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1、INTERNATIONAL STANDARD IS0 7827 Second edition 199409-15 Water quality - Evaluation in an aqueous medium of the “ultimate” aerobic biodegradability of organic compounds - Method by analysis of dissolved organic carbon (DOC) Qualit de I eau - gvaluation en milieu aqueux de la biod - non-volatile, or
2、having a negligible vapour pressure under the conditions of the test (see note 5 in 8.3); - not significantly adsorbable on glass and activated sludge (see note 6 in 8.3); - not inhibitory to the test microorganisms at the concentration chosen for the test. Inhibitory ef- fects can be determined as
3、described in 8.3, or by using any other method for determining the inhibitory effect on bacteria of a substance (e.g. IS0 81921. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time
4、of publica- tion, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most re- cent editions of the standards indicated below. Members of IEC and IS0 mai
5、ntain registers of cur- rently valid International Standards. IS0 8192:1986, Water quality - Test for inhibition of oxygen consumption by activated sludge. IS0 8245:1987, Water quality - Guidelines for the determination of total organic carbon (TOC). IS0 9408:1991, Water quality - Evaluation in an a
6、queous medium of the “ultimate” aerobic bio- degradability of organic compounds - Method by determining the oxygen demand in a closed respirometer. IS0 9439:1990, Water quality - Evaluation in an aqueous medium of the “ultimate” aerobic bio- degradability of organic compounds - Method by analysis of
7、 released carbon dioxide. IS0 9887:1992, Water quality - Evaluation of the aerobic biodegradability of organic compounds in an 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 2
8、3:27:35 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 7827:1994(E) Q IS0 aqueous medium - Semi-continuous activated 5 Test environment sludge method (SCAS). IS0 9888:1991, Water quality - Evaluation of the aerobic biodegradability of organic compounds in an aqueous me
9、dium - Static test (Zahn-We/lens method). Incubation shall take place in the dark or in diffused light in an enclosure which is maintained at 20 “C to 25 “C and which is free from vapours that are toxic to microorganisms. 3 Definitions 6 Reagents Use only reagents of recognized analytical grade. For
10、 the purposes of this International Standard, the following definitions apply. 6.1 Distilled or deionized water, containing less than 10 % of the initial DOC content introduced by the 3.1 “ultimate” biodegradation: The level of compound to be tested. degradation achieved when the test compound is to
11、tally utilized by microorganisms resulting in the pro- duction of carbon dioxide, water, mineral salts and new microbial cellular constituent (biomass). 6.2 Test medium 6.21 Composition 3.2 primary biodegradation: The level of degra- dation achieved when the test compound undergoes any structural ch
12、ange, other than mineralization, as the result of microbial action. 6.2.1.1 Solution a) Anhydrous potassium dihydrogenphosphate (KH,POJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,5 g 3.3 concentration of suspended solids (of an act
13、i- vated sludge): The amount of solids obtained by fil- tration or centrifugation of a known volume of sludge under specified conditions and drying at 105 “C at constant weight. 4 Principle Determination of the biodegradation of organic com- pounds by aerobic microorganisms using a test me- dium. Th
14、e organic compound is the sole source of carbon and energy in the medium. The concentration of the compounds used is such that the initial con- centration of organic carbon in the medium is betweeen 10 mg/l and 40 mg/l. If necessary, concentrations greater than 40 mg/l may be used. Measurement of th
15、e dissolved organic carbon (DOC) at the start (day 0) and the end of the test (day 28 or longer if necessary) and at least at three regular, intermediate time intervals. Determination of the percentage removal of DOC at each of these intervals. Evaluation of the biodegrad- ability of the compounds u
16、sed on the basis of these data. Specific analysis may give additional information on primary biodegradation. Anhydrous dipotassium hydrogenphosphate (K,HPOJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21,75 g Disodium hydrogenphosphate dihydr
17、ate (Na,HP0,.2H,O) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33,4 g Ammonium chloride (NH,CI) . . . . . . . . . . . . . . . . . . . . . . . . . . 0,5 g Water (6.1), quantity necessary to make up to .,.,. 1 000 ml NOTE 1 The correct composition of the medium is
18、 checked by the measurement of the pH-value, which should be 7.4. 6.2.1.2 Solution b) Dissolve 22,5 g of magnesium sulfate heptahydrate (MgS0,.7H,O) in 1 000 ml of the water (6.1). 6.2.1.3 Solution c) Dissolve 27,5 g of anhydrous calcium chloride (CaCI,) in 1 000 ml of the water (6.1). 6.2.1.4 Solut
19、ion d) Dissolve 0.25 g of iron(lll) chloride hexahydrate (FeCI,.GH,O) in 1 000 ml of the water (6.1). Prepare the solution freshly just before use. NOTE 2 It is not necessary to prepare this solution just before use if a drop of concentrated hydrochloric acid (HCI) or 0,4 g/l of ethylenediaminetetra
20、acetic acid (EDTA) is added. 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 23:27:35 MDTNo reproduction or networking permitted without license from IHS -,-,- Q IS0 IS0 7827:1
21、994(E) 6.2.2 Preparation For 1 litre of test medium, add to about 500 ml of water (6.1): - 10 ml of solution a); - 1 ml of each of the solutions b) to d). Make up 1 000 ml with the water. 7 Apparatus Ensure that all glassware is thoroughly cleaned and, in particular, free from organic or toxic matte
22、r. Usual laboratory equipment and 7.1 Apparatus, of sufficient sensitivity for the measurement of dissolved organic carbon (see IS0 8245). 7.2 Centrifuge. 8.1.3 Solution to check inhibition If necessary, prepare a solution containing, in the test medium (6.21, the test compound and the reference com
23、pound in the respective concentrations used for the preparation of solutions in 8.1 .I and 8.1.2. 8.2 Preparation of the inoculum Prepare the inoculum using the following sources or a mixture of them, to obtain a microbial population that offers sufficient biodegradative activity. NOTE 3 In certain
24、circumstances, pre-exposed inocula may be used, provided that this is clearly stated in the test results (e.g. percent biodegradation =x %, using pre- exposed inocula) and the method of pre-exposure is detailed in the test report. Pre-exposed inocula can be obtained from laboratory bio- degradation
25、tests conducted under a variety of conditions e.g. Zahn-Wellens test (IS0 9888) and SCAS test (IS0 9887) or from samples collected from locations where relevant environmental conditions exist (e.g. treatment plants dealing with similar compounds or contaminated areas). 7.3 Shaking device, for aerati
26、on and mixing. Use a suitable volume for inoculation (see note 4). 7.4 pH-meter. 7.5 Conical flasks, of appropriate capacity (e.g. 2 000 ml). 7.6 Device for filtration, with membrane filters of suitable porosity (nominal aperture diameter of 0,2 pm to 0,45 pm) which adsorb organic compounds or relea
27、se organic carbon to a minimum degree. 8 Procedure 8.1 Preparation of test solutions 8.1.1 Solution of the test compound Prepare a stock solution of the test compound in wa- ter (6.1) or test medium (6.2). Dilute a suitable amount of this solution in the test medium in order to obtain a final organi
28、c carbon concentration between 10 mg/l and 40 mg/l. 8.1.2 Solution of the reference compound Prepare a stock solution of the reference compound (an organic compound of known biodegradibility such as sodium acetate, sodium benzoate or aniline) in the same way as in 8.1 .I, in order to obtain a final
29、organic carbon concentration between 1 Omg/l and 40mg/l. NOTE 4 “Suitable volume” means - sufficient to give a population which offers enough biodegradative activity; - degrades the reference compound(s) by the stipulated percentage; - gives between 10s and 106 active cells/ml; - gives not more than
30、 the equivalent of 30 mg/l sus- pended solids of activated sludge in the final mixture. The content of DOC in the inoculum shall be less than 10 % of the content of DOC introduced by the test compound (e.g. 80 %) and a constant level of degradation is attained before the end of the 28 d test period,
31、 consider that the test is finished. Extend the test by 1 week to 2 weeks, if degradation has obviously started but has not reached a plateau. When measurements of organic carbon have to be postponed up to 48 h, keep the samples at 4 “C in the dark and in tightly stoppered flasks. If the samples Cop
32、yright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 23:27:35 MDTNo reproduction or networking permitted without license from IHS -,-,- Q IS0 IS0 7827:1994(E) have to be stored for more
33、than 48 h before meas- urement, store the samples at - 18 “C. Alternatively, add a suitable inorganic toxic substance, e.g. 20 ml/l of a solution containing 10 g/l of mercury(ll) chloride (HgCI,), to prevent microbial activity and store at 4 “C. 9 Calculation and expression of results 9.1 Calculatio
34、n For each test flask, determine the percentage elim- ination of dissolved organic carbon Dt using the equation where e0 eB0 et eBt is the average DOC concentration, in milli- grams per litre, at time 0, in each test flask FT; is the average DOC concentration, in milli- grams per litre, at time 0, i
35、n the blank test flask Fa; is the average DOC concentration, in milli- grams per litre, at time t, in each test flask F,; is the average DOC concentration, in milli- grams per litre, at time t, in the blank test flask F,. Round percentage results to the nearest whole num- ber. NOTES 7 The abiotic el
36、imination (flask F,) can be calculated ac- cording to the same equation, but without considering the blank values (if F, is inoculated to check the degree of ad- sorption, consider the blanks). If a significant loss of organic carbon is observed, no differentiation between biotic and abiotic elimina
37、tion is possible. In this case, other tests based on parameters clearly indicating biological processes should be performed, such as the respirometric test (IS0 9408) or the carbon dioxide production test (IS0 9439). 8 The degree of elimination of the mixture of test com- pound and reference substan
38、ce in the inhibition control (flask F,) can be calculated according to the same equation. If the percentage of elimination of the mixture is less than 35 % in 14 d, the test compound has inhibited the bio- degradation of the reference substance and is therefore assumed to be toxic. In this case, the
39、 test should be re- peated with a lower concentration of the test compound or with a pre-exposed inoculum. 9.2 Expression of results Compile a table of DOC percentage elimination for each concentration interval and each test vessel. If comparable results are obtained for the duplicate test vessels (
40、see 10.11, plot a mean elimination curve as a function of time (see example in annex A). Some parameters for the degradation can be deter- mined from this curve: in particular, if sufficient data are available, the lag time, the degradation time and the maximum level of degradation as described in 9
41、.2.1 to 9.2.3. If the test substance is not significantly eliminated abiotically (e.g. by adsorption) and the elimination curve has a typical shape with a lag and degradation phase, assign the measured DOC elim- ination to biodegradation. 9.2.1 Lag time tl In most of the degradation curves a so-call
42、ed lag time can be observed. This is normally defined as the time from inoculation until the degradation percentage has increased to at least 10 % of the starting DOC con- tent. This lag time is often highly variable and poorly reproducible. Note the lag time in days. 9.2.2 Maximum level of degradat
43、ion The maximum level of degradation is defined as the approximate level above which no further degradation takes place during the test. 9.2.3 Degradation time t2 The degradation time t2 is defined as the time from the end of the lag time t, till the time that about 90 % of the maximum level of degr
44、adation has been reached. Note the degradation time in days. 10 Validity of the test 10.1 Consider a test to be valid if, in the test flasks with the same test concentration and inoculum, the difference between the extreme degradation values found is less than 20 % DOC removal at the end of the test
45、. If this is not the case, repeat the test. 10.2 Consider the test results to be valid if, in the test with one of the proposed reference compounds, the percentage degradation after 14 d is more than 70 %. If this is not the case, repeat the test. Copyright International Organization for Standardiza
46、tion Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 23:27:35 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 7827:1994(E) 0 IS0 11 Test report The test report shall contain at least the following in- form
47、ation: a) a reference to this International Standard; b) all necessary information for the identification of the test compound; c) all the data (for example in tabular form) obtained and the degradation curve; d) the concentration of the test compound used and the DOC content of this concentration;
48、e) the name of the reference compound used and the degradation obtained with this compound; g) the main characteristics of the DOC analyser used; h) the incubation temperature of the test; i) if included, the percentage of degradation ob- tained in flask Fs (monitoring the abiotic elim- ination); j)
49、 if included, the percentage of degradation in flask F, (toxicity test) and a statement on the toxicity of the test compound; k) the reasons, in the event of rejection of the test (see clause IO); I) any alteration of the standard procedure or any other circumstance that may have affected the results. f) the source, the characteristics, the concentration or the volume of the inoculum used and informa- tion on any pretreatment; 6 Copyri