1、 STD=BSI BS EN IS0 -ENGL 1797 LbZ4bb9 0LO973 280 BRITISH STANDARD Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Static test (Zahn-Wellens method) The European Standard EN IS0 9W1999 has the status of a British Standard ICs 13.060.70 BS EN IS
2、0 9888:1999 BS 6068-5.13:1999 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BS EN IS0 9888.1999 AmdNo. Date This British Standard, having been prepared under the direction of the Health and Environment Sector Committee, was published under the authority of the Standards Comm
3、ittee and comes into effect on 15 September 1999 Comments O BSI 09-1999 National foreword This British Standard is the English language vemion of EN IS0 9888:lW. It is identical with IS0 9888: 1999. It supersedes BS EN 29888: 1993 which is withdrawn. The UK participation in its preparation was en!xu
4、sted by Technical Committee Em, Water quai - present to the responsible internationalEuropean committee any enquiries on the interpretation, or proposals for change, and keep the UK interests illfOed) - monitor related international and European developments and promulgate them in the UK A list of o
5、rganizations represented on this subcommittee can be obtained on request to its secretary. BS EN IS0 9888 is one of a series of standards on water quality, others of which have been, or will be, published as Sections of BS 6068. This standard has therefore been given the secondary identifier BS 6068
6、5.13. The various Sections of BS 6068 are comprised within Parts 1 to 7, which, together with Part O, are listed below. Part O Introduction Part 1 Glossa,ry Part 2 Physical, chemical and biochemical memds Part 3 Rudioiogid Methods Part 4 M.icrobioogical mwh Part 5 Biological methods Part 6 Sampling
7、Part 7 precision and accurmcy NOTE The tesis described in this British Standard should only be carried out by suitably qualified persons with an appropriate level of biological expertise. Sandard biological procedures should be followed throughout. Cross-references Attention is drawn to the fact tha
8、t CEN and CENELEC Standards normally include an annex which lists nonnative references to intemational publications with their corresponding European publications. The British Standards which implement these intemationai or European publications may be found in the BSI Standards Cataiogue under the
9、section entitled “International Standards Correspondence index“, or by using the “Find“ facility of the BSI Standards Electronic Catalogue. A British standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct applicati
10、on. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN IS0 title page, the EN IS0 foreword page, the IS0 title page, pages ii and iii, a blank page, pages 1 to 11, the ann
11、ex ZA page, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. i ISBN O 580 32760 4 STD.BS1 BS EN IS0 9888-ENGL 1999 m lb24bb9 0830995 O53 sl EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS0 9888 June 1999 I
12、Cs 13.080.00 Supersedes EN 29888:1993 English version Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Static test (Zahn- Wellens method) (IS0 9888: 1 999) uallt de bau - Evaluation, en milieu aqueux, de ia Modgmdabllit6 arobie uWme des compos
13、b) nonvolatile, or which have a negligible vapour pressure under the test conditions; c) not lost by foaming from the test solution; d) not inhibitory to the test microorganisms at the concentration chosen for the test. inhibitory effects can be determined using a suitable test method (e.g. see IS0
14、8192). If the test compound is toxic, the test concentration must be lowered, or a pre-exposed inoculum can be used. This International Standard is also applicable to the measurement of biodegradation and elimination of dissolved organic compounds in wastewater (also called “test compound in the met
15、hod). NOTE If more information is required to predict the behaviour of test compounds or wastewater in a treatment plant, a simulation test (e.g. the activated sludge simulation test IS0 11733) should be performed. For appropriate use of this method and for altemative biodegradation methods, see IS0
16、 15462. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties t
17、o agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IS0 and IEC maintain r
18、egisters of currently valid International Standards. IS0 6060:1989, Wafer quality - Determination of the chemical oxygen demand. IS0 8245, Water qualify - Guidelines for the determination of total organic carbon (TOC) and dissolved organic carbon (DOC). 1 EN IS0 9888:1999 3 Terms and definitions For
19、 the purposes of this Intemationai Standard, the following terms and definitions apply. 3.1 ultimate aerobic biodegradation breakdown of a chemical compound or organic matter by microorganisms in the presence of oxygen to carbon dioxide, water and mineral salis of any other elements present (mineral
20、ization) and the production of new biomass 3.2 primary biodegradation structural change (transformation) of a chemical compound by microorganisms resulting in the loss of a specific property 3.3 activated sludge biomass produced in the aerobic treatment of wastewater by the growth of bacteria and ot
21、her microorganisms in the presence of dissolved oxygen 3.4 concentration of suspended solids of an activated sludge amovnt of sotids obtained by filtration or centrifugation of a known volume of activated sludge and drying at about 105 C to constant mass 3.5 total organic carbon TOC all that carbon
22、present in organic matter which is dissolved and suspended in the water 3.6 dissolved organic carbon DOC that pari of the organic carbon in the water which cannot be removed by specified phase separation NOTE filtration using membranes with pores of 0,2 pm to 0,45 pm diameter. Phase separation may b
23、e specified for example by centrifugation at 40000 m-s-2 for 15 min or by membrane 3.7 chemical oxygen demand COD mass concentration of oxygen equivalent to the amount of a specified oxidant consumed by a chemical compound or organic matter when a water sample is treated with that oxidant under defi
24、ned conditions NOTE COD is expressed in this case as milligrams oxygen consumed per milligram or gram of test compound. 3.8 w Ph- time from the start of a test until adaptation and/or selection of the degrading microorganisms are achieved and the biodegradation degree of a chemical compound or organ
25、ic matter has increased to about 10 % of the maximum level of biodegradation NOTE Lag phase is recorded in days. 3.9 maximum level of biodegradation maximum degree of biodegradation of a chemical compound or organic matter in a test, above which no further biodegradation takes place during the test
26、NOTE Maximum level of biodegradation is recorded in percent. 2 - STD-BSI BS EN IS0 9888-ENGL 1999 D lb24bb9 08LLO2 991 R EN IS0 9888:1999 3.10 biodegradation phase time from the end of the lag phase of a test until about 90 % of the maximum level of biodegradation has been reached NOTE Biodegradatio
27、n phase is recorded in days. 3.11 piateau phase time from the end of the biodegradation phase until the end of the test NOTE Plateau phase is recorded in days. 3.12 pre-expoture pre-incubation of an inoculum in the presence of the test chemical compound or organic matter, with the aim of enhancing t
28、he ability of this inoculum to biodegrade the test material by adaptation andor selection of the microorganisms 3.13 preconditioning pre-incubation of an inoculum under the conditions of the subsequent test in the absence of the test chemical compound or organic matter, with the aim of improving the
29、 performance of the test by acclimatization of the microorganisms to the test conditions 4 Principle The biodegradation or elimination of water-soluble organic compounds or wastewater ingredients by aerobic microorganisms is determined using a static aqueous test system. The test mixture contains an
30、 inorganic medium, activated sludge as a mixed inoculum and an organic test compound as the sole source of carbon and energy other than the sludge. The amount of test compound added is chosen to result in an initial concentration of dissolved organic carbon (DOC) between 50 mgA and 400 mgil, or of c
31、hemical oxygen demand (COD) between 100 mg/i and 1000 mgil, depending on its water solubility and on its toxicity to the bacteria in the inoculum. Measurement of the concentration of DOC (or COD) is made at the beginning and end of the test (normally 28 d) and at intermediate time intervals, as requ
32、ired. To allow for any significant adsorption of the test compwnd onto the sludge, samples are also taken 3 h after the beginning of the test. Values obtained at this time are used as the basis for calculating the percentage of ultimate biodegradability at each sampling time. As additional informati
33、on, the total elimination of DOC or COD from the aqueous phase may be obtained by calculating the removal based on a measured value before addition of the salts of the test medium and the inoculum. Possible other abiotic elimination processes, such as stripping into the air, may be determined by an
34、abiotic elimination control without inoculum. Use of specific analysis may give additional information on primary biodegradability of test compounds. 5 Test environment Incubation shall take place in the dark or in diffuse light, at a temperature within the range 20 “C to 25 “C which shall not vary
35、by more than 2 “C during the test and in an enclosure which shall be free from gases and vapours which are toxic to microorganisms. 6 Reagents Use only reagents of recognized analytical grade, including the following. 6.1 Water, distilled or deionized, containing less than 1 mgA DOC. 3 STD=BSI BS EN
36、 IS0 7888-ENGL 1999 a Lb2Ybb7 0811003 828 D EN IS0 9888:1999 62 Testmedium 6.2.1 Composition 6.2.1.1 Solution a) Anhydrous potassium dihydrogenphosphate (KH2P04) 83 g Anhydrous dipotassium hydrogenphosphate (K2HP04) 21,75 g Disodium hydrogenphosphate dihydrate (Na2HP04.2H20) 33,4 9 Ammonium chloride
37、 (“ rotate to ensure adequate mixing. Each vessel shall be fitted with 2 mm to 4 mm inner diameter glass tubes or glass frits to introduce air. The air shall be free from organic carbon and toxic vapours and shall be presaturated with water vapour to reduce losses by evaporation. The glassware shall
38、 be carefully cleaned and, in particular, be free from traces of organic or toxic matter. 7.2 Measuring equipment, of sufficient sensitivity for the measurement of dissolved organic carbon (see IS0 8245) or the measurement of chemical oxygen demand (see IS0 6060) and, if required, for substance-spec
39、ific analysis. 7.3 Centrifuge or device for filtration, with paper filters or membrane filters (of pore sitehominal aperture diameter 0,2 to 0,45 pm) which adsorb or release organic carbon to a minimum degree. 7.4 pH-meter (usual laboratory equipment). 8 Procedure 8.1 Preparation of the test solutio
40、ns 8.1.1 Solution of the test compound in the water (6.1) or in the test medium (6.2.2), at a suitable concentration (e.g. 3 o00 mgA). In the case of wastewater, determine the TOC, DOC and pH. The test is acceptable to the wastewater if the DOC is 9% of the TOC, which indicates sufficiently water-so
41、luble compounds for this method based on DOC measurement. Add the wastewater directly or dilute it with water (6.1) to obtain the desired test concentration. If the wastewater has an extreme pH value (lo), neutralize to pH 7 f 1 with sodium hydroxide (6.3) or hydrochloric acid (6.4) solution. 8.1.2
42、Solution of the reference compound in the water (6.1) or in the test medium (6.2.2), at a suitable concentration (e.g. 3 o00 mgIl). Use a known biodegradable water-soluble organic compound (e.9. diethylene glycol, ethylene glycol, sodium benzoate or aniline) which have degradation degrees 90 %). 8.2
43、 Preparation of the inoculum Take a sample of activated sludge from the aeration tank of a biological wastewater treatment plant. Mix the sample well and wash the activated sludge by repeatedly (e.g. two to three times) adding tap water or the test medium (6.2), centrifuging or settling, and decanti
44、ng of the supernatant. Before use, determine the concentration of suspended solids (use e.g. IS0 11923). If necessary, concentrate the sludge by settling so that the volume of sludge added to obtain the desired concentration of suspended solids is minimal (about 10 % of the total volume). Keep the i
45、noculum aerated at room temperature until just before use. NOTE Depending on the purpose of the test, the wastewater treatment plant should receive wastewater which is predominantly municipal. Activated sludge may also be taken from a laboratory treatment plant. To get as many different species or s
46、trains of bacteria as possible, it may be preferable in special cases to make a mixture from various sources. Pre- exposed inocula may be used in certain circumstances. When such inocula are used, this should be clearly stated in the test results (e.g. percentage biodegradation using pre-exposed ino
47、cula) and the method of pre-exposure detailed in the test report. Pre-exposed inocula can be obtained from laboratory biodegradation tests conducted under a variety of conditions as appropriate. Suitable tests are e.g. a Zahn-Wellens test (this test, IS0 9888) already performed with the test compoun
48、d (see 8.3) or the SCAS test (IS0 9887). Inocula may also be collected from locations where relevant environmental conditions exist (e.g. wastewater treatment plants dealing with similar compounds). 5 8.3 Test Vessel Test compound FT Provide a sufficient number of glass vessels (7.1) in order to hav
49、e: - at least 1 vessel (symbol FT) for the test compound (8.1 .l); - at least 1 blank vessel (symbol FB) containing test medium and inoculum; - at least 1 vessel, for checking the procedure (symbol Fc) containing the rtwrence compound (8. Test Test Reference medlum compound compound (6.2) (8.1 .i) (0.1.2) (0.2) + - + + 2); Blank FB Inoculum check Fc - if needed, 1 vessel for checking a possible abiotic elimination (symbol Fs) containing the test compound (8.1 .l) but no inoculum, sterilized e.g. by addition of a suitable inorganic toxic compound to prevent mic
