Dhaka denim

During a manufacturing trip to Dhaka, Gina Tricot visited one of Bangladesh's largest textile mills for denim. We met the factory manager, Jamel, near Dhaka, Bangladesh, to discuss water consumption, chemicals, challenges and trends associated with denim manufacturing.  The factory has nearly 850 employees and its output is approximately 55,000 metres of fabric per day. Since its start in 2000, the company has prioritised use of the latest technology in order to reduce the environmental impact and energy consumption of its manufacturing activities.

Approximately how much water is required to manufacture denim fabric?
Our manufacturing process consumes about 1,200 cubic metres per day, which is 1 cubic metre for every 45 metres of fabric. Most types of fabric require about the same amount of water during manufacturing. About 10 per cent of our manufacturing is undyed fabric and the water consumption for that is much lower.

Is there any way to reduce the amount of water consumed?
Yes. Different types of machines require different amounts of water, so we always try to use machines with the latest technology. We reuse the condensation produced by the machines by collecting the steam and using the water again. We also reuse the water used for cooling.

What type of water purification system do you use?
The water in Dhaka is very hard, so it is necessary to lower the pH level before using the water in manufacturing processes. After the water is used, it is purified at our own ETP (Effluent Treatment Plant)[i] . We can treat approximately 30 cubic metres per hour. All water is treated in accordance with Bangladesh water regulations and the quality of the treated water is regularly checked by government officials.  The requirements on water treatment from the government as well as our customers are high.

Which chemicals are used in the manufacturing of denim fabrics? Which processes require the most chemicals? 
The dyes we use are synthetic indigo dyes and black liquid sulphur dyes. We also use sodium hydrosulfite, caustic soda, glucose, starch and softener. Chemicals are mostly used for dying and final finishing, but also for stabilisation of the fabric after weaving.

How do you inspect the chemicals that are used? 
All chemicals that we use meet the requirements of Öko-Tex, GOTS and REACH. Most of the chemicals are manufactured in Germany, Spain, Italy and Australia. Only the indigo is purchased from China. The cotton yarn that we use primarily comes from Pakistan and India.

Which part of the manufacturing process is the most labour intensive? Which part consumes the most energy?
At our factory, most employees work with weaving, where we have 180 weaving machines. When it comes to energy consumption, dying and stabilisation of the fabric requires the most energy in the form of water, steam and electricity.

What investments have you made in new, more environmentally friendly equipment?
Ever since we got started in 2000, we've consciously strived to choose the most environmentally friendly equipment possible. Our machines for warp dying have a closed-loop water system that requires much less water because you don't need to dip the thread as many times in the dyebath. Also, the dye doesn't oxidise as easily, which means that we are able to use about 30 per cent less salt.  Today, the most common way of dying denim is with an open water system, which consumes much more water and salt. We also use glucose reducing agents, which are environmentally friendly.  Just over 5 years ago, we were able to start using black liquid dyes manufactured in Spain, which are much more environmentally friendly than black solid dyes. That was a significant improvement for us.


What changes do you plan on implementing in the future to reduce your environmental footprint and energy consumption?
We're certain that the requirements and awareness of environmental issues and sustainable manufacturing will continue to increase. So, we will continue what we already started by trying to find the most environmentally friendly, energy-efficient alternatives. In 2014, we plan to start using new dyeing machines that are designed to use 40 per cent less energy and 40 per cent less chemicals than the machines we are using now. We also hope that there will be more options available in the future for environmentally friendly liquid dyes, because these require less water. Today, there are only a few suppliers to choose from, so the supply is limited and prices are high. But, there are already good environmentally friendly chemicals available that meet the requirements of REACH, GOTS and Öko-Tex.


[1] ETP (Effluent Treatment Plant), water treatment plants that have been specially designed for treating water used in industrial manufacturing processes.