Biodegradability Testing

OECD Biodegradability Tests

OECD 301 Testing– Ready/Ultimate Biodegradability (Includes OECD 310)

OECD 301 series (OECD 301A, OECD 301B, OECD 301C, OECD 301D, OECD 301E, OECD 301F) allows for direct, explicit certification of a material’s biodegradability under the terms of Ready or Ultimate Biodegradability.

What are Readily Biodegradable Materials?

Readily biodegradable materials rapidly break down into simpler substances. To qualify, at least 60% (or 70% for some tests) of the material’s organic carbon must convert to carbon dioxide within a 10-day period and fully within 28 days. This 10-day window starts once 10% of the carbon is converted.

What are Ultimately Biodegradable Materials?

Ultimately biodegradable materials (under the subclassification of Inherent Biodegradability) require 60% (or 70% for some tests) of the organic carbon in the material to be mineralized throughout the test. The test can be extended beyond 28 days.

Achieving the passing thresholds is representative of complete degradation of the test material as the remaining fraction of 30-40% of the organic carbon is assumed to be assimilated by the biomass or present as products of biosynthesis.

This is RespirTek’s most requested series of methods for those with products whose fate is a wastewater treatment facility. The results from these methods can often also be relevant to many disposal environments.

OECD 302B– Inherent Biodegradability: Zahn-Wellens/ EVPA Test

OECD 302B determines ultimate biodegradability of components in an aqueous aerobic environment. This test allows for the use of biomass that has been pre-adapted to the presence of the test material. Pre-adaptation of the biomass provides data regarding the test material’s biodegradability in long-term, steady-state conditions in which the introduction of the test material is persistent.

OECD 208– Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test4

OECD 208 determines the effects on seedling emergence and early growth of plants.

OECD 209– Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation)

OECD 209 assesses the effects of a substance on micro-organisms from activated sludge of wastewater treatment plants.

The test results serve as an indicator of suitable non-inhibitory concentrations of test substances and allow the determination of ECx and/or NOEC values of the test substance.

OECD 311– Anaerobic Biodegradability of Organic Compounds in Digested Sludge

OECD 311 is used to assess the biodegradability of organic chemicals under anaerobic digester conditions. Residual chemicals that are not degraded in standard aerobic treatment basins will often end up in anaerobic digesters as a last treatment option prior to discharge to the environment. This test method may also be useful for evaluating the biodegradation of solid-matrix materials whose expected fate is a digester system.

ASTM Biodegradability Tests

ASTM D5210– Standard Test Method for Determining the Anaerobic Biodegradation of Plastic Materials in the Presence of Municipal Sewage Sludge

ASTM D5210 is very similar to OECD 311 and is used to assess the biodegradability of organic chemicals in anaerobic conditions. This test method simulates conditions similar to that in an anaerobic digester, which is a biological reactor typically used to digest sewage sludge after water treatment. Residual chemicals that are not degraded in standard aerobic treatment basins will often end up in anaerobic digesters as a last treatment option prior to discharge to the environment.

ASTM D5338– Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials Under Controlled Composting Conditions, Incorporating Thermophilic Temperatures

ASTM D5338 evaluates the biodegradation of plastic materials under controlled composting conditions. Controlled composting conditions are considered those conditions where oxygen, temperature, moisture, and pH levels of the compost are maintained at optimal levels. Municipal and industrial composting facilities are the relevant disposal compartment for materials that undergo assessments based on this type of test method. The duration of the test can be up to 180 days. No explicit thresholds or classifications are permitted based on method language for certification purposes.

ASTM D5864– Standard Test Method for Determining Aerobic Aquatic Biodegradation of Lubricants or Their Components

ASTM D5864 evaluates the aerobic biodegradation of lubricants or lubricant components in aqueous solutions with low concentrations of inoculums. The test objective is to determine the degree of aerobic aquatic biodegradation of lubricants under laboratory conditions. A variety of inoculums sources from soil, surface water, and activated sewage sludge may be used. The test duration is at least 28 days or until a plateau in biodegradation is reached. No explicit thresholds or classifications are permitted based on method language for certification purposes.

ASTM D5988– Standard Test Method for Determining Aerobic Biodegradation in Soil of Plastic Materials or Residual Plastic Materials After Composting

ASTM D5988 evaluates the aerobic biodegradation of plastic materials in soil. No explicit thresholds or classifications are permitted based on method language for certification purposes. ASTM D5988 is equivalent to ISO 17556.

This method has also been employed to understand the biodegradation of non-composted materials in natural soil conditions.

ASTM D6400– Standard Specification for Compostable Plastics

ASTM D6400 is a specification providing criteria to make claims of “Compostable in municipal or industrial aerobic composting facilities”. The specification involves testing the plastic material for (1) disintegration (2) biodegradation and (3) ecological impacts. A heavy metals analysis is also conducted to ensure the material is within standard limits provided for healthy composting. The disintegration testing and biodegradation testing are conducted concurrently. Disintegration is evaluated by sieving the compost-plastic mixture after a set time to measure the amount of plastic that passes through the sieve. Biodegradation is a measure of the conversion of organic carbon to CO2 under aerobic, thermophilic composting conditions. ASTM D5338 is the test method used to evaluate the biodegradation. Ecological impacts are evaluated via OECD 208, which is a plant growth test. Residual compost is mixed with soil in specified proportions to evaluate the ability of standard plant-types to thrive in the compost residues. This specification allows for the classification of a plastic material of Compostable if all threshold criteria are met. ASTM D6400 testing ensures that the test material will complement the composting process at a municipal or industrial composting facility.

ISO Biodegradability Tests

ISO 17556– Determination of the ultimate aerobic biodegradability of plastic materials in soil by measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved

ISO 17566 evaluates biodegradability in a natural soil environment. The test can be extended up to two years.

ISO 16221– Guidance for determination of biodegradability in the marine environment

ISO 16221 evaluates biodegradability in marine seawater environment.

Usually, ISO standards are used to assess biodegradation when driven by an external regulatory or client source. The standards do not explicitly provide a threshold from which to base claims of “Biodegradable”, which is in contrast to a significant number of OECD and ASTM methods.

ISO 9439– Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium — Carbon dioxide evolution test

ISO 9439 evaluates the aerobic biodegradability of organic compounds in an aqueous medium using common sewage sludge found in wastewater treatment plants. This test method is similar in setup to OECD 301B. Biodegradation is measured as the percentage of organic carbon converted to CO2. The duration of the test is 28 days. No explicit thresholds or classifications are permitted based on method language for certification purposes.

ISO 14593– Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium — Method by analysis of inorganic carbon in sealed vessels (CO2 headspace test)

ISO 14593 evaluates the aerobic biodegradability of organic compounds in aqueous medium using common sewage sludge found in wastewater treatment plants. The test is conducted in sealed vessels similar to OECD 310. Biodegradation is measured as the percentage of organic carbon converted to CO2. The test duration is 28 days. No explicit thresholds or classifications are permitted based on method language for certification purposes.

ISO 14852– Determination of the ultimate aerobic biodegradability of plastic materials in an aqueous medium — Method by analysis of evolved carbon dioxide

ISO 14852 evaluates the ultimate aerobic biodegradability of plastic materials in aqueous medium. This test method is similar in setup to ISO 9439 but has been adapted to specifically address the challenges of testing plastic materials. Consequently, however, no explicit thresholds or classifications are permitted based on method language for certification purposes. Biodegradation is measured as the percentage of organic carbon converted to CO2. The test duration cannot exceed 6 months.

ISO 14855– Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions — Method by analysis of evolved carbon dioxide

ISO 14855 evaluates the ultimate aerobic biodegradability of plastic materials under controlled composting conditions. This test method is nearly identical to ASTM D5338 in execution. Controlled composting conditions are maintained throughout the test, including oxygen and moisture content, temperature, and pH. Biodegradation is measured as the percentage of organic carbon converted to CO2. The test duration is 180 days. No explicit thresholds or classifications are permitted based on method language for certification purposes.

Why RespirTek?

At RespirTek, our biodegradability testing labs offer comprehensive biodegradability assessments to ensure that your products meet domestic and international standards. We will partner with your team to help you find the right biodegradability tests for your needs. We use certified, internationally recognized testing methods to produce detailed, accurate results.

Our precision testing will provide detailed insight into your product’s biodegradation process, and we’ll communicate with you closely throughout the entire undertaking.

Please contact us at 228.392.7977 to schedule a free 30-minute consultation with our technical team to learn how your company can benefit from our biodegradability services.