Implementation of Effluent Treatment

Plants for Waste Water & Effect of

Untreated on Environment

Rois U. Mahmud1(G.L),Ashfaq R2,Main Uddin3,Tariqul Islam4,Rashedul

I5,Anupam Das6,Sane Malum7

Students (1-7) of “Department of Textile Engineering”. BGMEA

University Of Fashion & Technology.

Email:roisuddinhridoy@gmail.com

Name of industry: Niagara Textile Industry Ltd.

Date of site visit:08/06/2015

Acronyms and Abbreviations

AS Activated Sludge

ASP Activated Sludge Plant

BOD Biochemical Oxygen Demand

BOD5 5-day Biochemical Oxygen Demand

CO2 Carbon dioxide

COD Chemical Oxygen Demand

DFID Department for International Development

DO Dissolved Oxygen

ETP Effluent Treatment Plant

MLSS Mixed Liquor Suspended Solids

NaOH Sodium Hydroxide

SVI Sludge Volume Index

TDS Total Dissolved Solid

TSS Total Suspended Solid

Lime Calcium carbonate

ABSTRACT

The work is aimed on the implementation process of textile industries effluents & the present

pollution scenario in Bangladesh due to textile effluent and the consequent solution of the

problem by installation of effluent treatment plant.Despite of having ETP equipment almost all

industries in Bangladesh most of them don’t implement the system because of huge expenses.

On other hand the increasing industrialization is contributing severe pollution to the

environment by the toxic waste discharge. The liquid effluents from industries are causing a

major havoc to the environment, ecology, agriculture, aquaculture and public health since the

development of textile industries in the country. It had become a prerequisite to set up ETP in

each industrial establishment, particularly at dyeing industries that were discharging huge

amount of liquid waste to the rivers every day. But, for the successful implementation of ETPs,

industry owners will have to be socially responsible and at the same time, government should

provide the factory owners with logistic supports and relaxed timeframe to set up ETPs.

Keywords: Implementation process, Industrial Effluents; Water Quality; BOD; COD; TSS.

Introduction

Industrialization is an inevitable feature of economic intensification in a developing country. In

the way of employment-intensive industrialization, textile industries are playing an utmost

important role offering tremendous opportunities for the economy of Bangladesh. With the

industrial development in Bangladesh, the waste management systems did not develop

accordingly. Despite of having ETP equipment almost all industries are seen to discharge their

wastes into water and on land without any treatment or after partial treatment. Of the

environmental elements, water is the most affected as the big industries are usually situated on

the river banks and due to continuous receiving of the effluents the toxicity of these river water

increases day by day. The environmental pollution created by the industries has now become a

burning issue of the nation (Bhuiyan, M.A.H. et. al., 2011) (Islam and Jolly, 2007) (Jolly and

Islam, 2006). The major polluting industries like textile and dyeing, paints, tanneries, oil

refineries, chemical complexes, fish processing units, fertilizer factories, cement factories, soap

and detergent factories including light industrial units of Bangladesh discharge directly

untreated toxic effluents in the rivers (Jolly, Ph. D.thesis, 2011). The textile dyeing wastes

contain unused or partially used organic compounds, and high biochemical oxygen demand

(BOD) and chemical oxygen demand (COD).

It is a positive sign that many industries are also making progress in establishing and operating

their own ETPs to comply with national and international requirements, and also because of

increased personal awareness of the negative impacts of industrial effluent.

Objectives

1.To find out the implementation process of Effluent Treatment Plants of textile industries

2.To find out the used chemicals data in ETP

3.To find out the capacity of effluent treatment

4.To find out the effect of untreated water on environment

Literature Review

For making a Research paper on the implementation process of ETP & effect of untreated water

on environment under our Lecturer Mr.Rakib we made a visit at Niagara Textile LTD in

Chandra,Gazipur.After went there one disappointing matter we faced that the authority didn’t

give us any permission to take photo of ETP processes & units. We don’t know why they did

that may be for their security purpose.Then we went to ETP plant & the instructor of ETP told

us their ETP is a physico-chemical ETP plant.

With physico-chemical treatments generally used in Bangladesh (coagulation and flocculation)

it is possible to remove much, possibly all of the color depending on the process used. It is

however difficult to reduce BOD and COD to the value needed to meet the national effluent

discharge standard, and impossible to remove TDS. The removal rate is dependent on the

influent wastewater quality. The removal efficiency of this type of treatment has been found to

be 50% and 70% for BOD and COD respectively.After that we knew about the process flow chart

of the ETP and that is respectively screening, equalization tank, Sedimentation and Filtration,

Chemical Unit Processes,PH controller, Aeration Tank, Coagulation and Flocculation, Secondary

Clearifier & sludge collection Tank & Discharge Treated Water.We also know about the all

chemicals are used to treat the waste water in Niagara. These are Fe(SO4),Ca(CO3),HCL &

electro-polymer.We also collect the capacity of ETP. They treat about 120m3 water per

hour,that mean they treat about 2880m3 water per day.At the final stage we saw the discharge

& sludge tank and we collect the Data of discharge quality. After collecting the Data and

monitoring the discharge water color & odor we have reached a decision on that the quality of

discharge of Niagara is not so good. May be their waste water treatment is just like an Eye

wash. And they give up the discharge into the local cannel.That’s why their low quality treated

water may harm the cannel’s water.So that the authority should maintain the plant very

carefully to treat the water purely.

We also know about another important matter that whole water source of Niagara is

underground water. This is a really big matter of concern for our environmental balance of

underground water. And another matter is, Niagara authority do not use the used water by

recycling. So that day by day we may be loose our underground water level. So we recommend

here to the authority to use the treated water by recycling. So that our water level may not go

down day by day.

Methodology

In order to achieve the objectives of the study, an intensive field survey was conducted in

Niagara textile industry in chandra, Gazipur.At starting point of our visit we first saw the dyeing

process of the industry.Here we saw their conventional & modern dyeing machines used to dye

the fabric. We informed here as for conventional machine they use 150L water per Kg fabric for

dyeing & for modern machine they use 60to75L water per Kg fabric.And we also know about

the capacity of their effluent treatment plant. Then we went to see the ETP and here we talk

with the ETP instructor. He told us about their systems and processes of effluent treatment. He

also told us about the chemicals they use for treating effluent. After that we went to see the

whole process of ETP by our eye. At the end of the site we have examined the final water

sample produce through ETP system(color) & how they manage that water and sludge.From the

whole visit we collect the standard implementation process of ETP, Data of chemical they

used,their management,standard rate of their final treated water& also findout how useful that

water is for the environment etc.

Pollution Scenario Due to Textile Effluent

In Bangladesh, industrial units are mostly located at waterside. A complex mixture of hazardous

chemicals, both organic and inorganic, is discharged into the water bodies from all these

industries, usually without treatment. Thus, industrial units drain effluents directly into the

rivers without any consideration of the environmental degradation.

Textile and dyeing industries produce wastewater, or effluent, as a bi-product of their products,

which contains several pollutants originated from sizing, bleaching, mercerizing, fancy dyeing,

screen printing, yarn dyeing and finishing. Chemicals used in these industries include

acrylonitrile, chlorinated phenols, salicylanilide, organic mercurial compounds, and copper

ammonium carbonate(3). Organic components degrade water quality during decomposition by

depleting dissolved oxygen. The non- biodegradable organic components persist in the water

system for a long time and pass into the food chain. In-organic pollutants are mostly metallic

salts, and basic and acidic compounds. These inorganic components undergo different chemical

and biochemical interactions in the river system, and deteriorate water quality.

In knit dyeing, the local textile dyeing industries higher amount of wastewater which varies

from 150 - 330 liter per Kg of fabric, whereas the recommended amount of wastewater that

can be discharged from composite textile dyeing industries is 100 liter per Kg fabric as per

Environmental Conservation Rules, 1997 [4]. Disposal of these large amounts of wastewater

with highly toxic compounds to water body and irrigable land is extensively threatening to the

ecosystem and aquatic life and it also enters in our food chains. These lead to diminish the

fisheries and agricultural economy day by day. The pollution leads to yield of poor quality of fish

with the smell of chemicals. In general, pH of the effluent is found to above 11, which become

lethal to all species of fish.

Again, the textile industries dispose large quantities of sulphates in their wastewater; this can

be converted in the environment to hydrogen sulfide, a very poisonous gas. In addition, there is

a large body of evidence that shows that residual textile dyes which go along with the waste-

water can act as respiratory sensitizers and can lead to coughs, respiratory tract irritation ad

asthma [4].

It is to be noted that, textile effluent comprises of large quantity of salt along with wastewater

as dissolved solid. This salinity of the effluent is not removed by the conventional treatment of

the effluent. So, with or without treatment, this wastewater disposed to the water system leads

to increasing the salinity of water severely.

Thus, this indiscriminate discharge of untreated effluent to river deteriorates river water quality

to unacceptable level and heavily impacts on water supply, human health, fisheries and

agriculture. Recently, Government of Bangladesh (GoB) has conducted a study on survey of

environmental pollution from industries in greater Dhaka, with the assistance of the United

Nations Environmental Program (UNEP). Under the project, six clusters (Savar, Konabari,

Tejgaon, Tongi, Hazaribagh and Narayangonj) are classified to undertake sampling and analysis

the data to characterize wastewater.

Findings of the Study

## Implementation

# Effluent treatment methods:

At first we work with the method of effluent treatment method. Methods of effluent treatment

may be classified into three main categories: physical, chemical and biological, as listed in Table

[1]. Primary stages of treatment are mainly physical and include screening, sedimentation,

flotation and flocculation to remove fibrous debris, undissolved chemicals and particulate

matter. Primary treatment does not significantly remove color. Secondary stages are designed

to eliminate the organic load and consist of a combination of physico-chemical separation and

biological oxidation. Biological treatment does not remove sufficient color, COD and

electrolytes to be satisfactory on its own but is often the least costly method of treatment.

Physico-chemical separation depends on the forces of chemisorption to extract the colloidal

organic compounds from the liquid phase. Tertiary stages of treatment have become more

important but they make a major contribution to treatment costs. This stage is important for

the removal of color and no one treatment will deal with the removal of all types of color.

Biological processes must be protected from shock loads of industrial pollutants, especially

those containing toxic constituents. Preliminary stages include equalisation, neutralization and

disinfection. Major reasons for poor results from settling tanks include significant fluctuations

in flow, temperature and composition of waste liquors which cause convection currents and

stratification in the tanks and interfere with normal sedimentation. Balancing of flow and

composition together with cooling or heat recovery is necessary. Disinfection with chlorine may

protect the micro-organisms in the biological stage from toxic contamination.

Table 1 – Methods of effluent treatment

Our work site on which we work is a Physico-chemical Treatment Plant.

The basic units needed for a stand-alone physico-chemical treatment plant are screening, an

equalization unit, a pH control unit, chemical storage tanks, a mixing unit, a flocculation unit, a

settling unit and a sludge dewatering unit (Figure 1).

Figure 1: Typical Flow Diagram of a Physico-chemical Treatment

Plant in Bangladesh.

Physical Chemical Biological

Sedimentation Filtration Flotation Foam fractionation Coagulation Reverse osmosis Solvent extraction Ionising radiation Adsorption Incineration Freezing Distillation

Neutralisation (HCL) Reduction Oxidation Catalysis Ion exchange Electrolysis (Polymer)

Stabilised ponds Aerated lagoons Trickling filters Activated sludge Anaerobic digestion Fungal treatment

Now we describe about the processes of our visited site plant by following site

authorities flow chart:-

1.Screening: Screening is a mechanical process that separates particles on the basis of size.

There are several types, which have static, vibrating or rotating screens. Openings in the

screening surfaces range in size depending on the nature of the waste. In the case of textile

dyeing industries they should be small enough to catch pieces of cloth, which may damage

process equipment, reduce the effectiveness of the ETP or contaminate waterways.

2. Equalization/Collecting Tank:

The many steps in the textile dyeing process (pre-treatment, dyeing and finishing) mean that

wastewater quality and quantity varies considerably over time, however ETPs are usually

designed to treat wastewater that has a more or less constant flow and a quality that only

fluctuates within a narrow range. The equalization tank overcomes this by collecting and storing

the waste, allowing it to mix and ensuring that it becomes less variable in composition before it

is pumped to the treatment units at a constant rate. The purpose of equalization for industrial

treatment facilities are therefore:

• To minimize flow surges to physical-chemical treatment systems and permit chemical feed

rates that are compatible with feeding equipment.

• To help adequate pH control or to minimize the chemical requirements necessary for

neutralization.

• To provide continuous feed to biological systems over periods when the manufacturing plant

is not operating.

• To prevent high concentrations of toxic materials from entering the biological treatment

plant.

Mixing usually ensures adequate equalization and prevents settle able solids from depositing in

the tank. In addition, mixing and aeration may result in the oxidation of reduced compounds

present in the waste-stream or the reduction of BOD.

3.Sedimentation and Filtration:

The flocs formed in flocculation (see chemical unit processes for a description of flocculation)

are large enough to be removed by gravitational settling, also known as sedimentation. This is

achieved in a tank referred to as the sedimentation tank, settling tank or clarifier.

Sedimentation is also used to remove grit and suspended solids, to produce clarified effluent,

and to thicken the sludge produced in biological treatment. Flocculation and sedimentation

should remove most of the suspended solids and a portion of the BOD.

4. Chemical Unit Processes:

Chemical unit processes are always used with physical operations and may also be used with

biological treatment processes, although it is possible to have a purely physico-chemical plant

with no biological treatment. Chemical processes use the addition of chemicals to the

wastewater to bring about changes in its quality. They include pH control, coagulation, chemical

precipitation and oxidation. Niagara authority use Fe(SO4), Calcium carbonate(lime),HCL,

Electrolyte(polymer).

5. pH Control:

Waste from textile industries is rarely pH neutral. Certain processes such as reactive dyeing

require large quantities of alkali but pretreatments and some washes can be acidic. It is

therefore necessary to adjust the pH in the treatment process to make the wastewater pH

neutral. This is particularly important if biological treatment is being used, as the

microorganisms used in biological treatment require a pH in the range of 6-8 and will be killed

by highly acidic or alkali wastewater. Various chemicals are used for pH control. For acidic

wastes (low pH) sodium hydroxide, sodium carbonate, calcium carbonate or calcium hydroxide,

may be added among other things. For alkali wastes (high pH) sulphuric acid or hydrochloric

acid may be added. Acids can cause corrosion of equipment and care must be taken in choosing

which acid to use. Hydrocholoric acid is probably better from an environmental view point but

can corrode stainless steel therefore plastic or appropriately coated pumps and pipes must be

used.

6. Aeration Tank:

Aeration is required in biological treatment processes to provide oxygen to the microorganisms

that breakdown the organic waste. It may also be applied in the equalization tank to provide

mixing and to reduce oxygen demand by oxidizing the compounds present in wastewater. Two

main methods are used for this: either mechanical agitation of the water so that air from the

atmosphere enters the water; or by introducing air into the tank through blowers (to supply air)

and diffusers (to diffuse the air uniformly).

7. Coagulation and Flocculation:

Coagulation is used to remove waste materials in suspended or colloidal form. Colloids are

particles over a size range of 0.1 – 1 nm (10-8 – 10-7 cm). These particles do not settle out on

standing and cannot be removed by conventional physical treatment processes. In a small

sample of wastewater there will be both settleable solids and dispersed solids. A significant

portion of these non-settleable solids may be colloidal. Each particle is stabilized by negative

electric charges on its surface, causing it to repel neighboring particles, just as magnetic poles

repel each other. Coagulation is destabilization of these colloids by neutralizing the forces that

keep them apart so that they can agglomerate 2,3 (come together). This is generally

accomplished by adding chemical coagulants and mixing. Figure 2 illustrates how

these chemicals reduce the electric charges on colloidal surfaces.

Fig:2

The term ‘flocculation’ may be taken to cover those processes whereby small particles or small

groups of particles form large aggregates. Flocculation during wastewater treatment converts

finely divided suspended solids into larger particles so that efficient, rapid settling can occur.

The term is also used for the dramatic effect when polyelectrolytes are added and large stable

flocs are formed very quickly (Figure 3).

Fig:3

8.Secondary Treatment/ Secondary Clearifier:

The objective of secondary or biological treatment of industrial wastewater is to remove, or

reduce the concentration of, organic and inorganic compounds. Biological treatment processes

can take many forms but all are based on microorganisms, mainly bacteria. These

microorganisms use components of the effluent as their “food” and in doing so break them

down to less complex and less hazardous compounds, thus decreasing the BOD and COD. In the

process the microorganisms increase in number.The two most common forms of biological

treatment are:

• Activated sludge plants (ASPs)

• Biofilm based systems (often these are trickling filter systems).

Activated sludge (AS) is an aerobic flocculent slurry of micro-organisms which remove organic

matter from wastewater and are then removed themselves, usually by sedimentation.

Activated sludge is best suited to the removal of soluble organic matter because insoluble

organic matter can usually be removed more economically by physico-chemical means. Often,

however, wastewaters will contain both soluble and insoluble organic mater.

AS leaves the reactor with the treated effluent but is settled out in a clarifier and returned to

the aeration unit to recycle the bacteria. The amount of AS required for effective operation

varies according to the design of the ASP and the concentration and nature of the effluent

being treated. Suppliers of ASPs should be able to advise on the optimum amount of AS in the

system. The ratio of the amount of effluent in terms of BOD and the amount of AS (known as

the f/m ratio) is an important design and operating parameter and sometimes ASPs are

operating so as to maintain a fixed f/m ratio. If there is more AS in the ASP than desired a

portion is removed (this is called wasting) and disposed of.

In the ‘traditional’ trickling filter, the effluent is tricked over the surface of the slime-covered

media and the space between the particles of media is occupied by air which passively diffuses

through the filter (Figure 3). In the more recent design of the submerged fixed film reactor, the

particles of media are submerged in the effluent and the air is blown into the reactor from

below.

Both activated sludge and fixed film systems can produce high quality effluent but both have

advantages and disadvantages. In the AS process the settling and recycling of AS to the aerobic

reactor is vital, but the settling process can be difficult to accomplish. Fixed film systems do not

require recycling of biomass and so do not present this problem. Surplus AS needs to be

disposed of: this material must be disposed of appropriately so that the pollutants now present

in this sludge do not enter the water cycle (see the briefing note “Management of Textile

Dyeing Sludge” produced as part of this series for more information on this). The treated liquid

is discharged to the environment or taken for further treatment depending on the desired

standard of effluent quality or the required use of the wastewater.

9.sludge collection Tank & Discharge Treated Water:

Sludge is produced from the treatment of wastewater in on-site (e.g. septic tank) and off-site

(e.g. activated sludge) systems. This is inherently so because a primary aim of wastewater

treatment is removing solids from the wastewater. In addition, soluble organic substances are

converted to bacterial cells, and the latter is removed from the wastewater. Sludge is also

produced from the treatment of stormwater , although it is likely to be less organic in nature

compared to wastewater sludge. In Niagara they collect the sludge in the sludge bad and they

store it at least 3 to 4 month.After that they put that sludge in small packet and transfer that

packet at another place where they had planted these in the ground.

On another hand they dis charge their final treated water into the local cannel.They don’t use

the water by recycling . They told us for their lacking of modern technology of ETP they can’t

use the water by recycling.

Results and Discussion:

For all industries use ETP should follow a National Standards – Waste Discharge Quality

Standards for Industrial units & projects.

By law factories must monitor the quality of their wastewater and stay within national limits for

pollution. The Environment Conservation Rules, 1997 provide national standards for the quality

of industrial wastewater being discharged into certain places including open water bodies,

public sewers and irrigated land. They also provide specific discharge quality standards for key

parameters from certain industries, including the textile dyeing industry.

*Product Quality Checked:

Biological Oxygen Demand (BOD)

Chemical Oxygen Demand (COD)

Total suspended solids

Total dissolved solids

Color

pH et.

Table: Discharge Quality Standards for Classified Industries – Composite Textile Plant

In Niagara,they use 4 chemicals in their ETP.

*Required Chemicals and Their Functions in ETP:

HCL:

Function: Neutralize the waste water controlling the PH. It is auto dispensed in the

neutralization tank.

Polyelectrolyte:

Function: Used for sedimentation / sludge coagulation and also killing bacteria.

De-colorent(caco3):

Function: Used for removing color. It is used auto / manually in the sedimentation feeding tank.

ferrous sulphate:

Function: It is used to kill the harmful bacteria. It is used in the biological oxidation tank.

*Capacity of effluent treatment in Niagara:

Our visited site industry’s effluent treatment capacity is – 120m3/hour

That mean their capacity per Day is – 2880m3/day

*Data of discharge quality of our visited site:

Table: Physicochemical Characteristics(Approximate)

Physicochemical Characteristics

Untreated Effluent Treated Effluent

Color Dark- Blue Light-blue

Odor Unpleasant Small Odor

BOD Above 200 Around 100

COD Above 350 Around 250

PH 9.8 7.2-7.4

TDS 3300 1590

TSS 200 133

Temperature 430c 350c

At our visiting time we also find out one important matter that the whole industry use

*underground water* for their dyeing,finishing etc! And they also don’t use that used water by

recycling! They discharge the water into the cannel or River.

Recommendation

Here at first we would like to give thanks to prof.Engg.Dr. Ayub Nabi Khan(pro-vice of BUFT)for

managed the industry, Mr.Diamond sir for giving us the chance to visit Niagara&

Mr.Zahir(Trainee) to help us by giving his valuable time. On the other hand,at our visiting time

we knew that whole water source of Niagara is underground water. This is a really big matter of

concern for our environmental balance of underground water. And another matter is, Niagara

authority do not use the used water by recycling. So that day by day we may be loose our

underground water level. So we recommend here to the authority to use the treated water by

recycling. So that our water level may not go down day by day.Other matter is we don’t think

the ETP of Niagara is much modern for treating the effluent purely and also they may not treat

the effluent of factory at standard way. Because we saw the final treated water color is not

good as standard and discharge water have also much odor too. And authority discharge that

water into local cannel or River.So that this low quality treated water may harm the quality of

the cannel or river’s water and also harm the Environment badly.

Conclusion:

The recent awareness on the ETP requirement should be directed in a constructive way. We

realize that industrial effluent should be treated before drainage. Upon dis- cussed novel

methods can be applied to remove different dye also hazardous materials from industrial

effluents. The Government must come forward to facilitate ETP installation with technical

guidance and also with fi- nancing. Consideration for Common ETP can be made by the

Government, which will encourage small-scale industries to establish ETPs within their cost

limitations. Government’s recent stringent role against industry owner may pressurize them to

come up with compliance meas- ure regarding ETP installation, but in the long run, a good

result from the concept of ETP installation can only be ensured by proper monitoring and

environmental audit by Government afterward. Neither industry and private sector nor public

sector alone can be left responsible for realization on the intensity of the problem. Government

and the private sector should come into with its full glory to solve the problem mutually, which

aims at burning issue like environmental conservation.

REFERENCES:

1. Government of People’s Republic of Bangladesh, Ministry of Environment and Forests, The

Environment Conversation Rules 1997, Schedule 10, Rule 13 (Un-official English Version)

2. Islam, A. and Jolly, Y.N. (2007): Heavy metals in water and fishes of the tannery affected

vicinity of the river Buriganga, J. Bang., Aca, Sci., 31(2), 163-171.

3. Jolly, Y.N. and Islam, A. (2006): Heavy Metals in Water and Fishes of the River Shitalakkha,

Nuclear Science and Application, 15(20:13-20.

4. Jolly, Y.Nb., Ph.D. thesis, (2011): Evaluation of industrial effluents for irrigation, Dept. of

Applied Chemistry and Chemical Engineering, University of Dhaka, Bangladesh. pp. 174-178

5. Bhuiyan, M.A.H.; Suravi, N.I.; Dampare, S.B.; Islam, M.A.; Qurashi, S.B.; Ganyaglo, S. and

Suzuki, S. (2010): Investigation of the possible sources of heavy metal contamination in lagoon

and canal water in tannery industrial area in Dhaka, Bangladesh, Environ Monit Assess, 175,

633-649.

6. Web: www.bcas.net

7. Journal of Environmental Protection, 2013, 4, 301-308

http://dx.doi.org/10.4236/jep.2013.43035 Published Online March 2013

(http://www.scirp.org/journal/jep)

8. Guide for Assessment of Effluent Treatment Plants in

EMP/EIA Reports for Textile Industries. Department of Environment

Ministry of Environment and Forest, Bangladesh.