Water Pollution in the Textile Dye Industry

The textile industry is considered to be one of the largest consumers of fresh water. Nearly all of the water used to make textiles and fabrics is utilized during the dyeing process. This is the manufacturing step in which color is added after the fabric is woven. On average, nearly 40 gallons of water is used to color about two pounds of most manmade fabrics. Globally, we dye 39 million tons of polyester per year, using over one and one half million gallons of water annually. This water is added to pigments, pigment compounds and chlorine bleach. In addition, the water needs to be heated within a conventional process, which requires fossil fuel. Even in the most optimum of circumstances where in which waste water is treated before being released back to the earth, alarming levels of effluent discharge still exist. And in cases where uncontrolled and unsuitable conditions are in place, significant environmental damage is being cast upon our aquatic ecological system. Specifically, the conventional dyeing process uses a variety of toxic chemicals including chlorine, sulfide, formaldehyde, ammonia, oils, and grease components that deplete oxygen levels in water. In China, where most of the textile dye industry exists, they are producing 70 billion tons of wastewater annually,causing severe damage to the environment. Genetically, animals and plant life risk irreversible alteration. Even within the most optimum of water treatment technologies in place, this is clearly an unsustainable practice. In response to this problem, new technologies have emerged employing the usage of super critical carbon dioxide within a process to dye fabrics without the use of any water at all. By adding heat and pressure to CO2, it changes properties and when contained, becomes almost as dense as water. Experiments utilizing this process began about 25 years ago in Germany. Lack of funds and technological obstacles has prevented implementation on an industrial scale. Today, a company from the Netherlands known as DyeCoo has developed, built and brought to market the first waterless textile dyeing machine. Given the scale and scope of the problem, DyeCoo’s outstanding technical innovations combined with the subsequent environmental benefit are being heralded as major achievements. In February 2012, the company forged a business partnership with Nike, Inc. Reinier Mommall, CEO of DyeCoo heralded, “There is no water consumption, a reduction in energy use, no auxiliary chemicals required, no need for drying and the process is twice as fast. The excitement of Dyecoo’s success is tempered somewhat given the fact that the process only works on polyester. Although polyester makes up for about 25% of all textile processing, the technology does not work on natural fibers such as cotton. In response to this, yet another company has emerged near Barcelona, Spain with a process that manufactures blue cotton denim while dramatically cutting water consumption. Known as Clariant, they have developed a more sustainable way to produce blue denim. Like polyester, traditional methods of dyeing cotton are wasteful and pollute the earth. Some 2 billion pairs of blue jeans are manufactured each year, and each one required 2500 gallons of water to produce. The chemicals used in tandem with this process rival if not exceed that of polyester. Indigo is not water soluble, so it cannot penetrate cotton fiber. Reducing agents, such as sodium hydrosulfate separate the dye molecules from indigo so that the color will take to the fabric. In addition, conventional dyeing of denim has to be repeated some 6 to 15 times per production run to achieve the desired color using vast amounts of energy and water. Clariant has developed a sulfur based dye as a substitute for indigo. Additionally, by introducing other colors to the process such as black and gray, more design and fashion choices may be offered. These sulfur based dyes bond better with cotton fabric, eliminating wasteful rinsing and re-dyeing steps. A process that up until now had to be repeated up to 15 times on the same garment has been reduced to once, resulting in considerably less usage of water. The new dyes also allow for the finishing wash down process to be done with hydrogen peroxide instead of chlorine bleach. While making major strides in sustainability, these two companies have opened up new doors in the field of design and fashion. In addition to a broader spectrum of colors and shades, color fastness is easier to manage over longer production runs and designers can create previously unavailable effects on denim such as color gradients, shading, and imprinting. When an environmentally damaging process such as textile dye manufacturing can be improved on such a scale and create new fashion opportunities in the process, one wonders what other happy accidents are waiting to be discovered as we drive towards becoming more sustainable.