GB/T 43282.2-2023 Plastics—Determination of the aerobic biodegradation of plastic materials exposed to seawater—Part 2: Method by measuring the oxygen demand in closed respirometer (English Version)
Plastics—Determination of the aerobic biodegradation of plastic materials exposed to seawater—Part 2: Method by measuring the oxygen demand in closed respirometer
GB/T 43282.2-2023 Plastics - Determination of the aerobic biodegradation of plastic materials exposed to seawater - Part 2: Method by measuring the oxygen demand in closed respirometer
1 Scope
This document specifies a laboratory test method for determining the degree and rate of the aerobic biodegradation level of plastic materials. Biodegradation of plastic materials is determined by measuring the oxygen demand in a closed respirometer when exposed to seawater sampled from coastal areas under laboratory conditions.
The conditions described in this document might not always correspond to the optimum conditions for the maximum degree of biodegradation, however this test method is designed to give an indication of the potential biodegradability of plastic materials.
Note: This document addresses plastic materials but can also be used for other materials.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5667-3 Water quality - Sampling - Part 3: Preservation and handling of water samples
ISO 8245 Water quality - Guidelines for the determination of total organic carbon (TOC) and dissolved organic carbon (DOC)
ISO 10210 Plastics - Methods for the preparation of samples for biodegradation testing of plastic materials
ISO 10523 Water quality - Determination of pH
ISO 11261 Soil quality - Determination of total nitrogen - Modified Kjeldahl method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
pelagic zone
water body above the seafloor
Note 1: It is also referred to as the open water or the water column.
Note 2: The surface of the pelagic zone is moved by wind‑driven waves, is in contact with the atmosphere and exposed to sunlight. With increasing depth pressure increases, temperature decreases, and light and surface wave energy are attenuated.
[SOURCE: ISO 22766:2020, 3.4]
3.2
biochemical oxygen demand; BOD
mass concentration of the dissolved oxygen consumed under specified conditions by the aerobic biological oxidation of a chemical compound or organic matter in water
Note: It is expressed as milligrams of oxygen uptake per milligram or gram of test compound.
[SOURCE: GB/T 40611-2021, 3.1]
3.3
theoretical oxygen demand; ThOD
theoretical maximum amount of oxygen required to oxidize a chemical compound completely, calculated from the molecular formula
Note: It is expressed as milligrams of oxygen uptake per milligram or gram of test compound.
[SOURCE: GB/T 40611-2021, 3.2]
3.4
total organic carbon; TOC
amount of carbon bound in an organic compound
Note: It is expressed as milligrams of carbon per 100 mg of the compound.
[SOURCE: GB/T 40611-2021, 3.3]
3.5
dissolved organic carbon; DOC
part of the organic carbon in water which cannot be removed by specified phase separation. Phase separation can be achieved for example by centrifugation at 40000 m/s 15 min or by membrane filtration using membranes with pores of 0.2 μm to 0.45 μm diameter.
[SOURCE: GB/T 19276.2-2003, 3.7]
3.6
lag phase
time from the start of a test until adaptation and/or selection of the degrading microorganisms is achieved and the degree of biodegradation of a chemical compound or organic matter has increased to about 10 % of the maximum level of biodegradation (3.8)
Note: It is measured in days.
[SOURCE: GB/T 19276.2-2003, 3.8]
3.7
biodegradation phase
time from the end of the lag phase (3.6) of a test until the plateau phase has been reached
Note: It is measured in days.
[SOURCE: GB/T 19276.2-2003, 3.10, modified.]
3.8
maximum level of biodegradation
degree of biodegradation of a chemical compound or organic matter in a test, above which no further biodegradation takes place during the test
Note: It is measured in per cent.
[SOURCE: GB/T 19276.2-2003, 3.9]
3.9
plateau phase
time from the end of the biodegradation phase (3.7) until the end of a test
Note: It is measured in days.
[SOURCE: GB/T 19276.2-2003, 3.11]
3.10
pre-conditioning
pre‑incubation of an inoculum under the conditions of the subsequent test in the absence of the chemical compound or organic matter under test, with the aim of improving the test by acclimatization of the microorganisms to the test conditions
[SOURCE: GB/T 19276.2-2003, 3.13]
4 Principle
This document describes two variations of a test method for determining the biodegradability of plastic materials by the indigenous population of microorganisms in natural seawater using a static aqueous test system. The test is performed under mesophilic test conditions for up to two years by incubating plastic materials with either seawater only (“pelagic seawater test”) or with seawater to which low amount of sediment has been added (“suspended sediment seawater test”), coming from the same site as that from which the seawater was taken.
The system is contained in a closed flask, in a respirometer. The carbon dioxide evolved is absorbed in a suitable absorber in the headspace of the flasks. The consumption of oxygen (BOD) is determined, for example, by measuring the amount of oxygen required to maintain a constant volume of gas in the respirometer flasks, or by measuring the change in volume or pressure (or a combination of the two) either automatically or manually.
The level of biodegradation is determined by comparing the BOD with the theoretical amount (ThOD) and expressed in percentage. The influence of possible nitrification processes on the BOD shall be considered. The test result is the maximum level of biodegradation determined from the plateau phase of the biodegradation curve.
Standard
GB/T 43282.2-2023 Plastics—Determination of the aerobic biodegradation of plastic materials exposed to seawater—Part 2: Method by measuring the oxygen demand in closed respirometer (English Version)
Standard No.
GB/T 43282.2-2023
Status
valid
Language
English
File Format
PDF
Word Count
10500 words
Price(USD)
315.0
Implemented on
2024-6-1
Delivery
via email in 1~3 business day
Detail of GB/T 43282.2-2023
Standard No.
GB/T 43282.2-2023
English Name
Plastics—Determination of the aerobic biodegradation of plastic materials exposed to seawater—Part 2: Method by measuring the oxygen demand in closed respirometer
GB/T 43282.2-2023 Plastics - Determination of the aerobic biodegradation of plastic materials exposed to seawater - Part 2: Method by measuring the oxygen demand in closed respirometer
1 Scope
This document specifies a laboratory test method for determining the degree and rate of the aerobic biodegradation level of plastic materials. Biodegradation of plastic materials is determined by measuring the oxygen demand in a closed respirometer when exposed to seawater sampled from coastal areas under laboratory conditions.
The conditions described in this document might not always correspond to the optimum conditions for the maximum degree of biodegradation, however this test method is designed to give an indication of the potential biodegradability of plastic materials.
Note: This document addresses plastic materials but can also be used for other materials.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5667-3 Water quality - Sampling - Part 3: Preservation and handling of water samples
ISO 8245 Water quality - Guidelines for the determination of total organic carbon (TOC) and dissolved organic carbon (DOC)
ISO 10210 Plastics - Methods for the preparation of samples for biodegradation testing of plastic materials
ISO 10523 Water quality - Determination of pH
ISO 11261 Soil quality - Determination of total nitrogen - Modified Kjeldahl method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
pelagic zone
water body above the seafloor
Note 1: It is also referred to as the open water or the water column.
Note 2: The surface of the pelagic zone is moved by wind‑driven waves, is in contact with the atmosphere and exposed to sunlight. With increasing depth pressure increases, temperature decreases, and light and surface wave energy are attenuated.
[SOURCE: ISO 22766:2020, 3.4]
3.2
biochemical oxygen demand; BOD
mass concentration of the dissolved oxygen consumed under specified conditions by the aerobic biological oxidation of a chemical compound or organic matter in water
Note: It is expressed as milligrams of oxygen uptake per milligram or gram of test compound.
[SOURCE: GB/T 40611-2021, 3.1]
3.3
theoretical oxygen demand; ThOD
theoretical maximum amount of oxygen required to oxidize a chemical compound completely, calculated from the molecular formula
Note: It is expressed as milligrams of oxygen uptake per milligram or gram of test compound.
[SOURCE: GB/T 40611-2021, 3.2]
3.4
total organic carbon; TOC
amount of carbon bound in an organic compound
Note: It is expressed as milligrams of carbon per 100 mg of the compound.
[SOURCE: GB/T 40611-2021, 3.3]
3.5
dissolved organic carbon; DOC
part of the organic carbon in water which cannot be removed by specified phase separation. Phase separation can be achieved for example by centrifugation at 40000 m/s 15 min or by membrane filtration using membranes with pores of 0.2 μm to 0.45 μm diameter.
[SOURCE: GB/T 19276.2-2003, 3.7]
3.6
lag phase
time from the start of a test until adaptation and/or selection of the degrading microorganisms is achieved and the degree of biodegradation of a chemical compound or organic matter has increased to about 10 % of the maximum level of biodegradation (3.8)
Note: It is measured in days.
[SOURCE: GB/T 19276.2-2003, 3.8]
3.7
biodegradation phase
time from the end of the lag phase (3.6) of a test until the plateau phase has been reached
Note: It is measured in days.
[SOURCE: GB/T 19276.2-2003, 3.10, modified.]
3.8
maximum level of biodegradation
degree of biodegradation of a chemical compound or organic matter in a test, above which no further biodegradation takes place during the test
Note: It is measured in per cent.
[SOURCE: GB/T 19276.2-2003, 3.9]
3.9
plateau phase
time from the end of the biodegradation phase (3.7) until the end of a test
Note: It is measured in days.
[SOURCE: GB/T 19276.2-2003, 3.11]
3.10
pre-conditioning
pre‑incubation of an inoculum under the conditions of the subsequent test in the absence of the chemical compound or organic matter under test, with the aim of improving the test by acclimatization of the microorganisms to the test conditions
[SOURCE: GB/T 19276.2-2003, 3.13]
4 Principle
This document describes two variations of a test method for determining the biodegradability of plastic materials by the indigenous population of microorganisms in natural seawater using a static aqueous test system. The test is performed under mesophilic test conditions for up to two years by incubating plastic materials with either seawater only (“pelagic seawater test”) or with seawater to which low amount of sediment has been added (“suspended sediment seawater test”), coming from the same site as that from which the seawater was taken.
The system is contained in a closed flask, in a respirometer. The carbon dioxide evolved is absorbed in a suitable absorber in the headspace of the flasks. The consumption of oxygen (BOD) is determined, for example, by measuring the amount of oxygen required to maintain a constant volume of gas in the respirometer flasks, or by measuring the change in volume or pressure (or a combination of the two) either automatically or manually.
The level of biodegradation is determined by comparing the BOD with the theoretical amount (ThOD) and expressed in percentage. The influence of possible nitrification processes on the BOD shall be considered. The test result is the maximum level of biodegradation determined from the plateau phase of the biodegradation curve.
