Holiday Sweaters: use of AGMD/DCMD to treat textile waste

Knotty & Nice: New ways to treat textile wastewater

While holiday parties will be virtual this year, holiday sweaters in all their glittered, sometimes sequined, and knit glory are still making their annual appearance. Textile manufacturing is a multibillion dollar global industry, and novelty products like holiday sweaters comprise a significant market in the United States. We rely on textile products in our holiday sweaters, carpets, furniture, bedding, cars, hospitals, and more. In the United States alone, the textile market is projected to increase by 4.3% over the next seven years (1), which will lead to an increase in production waste as well. Wastewater from textile plants includes dyes, dispersants, and fixatives, or levelling agents, many of which are not biodegradable (2). In addition, dying is an inefficient process and high concentrations of textile dye never make it into the fabric. Removing the excess dye from waste water through various recycling methods is a current hot topic for research in fields of applied environmental sciences and wastewater management.

Membrane distillation is an emerging method for treating textile wastewater. New findings have shown success using direct-contact (DCMD) and air-gap (AGMD) flow cells to recycle textile effluent (3). DCMD is a conventional filtration technique, where the filter membrane makes contact with liquid phases on both sides. The feed solution is heated, so that gas phase water molecules can diffuse through the membrane and condense in the permeate tank (3). In AGMD, the permeate side is insulated from an air filled gap, which reduces conductive heat loss. New applications with AGMD may have some color removal and thermal efficiency benefits relative to DCMD (4). In a study from 2018, the use of commercial PTFE membranes with AGMD, successfully recovered pure water from a solution of salts, dye, and surfactant (4). Further research is needed to effectively evaluate the efficiency of membrane distillation as a treatment method, as effluent constituents vary within factories.

While the complexities in textile processing and the wastewater produced pose environmental challenges, consumers can engage in green initiatives like regifting, donating, or reusing holiday textiles to spread the joy just a bit further. ‘Tis the season!

References

  1. Textile Market Size, Share & Trends Analysis Report By Raw Material, By Product, By Application, By Region, and Segment Forecasts, 2020-2027. Grand View Research. Feb, 2020. Retrieved from https://www.grandviewresearch.com/industry-analysis/textile-market
  2. Singh R.P., Singh P.K., Gupta R., Singh R.L. (2019) Treatment and Recycling of Wastewater from Textile Industry. In: Singh R., Singh R. (eds) Advances in Biological Treatment of Industrial Waste Water and their Recycling for a Sustainable Future. Applied Environmental Science and Engineering for a Sustainable Future. Springer, Singapore. https://doi.org/10.1007/978-981-13-1468-1_8
  3. Leaper S, Abdel-Karim A, Gad-Allah TA, Gorgojo P. Air-gap membrane distillation as a one-step process for textile wastewater treatment. Chem Eng J. 2019;360:1330-1340. doi:https://doi.org/10.1016/j.cej.2018.10.209