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Plastics and packaging materials can be more fantastic
if it´s biodegradable

Instrument for biodegradability analyses

The degradation of biodegradable polymers and biodegradable plastics crucially depends on the environments they may end up in, such as soil, fresh or marine water, landfill or composting site. Owing to the great variations in natural conditions, several tests are needed to determine the fate of a polymer material in real life and to study its biodegradability in different environments. In aerobic environments, the biodegradability is usually determined by measuring oxygen demand in a closed respirometer or the amount of carbon dioxide evolved over time. When oxygen is not available under the anaerobic conditions, the measurement of released biogas (a mixer of methane and carbon dioxide) is the method for evaluating anaerobic biodegradability. Biodegradability test can be performed under “certification” or “screening” conditions. Certification conditions are required in cases where the results are intended to be used for certification and/or making public claims on biodegradability, whereas screening conditions are suggested for internal research purposes.

The Gas Endeavour® is a novel respirometer for both anaerobic and aerobic biodegradation analyses. For anaerobic biodegradability test, the Gas Endeavour® provides efficient and accurate data analyses on biogas release in any aqueous medium, controlled slurry digestion system and high-solids anaerobic digestion condition. In case of aerobic biodegradability test, the Gas Endeavour® is intended be used together with our patented in-situ carbon dioxide absorption kit to function as a closed respirometer system for measuring oxygen demand.  With help of in-situ carbon dioxide absorption kit, the Gas Endeavour® becomes a powerful tool and analysis platform for both anaerobic and aerobic biodegradability analyses in various environmental conditions and support the most of important ISO, European and American standards for anaerobic and aerobic biodegradability evaluation.

Analyse more and more professionally to make the most out of nature

Areas of application

related to anaerobic and aerobic biodegradability analyses

Gas Endeavour® allows for continuous and on-line monitoring of released biogas in any aqueous medium, controlled slurry digestion systems and high-solids anaerobic digestion conditions. The instrument can be used to perform anaerobic biodegradability analyses according to following norms:

  • ISO 14853 – ultimate anaerobic biodegradation of plastic materials in an aqueous system
  • ISO 13975 – ultimate anaerobic biodegradation of plastic materials in controlled slurry digestion systems
  • ISO 15985 – ultimate anaerobic biodegradation and disintegration under high-solids anaerobic digestion conditions
  • ISO 11734 – ultimate anaerobic biodegradability of organic compounds in digested sludge
  • ASTM D5511 – anaerobic biodegradation of plastic materials under high-solids anaerobic digestion
  • ASTM D5210 – anaerobic biodegradation of plastic materials in the presence of municipal sewage sludge
  • ASTM D5526 – anaerobic biodegradation of plastic materials under accelerated landfill conditions
  • OECD 311 – anaerobic biodegradability of organic compounds in digested sludge

Determination of aerobic biodegradability in soil, aqueous environment, seawater and marine sediment can be done by either measuring the oxygen demand in a closed respirometer or analysis of evolved carbon dioxide.

Together with the in-situ carbon dioxide absorption kit, Gas Endeavour® works as a volumetric respirometer and allows for continuous and on-line measurement of oxygen consumption or depletion caused by aerobic respiration of microorganisms. The instrument can therefore be used to perform aerobic biodegradability analysis according to following norms:

  • ISO 14851 – ultimate aerobic biodegradation of plastic materials in an aqueous system
  • ISO 17556 – ultimate aerobic biodegradation of plastic materials in soil
  • ISO 18830 – aerobic biodegradation of non-floating plastic materials in a seawater/sandy sediment interface
  • ISO 23977-2 – aerobic biodegradation of plastic materials exposed to seawater (part 2)
  • OECD 301 – ready biodegradability of chemical materials in aerobic aqueous medium

Aerobic biodegradability can also be measured based on analysis of evolved carbon dioxide according to following standards. However, test protocols based on same purpose are available based on measurement of oxygen demand in a closed respirometer which is the recommended method for Gas Endeavour® with a simplified system configuration, higher measurement precision and accuracy. 

  • ISO 14852 – ultimate aerobic biodegradability of plastic materials in an aqueous medium
  • ISO 22404 – aerobic biodegradation of non-floating materials exposed to marine sediment
  • ISO 19679 – aerobic biodegradation of non-floating plastic materials in a seawater/sediment interface
  • ISO 23977-1 – aerobic biodegradation of plastic materials exposed to seawater (part 1)

Gas Endeavour® can be configured for home composting analysis according to AS 5810 or ISO 14851. The same configuration may also be utilised to evaluate aerobic biodegradability of polymer samples under the same temperature range of controlled composting conditions using industrial compost as inoculum. This arrangement should be recognised as a simplified method based on measurement of oxygen demand or depletion caused by aerobic respiration of compost microorganisms. It does not necessarily comply with the “certification” method ISO 14855-1, but rather serves as a practical analytical tool of biodegradability evaluation under similar conditions of controlled composting facility for internal study or research purpose. 

  • AS 5810 – biodegradable plastics suitable for home composting
  • ISO 14855 -1 – ultimate aerobic biodegradation of plastic materials under controlled composting conditions
  • ASTM D5338 -15 – aerobic biodegradation of plastic materials under controlled composting conditions, incorporating thermophilic temperatures

– a novel tool for anaerobic and aerobic biodegradability assays

The Gas Endeavour® is a novel platform for low gas volume and flow analyses whenever there is a demand for high accuracy and precise measurements. The instrument can be used for research and industrial applications relating to biodegradability and compostability analyses. It provides significant improvement of efficiency and data quality while reducing operational time, analyses cost, labour, and dependency on individual laboratory skills.

You can find more information on the Gas Endeavour® page, the video, and the product brochure regarding biodegradability & compostability below. 

benefits & advantages

Highly precise and accurate data

The Gas Endeavour® gives you a better understanding of the degradation kinetics of biodegradable polymers. The precision of measurements and data calculations have been validated with the highest quality and standards.

Significant reduction in time consumption and labour requirements

Fully automated analytical procedures, extendable testing capacity and full control of experiments with remote access. The Gas Endeavour® reduces the time consumption and labour requirement for performing both anaerobic and aerobic biodegradability analyses and make the test being less skill dependent for precise and accurate data.

Standardised measurement procedures, data interpretations and reports

Real-time temperature and pressure compensations minimise the impact of possible variations in measurement conditions in analysis and standardise data presentation, satisfying the highest demands for data accuracy and precision. An adaptive nonlinear mathematical model is also implemented in the latest released Gas Endeavour® to achieve an outstanding high linearity for oxygen demand and carbon dioxide evolution measurement in all measurement ranges.

Compact and modular design

The modular approach enables flexible system set-up, easy upgrading options and simple maintenance. The Gas Endeavour® can easily be further expanded by connecting multiple instruments with a network switch in order to satisfy demands and shorten development times.

User-friendly operations with remote access

Simple to use and easy to learn. The web-based software application makes setting up and monitoring experiments very easy. The Gas Endeavour® allows easy access from a remote location using any computer, smartphone or tablet.

Reference

Biodegradability of plastics in soil

According to ISO 17556, the determination of ultimate aerobic biodegradability in soil can be performed by measuring the oxygen consumption or depletion caused by aerobic respiration of microorganisms using Gas Endeavour® as a fully automated closed respirometer. The plastic materials, which is the sole source of carbon and energy, is mixed with the sandy-loam soil and incubated at temperature 22 ±1 oC. 1.5 g plastic per 100 g soil was used for all plastic samples. During biodegradation of plastic materials over 200 days, the consumed oxygen is measured continuously by Gas Endeavour® and the biodegradability is calculated as the ratio of the consumed oxygen to the theoretical value.

The extremely low relative standard deviations can be observed for the cumulative oxygen consumption of blank, cellulose positive control, PHB powder samples (±1.6%, ±2.5% and ±6.0%, respectively). This supports a high level of confidence of the results obtained with Gas Endeavour®. Accordingly, the validity criteria of ISO 17556:2019 are fulfilled (i.e., the positive control reached 75.1% which is more than 60% at the end of the test) biodegradation and relative standard deviation of BOD values of all blanks are only ±1.6% which is far below ±20%). PHB powder material reaches about 100±10.2% of biodegradation in 100 days, but only 9.5±2.0% degradation for PHB granule over 200 days. PBS powder has 26.5±4.6% degradation in 200 days. No significant degradation can be observed for PLA granule and PLLA film over the full duration of incubation.

Reference

Ultimate anaerobic biodegradation of plastic materials in controlled slurry digestion systems

According to ISO 13975, the determination of ultimate biodegradability of plastic materials under anaerobic conditions in a controlled anaerobic slurry digestion system can be performed by measuring the volume of biogas produced using Gas Endeavour® and the amount of dissolved inorganic carbon (DIC) formed in excess of blank values. The instrument allows for continuous monitoring of released biogas with real-time temperature and pressure compensation, standardised measurement procedure, data interpretation and report. The level of biodegradability is calculated as the ratio of the sum of the net increase of produced biogas and DIC to the theoretical amount of evolved biogas.  

The figure shows the comparison of anaerobic biodegradability of semicrystalline polylactic acid (PLA) and polyhydroxybutyrate (PHB) samples in anaerobic mesophilic condition. Cellulose is used as a positive control and biodegradation is 81% after 15 days with a standard deviation of only ±3% which well fulfils the validity criteria, i.e., >70% and <±20%. Biodegradation of PHB and PLA samples are 88 ±2% and only 5 ±2%, respectively after 40 days incubation, which clearly demonstrates the different biodegradability characteristic for PHB and PLA materials under anaerobic condition.

Reference

Respiratory activity evaluation of soil organisms

The respiratory activity of the microorganisms in samples of soil, determined by measuring the biological oxygen demand, has long been related to soil fertility. Gas Endeavour® could be used to follow soil respiration in real-time and compare the microbial activity of standard soils or soils of natural origin. For instance, activity of soil organisms was examined in the breakdown of soil organic matter, as well as using microcrystalline cellulose as a reference sample to evaluate various commercially available sandy-loam soils for biodegradation at temperature 22 ±1 oC. The purpose is to select suitable type of soil for performing biodegedability test according to ISO 17556.

The degradation curves illustrate the different kinetics of cellulose biodegradation in the different soils and show that the fastest initial degradation rate and the highest biodegradability were achieved with Soil B. Using Soil C as an example, it is possible to distinguish a lag phase (day 0 to 6), where adaption of the soil inoculum to the cellulose occurs, a degradation phase, in which the microorganisms metabolize the sample, and a plateau phase, in which the biodegradation has ended.

The test is considered valid for all soils investigated except Soil A, as the degree of biodegradation of microcrystalline cellulose reached more than 60% in less than six months and all the blanks are within ±20% of the mean at the end of the test (i.e., the standard deviations are less than ±4% for all blanks).

Reference

Aerobic biodegradability of plastic materials in an aqueous medium

According to ISO 14851, the determination of aerobic biodegradability of plastic materials in an aqueous medium can be performed by measuring oxygen consumption or depletion caused by aerobic respiration of microorganisms using Gas Endeavour® as a fully automated closed respirometer. The plastic materials, which is the sole source of carbon and energy, is mixed with selected domestic wastewater, continuously agitated, and incubated at temperature 22 ±1 oC. During biodegradation of plastic materials, the consumed oxygen is measured continuously by Gas Endeavour® and the biodegradability is calculated as the ratio of the consumed oxygen to the theoretical value.

The experimental configuration using Gas Endeavour® includes oxygen supply and the biodegradation process is not inhibited by the limitation of available oxygen in the headspace of test flask. It is therefore convenience to perform the analysis with a higher sample amount. In the current study, the impact of sample concentration on the dynamic profile of biodegradability was demonstrated using microcrystalline cellulose. The validity criteria of ISO 14851 are fulfilled (i.e., all samples have > 60% biodegradability with standard deviations range from ±2.1% to ±9.8%, only ±3.5% for three blanks control which is far below the max limit ±20%) at the plateau phase within 60 days.  

Reference

Ultimate aerobic biodegradability of plastic materials in soil

According to ISO 17556, the determination of ultimate aerobic biodegradability in soil can be performed by measuring the oxygen consumption or depletion caused by aerobic respiration of microorganisms using Gas Endeavour® as a fully automated closed respirometer. The plastic materials, which is the sole source of carbon and energy, is mixed with the selected soil and incubated at temperature 22 ±1 oC. During biodegradation of plastic materials, the consumed oxygen is measured continuously by Gas Endeavour® and the biodegradability is calculated as the ratio of the consumed oxygen to the theoretical value.

The low standard deviations can be observed for the cumulative oxygen consumption of both blanks and samples (lower than ±4% and ±9%, respectively). This supports a high level of confidence of the results obtained with Gas Endeavour®. Accordingly, the validity criteria of ISO 17556:2019 are fulfilled (i.e., the positive control reached 60% biodegradation and BOD values of all blanks are within ±20%) and the PHB test material reached a 95% of biodegradation in 90 days.

Reference

Aerobic biodegradability under simulated composting environments

Gas Endeavour® can be configured to evaluate aerobic biodegradability of polymer samples using home or industrial compost under a simulated composting environment like any home composting or controlled composting sites. The instrument allows for continuous and on-line monitoring of oxygen demand or depletion caused by aerobic respiration of compost bacteria. This arrangement should be served as a practical analytical tool of biodegradability evaluation under similar conditions of home composting or controlled composting facilities for internal study or research purpose. Microcrystalline cellulose is often used as a positive control for the test validation. In the current study, biodegradability test of microcrystalline cellulose samples is evaluated at two different concentrations under a simulated composting environment at 58oC similar with a controlled composting condition. After the incubation of 100 days, the biodegradability of two cellulose samples is 87 ±8% and 62 ±11% for high and low concentrations, respectively. For the higher concentration cellulose sample, 72% biodegradability is achieved after 45 days. The validity criteria of ISO 14851 are fulfilled, i.e., the positive control reaches 70% after 45 days and the standard deviation of test result is within ±20%.

Reference

Aerobic biodegradability of plastic materials exposed to seawater

According to ISO 23977-2, the determination of aerobic biodegradation of plastic materials exposed to seawater can be performed by measuring the oxygen consumption or depletion caused by aerobic respiration of microorganisms from seawater or seawater with low amount of sediment using Gas Endeavour® as a fully automated closed respirometer. During biodegradation of plastic materials, the consumed oxygen is measured continuously by Gas Endeavour® and the biodegradability is calculated as the ratio of the consumed oxygen to the theoretical value. The experimental configuration using Gas Endeavour® includes oxygen supply and the biodegradation process is not inhibited by the limitation of available oxygen in the headspace of test flask. It is therefore convenience to perform the analysis with a higher sample amount.

The figure displays the ongoing biodegradation over 110 days of incubation with continuous agitation at a temperature of 22 ±1 oC. The test period typically does not exceed 1 year and is considered valid if the degree of cellulose reaches at least 60% after 180 days. In the current study, the biodegradation of cellulose in seawater is only 9% ±4% after 110 days, whereas higher biodegradation rates of 43% ±8% (higher sample concentration) and 63% ±5% (lower sample concentration) can be observed for tests in seawater and marine sediment, respectively. These results clearly illustrate a lower degree of biodegradation in seawater only, due to the lower microbial density in seawater compared to a higher microbial density in sediment.

Reference

Scientific reference for anaerobic biodegradability assay

Article title: “Assessment of models for anaerobic biodegradation of a model bioplastic: Poly(hydroxybutyrate-co-hydroxyvalerate)”

Authors: Cecily A. Ryan, Sarah L. Billington, Craig S. Criddle
Bioresource Technology (2018), 227, 205-213

Dept of Civil and Environmental Engineering, Stanford University (United States)

Five kinetic models of anaerobic digestion are evaluated to determine their suitability for modelling of anaerobic biodegradation of the bioplastic poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV). AMPTS® II was used to perform the actual anaerobic biodegradability analysis in order to produce kinetic degradation data for evaluating the model simulation.

Reference

Scientific reference for anaerobic biodegradation assay

Article: “Mechanical, rheological and anaerobic biodegradation behavior of a Poly(lactic acid) blend containing a Poly(lactic acid)-co-poly(glycolic acid) copolymer”

Authors: Kosar Samadi, Michelle Francisco, Swati Hegde, Carlos A. Diaz, Thomas A. Trabold, Elizabeth M. Dell, Christopher L. Lewis
Polymer Degradation and Stability (2019) 170, 109018

Rochester Institute of Technology (United States)

AMPTS® II was used to examine the thermophilic anaerobic biodegradation performance of PLA blends containing a highly degradable polymer.

BPC Instruments AB staff

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