test is commonly used to indirectly

measure the amount of organic compounds in water sample. Chemical Oxygen

Demand (COD) is expressed in terms of mg of oxygen required per litre of

water (mg/L) and was determined following the official method mentioned in

APHA (1998). The organic matter present in the sample gets oxidized

completely by potassium dichromate (K2Cr2O7) in presence of sulphuric acid to

produce carbon dioxide and water. The excess of K2Cr2O7 remaining after the

reaction is titrated with Ferrous ammonium sulphate, Fe(NH4)2 SO4. The

dichromate consumed gives the oxygen required for the oxidation of organic

matter. COD results can be obtained in 3-4 hrs as compared to 3-5days required

for BOD test. Further, the test is relatively easy, precise, and is unaffected by

interferences as in the BOD test.

Apparatus

1. Reflux apparatus consisting of Leibig condenser

2. Heating mantle

3. Burette.

Reagents

1. Standard Potassium Dichromate Reagent-Digestion solution (K2Cr2O7

0.00833 M):- Weigh accurately 4.913 gm of potassium dichromate and

33.3 gm of mercuric sulphate in a beaker and the contents were dissolved

in 167 ml of concentrated sulphuric acid and transferred to 1000 ml

standard flask and the volume was made up to 1000 ml using distilled

water.


2. Sulphuric Acid Reagent- Catalyst solution:- 3 gm of silver sulphate crystals

were weighed and dissolved in 300 ml Con. H2SO4

3. Standard Ferrous Ammonium Sulphate solution [Fe(NH4)2 (SO4)2. 6H2O]

(0.025 M):- 4.9 gm of Fe(NH4)2 (SO4) 2 . 6H2O in 150 ml water and 2.5 ml

Con. H2SO4, then made up to 500 ml.

4. Diphenylamine indicator

5. Mercuric sulphate crystals

To 0.4 gm HgSO4 taken in a reflux flask 10 ml of sample diluted to 20

ml was added. 50 ml of concentrated K2Cr2O7 solution was placed into the flask

together with glass pieces. 30 ml H2SO4 containing Ag2SO4 was added and

mixed thoroughly. The flask was connected to a condenser. The contents were

mixed thoroughly before heating. Care was taken since improper mixing result

in bumping and the sample may be blown out. It was then refluxed for one hour,

then cooled and the condense was washed out with distilled water. The sample

was diluted to 150 ml and cooled. The excess of K2Cr2O7 was then titrated with

0.025 M Fe (NH4)2 (SO4 )2. 6H2O using diphenylamine indicator. The end point

of the titration was the first sharp colour change from blue - green to reddish

brown. A blank was also run simultaneously in the same manner using distilled

water.

Calculation

( ) ( )A B x M x 8 x 1000 COD mg / L

Volume of sample, ml

−=

Where, A = Volume of Ferrous Ammonium sulphate added to the blank (ml)


B = Volume of Ferrous Ammonium sulphate added to the sample (ml)

M = Molarity of Ferrous Ammonium sulphate

8= milliequivalent weight of O2

3.2.11 Determination of Chloride

Chlorine in the sample reacts with silver nitrate, AgNO3 solution to give

silver chloride, AgCl which is a white precipitate.

Reagents

1. 0.02 N NaCl: - 1.17 gm of NaCl was dissolved in distilled water and made

up to 1 litre.

2. 0.02 N AgNO3:- 3.4 gm of AgNO3 was dissolved in distilled water and

made up to 1 litre. This was then standardized by titrating against the

standard NaCl solution and stored in amber coloured bottle away from

light.

3. K2Cr2O7 indicator:- 5% aqueous solution of pure K2Cr2O7 was taken .

5 ml of the sample was taken in a porcelain dish and diluted it to about

25 ml with distilled water. 5 to 6 drops of K2Cr2O7 was added and titrated with

standard AgNO3 solution with stirring till the first brick red tinge appeared.

Calculation

( )N x V x Equivalent weight of Chlorine 35.5Chloride in mg / Litre

Volume of aliquot taken=

Where N = Normality of AgNO3

V = Volume of AgNO3


3.2.12 Determination of Total Suspended Solids (TSS)

The term TSS applies to the dry weight of the material that is removed

from a measured volume of water sample by filtration through a standard filter.

To achieve reproducibility and comparability of the results, close attention of

procedural details, especially filter characteristics and time and temperature of

drying is required.

Apparatus

1. Filtration apparatus

2. Filter paper

3. Weighing dishes

4. Evaporating dishes

A known volume of sample (100 ml) was filtered using filtration

apparatus attached with suction pump. The filter paper was removed from

filtration apparatus and transferred it to a crucible ignited to a constant weight

(W1). It was then dried for 1 hour at 130⁰C in a hot air oven, cooled in a

desiccator and weight of the crucible was recorded (W2). The process of drying,

cooling, desiccating and weighing was repeated until a constant weight was

obtained.

Calculation

( ) ( )2 1W W x 1000Total suspended solids mg / L

Volume of sample, ml

−=


3.3 Results

The effluent sample collected from the Dye house of coir industry in

Alleppy, Kerala, South India, was black in colour, with pungent smell and the

experimental data on various physico-chemical properties of water samples is

presented in Table 3.1. The physicochemical values of effluent sample showed

a considerably high load of pH, TSS, BOD/COD and chloride compared to

General Standards of discharge of environmental pollutants published by

Central Pollution Control Board. However, there observed a significant decline

in the values for the samples collected from treatment plant and nearby pond

except in case of pH and DO.

The analysis of the raw effluent showed its highly acidic nature with a

pH value of 8.6 ±0.3. The pH values of treated as well as pond water showed

alkaline character with values 7.8 ±0.5 and 7.5 ±0.2 respectively.

The temperature of raw effluent was very high when compared to the

other two. It was observed that raw effluent was having a temperature of

52.2±0.7 ⁰C whereas it decreased to 32.3 ±0.4 ⁰C and 28.0 ±0.3 ⁰C for samples

collected from treatment plant and the nearby pond respectively.

The Dissolved Oxygen (DO) for coir industry effluent at each sampling

site was as shown in Table 3.1. The DO values ranged from 2.09 ±0.41 to

4.98±1.31 mg/L and showed an increasing trend from effluent source to final

outlet.

The Biological Oxygen Demand (BOD) values showed greater

variations in different sites. The effluent discharge collected from source had a

BOD of 850.0±9.65 mg/L whereas samples S2 and S3 showed BOD of 585.34

±3.83 and 442.26 ±8.33 respectively.


Fig 3.1. The raw effluent tank of a coir dyeing industry. The sample S1 was collected from this tank.

Fig 3.2. An effluent treatment plant in the coir dyeing industry. The sample S2 was collected from the outlet of this treatment plant.


Table 3.1: Physico-chemical parameters of coir industry effluents

SI No

Parameters Sample 1

S1

Sample 2

S2

Sample 3

S3

Standard values (for

Inland Surface water)*

1 pH 8.6 ±0.3 7.8 ±0.5 7.5 ±0.2 5.5-9.0

2 Temperature (⁰C) 52.2 ±0.7 32.3 ±0.4 28.0 ±0.3 -

3 D.O (mg/L) 2.09 ±0.41 3.95 ±0.72 4.98 ±1.31 6.0

4 BOD (mg/L) 850.0 ±9.65 585.34 ±3.83

442.26 ±8.33 30

5 Total hardness

(mg/L) 230.44 ±5.44

180.95 ±4.11

152.88 ±6.12 200

6 Electrical

Conductivity (m mho/cm)

5.7 ±1.2 4.4 ±0.8 2.8 ±0.4 -

7 COD (mg/L) 1376.54±12.23 896.34 ±8.65

528.36 ±9.48 250

8 Chloride (mg/L) 676.58 ±13.11 665.34 ±7.89

274.4 ±14.32 250

9 T.S.S(mg/L) 815.2 ±2.5 734.6 ±5.8 350.1 ±3.2 100

*General effluent standards for discharge of Environmental pollutants as per Schedule-VI, Part A, GSR 801(E) dt 31.12.93.

Values are calculated from three replicas and are represented as mean

±SD. Sample 1- Water collected from raw effluent (outlet of finishing tank),

Sample 2- Water collected from the treatment plant, Sample 3- Water collected

from nearby pond (approx. 500m away from discharge).


The total hardness of raw effluent was 230.44 ± 5.44 mg/L and showed

a decreasing trend after treatment with a value of 180.95 ± 4.11 mg/L for S2

and 152.88 ± 6.12 mg/L for S3.

The electrical conductivity value of raw effluent was observed as 5.7 ±

1.2 m mho/cm whereas that of treated effluent was 4.4 ± 0.8 m mho/cm. The

pond water showed a less value of 2.8 ± 0.4 m mho/cm.

The Chemical Oxygen Demand (COD) level of the raw effluent was

1376.54 ± 12.23 mg/L whereas the values of sample from treatment tank and

nearby pond were 896.34 ± 8.65 and 528.36 ± 9.48 mg/L respectively. BOD

and COD level of the effluent were high as compared to BIS Standards.

The chloride content of samples were too high and were respectively

676.58 ± 13.11, 665.34 ± 7.89 and 274.4 ± 14.32 mg/L for raw, treated effluents

and pond water.

TSS (Total suspended solids) of raw effluent was observed as 815.2 ±

2.5 mg/L and for treated effluent, the value was 734.6 ± 5.8 mg/L. TSS was

further decreased to 350.1 ± 3.2 mg/L for the sample taken from pond.

3.4 Discussion

Many of the South Asian countries especially those developing ones are

experiencing severe environmental problems due to rapid industrialization. The

effluent discharged by textile and coir industries leads to soil and water

pollution and ultimately makes the livelihood of poor more pathetic. The results

of different physico-chemical parameters of the effluent samples from source to

sink of the selected coir industry were falling above the limits of General

standards for discharge of Environmental pollutants (as per schedule of


Environmental Protection Rules; 1993). The effluent generated was highly

coloured, foul smelling and have acidic pH with high temperature. The colour

was black due to mixture of dyes used in the dyeing process. The presence of

colour in the effluents due to high exhaustion rate of unused dyes reduces light

penetration, thereby limiting the biological activity in it which ultimately

reduces the self purification capacity of the ecosystem (Sarnaik and Kanekar,

1995; Banat et al., 1996).

pH is one of the important measurement of waste waters since effluents

with extreme pH is difficult to treat by any biological means. If the effluent is

typically acidic (<5) or alkaline (>7.5), there is a need of neutralization. High or

low pH affects the chemical reactions in aquatic environment and would kill

aquatic life. In the present study, the pH of dye effluent was observed to be 8.6

± 0.3 which was similar to the study of Arun and Bhaskara (2010). Biyearly

average pH values of 8.1, 8.7, 6.3 and 6.9 were observed for samples collected

from different industries of Taloja industrial area, Mumbai (Ram et al., 2011).

The high pH in the waste water limits the growth of microorganisms and

thereby renders the bioremediation in water ecology (Banat et al., 1996). The

pH values changed to 7.8 ±0.5 after treatment. This might be due to the

chemicals used for neutralizing the effluent. The most important cause for

damage to external environment was many of the coir industries does not have

treatment plant and discharges the waste water directly to nearby streams.

Temperature is one of the most important ecological factors which

control behavioural characteristics of aquatic organisms, solubility of gases and

salts in water. In the present study it was observed that the temperature of the

effluent was considerably high (52.2⁰C) and when discharged directly to

streams it brings down the solubility of gases in water and makes aquatic life in


danger. Increase in temperature may become barrier to fish migration and

affects species reproduction.

Dissolved Oxygen (DO) is an index of physical and biological processes

going on in water. Non polluted waters are usually saturated with DO. The two

main sources of DO in water are diffusion from air and photosynthetic activity

within water. Oxygen is considered to be a limiting factor, especially in lakes

and in waters with heavy load of organic material. Low DO may prove lethal

for many of the organisms. DO is affected by thermal pollution, sewage and

effluents. From the DO value, we can control the rate of aeration during

biological treatment of effluents. The DO of the coir industry effluent was

observed to be lower than the treated solution and nearby water body indicating

possible pollution. DO value of samples increased from 2.09 ±0.4 to 3.95 ±0.72

after treatment and to 4.98 ±1.31 that of pond water. A healthy water body

should have a DO of at least 5.2 mg/L. The low level of DO could lead to

production of hydrogen sulphide gas in presence of organic materials and

sulphates (WHO, 2002) due to action of anaerobic organisms. Also the water

becomes uninhabitable to gill breathing aquatic organisms. The low DO value

of raw effluent was due to high temperature since warm water hold less DO

than cold water. The results were in agreement with other reports that

mentioned about industrial effluents. Adewoye et al. (2005) had earlier reported

that indiscriminate deposition of effluent in to an aquatic system might decrease

the dissolved oxygen concentration.

Technically BOD is the amount of oxygen utilized by micro organisms

in aerobic degradation of the dissolved organic matter in water over a 5-day

period. The demand of oxygen is in general proportional to the amount of

oxidizable organic matter present in the solution. BOD test can be affected by


number and type of micro organisms present in the sample. Some samples,

especially those having toxic substances do not have microorganisms. In such

cases, microorganisms can be added to it. The pH favourable for the growth of

micro organisms is in the range 6.5 to 8.3. The high levels of BOD are

indicators of low available oxygen for the utilization of organic matter by

microorganisms and thus describe the pollution strength. BOD value of raw

effluents from coir industry was 850 ±9.65 mg/L indicated the high load of

organic pollutants. Similar results were observed in waste water effluents from

an Industrial area in Mumbai (Ram et al., 2011). The experimental data of

present investigation shows a BOD value of 585.34 ±3.83 in treated effluent

samples and 442.26±8.33 for the sample collected from nearby pond which was

extremely higher than the permissible limits. A study by Husain and Hussain

(2012) showed that discharge of dyeing and printing waste water to River Bandi

in Rajasthan increased the BOD and COD levels to 2700 mg/L and 460 mg/L

respectively. BOD directly affects the dissolved oxygen (DO) in rivers and

streams. The greater the BOD, less oxygen is available to higher forms of

aquatic life. The consequences of high BOD are the same as those for low DO:

aquatic organisms become stressed, suffocate and die (Ram et al., 2011)

Hardness is defined as the concentration of multivalent metallic cations

present in solution. Here the hardness of water samples shows a decreasing

trend from 230.44 ±5.44 to 152.88 ±6.12 and it might be due to settling of these

ions during treatment. Hard water is primarily of concern because it requires

more soap for effective cleaning, causes yellowing of fabrics, toughens

vegetables cooked in the water and forms scales in boilers, water heaters, pipes

and cooking utensils. The hardness of good quality water should not exceed 250

mg/L measured as calcium carbonate equivalents. Magnesium hardness

particularly associated with sulphate ion, has a laxative effect in person


unaccustomed to it. The total hardness value of the present study was found to

be within permissible limits.

Conductivity of water sample is its ability to carry electrical current and

is a measure of the total dissolved solid concentration such as NaCl. Salinity of

water is determined by measuring its electrical conductivity and is the most

important parameter in determining the suitability of water for irrigation.

Effluent has the highest conductivity of 5.7 ±1.2 followed by the treated one.

Pond water has observed to display the lowest conductivity value of 2.8 ±0.4.

The decrease in conductivity from source to sink is due to physical treatment of

the waste water. The high value of conductivity reveals the factor that this water

is not suitable for irrigation as it causes heavy metal accumulation.

The Chemical Oxygen Demand (COD) is a measure of chemically

oxidisable organic matter in the waste water. Here effluent has the highest COD

value revealing the fact that it contains more chemically oxidisable matter and

shows the highly toxic effect when it is given out to the surroundings without

treatment. COD value reduced considerably after treatment indicates the

degradation of toxic chemicals. COD values are extensively used in the analysis

of domestic and industrial waste water. In conjugation with BOD test, COD test

is helpful in indicating toxic conditions and the presence of biologically

resistant organic substances. COD test has an advantage over BOD in that the

result can be obtained in about 3h, as compared to 5 days required for BOD test.

Here the COD value of the effluent has been observed to be 1376.54 ±12.23

mg/L (Table-3.1) which is very high as compared to the COD levels in pond

water and the treated solution. High COD value of 3027 mg/L was observed in

a study conducted on Indigo dye effluent (Dogan and Hauk, 2012) reveals the

fact that dye waste water contains high load of inorganic pollutants also.


Chloride occurs in all natural waters in widely varying concentrations.

Excessive chloride (>250 mg/L) imparts a salty taste to water. From the results,

it can be observed that the raw effluent has the maximum chloride content of

676.58 ± 13.11 mg/L and after treatment it decreased to 665.34 ±8.65 and

became 274.40 ±14.32 when the effluent reached nearby pond (Table 3.1). The

results indicate chloride content of coir industry effluent was above the

acceptable limit of 250 mg/L. High chloride contents are harmful for

agricultural crops if such wastes containing high chlorides are used for

irrigation purposes (Agarwal, 1996).

Total suspended solids of effluent are extremely valuable in the analysis

of polluted water. They cut down the light transmission through the water and

so lower the rate of photosynthesis in aquatic flora. It is a major parameter used

to evaluate the strength of domestic waste water and to determine the efficiency

of the treatment unit. The Suspended solids are responsible for the conditions

generally referred as 'soil sickness' of the soil when the soil pores are clogged

by suspended matter. It leads to anaerobic conditions in the root zone because of

which organic acids are liberated. Further, aerobic conditions necessary for soil

microbial processes are also inhibited to denitrification and loss of nitrogen.

H2S is also produced which will be toxic to plants. These conditions are

associated with 'soil sickness'. The levels of TSS in effluent sample were

observed to be 815.2 ±2.5 mg/L and that of treated and pond water were

734.6±5.8 and 350.1 ±3.2 mg/L respectively (Table-3.1). Chemical coagulation

found to be mainly responsible for removing dissolved solids, suspended solids

(TSS) and COD from the effluent (Lin and Peng, 1994) and it is further

enhanced when used with activated sludge process (Lin and Liu, 1994). The

success of biological wastewater treatment is governed by the abilities of

microorganisms to induce floc formation, facilitating the separation of particles


from the treated water. This was indicated by the values of TSS, BOD and COD

of sample 2 and sample 3. The general decrease in physiochemical load in the

effluent from source to sink suggested a gradual decline in pollution level.

More efforts are needed in order to maintain the values according to

National Standards limit. The study also showed the importance of a treatment

method which substantially reduces the pollutants prior to the discharge of this

waste water to nearby streams.

The experimental data suggests a need to implement common

objectives, compatible policies and programmes for improvement in the dye

waste water treatment methods. As much work is not available on the toxicity

induced by the effluents from coir industry in Kerala and perhaps this is the first

specific report. In this work, we are trying to bring this very serious pollution

problem to the public for proper care and remediation as Alappuzha, the Venice

of East and the present tourist spot is getting spoiled.

physico-chemical parameters of coir industry...

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