[ TEXTILE WASTEWATER TREATMENT][ The anaerobic treatment process is a high quality one having some favorable opportunities such as; low cost, simple

operational mechanism and able to produce less volume of excess sludge, and the organic matter can be converted into

energy in the form of biogas. Therefore, anaerobic process is a highly beneficial process in terms of environmental

protection and the process is economically viable. In Bangladesh, anaerobic process is completely a novel technology.]

2013

International University of Business Agriculture and Technology

Sakil Ahmed

UASB Process

High organic loaded wastes and wastewater creates environmental pollution. The textile

wastewater is a serious environmental challenge faced by Bangladesh textile sub sector. The

textile wastewater contains organic compounds and synthetic chemicals. Certain chemicals

which are used in the textile industry cause environmental or health problems. Due to

presence of chemicals, it cause instance allergic skin reaction or even cause cancer.

Environmental degradation by the industrial sector is a matter of serious concern in

Bangladesh. Textile processing industries is one of the most important industries of

Bangladesh with regard to production, export and labor force employment. The major raw

material for textile processing is grey fabric and most of materials consist of cotton and

blended fabric. Textile processing employs a variety of chemicals depending on the nature of

raw material and products such as; enzymes, detergents, dyes, acids, soda and salt. The

textile wastewater is a highly polluted in terms of organic matter and suspended matter such

as fibers, grease and chemicals. The textile wastewater is usually hot and alkaline with strong

smell and color due to use of chemicals dyes. Studies reveled that wastewater from textile

industry is highly toxic and has inhibitory effects on an activated sludge and nitrification.

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Direct discharge of Textile wastewater in the waterwaysDirect discharge of Textile wastewater in the waterways

Picture-1: Direct Discharge of Textile wastewater in the waterways of Bangladesh.

Anaerobic Process:

The anaerobic treatment process is a high quality one having some favorable opportunities

such as; low cost, simple operational mechanism and able to produce less volume of excess

sludge, and the organic matter can be converted into energy in the form of biogas. Therefore,

anaerobic process is a highly beneficial process in terms of environmental protection and the

process is economically viable. In Bangladesh, anaerobic process is completely a novel

technology. It can reduce environmental pollution and can achieve energy in terms of biogas

from wastewater. In this process in absence of oxygen, it converts organic compounds to CH 4

and CO2. This CH4 is an alternative source of bio-energy which will be utilized for power

generation. The remaining sludge will be converted to bio-fertilizer and will be used

commercially for increasing crop production. This anaerobic digestion is a promising process

used widely for the treatment of textile wastewater in tropical and subtropical countries like

India, Brazil, Mexico and Malaysia (Zeeman and Lettinga et al., 1999).

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The successful application of anaerobic technology for treating textile wastewater depends on

high-rate bioreactors which achieve a high reaction rate per unit reactor volume by retaining

the biomass in the reactor for long period. Solid retention time (SRT) is not dependent on the

hydraulic retention time (HRT). The Up-flow Anaerobic Sludge Blanket (UASB) process is a

“high rate” anaerobic treatment process. The major significant features of UASB reactor are as

follows:

A). It has high rate of anaerobic treatment capacity,

B). Treatment efficiency well under mesophilic temperature condition,

C). High organic loaded wastewater can be treated,

D). The process is simple and operation costs are very low,

E). High organic matter removal efficiency,

F). Bio-energy production through the biogas and

G). Very low sludge production compared to conventional treatment process.

Objectives:

The following objectives of the present experiment are as follows:

i. Reduction of organic load pollution from textile wastewater by using Bioreactor

system

ii. Investigation of biological ETP process by using UASB process.

iii. To protect the environmental bio-degradation of riverine systems

iv. Bioreactor system can serve as Bio-energy and Bio-fertilizer from textile

wastewater which is an economic and integration process

v. Through the combined process, the final effluent can be used in irrigation and

aquaculture system

UASB Process:

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Most of the developing countries do not maintain any treatment process for textile wastewater

and some of the countries just follow the traditional methods such as stabilizing ponds for

wastewater treatment without applying the anaerobic treatment (de Sousa et al., 2001; Melo

et al., 2000). Stabilizing pond takes very long time, extensive land area is required, spread a

serious noxious smell and causes the air pollution and acts as breeding field for mosquitoes

which affect seriously the public health and spreads diseases. Many studies were conducted

to assess the treatment feasibility on anaerobic treatment process (Alaerts et al., 1990, 1993).

The Up-flow Anaerobic Sludge Blanket (UASB) process is a “high rate” anaerobic treatment

process. The UASB treatment system has been developed first time in Netherlands in 1970s

(Lettinga and Vinken, 1980). Thereafter, the intensive use of UASB system has been

developed for sewage treatment over the past decades in developing countries in the tropical

and subtropical regions such as Brazil, Colombia, China, India, and Mexico (Ciftci and Oztiirk

1995). Under the UASB process treatment mechanisms are shown in Figure-1.

Since 1981, anaerobic digestion process has greatly increased as because of low cost and

generation of CH4 in terms of bio-fuel from wastewater. In Europe, more than 36,000

anaerobic treatment plants have been operating using anaerobic treatment systems and

producing over 15 million m3·d-1 of methane which are using as bio-fuel (Tilche and

Malaspina 1998). In Mexico, presently treating the wastewater 2.5 m3 S-1 which is in

terms of 590 tons COD per day (Monroy, et al., 2000). Von Sperling (1996). During the

earlier development of anaerobic treatment, the main drawback was the low rate of

treatment process i.e., the reactor operated under the long Hydraulic Retention Time

(HRT). It has already been proved that the (UASB) system can be widely used in low and

high temperature conditions with shorter retention time (Harada et al., 1996; Uemura and

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Harada, 2000).

Bio-filtration Process

The Down-flow Hanging Sponge (DHS) system has been developed first-time in Japan to

make the standardized effluent quality of wastewater. The novel combined process of UASB

and DHS system is very appropriate technology for the significant reduction of organic matter

from the wastewater. The UASB and DHS combined system has been developed by

Professor Heideki Harada and his research group, Nagaoka University of Technology,

Nagaoka, Japan (Uemura and Harada, 2000). The aerobic bio-filtration process treatment

mechanisms are shown in Figure-2

Fig-2: Schematic frame of bio-filtration process for the reduction of carbon from wastewater

Ii). Full Scale Project on UASB and Bio-filtration Process:

Although this pilot project is successfully running but it is needed to setup as full scale mode

under a textile industry. A schematic flowchart and operational overview of the combined

system of UASB and bio-filtration system is shown in Figure-5. The full scale model of the Bio-

rector design is described as below:

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Fig-5: Flow-chart of the bioreactor process system.

A typical type of UASB and Bio-filtration experimental design is shown in Figure-6. The raw

textile wastewater will be fed from the bottom portion of the UASB reactor under the up-flow

mode direction. Continuous feeding will be made by using pump from the raw feeding tank.

The UASB effluent will be distributed at the top of the bio-filter by a distributor arm that rotates

and spray the UASB effluent homogenously. The total capacity volume of the ETP system will

be 60 m3h-1. A total amount of the bio-filter volume will be used at HRT is 4 h which depends

on bio-filter volume. A clarifier will be constructed under the Bio-tower for finally settle the

suspended particles.

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Fig: Typical reactor design of UASB and DHS combined system for textile

wastewater treatment.

Two months will be needed to stabilize the UASB process and then the inoculation of seedling

process will be started. The organic materials loads will be calculated on the basis of

Biological Oxygen Demand (BOD) and the Chemical Oxygen Demand (COD). During the

experiment, the following pollution parameters will be determined such as; Suspended Solids

(SS), Volatile Suspended Solids (VSS), NH4-N, nitrification and denitrification process. Under

the proposed experiment the CODt mass balance of the whole treatment process will also be

estimated to testify the pollution removal efficiency rate. Finally the final treated effluent will be

used in irrigation and aquaculture system for the production purposes.

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