ISO 14852 Determination of the Ultimate Aerobic Biodegradability of Plastic Materials in an Aqueous Environment - Method by Analysis of Released Carbon Dioxide

With the increasing use of plastics, their recovery and disposal have become a significant challenge. Recycling should be promoted as a top priority. Biodegradable plastics are emerging as one of the available options to address these environmental challenges. Plastic materials, such as products or packaging destined for composting facilities, must be potentially biodegradable. Therefore, determining the potential biodegradability of such materials and obtaining an indication of their potential biodegradability is crucial.

The International Organization for Standardization (ISO) standard, "ISO 14852 Determination of ultimate aerobic biodegradability of plastic materials in aqueous media - Method for the analysis of carbon dioxide evolved," describes a method for determining the degree of aerobic biodegradability of plastic materials, including those containing formulation additives, by measuring the amount of carbon dioxide evolved. This method involves exposing the test material to an inoculum derived from activated sludge under aerobic conditions in a synthetic environment under standard laboratory conditions.

Although the conditions used in this standard do not necessarily correspond to optimum conditions that would allow maximum biodegradation to occur, this test method is designed to measure the biodegradation of plastic materials and provide an indication of their potential biodegradability.

This method allows to improve the assessment of biodegradation by calculating the carbon balance.

This method is applicable to the following materials:

• Natural or synthetic polymers, copolymers or mixtures thereof.
• Plastic materials containing additives such as plasticizers, colorants or other compounds.
• water soluble polymers.
• Materials that do not inhibit microorganisms present in the vaccine under the test conditions. Inhibitory effects can be determined using an inhibition control or other suitable method (e.g., ISO 8192). If the test material is inhibitory to the vaccine, a lower test concentration, another vaccine, or a previously exposed vaccine can be used.

For the purposes of this standard, ultimate aerobic biodegradability: refers to the rate of degradation of an organic compound by microorganisms in the presence of oxygen, expressed as the percentage of conversion into carbon dioxide, water and mineral salts of other elements present (mineralization) and new biomass.

The ISO 14852 standard is a globally accepted method for assessing the biodegradability of plastic materials in aqueous environments. This standard is critical for industries developing biodegradable plastics because it provides a standardized approach for measuring how effectively a material is degraded under aerobic conditions using microorganisms.

This standard includes a laboratory-based method for determining the aerobic biodegradability of plastic materials in an aqueous environment, including those containing additives such as plasticizers or colorants. This standard focuses on measuring the amount of carbon dioxide produced during microbial degradation. This indicates the extent to which the material has been degraded by microorganisms.

This method is designed to simulate the conditions in which plastics might be found in environments such as wastewater treatment plants or natural water systems and provide information about their potential environmental impacts. It is particularly important for assessing biodegradable plastics aimed at reducing pollution in environments such as marine environments, where approximately 8 million tons of plastic are discarded annually.

The ISO 14852 test method involves exposing a plastic material to an inoculum (typically activated sludge, mature compost, or soil) under controlled aerobic, mesophilic (moderate temperature) conditions. The key steps are:

• Test setup: Plastic material, used as the sole carbon source, is placed in a synthetic aqueous medium with a carbon concentration of 100–2000 mg/L. If higher concentrations are used, an optimized medium is required. Inoculum containing active microorganisms is added to initiate degradation.
• Aeration and incubation: To maintain aerobic conditions, the test mixture is continuously aerated with carbon dioxide-free air. The apparatus is shaken in the test bottles for a period generally not exceeding six months, depending on the degradation kinetics of the material.
• Carbon dioxide measurement: Carbon dioxide released during microbial degradation is captured and measured using a suitable analytical method, such as titration or infrared spectroscopy. The degree of biodegradation is calculated by comparing the carbon dioxide released, expressed as a percentage, to the theoretical maximum carbon dioxide that the material can produce.
• Optional carbon balance: This standard allows a carbon balance calculation to enhance the biodegradation assessment and provide a more comprehensive understanding of the breakdown of the material.
• Inhibition control: To ensure that the material does not inhibit microbial activity, tests include an inhibition control or reference to standards such as ISO 8192. If inhibition occurs, adjustments are made, such as lowering the test material concentration or using a pre-exposed inoculum.

The conditions in ISO 14852 are not optimized for maximum biodegradation, but are standardized to provide a consistent measure of a material's biodegradability potential. This standard is applicable to a wide range of materials, including:

• Natural and synthetic polymers, copolymers or blends.
• Plastics containing additives such as plasticizers or colorants.
• Materials designed for applications where biodegradability in aqueous environments is critical, such as packaging or agricultural films.

This standard is particularly valuable for:

• Manufacturers: To verify biodegradability claims for marketing and certification (e.g. compliance with BS EN 13432, which requires 90 percent biodegradation within a specified period).
• Researchers: Studying degradation mechanisms and developing new biodegradable materials.
• Regulators: Enforce environmental standards and reduce plastic waste in aquatic ecosystems.

The ISO 14852 standard is vital in addressing the global plastic pollution crisis. With an estimated 150 million tons of plastic currently in the oceans and thousands more tons of microplastics added each year, biodegradable plastics offer a potential solution to reduce environmental damage. By providing a reliable method for testing biodegradability, this standard ensures that materials marketed as biodegradable can effectively degrade in natural or managed environments, reducing risks to marine life and ecosystems.

Additionally, this standard supports innovation in sustainable materials. Research has shortened testing time and increased reproducibility. This development allows for faster evaluation of new biodegradable materials.

Meanwhile, while the ISO 14852 standard is a robust standard, the test conditions do not reflect optimal conditions for maximum biodegradation, so results reflect potential rather than real-world performance. Furthermore, variability in natural inoculants, such as soil from different regions, can impact reproducibility.

Consequently, the ISO 14852 standard is fundamental for assessing the aerobic biodegradability of plastics in aqueous environments. It supports the development of sustainable materials by providing a standardized and reproducible method for assessing how effectively plastics can be degraded by measuring carbon dioxide evolution. This and similar standards play a critical role in ensuring that biodegradable plastics fulfill their environmental promise, paving the way for a cleaner, more sustainable future.

Our organization, which has been operating for many years and meticulously follows global developments in science and technology, employs a team of experienced professionals and a broad infrastructure to conduct testing, measurement, and analysis in a wide range of areas for businesses across all sectors. In this context, we also provide testing services in accordance with the ISO 14852 standard "Determination of the ultimate aerobic biodegradability of plastic materials in aqueous media - Method for the analysis of released carbon dioxide."