Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
BS EN ISO 14855 — Determination of Ultimate Aerobic Biodegradability of Plastics under Controlled Composting Conditions Standard Series
Determination of the Ultimate Aerobic Biodegradability of Plastics under Controlled Composting Conditions (2012/2009 Edition)
♻️ BS EN ISO 14855 is a method standard for the determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions, developed jointly by ISO/TC 61 “Plastics” and CEN/TC 249 and published in the UK by BSI as a British Standard. The series evaluates the degree of plastic biodegradation by analyzing the carbon dioxide evolved during degradation — the core test method for “compostable plastic” certification, biodegradable material R&D, and product compliance claims.
💡 The core logic of biodegradability testing: under composting conditions, microorganisms decompose the plastic and its carbon is converted to carbon dioxide (CO₂). By measuring the CO₂ released relative to the material’s theoretical carbon content, the “ultimate biodegradation rate” can be quantified.
1. Series Overview 📌
The BS EN ISO 14855 series comprises two parts. Part 1 (2012 edition) specifies the general method; Part 2 (2009 edition) specifies the gravimetric measurement of carbon dioxide evolved in a laboratory-scale test. Together they supersede the 2004 BS EN ISO 14855. UK participation was entrusted to Technical Committee PRI/21 (Testing of plastics).
2. Series Structure and Scope 🧩
The parts and their scopes are shown below. The series applies to the evaluation of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions.
| Standard | Title | Core Content | Typical Use |
|---|---|---|---|
| BS EN ISO 14855-1:2012 | Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions — Method by analysis of evolved carbon dioxide — Part 1: General method | General rules for controlled composting conditions, CO₂ analysis, and biodegradation rate calculation | Compostable plastic certification, biodegradable material evaluation |
| BS EN ISO 14855-2:2009 | Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions — Method by analysis of evolved carbon dioxide — Part 2: Gravimetric measurement of CO₂ evolved in a laboratory-scale test | Gravimetric measurement of evolved CO₂ to calculate biodegradation rate | Precise laboratory measurement, alternative method verification |
⚠️ Test conditions must be strictly controlled: the compost inoculum (active compost), temperature (typically about 58 °C), humidity, aeration, and test duration all affect the result. Tests must run under the specified controlled conditions to be reproducible and comparable.
3. General Method (Part 1) 🔍
BS EN ISO 14855-1 specifies the general method, mainly covering:
- Test principle: under controlled composting conditions, mix the plastic specimen with active compost, continuously aerate, and measure the CO₂ evolved.
- Test conditions: specify the compost medium, temperature, humidity, aeration rate, and test duration (usually weeks to months).
- CO₂ analysis: measure the evolved CO₂ by absorption, titration, or infrared methods.
- Biodegradation rate calculation: express the biodegradation rate as the percentage of the carbon in the evolved CO₂ relative to the specimen’s theoretical carbon content.
- Assessment and reporting: judge compostability by the biodegradation level achieved (e.g., above 90%) within the test period.
4. Gravimetric Measurement (Part 2) ⚖️
BS EN ISO 14855-2 specifies the gravimetric measurement of CO₂ evolved in a laboratory-scale test:
- Principle: absorb the evolved CO₂ in an alkaline solution (e.g., barium hydroxide / sodium hydroxide) and determine the CO₂ by weighing the absorption gain or by titration.
- Apparatus: specify the test vessel, aeration and absorption system, and temperature control requirements.
- Measurement and calculation: weigh the absorbent periodically and calculate the cumulative CO₂ release and biodegradation rate.
- Relationship with Part 1: Part 2 may be used as an alternative or supplement to the general method, especially where higher precision or verification is needed.
| Method | CO₂ Measurement | Feature | Application |
|---|---|---|---|
| General method (Part 1) | Absorption / titration / infrared | General, broad applicability | Certification evaluation, routine testing |
| Gravimetric (Part 2) | Weighing after absorption / titration | Precise, relatively simple apparatus | Laboratory research, verification |
✅ Assessment reference: many compostable plastic certification schemes require an ultimate biodegradation rate of at least 90% within the specified test period (and compliance with additional requirements such as disintegration and ecotoxicity). The specific limit depends on the relevant certification scheme.
5. Engineering Practice 🛠️
- 🔍 Product certification: compostable tableware, packaging bags, and other products require biodegradation rate testing per this series as certification evidence.
- 🔧 Material R&D: evaluate the effect of biodegradable material formulations and additives (e.g., PLA, PBS, PBAT) on degradation performance.
- 📊 Comparative evaluation: comparisons between materials or formulations must be run under identical controlled conditions.
- 📋 Compliance claims: claims of “compostable” or “biodegradable” should be supported by traceable test reports based on the standard test methods.
6. Test Duration and Result Assessment 📅
Biodegradation tests typically run for weeks to months, and the end condition and assessment significantly affect the result. The standard generally specifies that the test ends when the biodegradation curve reaches a plateau (little change over several consecutive weeks) or when the agreed test period is reached. Assessment should consider:
- 📈 Biodegradation rate: the carbon in the evolved CO₂ as a percentage of the theoretical carbon content.
- ⏱️ Test duration: most compostable certification schemes require reaching the agreed level within a defined period (e.g., 180 days or six months).
- 🏗️ Disintegration: sieving of the compost after the test to evaluate physical breakdown.
- 🌿 Compost quality and ecotoxicity: evaluate phytotoxicity and ecotoxicity to ensure no harmful residues.
It is important to note that ultimate biodegradability (mineralization of carbon to CO₂) differs from disintegration (physical fragmentation). A material may disintegrate well but degrade slowly. To be judged “compostable”, a product should meet the biodegradation, disintegration, and ecotoxicity requirements together, as defined by the relevant certification scheme.
7. Frequently Asked Questions ❓
❓ Q: How is the biodegradation rate calculated?
A: Biodegradation rate = (carbon in evolved CO₂ ÷ theoretical carbon content of specimen) × 100%, where the theoretical carbon content is computed from the material’s chemical composition.
A: Biodegradation rate = (carbon in evolved CO₂ ÷ theoretical carbon content of specimen) × 100%, where the theoretical carbon content is computed from the material’s chemical composition.
❓ Q: Why is active compost required as the inoculum?
A: Microorganisms in the compost drive degradation. Using active, mature compost ensures sufficient microbial activity so that degradation reflects the material’s behavior in a real composting environment.
A: Microorganisms in the compost drive degradation. Using active, mature compost ensures sufficient microbial activity so that degradation reflects the material’s behavior in a real composting environment.
❓ Q: How is the gravimetric method (Part 2) vs. the general method (Part 1) chosen?
A: Part 1 is a general, broadly applicable method; Part 2 uses gravimetric measurement, suited to precise laboratory determination and verification. Choose by purpose and precision, or cross-check.
A: Part 1 is a general, broadly applicable method; Part 2 uses gravimetric measurement, suited to precise laboratory determination and verification. Choose by purpose and precision, or cross-check.
🔍 Q: What biodegradation level counts as “compostable”?
A: Common certification requires an ultimate biodegradation rate of at least 90% within the agreed test period, together with additional disintegration, compost quality, and ecotoxicity requirements; the specific limit depends on the relevant standard or certification scheme.
A: Common certification requires an ultimate biodegradation rate of at least 90% within the agreed test period, together with additional disintegration, compost quality, and ecotoxicity requirements; the specific limit depends on the relevant standard or certification scheme.