Some standard content:
[CS 13.300;13.020.40
National Standard of the People's Republic of China
GB/T 27850—2011
Chemicals
Ready biodegradability
Cheruicals-Ready biodegradability-General considerationsIssued on 2011-12-30
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of ChinaStandardization Administration of the People's Republic of China
Implementation on 2012-08-01
Normative references
Terms, definitions and abbreviations
Information on test substance
Overview of methods
General procedure and preparation of the test
Test operation
Quality assurance and quality control
9Data and report
Appendix A (informative)
Treatment of the inhibitory effect of the test substance on the growth of the inoculumAppendix B (informative)Treatment of poorly soluble test substancesAppendix C (informative)Calculation and determination of relevant parametersD (informative)Correction of oxygen consumption by nitrificationTTKONKAA
GB/T 27850—2011
TTTKAONTKACA
This standard was drafted in accordance with the rules of GB/T1.1—2009. GB/T27850—2011
This standard is one of the series of standards for the rapid biodegradability of chemicals. It is used in conjunction with the six standards of GB/T21801 Respirometric test for rapid biodegradability of chemicals, GB/T21802 Improved MIT1 test for rapid biodegradability of chemicals (1)1, GB/T21803 "DOC reduction test for rapid biodegradability of chemicals", GB/T21831 "Rapid biodegradability of chemicals: closed bottle test", GB/T21856 "Carbon dichloride production test for rapid biodegradability of chemicals" and GB/T21857 "OECD screening test for improved rapid biodegradability of chemicals". This standard is consistent with the technical content of the Organization for Economic Cooperation and Development (OECD) Chemical Testing Guide No. 301 (1992) Ready Biodegradability (English version).
This standard has been modified as follows: The measurement unit has been changed to the legal unit of measurement in my country. The information background introduction in the preface of OECD301&Ready biodegradability has been deleted; "Stability period", "Ready biodegradability" and "Inherent biodegradability" have been included in the provisions of terms, definitions and abbreviations, and the definitions consistent with the national standards already issued in my country have been adopted. This standard was proposed and coordinated by the National Technical Committee for the Management of Hazardous Chemicals (SAC/TC251). The drafting units of this standard are: Chemical Registration Center of the Ministry of Environmental Protection, Nanjing Institute of Environmental Sciences of the Ministry of Environmental Protection, Beijing Normal University, Chinese Research Academy of Environmental Sciences, and Safety Evaluation Center of Shenyang Research Institute of Chemical Industry. The main drafters of this standard are: Liu Chunxin, Zhou Hong, Huang Xing, Liu Jining, Shi Lili, Zhu Jianrong, Quan Xiangchun, Li Handong, and Zhao Yubang. TTTKANYKACA
1 Scope
Chemicals, Ready biodegradability, General GB/T 27850—2011
This standard specifies the terms and definitions, method overview, general test procedures and preparation, quality assurance and quality control, data and reports for the rapid biodegradability of chemicals.
This standard is applicable to the screening and testing of the rapid biodegradability of chemicals under aquatic and atmospheric conditions. 2 Normative references
The following documents are indispensable for the application of this document. For dated references, the versions with the date shall apply to this document. For undated references, the latest version (including all amendments) shall apply to this document. GB/ 21801
Respirometric test for rapid biodegradability of chemicals Improved MIT II> test for rapid biodegradability of chemicals GB/T 21802
GB/T 21803
GE/T 21831
DOC reduction test for rapid biodegradability of chemicals Closed bottle test for rapid biodegradability of chemicals GB/T 21856
Ready biodegradability
Carbon dioxide production test
Chemicals
GB/T 21857
Modified OECD screening test for the ready biodegradability of chemicals 3 Terms, definitions and abbreviations
The following terms, abbreviations and abbreviations apply to this document. 3.1 Terms and definitions
Dissolved oxygen, DO
The concentration of oxygen dissolved in water, expressed in mg/L. 3.1.2
Biochemical oxygen demand, BOD
The amount of oxygen consumed by microorganisms to decompose organic matter, expressed as milligrams of oxygen consumed per milligram of test substance (mg/m). 3.1.3
Chemical oxygen demand demand, COEThe amount of oxidant consumed by a certain amount of dichromate to oxidize the reducing substances in a water sample under strong acid and heating conditions, which can be expressed as milligrams of oxygen consumed per gram of the test substance (mg/m3). 3. 1. 4
dissolved organic carbon
dissolved organic carbon, DoCThe organic carbon content in the solution usually refers to the organic carbon content in the bottle after passing through a 0.45 μm filter membrane, and the organic carbon content in the supernatant after centrifugation at 4000/mI for 15 minutes. 3. 1.5
theoretical oxygen demand, ThoDThe total amount of oxygen required for the complete oxidation of the test substance calculated based on the molecular formula, which can be expressed as the amount of oxygen consumed per gram of the test substance (mg/mg).
Theoretical carbon diaxidetheoretical carbon diaxide+ ThcOzThe amount of carbon diaxide that should be produced by the complete inorganicization of a known amount of carbon contained in the test substance, calculated by calculation. Usually expressed as milligrams of carbon dioxide produced per milligram of the test substance (mg/mg). 3.1.7
Total organic carbontohal organic carbon, TOCThe total amount of organic carbon in the test sample (including the total organic carbon in the sample and the flotation. 3.1.8
Total carbontotal carbon, TC
The total amount of organic carbon and inorganic carbon in the test sample. 3.1.9
Primary biodegradationprirmary biodegradatlonThe process in which the chemical structure of the test substance changes under the action of organisms, resulting in the loss of its characteristics. 3.1.10
Ultimate biodegradation (aerobic)The process in which the test substance is completely decomposed by microorganisms into disulfide carbon water, mineral salts and the formation of new microbial cell components (biomass). 3.1. 11bZxz.net
Readily biodegradable (chemicals) A class of chemicals that are ultimately degraded by specific degradation screening tests. These screening tests assume that the test substances can be rapidly and steadily biodegraded in the aerobic environment of water.
Inhereatly biodegradable (chemicals) A class of chemicals that are determined to be biodegradable (primary or final) by biodegradation tests. 3.1. 13
Treatability
Treatability
The ability of a compound to be removed during the biological treatment of sewage without affecting the normal operation of the biological treatment process. Generally, compounds with rapid biodegradability are treatable, but not all compounds with inherent biodegradability are treatable. The same is true for abiotic treatment processes.
Jag phase
The period from the start of the test to the time when the degradation rate reaches 10%. 3. 1. 15
Degradation period phase
Station periodThe period from when the degradation rate reaches 90% of the maximum degradation rate. 3. 1.16
Month10-d window
10-d window
10-d windowThe 10-d test period after the biodegradation rate reaches 10%. 3. 1.17
Platean
The period during which the biodegradation rate tends to be stable (at least three measurements). 2
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Ready biodegradabilityThe biodegradability of the test substance when it is in contact with the inoculum for a limited time. 3. 1. 19
Inherent biodegradabilityGB/T27850-2011
The biodegradation potential of the test substance when it is in contact with the inoculum for a long time under the optimal test conditions (not mentioned in the standard). 3.2 Abbreviations
3.2.1IC: inorganic carbon (inorganic carbon) 4 Test substance information
Test substance information includes:
a) molecular formula and structure
b) solubility in water:
vapor pressure:
d) adsorption;
purity;
proportion of main components!
carbon content;
microbial decay.
5 Method Overview
5.1 Principle
After the inorganic culture medium containing the test substance is dissolved or suspended in the inoculum, the test substance is used as the only organic carbon source and aerobically cultivated in the dark or scattered light. The error of the endogenous active band of the inoculum is corrected by a blank control group containing the inoculum but not the test substance. If the test substance may have an inhibitory effect on the plant, refer to Appendix A for operation. The changes in parameters such as DC reduction, oxygen consumption or C production are measured at fixed time intervals, the rapid biodegradation rate of the test substance is calculated, and the biodegradation curve is drawn. The silt content or concentration of the intermediate products of degradation of the test substance at the beginning and end of the test can also be determined by chemical analysis to evaluate the primary biodegradability of the test substance. The test should usually last for 28 days. If the biodegradation curve reaches a stable period (at least 3 consecutive measured values on the curve remain stable) after 28 days, the test can be ended; if the biodegradation curve has not reached a stable state on the 28th day, the test period should be extended, but the chemical should not be classified as a rapidly biodegradable substance at this time. 5.2 Scope of application and selection of methods
If the solubility concentration of the test substance in water is not less than 100 mg/L and no scattering and adsorption occur, the six test methods given in GB/T21801.GB/T21802, GB/T21803, GB/T21831, GB/T21856 and GB/T21857 can be used for test substances that are poorly soluble in water, volatile or adsorbable. The corresponding test methods are shown in Table 1. 3
GB/T 27850-2011
Test items
GB/T 21803
LOC reduction test
GB/T 21856
CO. generation test
GB/T 21802
MITI test (I)
GB/T21831
Closed bottle test
GB/T21857
Improved OFCD screening
GR/T21R01
Respiratory blood test
Table 1 Applicable scope of test method
Analytical method
Drop in water
Determination of dissolved organic carbon
Respirometric method: determination of CO, production
Respirometric method; determination of oxygen consumption
Respirometric method, determination of dissolved oxygen
Determination Soluble organic carbon
Determination of oxygen consumption basis
Not applicable
Depends on its physical condition
Not applicable
Applicable compound type
Volatility
Not applicable
Depends on its physical condition
Not applicable
Depends on the specific situation
Adsorbability
Depends on the specific situation
Depends on the specific situation
For the treatment method of the test substance that is poorly soluble in water and volatile, please refer to Appendix B, but the method specified in GB/T21802 does not allow the use of solvents or emulsifiers. When using a test container with a completely closed bottle stopper and sufficient gas space at the top, some moderately volatile test substances can use the method given in GB/T21803. In order to evaluate and correct the influence of physical loss, a sterile control group should be set up. 5.3 Passing level
The passing level of rapid biodegradability is 70% IOC removal rate, and 60% ThOD removal rate or ThCO2 production in respirometer measurement. In the 28-day test period, the passing level should be reached in a 10-day observation period, with the following exceptions: the 10-day observation period starts from the biodegradation to 10% of IOC removal rate, ThOD removal rate or ThCO2 production, and should be terminated before the 28-day test period. If the biodegradation of the test substance reaches the passing level after 28 days, it is not rapidly biodegradable. The method given in GB/T21802 is not suitable for the 10-day observation period. For the method given in GB/T21831, a 14-day observation period is more appropriate than a 10-day observation period.
5.4 Reference substance
According to the rapid biodegradability standard, a rapidly biodegradable substance is selected as a reference substance, and a blank control group is set up for parallel testing.
This standard recommends aniline (fresh steamed stuffing), sodium acetate or sodium benzoate as reference substances. Potassium hydrogen phthalate may also be used. 6 General test procedures and preparations
6. 1 Test conditions
The test conditions of the six test method standards are shown in Table 2. Concentration of each element in the tested inoculum (mg/L) mg/L (in DOC) mg/L (in ThOD) mg/L (in SS) mL/L (secondary effluent) cells/L (cells) Temperature/' SS is a suspended cell, 6.2 Main receiver equipment DOC disinfection glass test 10-~40 Table 2 Test conditions
CO, produces
10°~10
Respirometer adjustment
test
50--100
0, 05--0. 1
The instruments and equipment used in each method can be found in the corresponding method standard specifications. 6.3 Test water
Incoming ECL
Screening test
10--40
GB/T 27850—2011
Out of closed bottle
10*~[0°
0. 05~0.1
MITI test
Test (I)
10°-10#
7 Generally good
Use high-purity deionized water or distilled water that does not contain inhibitory substances (such as Cu-) to ensure that the total organic carbon content in the water is not higher than 10% of the DOC concentration of the test substance. The same batch of water should be used for the same series of tests. The DOC in the test water should be determined before the test, except for the closed bottle test specified in GB/T21831, but the oxygen consumption of the test water should be low. 6.4 Culture medium
First, use analytically pure reagents to prepare an appropriate concentration of inorganic culture medium stock solution. At the beginning of the test, use the stock solution and distilled water to prepare the test medium. The stock solution includes phosphate solution, ammonium chloride solution, calcium chloride solution, magnesium sulfate solution, and ferric chloride solution. The concentration, usage ratio and preparation method of inorganic media, trace elements and growth factors in the required stock solution and test medium can be found in the corresponding method standards. The GB/T 21857 culture medium contains very little inoculum and only contains low concentrations of trace elements and growth factors. The culture medium for this test should be supplemented with other compounds.
The culture medium used in the same test should be prepared from the same batch. 6.5 Addition of test and reference substances
The method of adding test and reference substances to the reaction mixture is related to their physical and chemical properties such as water solubility. For test substances or reference substances with a solubility in water exceeding 1 μg/L, they should be dissolved in test water in advance to prepare a stock solution of appropriate concentration, and then diluted to prepare the final test solution during the test. Poorly soluble test substances or reference substances should be directly dissolved in the culture medium to avoid dilution of the buffer solution. Insoluble test substances or reference substances should be directly added to the final test culture medium and ensure homogenization. For the addition method of poorly soluble and insoluble substances, please refer to Appendix B. Organic solvents and emulsifiers should not be used in the method specified in GB/T21802. 6.6 Inoculum
6.6.1 Selection of inoculum
The inoculum can be taken from activated sludge, unsterilized sewage treatment plant effluent, surface water and soil, or a mixture of the above. To ensure the test accuracy, the activated sludge used in the test methods specified in GB/T21801, GB/T21803 and GB/T21856 should be taken from domestic sewage treatment plants or pilot-scale treatment devices that mainly treat domestic sewage. The test methods specified in GB/T21831 and GB/T21857 only use low-concentration inoculums and do not use activated sludge. The primary effluent of urban sewage treatment plants or test devices that treat actual domestic sewage is preferably used as inoculum. The inoculum used in the test method specified in G/T21802 is a mixture of multiple sources. For detailed descriptions of the sources and preparations of inoculums for each method, please refer to the corresponding method standard specifications. 6.6.2 Pretreatment of inoculum
To reduce the blank value and improve the accuracy of the test method, the inoculum can be pretreated under the test conditions, but the test substance is not pre-differentiated. Pretreatment includes aeration culture of activated sludge (in the test medium without the test substance) or secondary effluent at the test temperature for 5 days to 1 day. The inoculum in the test method specified in GB/T21802 should not be pretreated. 6.7 Sterile control group
Set up a sterile control group without inoculum, and detect whether the test substance is biodegradable by measuring the IO removal, oxygen absorption or CO production. It can be sterilized by filtering with a microfiltration membrane with a pore size of 0.2 μm to D. 45 μm or adding appropriate concentrations of toxic substances. Among them, the samples sterilized by membrane filtration should be stored under sterile conditions. In the test with DOC removal rate as the biodegradation index, especially when using activated sludge for inoculation, in order to exclude the influence of the adsorption of the test substance, it is advisable to set up an adsorption control group that has been inoculated and sterilized. 6.B Sampling and number of containers
Each group should have at least two flasks or containers for the test substance and inoculum, at least two flasks or containers for the inoculum, and one flask or container for the reference substance and inoculum. If a sterile control group, a sterile control group, and an adhesion control group are set up, the corresponding containers should be added. GB/T21802 and GB/T21831 have special requirements for the number of flasks. The number and requirements of flasks or other containers can be found in the corresponding test method standards. The LOC and/or other parameters of the test suspension and inoculated blank parallel groups should be tracked and measured. The DOC of other groups should be tracked and measured.
In principle, the test should ensure sampling and testing to obtain the removal rate within the 10-day observation period, but due to the lag period and degradation rate fluctuations of the degradation process, this general rule cannot accurately describe the sampling frequency. 7 Experimental operation
For detailed descriptions of the group design and specific operations of each method test, please refer to the corresponding method standard specifications. Quality assurance and quality control
The following points should be noted:
The test water should be high-purity water. The impurities contained in the water, ion exchange resins, and substances produced by the lysis of bacteria and algae should be prevented from contaminating the test water and causing excessive blank values; 6
b) The amount of DOC in the added inoculum should be as low as possible compared with the organic carbon content in the test substance: GB/T 27850—2011
Use the reference material as the control group for the procedure and conduct the test at the same time. Aniline (new steamed stuffing), sodium benzoate or sodium benzoate can be completely degraded when used as the reference material by the above method; d) The degradation process is characterized by measuring parameters such as D()C reduction, CO. production and oxygen consumption. In order to confirm the starting and ending points of biodegradation, the sampling and measurement frequency should be high enough; c
In view of the characteristics of biodegradation and the complex bacterial population in the inoculum, the measurement should be no less than two times. Generally, the higher the concentration of microorganisms initially added to the test medium, the smaller the difference in repeated measurement results! At the end of the stable period, the test, or the 10-day observation period, the maximum relative deviation of the degradation rate between parallel tests is less than 20%, and the degradation percentage of the reference material has reached the passing level when the test is carried out for 14 days; g) In the toxicity test containing the test substance and the reference material, if the degradation percentage within 14 days is lower than 35% (calculated by total DOC) or 25% (calculated by total ThOD or ThCO,), it can be determined that the test substance has an inhibitory effect on the inoculum (for other rate tests, see Appendix A), and the test substance with a lower concentration should be re-selected on the premise that it does not seriously affect the determination accuracy of DOC) or a higher concentration of inoculum (should not be higher than 30 mg/L) to repeat the test
h) The specific impact of other conditions in each method on the validity of the test results can be found in the corresponding method standard specifications. 9 Data and Reporting
9.1 Data Processing
For the test samples inoculated with the test substance and the blank samples inoculated without the test substance, the average values of the two test groups are used to calculate the degradation percentage D at each sampling. See the detailed instructions for each method. Draw a degradation percentage D,-test time t curve to represent the degradation process, and mark the 10-day observation period on the degradation curve. Calculate and report the removal percentage at the stable period, the end of the test or the end of the 10-day observation period. In the method specified in GB/I21801, the nitrification of nitrogen-containing test substances (see Appendix C and Appendix D) can affect the absorption of oxygen.
When the information of the test substance is incomplete and ThOD cannot be calculated, the COD value can be used instead to calculate the degradation percentage; when determining COD, some chemicals are not easily oxidized, resulting in COD values that are usually lower than ThCOD, making the final biodegradation percentage higher than the actual value. When the chemical analysis data of the test substance are available, the primary biodegradation percentage should be calculated according to formula (1): D = S = S × 100
Wherein:
D, —— primary biodegradation percentage at time t (at the end of the test, usually 28 days), %; S, —— the residual amount of the test substance in the test group at the end of the test, in milligrams (mg); S, —— the residual amount of the test substance in the sterile control group at the end of the test, in milligrams (mg). For the calculation of the test results obtained by each method, see the standard details of each method. 9.2 Result Report
The test report should include the following:
a) Test substance:
Physical attributes and basic physicochemical properties;
—— identification data of the test substance.
b) Test conditions:
-Inoculum: state and sampling location, concentration and treatment method: proportion and condition of industrial wastewater in sewage (if known); -.-(1)
GB/T 27850—2011
Test cycle and temperature;
If the test substance is a very insoluble substance, provide the method for preparing the test substance solution/suspension; the test method adopted; the reason for and explanation of the change in the test steps; the use of reference substances.
Results:
Fill the data into the "Data Table\;
Any observed inhibition
Any observed non-biological degradation
-Chemical analysis data of the test substance (if any): Analytical data of the degradation intermediates of the test substance (if any); "Degradation rate-time curve" of the test substance and reference substance, including lag phase, degradation period, 10-day observation period and slope, stable period. Percent degradation at the end of the test and (or) the end of the 10-day observation period. d) Discussion of results.45 μm microfiltration membrane or add appropriate concentration of toxic substances for sterilization. The samples sterilized by membrane filtration should be kept under sterile conditions. In the test with DOC removal rate as the biodegradation index, especially when using activated sludge for inoculation, in order to eliminate the influence of adsorption of the test substance, it is advisable to set up an adsorption control group that has been inoculated and sterilized. 6, B Sampling and number of containers
Each group should have at least two flasks or containers for the test substance and inoculum, at least two flasks or containers for inoculum, and one flask or container for reference and inoculum. If a sterile control group, a sterile control group and an adsorption control group are set up, the corresponding containers should be added. GB/T21802 and GB/T21831 have special requirements for the number of flasks. The number and requirements of flasks or other containers can be found in the corresponding test method standards. The LOC and/or other parameters of the test suspension and inoculated blank parallel groups should be tracked and measured. The DOC of other groups should be tracked and measured.
In principle, the test should ensure sampling and testing to obtain the removal rate within the 10-day observation period. However, due to the fluctuation of the lag period and degradation rate of the degradation process, this general rule cannot accurately describe the sampling frequency. 7 Experimental operation
For detailed descriptions of the group design and specific operations of each method test, please refer to the corresponding method standard specifications. White Quality Assurance and Quality Control
The following matters need to be noted:
The test water should be high-purity water. It should be prevented that the impurities contained in the water, ion exchange resins, and substances produced by the lysis of bacteria and algae a
contaminate the test water and cause excessively high blank values; 6
b) The amount of DOC in the added inoculum should be as low as possible compared with the organic carbon content in the test substance: GB/T 27850—2011
Use the reference substance as the control group of the procedure and conduct the test at the same time. Aniline (new steamed stuffing), sodium benzoate or sodium benzoate can be completely degraded when used as reference materials by the above method; d) Determination of parameters such as D () C reduction, CO. production and oxygen consumption to characterize the degradation process. In order to confirm the starting and ending points of biodegradation, the sampling and measurement frequency should be high enough; c
In view of the characteristics of biodegradation and the complex bacterial population in the inoculum, the measurement should be no less than two times. Generally, the higher the concentration of microorganisms initially added to the test culture medium, the smaller the difference in repeated measurement results! At the end of the stable period, the test or the 10-day observation period, the maximum relative deviation of the degradation rate between parallel tests is less than 20%, and the degradation percentage of the reference material has reached the passing level at the 14th day of the test; g) In the toxicity test containing the test substance and the reference material, if the degradation percentage is less than 35% (calculated as total DOC) or 25% (calculated as total ThOD or ThCO) within 14 days, it can be determined that the test substance has an inhibitory effect on the inoculum (for other rate tests, see Appendix A), and the test substance with a lower concentration should be re-selected on the premise that it does not seriously affect the determination accuracy of DOC) or a higher concentration of inoculum (should not be greater than 30 mg/L) to repeat the test.
h) For the specific effects of other conditions in each method on the validity of the test results, please refer to the corresponding method standard specifications. 9 Data and Report
9.1 Data Processing
For the test starters inoculated with the test substance and the blank inoculated without the test substance, the average value of the two test groups is used to calculate the degradation percentage D at each sampling. For details, please refer to the detailed rules for each method. Draw a degradation percentage D,-test time t curve to represent the degradation process, and mark the 10-day observation period in the degradation curve. Calculate and report the removal percentage at the end of the stable period, the end of the test or the end of the 10-day observation period. In the method specified in GB/I21801, the nitrification of nitrogen-containing test substances (see Appendix C and Appendix D) can affect the absorption of oxygen.
When the information of the test substance is incomplete and ThOD cannot be calculated, the COD value can be used instead to calculate the degradation percentage; when determining COD, some chemicals are not easily oxidized, resulting in COD values that are usually lower than ThCOD, making the final biodegradation percentage higher than the actual value. When the chemical analysis data of the test substance are available, the primary biodegradation percentage should be calculated according to formula (1): D = S = S × 100
Wherein:
D, —— primary biodegradation percentage at time t (at the end of the test, usually 28 days), %; S, —— the residual amount of the test substance in the test group at the end of the test, in milligrams (mg); S, —— the residual amount of the test substance in the sterile control group at the end of the test, in milligrams (mg). For the calculation of the test results obtained by each method, see the standard details of each method. 9.2 Result Report
The test report should include the following:
a) Test substance:
Physical attributes and basic physicochemical properties;
—— identification data of the test substance.
b) Test conditions:
-Inoculum: state and sampling location, concentration and treatment method: proportion and condition of industrial wastewater in sewage (if known); -.-(1)
GB/T 27850—2011
Test cycle and temperature;
If the test substance is a very insoluble substance, provide the method for preparing the test substance solution/suspension; the test method adopted; the reason for and explanation of the change in the test steps; the use of reference substances.
Results:
Fill the data into the "Data Table\;
Any observed inhibition
Any observed non-biological degradation
-Chemical analysis data of the test substance (if any): Analytical data of the degradation intermediates of the test substance (if any); "Degradation rate-time curve" of the test substance and reference substance, including lag phase, degradation period, 10-day observation period and slope, stable period. Percent degradation at the end of the test and (or) the end of the 10-day observation period. d) Discussion of results.45 μm microfiltration membrane or add appropriate concentration of toxic substances for sterilization. The samples sterilized by membrane filtration should be kept under sterile conditions. In the test with DOC removal rate as the biodegradation index, especially when using activated sludge for inoculation, in order to eliminate the influence of adsorption of the test substance, it is advisable to set up an adsorption control group that has been inoculated and sterilized. 6, B Sampling and number of containers
Each group should have at least two flasks or containers for the test substance and inoculum, at least two flasks or containers for inoculum, and one flask or container for reference and inoculum. If a sterile control group, a sterile control group and an adsorption control group are set up, the corresponding containers should be added. GB/T21802 and GB/T21831 have special requirements for the number of flasks. The number and requirements of flasks or other containers can be found in the corresponding test method standards. The LOC and/or other parameters of the test suspension and inoculated blank parallel groups should be tracked and measured. The DOC of other groups should be tracked and measured.
In principle, the test should ensure sampling and testing to obtain the removal rate within the 10-day observation period. However, due to the fluctuation of the lag period and degradation rate of the degradation process, this general rule cannot accurately describe the sampling frequency. 7 Experimental operation
For detailed descriptions of the group design and specific operations of each method test, please refer to the corresponding method standard specifications. White Quality Assurance and Quality Control
The following matters need to be noted:
The test water should be high-purity water. It should be prevented that the impurities contained in the water, ion exchange resins, and substances produced by the lysis of bacteria and algae a
contaminate the test water and cause excessively high blank values; 6
b) The amount of DOC in the added inoculum should be as low as possible compared with the organic carbon content in the test substance: GB/T 27850—2011
Use the reference substance as the control group of the procedure and conduct the test at the same time. Aniline (new steamed stuffing), sodium benzoate or sodium benzoate can be completely degraded when used as reference materials by the above method; d) Determination of parameters such as D () C reduction, CO. production and oxygen consumption to characterize the degradation process. In order to confirm the starting and ending points of biodegradation, the sampling and measurement frequency should be high enough; c
In view of the characteristics of biodegradation and the complex bacterial population in the inoculum, the measurement should be no less than two times. Generally, the higher the concentration of microorganisms initially added to the test culture medium, the smaller the difference in repeated measurement results! At the end of the stable period, the test or the 10-day observation period, the maximum relative deviation of the degradation rate between parallel tests is less than 20%, and the degradation percentage of the reference material has reached the passing level at the 14th day of the test; g) In the toxicity test containing the test substance and the reference material, if the degradation percentage is less than 35% (calculated as total DOC) or 25% (calculated as total ThOD or ThCO) within 14 days, it can be determined that the test substance has an inhibitory effect on the inoculum (for other rate tests, see Appendix A), and the test substance with a lower concentration should be re-selected on the premise that it does not seriously affect the determination accuracy of DOC) or a higher concentration of inoculum (should not be greater than 30 mg/L) to repeat the test.
h) For the specific effects of other conditions in each method on the validity of the test results, please refer to the corresponding method standard specifications. 9 Data and Report
9.1 Data Processing
For the test starters inoculated with the test substance and the blank inoculated without the test substance, the average value of the two test groups is used to calculate the degradation percentage D at each sampling. For details, please refer to the detailed rules for each method. Draw a degradation percentage D,-test time t curve to represent the degradation process, and mark the 10-day observation period in the degradation curve. Calculate and report the removal percentage at the end of the stable period, the end of the test or the end of the 10-day observation period. In the method specified in GB/I21801, the nitrification of nitrogen-containing test substances (see Appendix C and Appendix D) can affect the absorption of oxygen.
When the information of the test substance is incomplete and ThOD cannot be calculated, the COD value can be used instead to calculate the degradation percentage; when determining COD, some chemicals are not easily oxidized, resulting in COD values that are usually lower than ThCOD, making the final biodegradation percentage higher than the actual value. When the chemical analysis data of the test substance are available, the primary biodegradation percentage should be calculated according to formula (1): D = S = S × 100
Wherein:
D, —— primary biodegradation percentage at time t (at the end of the test, usually 28 days), %; S, —— the residual amount of the test substance in the test group at the end of the test, in milligrams (mg); S, —— the residual amount of the test substance in the sterile control group at the end of the test, in milligrams (mg). For the calculation of the test results obtained by each method, see the standard details of each method. 9.2 Result Report
The test report should include the following:
a) Test substance:
Physical attributes and basic physicochemical properties;
—— identification data of the test substance.
b) Test conditions:
-Inoculum: state and sampling location, concentration and treatment method: proportion and condition of industrial wastewater in sewage (if known); -.-(1)
GB/T 27850—2011
Test cycle and temperature;
If the test substance is a very insoluble substance, provide the method for preparing the test substance solution/suspension; the test method adopted; the reason for and explanation of the change in the test steps; the use of reference substances.
Results:
Fill the data into the "Data Table\;
Any observed inhibition
Any observed non-biological degradation
-Chemical analysis data of the test substance (if any): Analytical data of the degradation intermediates of the test substance (if any); "Degradation rate-time curve" of the test substance and reference substance, including lag phase, degradation period, 10-day observation period and slope, stable period. Percent degradation at the end of the test and (or) the end of the 10-day observation period. d) Discussion of results.1 Data processing
For the test samples inoculated with the test substance and the blank samples inoculated without the test substance, the average values of the two test groups are used to calculate the degradation percentage D at each sampling. See the detailed instructions for each method. Draw a degradation percentage D,-test time t curve to represent the degradation process, and mark the 10-day observation period in the degradation curve. Calculate and report the removal percentage at the stable period, the end of the test or the end of the 10-day observation period. In the method specified in GB/I21801, the nitrification of nitrogen-containing test substances (see Appendix C and Appendix D) can affect the absorption of oxygen.
When the information of the test substance is incomplete and ThOD cannot be calculated, the COD value can be used instead to calculate the degradation percentage; when determining COD, some chemicals are not easily oxidized, resulting in COD values that are usually lower than ThCOD, making the final biodegradation percentage higher than the actual value. When the chemical analysis data of the test substance are available, the primary biodegradation percentage should be calculated according to formula (1): D = S = S × 100
Wherein:
D, —— primary biodegradation percentage at time t (at the end of the test, usually 28 days), %; S, —— the residual amount of the test substance in the test group at the end of the test, in milligrams (mg); S, —— the residual amount of the test substance in the sterile control group at the end of the test, in milligrams (mg). For the calculation of the test results obtained by each method, see the standard details of each method. 9.2 Result Report
The test report should include the following:
a) Test substance:
Physical attributes and basic physicochemical properties;
—— identification data of the test substance.
b) Test conditions:
-Inoculum: state and sampling location, concentration and treatment method: proportion and condition of industrial wastewater in sewage (if known); -.-(1)
GB/T 27850—2011
Test cycle and temperature;
If the test substance is a very insoluble substance, provide the method for preparing the test substance solution/suspension; the test method adopted; the reason for and explanation of the change in the test steps; the use of reference substances.
Results:
Fill the data into the "Data Table\;
Any observed inhibition
Any observed non-biological degradation
-Chemical analysis data of the test substance (if any): Analytical data of the degradation intermediates of the test substance (if any); "Degradation rate-time curve" of the test substance and reference substance, including lag phase, degradation period, 10-day observation period and slope, stable period. Percent degradation at the end of the test and (or) the end of the 10-day observation period. d) Discussion of results.1 Data processing
For the test samples inoculated with the test substance and the blank samples inoculated without the test substance, the average values of the two test groups are used to calculate the degradation percentage D at each sampling. See the detailed instructions for each method. Draw a degradation percentage D,-test time t curve to represent the degradation process, and mark the 10-day observation period in the degradation curve. Calculate and report the removal percentage at the stable period, the end of the test or the end of the 10-day observation period. In the method specified in GB/I21801, the nitrification of nitrogen-containing test substances (see Appendix C and Appendix D) can affect the absorption of oxygen.
When the information of the test substance is incomplete and ThOD cannot be calculated, the COD value can be used instead to calculate the degradation percentage; when determining COD, some chemicals are not easily oxidized, resulting in COD values that are usually lower than ThCOD, making the final biodegradation percentage higher than the actual value. When the chemical analysis data of the test substance are available, the primary biodegradation percentage should be calculated according to formula (1): D = S = S × 100
Wherein:
D, —— primary biodegradation percentage at time t (at the end of the test, usually 28 days), %; S, —— the residual amount of the test substance in the test group at the end of the test, in milligrams (mg); S, —— the residual amount of the test substance in the sterile control group at the end of the test, in milligrams (mg). For the calculation of the test results obtained by each method, see the standard details of each method. 9.2 Result Report
The test report should include the following:
a) Test substance:
Physical attributes and basic physicochemical properties;
—— identification data of the test substance.
b) Test conditions:
-Inoculum: state and sampling location, concentration and treatment method: proportion and condition of industrial wastewater in sewage (if known); -.-(1)
GB/T 27850—2011
Test cycle and temperature;
If the test substance is a very insoluble substance, provide the method for preparing the test substance solution/suspension; the test method adopted; the reason for and explanation of the change in the test steps; the use of reference substances.
Results:
Fill the data into the "Data Table\;
Any observed inhibition
Any observed non-biological degradation
-Chemical analysis data of the test substance (if any): Analytical data of the degradation intermediates of the test substance (if any); "Degradation rate-time curve" of the test substance and reference substance, including lag phase, degradation period, 10-day observation period and slope, stable period. Percent degradation at the end of the test and (or) the end of the 10-day observation period. d) Discussion of results.
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