Implementation of Effluent Treatment Plants for Waste

Water & Effect of Untreated on Environment (Part-1)

Rois U. Mahmud
Department of Textile Engineering
BGMEA University Of Fashion & Technology
Email: roisuddinhridoy@gmail.com
Name of industry: Niagara Textile Industry Ltd.  

Part-2

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 time frame 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 find out 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.

Waste water from dyeing mill

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

Physical Chemical Biological

Sedimentation Neutralisation (HCL) Stabilised ponds
Filtration Reduction Aerated lagoons
Flotation Oxidation Trickling filters
Foam fractionation Catalysis Activated sludge
Coagulation Ion exchange Anaerobic digestion
Reverse osmosis Electrolysis (Polymer) Fungal treatment
Solvent extraction
Ionising radiation
Adsorption
Incineration
Freezing
Distillation

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. 

  Part-2
General Flow diagram for Effluent Treatment Plant