INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

Case Study #242

1. Headline: EP3 - Pollution Prevention Assessment for a

Textile Dyeing Facility

2. Background:

What is EP3?

The United States Agency for International Development

(USAID) is sponsoring the Environmental Pollution

Prevention Project (EP3) to establish sustainable programs

in developing countries, transfer urban and industrial

pollution prevention expertise and information, and

support efforts to improve environmental quality. These

objectives are achieved through technical assistance to

industry and urban institutions, development and delivery

of training and outreach programs, and operation of an

information clearinghouse.

EP3's Assessment Process

EP3 pollution prevention diagnostic assessments consist of

three phases: pre-assessment, assessment, and post-

assessment. During pre-assessment, EP3 in-country

representatives determine a facility's suitability for a

pollution prevention assessment, sign memoranda of

agreement with each facility selected, and collect

preliminary data. During assessment, a team comprised of

US and in-country experts in both pollution prevention and

the facility's industrial processes gathers more detailed

information on the sources of pollution, reducing this

pollution. Finally, the team prepares a report for the

facility's management detailing its findings and

recommendations (including cost savings, implementation

costs, and payback times). During post-assessment, the EP3

in-country representative works with the facility to

implement the actions recommended in the report.

Summary

This assessment evaluated a textile dyeing facility. The

objective of the assessment was to propose a program of

pollution prevention that would: (1) reduce the quantity

of toxics, raw materials, and energy used in the

manufacturing process, thereby reducing pollution and

worker exposure, (2) demonstrate the environmental and

economic value of pollution prevention methods to the

dyeing industry, and (3) improve operating efficiency and

product quality.

The assessment was performed by an EP3 team comprised of

an expert in textile dyeing and a pollution prevention

specialist.

Facility Background

This facility is an integrated textile mill. Starting with

polyester and rayon viscose fibers, the facility produces

dyed yarn and fabric with an average content of 65 percent

polyester and 35 percent rayon. The facility employs 270

workers who work 296 days per year. In 1993, production

volume was 1,134,059 kg of material dyed, with an

additional 1,227,974 kg of fabric finished but not dyed.

3. Cleaner Production Principle: The assessment identified

various cleaner production applications including: process

modification, good housekeeping, new technology,

recycling, and material substitution.

4. Description of Cleaner Production Application:

Manufacturing Process

Textile dyeing at this facility involves a number of steps

that must be carried out in proper sequence and under

optimal conditions. In general, the process involves

filling tanks containing fabrics with water, and

sequentially (1) heating, (2) rinsing, (3) adding dyes,

bleaches, and other chemicals, (4) cooling, and (5)

combing or ironing the fabric. This process involves

numerous changes of water, and several additions of dyes,

bleaches, and other chemicals. All fabric is dyed in jets

with nominal capacities of 50 kg, 150 kg, 350 kg and 750

kg of fabric. Yarn is dyed in a 200 kg cone-dryer.

Existing Pollution Problems

At the time of the assessment, there were a number of

pollution problems at the facility, including excessive:

(1) use of water, (2) use of chemicals, (3) suspended

solid concentrations in wastewater, (4) energy use due to

lack of process standardization, leaking steam traps, and

lack of process standardization, leaking steam traps, and

lack of a peaking generator, and (5) emissions from the

oil-fired boiler.

Pollution Prevention Opportunities

The assessment identified eight pollution prevention

opportunities that could address the problems identified

above, with significant environmental and economic

benefits to the facility. Below are listed the

opportunities for pollution prevention recommended for the

facility, and presents the environmental benefits, savings

and implementation costs for each.

Summary of Recommended Pollution Prevention Opportunities:

--Recycling of dye cooling water--Install piping and

valves - conserve water. Costs of $750 (US) with a

financial benefit of $400 (US) per year and a pay back

period of 20 months.

--Recycling of air conditioning system water--Install

piping and a tank - conserves water and chemicals. Costs

of $6,700 (US) with a financial benefit of $4,900 (US) per

year and a pay back period of 14 months.

--Softener system-- Install a digital hardness monitor -

conserves water and chemicals. Costs of $3500 (US) with a

financial benefit of $1,700 (US) per year and a pay back

period of 24 months.

--Solids in effluent--Install screens in drain lines -

reduces pollutant level in wastewater. Costs of $600

(US).

--Operator work system--Deliver training reduces power and

water consumption

--Steam traps--implement maintenance plan - reduces VOCs.

--Bleaching-- Recycle rinse water - reduces use of water

and chemicals. Costs of $2,200 (US).

--Boilers--Install a digital monitoring system- reduces

emissions. Costs of $1000 (US).

--Power consumption--Install a peak load generator.

The total costs of the opportunities is $14,750 (US) with

estimated financial benefits of $7000 (US).

Of the opportunities identified, three were studied in

enough detail to quantify potential savings. For an

investment of just under $ 11,000 (US), the facility can

reduce its water and salt consumption and save about $

7,000 (US) per year. The average payback period for these

actions is approximately 20 months. Additional savings

from bleach rinse recycling, steam trap repair, and boiler

combustion efficiency changes were not quantified.

Recycling of Cone-dye Cooling Water. Well water with a

hardness of approximately 600 ppm is pumped to a tank with

a capacity of 60 cubic meters. From there, it is sent

through a softener that reduces hardness to 3-5 ppm. This

softened water is used for most factory processes. The

cone-dyeing operation uses soft water for non-contact

cooling water through the jacket of the dye tank. Non-

contact cooling water is also used to cool the dye bath

recirculating pump packing gland. Recycling these two

streams is an opportunity and could be accomplished by

sending the water back to the soft water pool that at the

present time receives the cooling water from the jet

dryers.

Recycling of Air Conditioner System Water. The air

conditioner systems for the spinning and weaving rooms use

soft water evaporation for cooling. The water currently

used is taken from the softeners that serve the dye room.

Fifty percent of this water is lost to evaporation, while

the rest is dumped into the sewer system. This water use

has caused problems in the dye room by causing shortages

of soft water. The plant has purchased, but not installed,

new softeners solely to produce water for the air

conditioner system. When the new softeners are installed,

the non-evaporated air conditioning system water should be

recycled back to the new softener system.

Improving Softener Regeneration and Service. The current

dye room softener system has three softeners, each of

which treat well water. In the wash, regeneration, and

rinse steps, the operators calculate the water hardness

using a colorimetric method. The wash time is excessive

and the point at which the softeners are regenerated is

chosen solely on the basis of time since the last

regeneration, resulting in the loss of soft water. A

digital system should be installed to determine the

rinsing and service hardness end points, allowing

operators to determine the exact end point for the wash

period and the maximal supply capacity of each softener.

Reduce Suspended Solids in Effluent. Five screens should

be installed in dye room drains with the objective of

reducing suspended solids in the effluent. The screens

should be designed and installed to allow easy periodic

cleaning. It is possible that in the near future the plant

will need to install an industrial waste water treatment

system; any decrease in loading now will allow a reduction

in waste water treatment plant initial investment and

running cost.

Improve Worker Training. Operators of the dye machines

have different methods for operating each machine, even

though a procedure sheet is supposedly followed. At each

shift change, the new operator switched to a different

method, e.g., increasing the number of rinsing steps or

changing the timing for the different processes. Because

of this lack of process standardization, there are energy,

water, and chemical losses. Training courses in standard

operating procedures should be conducted.

Develop a Maintenance Plan for Steam Traps. Heat transfer

losses caused by leaking steam traps amounts to about 10-

15 percent of energy costs. Using leaking steam traps not

only wastes energy, but also results in inefficient dye

bath heating and the cost of damage to steam lines,

valves, fittings, and other equipment. A training course

for workers in the operation of ultrasonic equipment

should be established and a preventive plan for

maintenance of steam traps should be developed.

Recycling Bleaching Process Rinse Water. There is an

opportunity to recycle rinse waters from the bleaching

process by installing a 25 cubic meter tank to store the

rinse water of one batch and use it for the one that

follows. Thirty-six tons of product would need to be

bleached to recover the initial $ 2,200 (US) investment.

Improve Boiler Combustion Efficiency Monitoring. The

combustion efficiency of the oil-fired boiler is not

monitored continuously, but measured by an outside

contractor four timer a year. Installation of a digital

monitoring system will allow the efficiency of the

combustion to be determined whenever parameters change,

such as when a new lot of oil is received. This change

will result in reductions in fuel use and particulate

matter emissions. Payback time will depend on the amount

of combustible efficiency improvement.

Utilization of a Peaking Generator. During 1993, the

factory paid a total of $ 105,600 (US) in maximum and peak

demand power charges. Installation of a peaking generator

could yield substantial reductions in net power costs,

although net emissions effects will be negligible. If a

natural gas generator is chosen and bio-gas from the local

landfill is used, there may be a small net positive effect

on emissions. While the size, and therefore cost, of the

needed generator cannot be calculated, other textile

plants have indicated a payback time of approximately 11

months.

5. Economics: See above.

6. Advantages: See above.

7. Constraints: See above.

8. Contacts:

EP3 Clearinghouse (UNITED STATES)

TEL: 1 (703) 351-4004

FAX: 1 (703) 351 6166

Internet: apenderg@habaco.com

9. Keywords: textile, dyeing, recycling, process

modification, good housekeeping, new technology, material

substitution, EP3, polyester, rayon, viscose, steam strap,

bleaching, air-conditioning, USAID

10. Reviewer's comments: This case study was carried out in a

developing country in which EP3 has an established

programme. It was submitted to UNEP IE and edited for the

ICPIC diskette in August 1995. It has not undergone a

formal technical review.