Grantee Research Project Results
Final Report: Threading the Needle: Composting to Colorants
EPA Grant Number: SU836765Title: Threading the Needle: Composting to Colorants
Investigators: Sarkar, Ajoy K.
Institution: Fashion Institute of Technology
EPA Project Officer: Page, Angela
Phase: I
Project Period: October 1, 2016 through September 30, 2017
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2016) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , P3 Awards , P3 Challenge Area - Chemical Safety
Objective:
Textile waste accounts for approximately six percent of the total generated municipal waste. Since population growth and consumption of textiles are closely intertwined, the problem of waste generation and disposal with consequent strain on the environment will only intensify in the coming decades. Novel approaches to sustainability in the textile and clothing supply chain that will have an impact on reducing the stress on the environment are greatly needed. Ideas include measures to reduce pollution at the manufacturing stage, as well as actions to reduce waste after consumer use. At the manufacturing stage, the potential of natural colorants to reduce pollution is an intriguing idea. On the other end of the spectrum, biodegradation or composting of textiles instead of disposing in landfills is a potential solution to the textile waste problem. We proposed to "Thread the Needle," in other words, plot a route between the two seemingly disparate solutions, namely composting of textile waste and use of natural colorants for textiles. Specifically, this project demonstrated the potential for transforming fabric waste from any point in the supply chain — design, garment production, or post-consumer textile waste — to create new raw material; in particular, natural colorants that can be used to reduce pollution at the manufacturing stage.
Summary/Accomplishments (Outputs/Outcomes):
Fashion design students use 100% cotton muslin fabric for their draping, sewing, and patternmaking classes. In the course of 1 week, classrooms at FIT generate over 100 lbs. of cotton muslin scraps. Traditionally, this waste has gone to landfills. For this project, cotton muslin collection bins were placed in classrooms. Fabric then was shredded and readied to be biodegraded. Compost mixtures were started with 50% food waste and 50% cotton muslin plus added moisture. After all of the water, food, and textile waste were added to the composter, they were mixed thoroughly by spinning the composter. The composter was spun every other day to increase available oxygen and maintain aerobic conditions. Finally, the decomposed material was moved to a vermicomposting system containing redworms (Eisenia foetida) for final decomposition and maturation. Upon completion of composting, the finished humus was tested for overall agricultural quality using the U.S. Composting Council’s Test Methods for the Examination of Composting and Compost by an independent certified testing laboratory. The quality of the compost was found to be good as per values of total nitrogen, organic matter, and carbon-to-nitrogen ratio.
The second objective of the study was to utilize cotton compost as addition to agriculture growth media to cultivate dye plants. The purpose of the agriculture portion of the study was to determine whether the benefits from adding composted cotton to agriculture media are significant. The study was conducted in controlled greenhouse environments to determine whether there is a noticeable difference in germination rate and seedling development comparing plant medium with 10% composted cotton (referred to as “treated”) and the same soil without cotton compost (referred to as “untreated”). The study focused specifically on two plants that yield natural colorants. Japanese Indigo (Polygonum tinctorium) was explored partly due to the popularity of denim, and partly due to current re-shoring activity of major U.S. textile mills. Dyers’ Coreopsis (Coreopsis tinctoria), also called plains coreopsis or calliopsis, was studied due to its popularity with craft dyers, as it provides a variety of colors including yellow, orange, red, and brown.
In order to control variants, the indigo plants and coreopsis plants were grown separately under lights in two unattached grow tents to avoid light, pathogen or pest contamination. Both sets of plants were grown from high-quality, professionally collected and winnowed seed. Each tent contained one 540-watt LED emitting the proper red and blue color spectrum, to bring the plants from germination (blue) through harvest (red). For coreopsis, the germination rate was 16.36% for the untreated versus 37.09% for the compost-enriched soil. For indigo, the germination rate was 42.11% and 40% for treated and untreated soil, respectively. The light height from the plant tips was adjusted between 45”- 48” based on plant activity. Length of day, temperature, relative humidity, alkalinity, watering and nutritional application and contents were monitored. Both the indigo and coreopsis were under light 18 hours per day and in complete darkness for 6 hours per day for 90 days, with the coreopsis length of day intentionally declined by one hour per day after healthy vegetative growth was attained in order to initiate flowering. This was not necessary with the indigo. As the indican appears in the leaf and flowering is of no advantage, the light was continued at 18-hour days throughout the experiment. The ambient temperature was monitored at 70-75º F, and the soil temperature kept at 72ºF. The relative humidity achieved was 45%, the pH averaged 6.5 – 7.5. The plants were watered at the same time every day with the same equipment in order to achieve a consistent environment. Nutrition was applied twice per week, using commercially purchased organic inputs of nitrogen, phosphorous, and potassium in different ratios. Nitrogen was favored for vegetative growth, phosphorous for building roots, and potassium to produce proficient flower blooms, in order to create enough biomass to extract color. The same person applied nutritional inputs to both sets of plants in order to maintain procedural consistency. It was observed that the seedlings in the treated group were noticeably healthier and longer in height. Subsequently, the seedlings were transferred to pots that measured 6.25” by 6.25” by 10” deep at a seedling height of approximately 6” tall. After seven weeks, the coreopsis plants began to flower. It was observed that flowers from the treated soil had larger petals and seemed brighter.
The final objectives were to extract natural colorants from plants and evaluate the extracted natural colorants for color depth and colorfastness properties on a cotton fabric. Flowers from the coreopsis plants were dried and pulverized. Extraction of colorant was done in a soxhlet apparatus using ethanol. Finely crushed dried flowers were packed in an extractor thimble, and extraction was conducted with ethanol. The extractant was used as the dyeing medium for dyeing cotton fabric pre-mordanted with aluminum sulfate. Distilled water extraction was another method that was investigated. Dried flowers were boiled in water. After filtration, the extractant was used as the dyeing medium along with aluminum sulfate as the mordant. The function of the mordant was to impart affinity and form a bridge between the natural colorant and the cellulosic fabric. For the aqueous extractant, dyeing was done in a computer-controlled IR dyeing machine. Fabric was introduced into the dyeing solution at room temperature. Temperature was raised to a boil, and dyeing continued at boil for an hour. After dyeing, fabric was rinsed in deionized water, washed using a non-ionic detergent and air-dried. Color strength was evaluated using K/S values generated by a spectrophotometer. K/S is a function of color depth. The higher the value of K/S, the greater the color strength.
Initial results show that the fabric dyed with ethanol-extracted coreopsis colorant from treated soil had a higher K/S value compared with a K/S value for untreated soil. Similarly, fabric dyed with water-extracted coreopsis colorant from treated soil had a higher K/S value compared with the K/S value for untreated soil. Indigo pigment was extracted from Japanese Indigo by two methods. In the first method, harvested leaves were steeped in warm water in an indigo vat for 48 hours. After straining the liquid, sodium carbonate was added to make the vat alkaline, followed by aerating the vat for 15 minutes to precipitate the pigment. Sodium hydrosulfite was then added and the bath allowed to stand for an hour. Subsequently, cotton fabric was introduced into the vat for 10 minutes. After 10 minutes, the fabric was removed and oxidized by drying in air for 15 minutes. The process was repeated three times. Initial results show that the fabric dyed with indigo colorant from treated soil had a slightly higher K/S value compared with the K/S value for untreated soil. Finally, the dyed fabric was air-dried overnight, rinsed in deionized water and washed using a non-ionic detergent. The second method involved fermentation of indigo leaves in a warm and moist environment inside a thermocol container. The leaf pile is being turned over once a week to ensure uniform fermentation. The process will be continued for four to six weeks. At the end of the fermentation process, the resulting pigment will be reduced with alkali and used for dyeing cotton fabric. The fermentation experiments are currently underway.
Fabrics dyed with colorants from untreated soil and treated soil were also tested for colorfastness. Colorfastness to washing and perspiration were done according to AATCC Test Method 61 and AATCC Test Method 15, respectively. Light-fastness testing was done according to AATCC Test Method 16E. Change in shade was evaluated using the AATCC Gray Scale for Evaluating Change in Color, and color transfer was evaluated using the AATCC Gray Scale for Evaluating Staining. Scales ranged from 1 to 5 with higher grades indicating better performance. The colorfastness data indicates that natural indigo colorant performed better in all tests as compared to both aqueous and ethanol-extracted coreopsis. Therefore, for Phase II, additional studies will be focused on natural indigo colorant.
Conclusions:
The project accomplished the stated goal of sustainability as defined in the National Environmental Policy Act of 1969 (NEPA), which is to “create and maintain conditions, under which humans and nature can exist in productive harmony, that permit fulfilling the social, economic, and other requirements of present and future generations.” In addition to the environmental aspect of sustainability, the project enhanced the social aspect of sustainability through education of the community in general, and in particular, the student population. The economic aspect of sustainability was addressed by this project through its potential for adoption and long-term viability. Moving forward, the study will be extended to all forms of textile waste, with the compost being used on small farms and expanding the scope of the project to growing natural fibers. The ultimate goal is to germinate the rudiments of a circular fashion economy where waste from one cycle is used to create raw materials for a successive cycle, and also to create new jobs and opportunities in the process.
Supplemental Keywords:
waste to materials, environmentally benign substitute, sustainable manufacturing, environmental education, natural dyes, cotton muslinThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.