1. What does “biodegradation” mean?

Biodegradation is the biological breakdown of organic contaminants by microorganisms like fungi or bacteria when oxygen is present. The assessment system for biodegradation of textiles, developed by the Hohenstein Institute, includes the evaluation of the aerobic biodegradability of textiles via a controlled soil burial within a defined test period. Controlled means, there are sufficient oxygen and living organisms in the soil. The microorganisms have multiple biological degradation mechanisms for materials consisting of natural and synthetic fibres.

2. Why is the soil burial test used as test method?

It must be ensured that products destined for the landfill or composting actually degrade in the soil and that possible residues contained from finishing do not have a negative effect in the soil. Thus, quoting the U.S. Environmental Protection Agency, the biodegradation is one of the most important factors in assessing the environmental fate of materials or products.

3. For which products and branches of industry is this test suitable?

Testing the biodegradation is suitable for all products, especially for those which degrade extremely fast or very slow under the action of microorganisms.

  • Manufacturers, finishers and traders of yarns, fibers, filaments, nonwovens, textiles and garments
  • Geo- and agrotextiles
  • Producers of technical textiles for e.g. automotive industry
  • Chemical industry
  • Recycling companies

4. How important is this test regarding the whole sustainable context in the textile chain?

After the use there are several opportunities for textiles:
Either there is a way of return into the cycle as second hand products, by down-cycling, up-cycling or recycling. Otherwise the disposal is pending. This can be done by thermal recycling, landfill or composting. For a complete sustainable profile, manufacturers need to realize that not only the environmental impact of product components and the manufacturing process are relevant, but also the environmental fate of the product once it reaches the end of its useful life.

Relevant for marketing

5. What kind of marketing tools can be purchased?

Products whose residues are classified as ecotoxicological safe in the test assessment, can be awarded with the Hohenstein certificate “Biodegradable” (for B2B) or a Hohenstein quality label “Biodegradable” (for B2C). The label shows the rate of mass loss in percentage. On the back the test parameters are listed.

6. What are the advantages of this product reward?

  • Product optimization
  • Identification of biodegradable textiles
  • Interesting for the risk assessment of functional textile finishing
  • Providing a neutral reference for product comparison, e.g. for choosing suppliers

in B2B sector:

  • Independent evidence of biodegradation as selling point / differentiation feature
  • Assessment of recycling processes
  • Quality assurance by ecotoxicological safety
  • Comparison of degradation rate of different products tested under the same conditions

in B2C sector:

  • Marketing tool – advertising effect and selling point
  • Quality assurance of ecotoxicological safety
  • Supporting purchase decisions
  • Expending target groups e.g. ”Lifestyles of Health and Sustainability“

7. What are the requirements for my product to receive a certification or label?

The marketing tools certificate & quality label “biodegradation” can be awarded, provided that a decomposition has occured and the ecotoxicological safety has been detected.

8. What is the difference between a certification and a label?

The quality label serves as an advertising tool for the B2C business (e.g. as a hang tag on the product), the certificate serves as a document for the B2B sector.

9. What are the steps to get a certification?

  • Sending the test material to the Hohenstein Laboratories (including sufficient precise product descriptions such as material composition, article number etc.)
  • Passing the test requirements (see question 7)
  • Certification: signing the declaration of conformity
  • Label: signing declaration of conformity and label use agreement
  • Issuance of the certificate / label file

10. What are the costs for certification and label user fee?

  • Hohenstein certificate in German and English: 500 €
  • Hohenstein quality label in German and English: 850 €
  • Related costs for each additional language: 200 €

11. How to evaluate the biodegradation of products?

The test is based on European Standards containing the soil burial for testing the degradation behaviour as well as the environmental compatibilities of the residues. The test is performed under standardized laboratory conditions or under field conditions (exposed to the external climatical conditions). Besides, additional microorganisms can be added to controllably accelerate the degradation process.

12. What are the requirements for a sample for being tested?

  • Information about the material properties e.g. the percentage composition of the material or material mix, weight per unit area, volume, surface structure, thread construction and finishing
  • The material samples are applied in equal sizes for a defined relative contact surface = 100 cm2 (5x20cm)

13. What is the most reasonable test method for my product?

The customer is free to choose the period of soil burial, the soil burial conditions as well as whether to test with or without additional microorganisms for a faster degradation. Based on our testing experience, we offer three proven standards:

  • For all regenerated and mixed fibres, we recommend a soil burial under laboratory conditions without additional microorganisms.
  • For synthetic fibres such as PES or PA we recommend soil burial under laboratory conditions with additional microorganisms for a faster degradation, since synthetic fibres usually decay relatively slow.
  • For natural fibres we recommend soil burial under field conditions without additional microorganisms. This slowed degradation may be of interest to compare the degradation behaviour of different fast degrading products, or to elaborate the impact of textile finishing to the decay behaviour.

In principle we enable individual experimental set-ups, e.g. the soil burial of a fully assembled product, the measurement of tensile strength, or an extension of the test period within the two years. Feel free to contact us for further details.

14. What is the test procedure?

  • First, four dates of excavation are scheduled, depending on the total soil burial time
  • After material preparation, the test specimens are buried in test soil together with the control material under predefined conditions.
  • After the several incubation times, samples are excavated. The residues will be cleaned up. Several parameters, like the loss of mass and the visual appearance of the sample as well as the ecotoxicological safety of substances released to the test soil influence the subsequent evaluation and rating.

18. How much material is necessary for the test procedure?

Depending on the soil burial time and the required material specimens, about 0,25 m2 per sample material / test are required.