1、INTERNATIONAL STANDARD ISO 18749 First edition 2004-02-15 Reference number ISO 18749:2004(E) ISO 2004 Water quality Adsorption of substances on activated sludge Batch test using specific analytical methods Qualit de leau Adsorption des substances sur la boue active Essai de lot utilisant des mthodes
2、 analytiques spcifiquesISO 18749:2004(E) ii ISO 2004 All rights reserved PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and ins
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6、iting from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in SwitzerlandISO 18749:2004(E) ISO 2004 All rights re
7、served iii Contents Page 1 Scope 1 2 Terms and definitions 1 3 Principle 2 4 Reagents and materials 2 5 Apparatus . 4 6 Test environment . 5 7 Procedure . 5 8 Calculation . 7 9 Validity of the test 9 10 Test report 9 Bibliography . 10ISO 18749:2004(E) iv ISO 2004 All rights reserved Foreword ISO (th
8、e International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committ
9、ee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechn
10、ical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member
11、bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying
12、any or all such patent rights. ISO 18749 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 5, Biological methods.ISO 18749:2004(E) ISO 2004 All rights reserved v Introduction This test is used as a screening test to determine the degree of adsorption of substances on act
13、ivated sludge or primary sludge in waste water treatment plants. General information on the adsorption and desorption of test compounds may also be obtained by other tests (see e.g. Reference 5 in the Bibliography) vi INTERNATIONAL STANDARD ISO 18749:2004(E) ISO 2004 All rights reserved 1 Water qual
14、ity Adsorption of substances on activated sludge Batch test using specific analytical methods WARNING Activated sludge and sewage contain potentially pathogenic organisms. Take appropriate precautions when handling them. Handle with care toxic test compounds and those whose properties are unknown. 1
15、S c o p e This International Standard specifies a screening test method for the determination of the degree of adsorption of substances on to the activated sludge or primary sludge in a waste water treatment plant. The conditions described in this International Standard normally correspond to the op
16、timum conditions for the adsorption to occur at the chosen activated-sludge concentration and water hardness during the test period. The method applies to substances for which an analytical method with sufficient accuracy is available and which, under the conditions of the test and at the test conce
17、ntration used, a) are water-soluble; b) or, if only slightly water-soluble, allow sufficiently stable suspensions, dispersions or emulsions to be prepared; c) are not significantly removed from the test solution during the test by known abiotic processes such as stripping or foaming; d) do not deflo
18、cculate activated sludge; e) are not readily biodegradable (for a discussion of biodegradability, see ISO/TR 15462). An important parameter that can influence the reliability of the test results is the stability of the test compound during the test. If no information on the stability is available, i
19、t is recommended that this be checked before the test. If any transformation (e.g. due to hydrolysis) is observed, it is recommended that the degree of adsorption of the transformation products be determined, if possible. Since biodegradability of the test compound may also lead to an incorrect asse
20、ssment of the degree of adsorption, it is recommended that the biodegradability be investigated in advance using standard biodegradation tests which are preferably based on oxygen consumption or on carbon dioxide production and in which adsorption has no influence on the test result. If biodegradati
21、on cannot be excluded, sterilized sludge may be used (see Clause 7). There is generally no need to carry out adsorption tests on substances which are readily biodegradable as they are sufficiently removed biologically in waste water treatment plants. Substances which are easily adsorbed on activated
22、 sludge in waste water treatment plants are preferably removed by adsorbing them in sludge digesters and degrading them anaerobically. For such substances, high adsorption may be a reason for carrying out anaerobic biodegradation tests. An overview of standardized biodegradation tests is given in IS
23、O/TR 15462. The test compound concentrations used in this method are usually very low and therefore no negative effects are to be expected on the capacity of the activated sludge to adsorb even toxic test compounds. When there is any doubt, it is recommended that microscopic investigations of the fl
24、ocs and suitable toxicity tests such as that specified in ISO 8192 be carried out. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply.ISO 18749:2004(E) 2 ISO 2004 All rights reserved 2.1 activated sludge biomass and inert matter produced in the aerob
25、ic treatment of waste water by the growth of bacteria and other microorganisms in the presence of dissolved oxygen 2.2 degree of adsorption on activated sludge percentage of a test compound eliminated by any process except biodegradation and stripping under the conditions of a specific aqueous batch
26、 test by activated or primary sludge, determined by comparing the concentration at the beginning of the test with that at the end 2.3 distribution coefficient the ratio of the concentration of a test compound in the sludge to its concentration in the aqueous phase 2.4 concentration of suspended soli
27、ds in an activated sludge amount of solids obtained from a known volume of activated sludge by filtration or centrifugation under specified conditions and drying at about to constant mass 3P r i n c i p l e The method determines the degree of adsorption, and, optionally, the distribution coefficient
28、 and mass balance, of water-soluble organic substances on activated or primary sludge using an aqueous batch-test system. The test mixture usually comprises an inorganic-salt test medium, activated sludge and the test compound. The hardness of the test medium, the concentration of suspended solids i
29、n the activated sludge and the amount of test compound added are specified to simulate real conditions of waste water treatment plants. Thus, the initial concentration of the test compound is usually as low as possible within the sensitivity range of the analytical methods available. The concentrati
30、on of the test compound is measured using substance-specific analytical methods at the beginning, during and at the end of the test (normally ). The measured values are used as the basis for calculating the degree of adsorption and, optionally, the distribution coefficient and the mass balance. The
31、measurement of elimination in the test vessels generally allows no direct differentiation between adsorption and other elimination mechanisms such as complex formation, flocculation, precipitation, sedimentation or biodegradation. More information can be obtained by using an abiotic elimination cont
32、rol without activated sludge, sterilized sludge and/or by determining biodegradation of the test compound with appropriate tests. 4 Reagents and materials Use only reagents of recognized analytical grade. 4.1 Water Use distilled or de-ionized water containing less than of dissolved organic carbon (D
33、OC) per litre. 4.2 Test medium 4.2.1 Preparation of solution A Anhydrous potassium dihydrogen phosphate (KH 2 PO 4 ) Anhydrous dipotassium hydrogen phosphate (K 2 HPO 4 ) Disodium hydrogen phosphate dihydrate (Na 2 HPO 4 2H 2 O) Dissolve in water (4.1) and make up to 105 C 24 h 1mg 8,5 g 21,75 g 33,
34、4 g 1 000 mlISO 18749:2004(E) ISO 2004 All rights reserved 3 It is recommended that this buffer solution be checked by measuring its pH. If it is not about , prepare a new solution. 4.2.2 Preparation of solution B Dissolve of magnesium sulfate heptahydrate (MgSO 4 7H 2 O) in water (4.1) and make up
35、to . 4.2.3 Preparation of solution C Dissolve of calcium chloride dihydrate (CaCl 2 2H 2 O) in water (4.1) and make up to . 4.2.4 Preparation of solution D Dissolve of sodium hydrogen carbonate (NaHCO 3 ) in water (4.1) and make up to . 4.2.5 Preparation of test medium The test medium is prepared at
36、 the beginning of each test by adding the correct amounts of stock solutions A to D to the test compound as described in Clause 7. It is important to follow the instructions in Clause 7 to avoid precipitation of the salts. The hardness of the test medium is adjusted to a value which will depend on t
37、he usual water hardness in the region concerned or on the purpose of the test. Mixing of each of solutions A to D and making up to with water (4.1) will give a hardness of ( of Ca 2+ , of Mg 2+ ) and a hydrogen carbonate (HCO 3 ) concentration of , which is typical for many waste waters. If required
38、 another hardness may be used. In this case, change the amounts of solutions B and C added, bearing in mind that an extra of solution B corresponds to an increase in Mg 2+concentration of and an extra of solution C to an increase in Ca 2+concentration of . Indicate the hardness used and theratio cl
39、early in the test report. If a test compound influences the pH of the mixture significantly at the chosen concentration (e.g. if the pH is outside 6,0 to 9,0), an increase in the buffer capacity of the test medium may be required. In such cases, add more of solution A, e.g. instead of . Solutions A
40、to D may be stored for up to 6 months in the dark at room temperature. 4.3 Preparation of stock solutions of test compound and reference material Dissolve the test compound in water (4.1) or in test medium (4.2) at a suitable concentration. Suitable means a concentration which simulates real environ
41、mental conditions (e.g. of waste water), but which is high enough to allow a sufficiently accurate quantitative determination of the test compound remaining at the end of the test to be made, using the intended analytical procedure, even after elimination of about by adsorption. In the case of subst
42、ances which are toxic to activated sludge and might for this reason influence the adsorptive capacity of the sludge and hence the test result (see Clause 1), the concentration shall be low enough to avoid this effect. The concentration may also be governed by the intended purpose of the test, for ex
43、ample the simulation of an exposure scenario at a given environmental concentration. If there is no special request or other information, a concentration of to is appropriate for substance-specific analysis and of DOC/litre in the case of DOC analysis (see Clause 7). Prepare the stock solution fresh
44、ly before use or store it, depending on the stability of the test compound, in the dark at about . It is generally not necessary to test slightly water-soluble test compounds at levels above their solubility in water, as they are mechanically removed in waste water treatment plants, e.g. by sediment
45、ation. In such cases, therefore, the concentration of the solution has to be below the solubility in water under the test conditions, but high enough to allow a sufficiently accurate determination at the end of the test, even after elimination of aboutby adsorption. If substances pass into waste wat
46、er treatment plants in the form of stable emulsions or dispersions and hence enter the environment in this form, they can be tested in this form if available. To decide whether a test compound is sufficiently water-soluble, it is recommended that a sample be taken from the freshly prepared stock sol
47、ution and the total organic carbon (TOC) determined directly and, after 7,4 0,5 12,3 g 1 000 ml 29,4 g 1 000 ml 22,4 g 1 000 ml 10 ml 1 000 ml 2,5 mmol/l 80 mg/l 12 mg/l 162 mg/l 1 ml 0,05 mmol/l 1 ml 0,2 mmol/l Ca/Mg 100 ml 10 ml 90 % 1 mg/l 5 mg/l 40 mg 4 C 90 %ISO 18749:2004(E) 4 ISO 2004 All rig
48、hts reserved centrifugation at about for , the dissolved organic carbon (DOC) determined. The test is applicable to a particular test compound if the DOC is of the TOC. To check the procedure and the adsorptive properties of the sludge, it is recommended that a reference compound be used which is su
49、fficiently water-soluble, non-volatile and poorly biodegradable, and has a degree of adsorption after . Use preferably a water-soluble dyestuff at a concentration which gives a photometric extinction coefficient of 0,4 to 1,0. Basic Violet 4 (light absorption maximum ) has shown its suitability in a round-robin test. Dissolve the reference compound in water (4.1) or in test medium (4.2), at a suitable concentration, and determine the degree of adsorption. 4.4 Preparation of activated sludge Take a sampl
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