1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 12176:1998 The Euro
2、pean Standard EN 12176:1998 has the status of a British Standard ICS 13.030.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Characterization of sludge Determination of pH valueThis British Standard, having been prepared under the direction of the Health and Environment Sect
3、or Board, was published under the authority of the Standards Board and comes into effect on 15 June 1998 BSI 1998 ISBN 0 580 29142 1 BS EN 12176:1998 Amendments issued since publication Amd. No. Date Text affected National foreword This British Standard is the English language version of EN 12176:19
4、98. The UK participation in its preparation was entrusted to Technical Committee EH/5, Sludge characterization, which has the responsibility to: aid enquirers to understand the text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep
5、the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European public
6、ations referred to in this document may be found in the BSI Standards Catalogue under the 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 provi
7、sions of a contract. Users of British Standards are responsible for their correct application. 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 title page, pages 2 to 6,
8、 an inside back cover and a back cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN
9、national Members. Ref. No. EN 12176:1998 E EUROPEAN STANDARD EN 12176 NORME EUROPE ENNE EUROPA ISCHE NORM February 1998 ICS 13.030.20 Descriptors: Sludges, sewage treatment sludges, tests, measurements, ph, samples, preparation, potentiometric methods English version Characterization of sludge Deter
10、mination of pH-value Caracte risation des boues De termination de la valeur du pH Charakterisierung von Schlamm Bestimmung des pH-Wertes This European Standard was approved by CEN on 16 January 1998. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the condit
11、ions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three o
12、fficial versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austri
13、a, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 12176:1998 BSI 1998 Foreword This European Standard has been prepared by Technical Committee CEN/TC 308, Characterization
14、 of sludges, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by August 1998, and conflicting national standards shall be withdrawn at the latest by August 1
15、998. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway
16、, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Contents Page Foreword 2 0 Introduction 3 1 Scope 3 2 Normative references 3 3 Definitions 3 3.1 pH value 3 3.2 Standard buffer solutions 3 4 Principle 3 5 Interferences 3 6 Hazards 4 7 Reagents 4 8 Apparatus 4 9 Preparation of samples 4
17、 9.1 Sample preservation 4 9.2 Preparation of liquid sludge samples 4 9.3 Preparation of paste-like and solid sludges 4 10 Measurement of pH-value 4 10.1 pH meter set up and standardization 4 10.2 Measurement 4 11 Expression of results 5 12 Test report 5 Annex A (normative) Primary pH-standard refer
18、ence solutions (according to ISO 10523) 6 Annex B (informative) Bibliographical references 6Page 3 EN 12176:1998 BSI 1998 0 Introduction The pH value is a necessary parameter for monitoring the treatment of urban and comparable industrial sludges as well as of sludges from water supply treatment pla
19、nts and to assess the suitability of the use of sludge in agriculture or for its disposal to land fill. The pH value of liquid sewage sludge may be used to monitor digester performance. 1 Scope The scope of this standard is the sludges, i.e. and sludges products from: storm water handling; night soi
20、l; urban wastewater collecting systems; urban wastewater treatment plants; treating industrial wastewater similar to urban wastewater (as defined in Directive 91/271 EEC); water supply treatment plants; water distribution systems; but excluding hazardous sludges from industry. This method is applica
21、ble to the determination of pH values of sludges which include liquid, paste-like or solid matter. If the sludge sample is sufficiently liquid, direct measurement should be made. If the sludge sample contains relatively high percentages of solids the measurement should be carried out after dilution
22、with water. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendment t
23、o or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. prEN 12880, Characterization of sludges Determinaton of dry residue and water content.
24、ISO 3696, Water for analytical laboratory use Specification and test methods. ISO 10523:1994, Water quality Determination of pH. 3 Definitions For the purpose of this standard the following definitions apply: 3.1 pH-value the pH value of an aqueous solution is theoretically a function of the electro
25、motive force of a measuring cell (e.g. a glass electrode and a calomel electrode) which is defined by the equation given in annex A of ISO 10523:1994. The practical pH scale refers to exactly specified buffer solutions 3.2 standard buffer solutions solutions of certain concentrations of pure substan
26、ces or mixtures thereof with defined pH values 4 Principle A suitable aqueous suspension of the solid or paste-like sludge is prepared and the pH value of the suspension is determined potentiometrically. In liquid samples the measurement is made directly. 5 Interferences Substances present at their
27、normal concentration in these types of samples do not cause significant interference. The pH value of suspensions is dependent, to a considerable extent, on the carbon dioxide equilibrium. Therefore manipulation after the sampling of liquid sludge and after the preparation of suspensions should be k
28、ept to a minimum. If oil or grease is visible in the sample, it should be removed by filtration through a pad of cotton wool (8.9) prior to carrying out the measurement. The presence of sulfides or arsenic may poison the glass interface of the electrode. Electrodes with a low “alkali error” should b
29、e used for the measurement of sludges expected to be of a high pH. NOTE 1 Glass electrodes normally respond to sodium ions at pH values above 9. This may cause errors in the measurement of the pH values of samples such as lime conditioned sludges. NOTE 2 A film may form on the surface of the pH-elec
30、trodes due to oil and grease. This may lead to errors in the measuring results. Inorganic film-forming substances may also interfere if not removed from the pH-electrodes between determinations. NOTE 3 If sludge samples are taken from a digester, digester gas may escape causing changes in the carbon
31、 dioxide content, which may lead to errors in the measured results.Page 4 EN 12176:1998 BSI 1998 6 Hazards Samples of sewage sludge are liable to ferment. Do not store them in the open laboratory. If samples must be stored, then store them at (0 to 4) C. When handling a stored sample wear gloves, fa
32、ce and eye protection and sufficient body protection to guard against bottles bursting. Use bottle carriers. The gas evolved is usually flammable so all equipment in the vicinity should be flame-proof and sources of ignition absent. Bursting glass bottles can produce micro-organism contaminated shra
33、pnel. Plastic bottles can also burst and produce a hazardous spray and aerosol. Ensure that all spillages are cleared up. Do not handle broken glass directly. There is also a danger of hydrogen sulfide formation during storage. Cap loosely to avoid pressure build-up. Sludge usually contains harmful
34、organisms. Cleanliness is essential. Keep sludge away from food and eating. Protect all cuts. 7 Reagents Analytical grade reagents shall be used. 7.1 Water For the preparation of standard buffer solutions (see 3.2) freshly distilled or deionised water freshly taken from a column according to ISO 369
35、6, Grade 3 shall be used. It shall be free from carbon dioxide and have a conductivity of# 2mS/cm. 7.2 Standard buffer solutions These shall be in accordance with ISO 10523 and annex A (normative). Such solutions are available commercially. 7.3 Ethanol, (CH 3 CH 2 OH), 70 % V/V. 7.4 Acetone, (CH 3 C
36、OCH 3 ). 8 Apparatus 8.1 pH-meter Temperature compensated input resistance$ 10 12 V readable to at least pH = 0,05, slope correction in mV/pH. 8.2 Glass electrode and reference electrode The glass electrode measuring system shall have a zero voltage at pH = 7. This may consist of a glass electrode a
37、nd a reference electrode, or a combination electrode system, see 2 and 3. NOTE Some problems are associated with the reference electrodes and it is recommended that these should be tested before use. The use of a symmetrical pH-measuring system is suggested, i.e. glass and reference electrode of the
38、 same type, e.g. Ag/AgCl electrode system. Reference electrodes with gelled filling solutions should not be used. 8.3 Thermometer, capable of measuring to the nearest 0,58C. 8.4 Mechanical shaking apparatus 8.5 Sample bottles, plastics or borosilicate glass, wide mouthed. 8.6 Stoppered conical flask
39、, Erlenmeyer type, 150 ml. 8.7 Balance, accuracy 0,01 g. 8.8 Drying oven, (105 5)8C. 8.9 Cotton pads 8.10 Soft tissue, and other usual laboratory devices. 9 Preparation of samples 9.1 Sample preservation Sludge samples can change composition through biological or chemical activity. Therefore, they s
40、hould be analysed as soon as possible after sampling. Liquid sludge samples will lose carbon dioxide on exposure to air. They shall therefore be kept in a closed partially filled container until the pH value is determined. Handling should be minimized to avoid loss of carbon dioxide. If prolonged st
41、orage of sludge samples is unavoidable they should be stored at (0 to 4)8Ci na refrigerator. 9.2 Preparation of liquid sludge samples These samples usually contain less than 50 g dry matter per kg sludge and do not require any preparation before pH-measurement. NOTE If visible oil or grease is prese
42、nt it should be removed by filtration through a cotton wool pad prior to step 10.1. Use the filtrate at step 10.2. 9.3 Preparation of paste-like and solid sludges Weigh an amount of sample equivalent to approximately 5,0 g dry matter into a conical flask (8.6). Add water (7.1) to make the total weig
43、ht (100 1) g. Stopper the flask and shake mechanically (8.4) for at least 15 min, until the sample is thoroughly dispersed. In some cases it may be necessary to break down the solids prior to shaking. Proceed as in clause 10. NOTE 1 Whilst it is preferable that precise quantities of sludge (expresse
44、d as dry matter) are used, this may not always be possible. Estimates of the dry matter content may be made in the interests of speed. NOTE 2 Determine the dry solids content of the sludge in accordance with prEN 12880 by drying the sample at (105 5)8C. NOTE 3 If visible oil or grease is present aft
45、er shaking, follow the note given in 9.2. 10 Measurement of pH value 10.1 pH-meter set up and standardization Measure the temperature of the sample and set the temperature control on the pH-meter (8.1) following the manufacturers instructions. Standardize the pH-meter using standard pH-buffer soluti
46、ons (7.2). NOTE The range of pH values of the standard buffer solutions preferably includes that of the sample. 10.2 Measurement Rinse the electrodes (8.2) thoroughly with water (7.1). Ensure that the sludge sample is well dispersed by swirling. Immediately, place the electrodes in the sample. Read
47、the steady pH value from the pH-meter (8.1) after approximately 30 s to 60 s. Remove the electrodes and rinse with water (7.1). At the end of the batch of samples clean the electrodes with a soft wet tissue (8.10) and rinse the electrodes thoroughly with water. If the samples contained organic impur
48、ities use ethanol (70 %) (7.3), acetone (7.4) or warm detergent solution for cleaning. NOTE 1 Only use organic solvents for a short time as they decrease the sensitivity of glass electrodes by dewatering the leached layer of the glass membrane. NOTE 2 If the suspended phase separates from the liquid
49、 phase, it is preferable that the electrodes are placed in the liquid phase.Page 5 EN 12176:1998 BSI 1998 11 Expression of results The pH value shall be rounded to one decimal place. In addition, the temperature to which the pH-meter is compensated shall be specified. EXAMPLES pH value at 258C: 6,3 pH value in the sludge suspension at 208C: 8,8 pH value in the filtrate at 208C: 8,4 12 Test report The test report shall contain the following information: reference to this European Standard; all information necessar
