Chemical & microbiological analysis of sludge over the last 40 years: much ado about what?

Transcription

1 Chemical & microbiological analysis of sludge over the last 40 years: much ado about what? K. Clive Thompson Chief Scientist ALcontrol Laboratories

2 Disclaimer The views expressed in this presentation are solely those of the author and not necessarily those of ALcontrol Laboratories

3 Contents 1. Project Horizontal 2. General background 3. Fit for purpose analysis and validation 4. Possible way forward 5. Acceptable and unacceptable risks

4 Project HORIZONTAL Project HORIZONTAL started in December 2002 with the aim to develop horizontal and harmonised European standards in the field of sludge, soil, and treated biowaste to facilitate the regulation of these major streams in the multiple decisions related to different uses and disposal governed by EU Directives. The longer term aim is for one standard (for each method) to cover most types of environmental solid samples including sludges, soils, composts biowastes and now wastes The work started with desk studies on all topics relevant in the project to evaluate the feasibility of the development of a horizontal standard or horizontal standards for sampling, biological parameters, hygienic parameters, organic parameters, inorganic parameters, mechanical properties and leaching. It finished with Europe s largest method validation trial

5 General Background (1) 1. Misperceptions about sewage sludge abound e.g People prefer to believe these alarmist conspiracy theory websites rather than the EPA and other Government organisation rational non-emotive websites 3. Many of these misperceptions arise from modern instrument limits of detection (LODs) Many organic pollutants can be detected at ppt and even some at sub-ppt levels 4. Many also believe the 4 of 5 significant figure result values reported without any idea of the typical result uncertainty

6 General Background (2) and 70s lack of reliable low level sludge analysis methods and equipment 5. However, many experienced qualified analysts. (e.g. UK ONC; HNC; LRSC; GRSC day release options). These disappeared with expansion of the universities in the UK 6. Analytical science training became a Cinderella subject 7. The Open University Foundation Degree in Analytical Science by distance learning started to improve the situation until the 2009 government financial cutbacks closed down this route

7 General Background (3) 8. Current situation: - plenty of highly automated expensive analytical equipment printing out results to 4 or 5 significant figures often to very low concentrations, but severe lack of experienced qualified analysts in many labs to run/oversee the equipment and/or interpret the results obtained. 9. Technicians tend to just load sample changers and carry out basic maintenance, little experience in method development as once ISO accreditation is achieved, it can be very costly to introduce a significant method variation and have to revalidate the method

8 Some Previous Sewage Sludge Issues in 1970 & 80s 1. Fluoride incident Rare metal contamination 3. Spreading of raw untreated sludges 4. High toxic metal containing effluents were common 5. Serious consideration given to economic extraction of metals from sludge. (e.g. silver)

9 A Typical Example from A CAVEAT FOR FARMERS, FOR INSURERS, FOR BANKS WHICH HOLD THE MORTGAGES ON FARMS, AND for SUBSEQUENT BUYERS OF THE SLUDGED FARM LAND MYTH: Fertilizing with sewage sludge biosolids increases yields. Actually lime decreases yields, and so does repeated sludging. It is the water in sludge that causes crop growth, but the go-along chemicals increase toxic inorganic and organic pollutants in the soil and leaching of polluting nitrates to ground water and phosphorus to surface waters. Class A sludge has so little nitrogen that huge amounts have to be applied to reach the agronomic rate for nitrogen, which again results in heavy application of toxic chemicals, radioactivity, etc. in the sewage biosolids.

10 Importance of Fit for Purpose Analysis 1. About 10 years ago, it was estimated that unfit for purpose analysis cost the UK about 0.5 Billion per annum. This figure is now probably nearer ~ 1Billion per annum 2. Unfit for purpose results can have adverse health and safety implications 3. How to ensure that CEN (European) methods give comparable results for any given sample in relation to the requirements of the various relevant directives in the 28 EC countries?

11 Is the current validation process for ISO/CEN standards fit for purpose? (1) For project Horizontal (total cost ~ 12 m): - 1. All method validation samples were dried and typically less than 100 µ particle size (even for % dry solids) 2. The validation samples were not analysed before circulating them. 3. Many parameters concentrations were close to or below LOD 4. For preparation steps in metal and organics analysis, one lab should have analysed an aliquot of all extracts

12 Is the current validation process for ISO/CEN standards fit for purpose? (2) 1. In the past it has been very rare for an ISO/CEN method to be rejected because it has poor validation data

13 Is the current validation process for ISO/CEN standards fit for purpose? (3) 1. Does it ensure the method is fit for purpose? 2. Should it be refined? 3. If yes, how should it be refined? 4. I do not know the complete answer to this

14 Empirical versus non-empirical methods 1. Only need prescriptive standards, without options, for empirical methods where the results are defined by the method. (e.g. BOD; COD; SS, free cyanide and all leaching (non-total) tests) 2. For non-empirical methods, especially for complex equipment organic methods and total metals, good practice guideline standards would probably be better. Rather than state follow the manufacturers instructions

15 How could the situation be improved? 1. Adopt an ongoing performance based approach Precision targets Bias targets Detection limit targets (regulatory limits cannot be cited in ISO/CEN standards) (NOTE: -Method validation is a once every 3-5 year event and not an ongoing continuing process) 2. Provision of lower-cost reference materials 3. Blind proficiency testing 4. Production of ISO good practice documents (such as EN ISO :2006, Application of inductively coupled plasma mass spectrometry (ICP-MS) Part 1: General guidelines,

16 Some examples of international standard validation (1) 1.Cyanide Project Horizontal 2. Mercury 3. Leaching test (Contest proficiency scheme) 4. PAHs 5. Detergents 6. E. coli 7. Salmonella

17 Validation data from ISO 11262:2003 Soil quality Determination of cyanide Table 1 Danish Validation Data - Samples C, E, F are Danish Soils Total cyanide N A N X mean mg/kg S R mg/kg V R % r mg/kg R mg/kg Soil C ,5 27,7 23,5 125 Soil E ,0 425, Soil F ,41 0,19 47,2 0,276 0,55 Easily liberatable cyanide N A N X mean mg/kg S R mg/kg V R % r mg/kg R mg/kg Soil C ,5 6,6 87,5 1,3 18,4 Soil E ,7 56,1 79,4 34,5 157 Soil F ,34 0,17 50,0 0,24 0,48

18 Validation data from ISO 11262:2011Soil quality Determination of total cyanide ISO 11262:2011 Table 1 Validation data interlaboratory comparison "Contaminated soil",september 2009 Samples 1 to 3: contaminated soil from former gasworks sites in the area of Berlin (Germany) Sample N L N A N X mean S r Vr S R V R r R mg/kg mg/kg % mg/kg % mg/kg mg/kg Soil ,0 5,0 4,7 19,5 18,3 13,8 54,1 Soil ,2 2,4 3,2 11,8 15,5 6,7 32,7 Soil ,2 1,3 2,6 6,6 13,6 3,5 18,2 N L N A N X mean S r V r S R V R r R is the number of laboratories is the number of accepted laboratories; is the number of accepted single values; is the mean value; is the repeatability standard deviation; is the relative repeatability standard deviation; is the reproducibility standard deviation; is the relative reproducibility standard deviation; is the repeatability limit; is the reproducibility limit.

19 What are the implications of the previous two ISO slides? Standard Sample Parameter Result incl ~95% confidence limits (mg/kg) ISO 11262:2003 Soil E Total cyanide 2039 ± 2283 ISO 11262:2003 Soil E Easily liberatable cyanide 71 ± 157 ISO 11262:2011 Soil 1 Total cyanide 107 ± 54 No comments about the 2003 version result confidence limits were ever received!!!

20 Validation data from ISO 17380:2012 Determination of total cyanide and easily liberatable cyanide Continuous-flow analysis method Total cyanide Sample N N Measurements X mean mg/kg CV r % CV R % r mg/kg R mg/kg Soil I Soil II Soil III Standard 14 (0) 14 (0) 13 (1) 12 (2) 28 7,73 4,6 13,3 0,99 2, ,8 2,5 10,5 2,21 9, ,1 10,8 16,8 58, ,8 1,9 9,6 3,18 17,2 N is the number of laboratories left over after rejection of statistical outliers ( ) is the number of rejected results; X mean is the mean value, in milligrams per kilogram (mg/kg); CVr is the relative repeatability standard deviation, in per cent (%); CVR is the relative reproducibility standard deviation, in per cent (%); r is the repeatability, in milligrams per kilogram (mg/kg); R is the reproducibility, in milligrams per kilogram (mg/kg).

21 Validation data from ISO 17380:2012 Determination of total cyanide and easily liberatable cyanide Continuous-flow analysis method Easily liberatable cyanide Sample N N Measurements X mean mg/kg CV r % CV R % r mg/kg R mg/kg Soil I Soil II Soil III Standard 12 (0) 12 (0) 12 (0) 11 (1) 24 1,70 8,8 35,8 0,42 1, ,18 7,9 27,1 1,15 3, ,3 7,3 24,0 3,36 11, ,1 2,2 4,7 1,45 3,18 N is the number of laboratories left over after rejection of statistical outliers ( ) is the number of rejected results; X mean is the mean value, in milligrams per kilogram (mg/kg); CVr is the relative repeatability standard deviation, in per cent (%); CVR is the relative reproducibility standard deviation, in per cent (%); r is the repeatability, in milligrams per kilogram (mg/kg); R is the reproducibility, in milligrams per kilogram (mg/kg).

22 What are the implications of the previous two ISO 17380:2012 slides? Standard Sample Parameter Result incl ~95% confidence limits (mg/kg) ISO 17380:2012 Standard Total cyanide 64 ± 17 (not 1.7) ISO 17380:2012 Soil III Total cyanide 193 ± 58 ISO 17380:2012 Standard Easily liberatable cyanide 24 ± 3.2 ISO 17380:2012 Soil III Easily liberatable cyanide 16.3 ± 11

23 Precision, Bias and Accuracy Do not necessarily equate high precision with accuracy Precise Rubbish Lab1 XXX XXX XXX Lab2 XXX XXX XXX Lab3 XXX XXX XXX The repeat analysis result is the same so it must be right!!! This logic is wrong!!! Lab4 XXX XXX XXX

24 Example of the Draft Horizontal CEN Mercury Standard Validation Data The individual mean accepted lab results for one of the two sludge samples (across the 5 accepted participating labs) were: ; 0.90; 1.07; 1.31; 1.44 mg/kg. There were two outlier labs. Thus the data from 2 out of 7 (29%) participating labs were outliers. The mean was 1.2 mg/kg. This was the only sample with a mean mercury level above 1 mg/kg There were 48 method options

25 Project Horizontal LAS Validation Trial Results 7.9% within 78.6% between 3.1% within 46.5% between LAS Soil 3 results LAB Result mg/kg 64L L L L L L 68.9 LAS Sludge1 results LAB Result mg/kg 27L L L L L L 5743

26 Project Horizontal PCB(7)Validation Trial Results PCB(7) Sludge results LAB Result µg/kg L 93 17L 94 54L L L L L 152 8L 152 4L L L 217 6L L L L L L L L % RSD within labs 51.2% RSD between labs

27 Now the black art area: - Project Horizontal: - sludge microbiology validation trial results You ain t seen nothing yet!!! Context For E. coli the critical level is ~ cfu/g dried solids For Salmonella the target was set as absence in 50 g of sludge

28 HYG The next six slides relate to the results of the Project Horizontal-HYG validation results HORIZONTAL-HYG Presentation of statistical analysis results of E. coli and Salmonella spp Validation study 81 slides were presented at a meeting in Brussels All results as cfu/g

29 Assessment of the precision of the methods HYG E. Coli, Matrix B: Anaerobic treated biowaste (ATB)- batch 1 FILTRATION METHOD MICROTITRE PLATE (MPN) MACROMETHOD (MPN ) Lab A B C A B C A B C > LQ > LQ > LQ > LQ > LQ > LQ > LQ Golden rule: - Eyeball data before attempting to process it!!! (GIGO)

30 Assessment of the precision of the methods HYG E. coli, Matrix B: ATB - batch 1 FILTRATION METHOD MICROTITRE PLATE (MPN) MACROMETHOD (MPN ) Lab A B C A B C A B C > LQ 3 m = m = m = r (log)= r (log)= > LQ > LQ > LQ r (log)= > LQ > LQ then max. ratio=2.8 then max. ratio=2.4 then max. ratio= R (log)= R (log)= R (log)= then 210 max. 500 ratio= then > LQmax ratio= then 2303 max. 424 ratio=

31 Assessment of the precision of the methods HYG Salmonella: - Matrix B: ATB - batch 2 FILTRATION METHOD MACROMETHOD (MPN ) PRES. / ABS. METHOD Lab A B C A B C A B C > LQ > LQ > LQ Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence > LQ > LQ Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence > LQ > LQ Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence > LQ > LQ Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence > LQ > LQ Presence Presence Presence Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence > LQ > LQ Presence Presence Presence

32 Assessment of the precision of the methods HYG Salmonella: - Matrix B: ATB - batch 2 m = No data processing r (log)= FILTRATION METHOD MACROMETHOD (MPN ) PRES. / ABS. METHOD then max. ratio=1.9 Lab A B C A B C A B C > LQ > LQ > LQ Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence 3 R (log)= > LQ > LQ Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence then max. ratio= > LQ > LQ Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence > LQ > LQ Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence > LQ > LQ Presence Presence Presence Presence Presence Presence > LQ > LQ > LQ Presence Presence Presence > LQ > LQ Presence Presence Presence

33 Assessment of the precision of the methods HYG Salmonella Matrix G: Composted Biowaste (CBW) - batch 1 FILTRATION METHOD MACROMETHOD (MPN ) PRES. / ABS. METHOD Lab A B C A B C A B C 1 - < LD Presence Presence Presence Presence Presence Presence Presence Presence Presence Presence Presence Presence Presence Presence Presence Presence Presence Presence 7 1 < LD < LD Absence Presence Presence Presence Presence Presence 9 < LD > LQ > LQ 230 Present Present Present Presence Presence Presence < LD Presence Presence Presence 13 < LD < LD < LD Presence Presence Presence > LQ Presence Presence Presence

34 Assessment of the precision of the methods HYG Salmonella Matrix G: CBW - batch 1 FILTRATION METHOD MACROMETHOD (MPN ) PRES. / ABS. METHOD Lab A B C A B C A B C 1 - < LD Presence Presence Presence Presence Presence Presence 3 m 414= m 230= Presence Presence Presence Presence Presence Presence Presence Presence Presence 6 r (log)= r (log)= Presence Presence Presence 7 1 < LD < LD Absence Presence Presence then max. ratio=221.0 then max. ratio= Presence Presence Presence 9 < LD > LQ > LQ 230 Present Present Present Presence Presence Presence 11 R (log)= R (log)= then < LDmax. 46 ratio= then2max. ratio= Presence Presence Presence 13 < LD < LD < LD Presence Presence Presence > LQ Presence Presence Presence

35 Legionella analysis Recent Proficiency Scheme Results Wide variation on Legionella proficiency results (easy samples to analyse) Legionella spp. July 2014 Assigned value 1652 cfu/l 137 cfu/l Z = -2.0; 34,000 cfu/l Z = +2.4 Range <100 to 34,000 cfu/l Legionella spp. July 2014 Assigned value cfu/l 1200 cfu/l Z = -2.4; 187,000 cfu/l Z = +1.6 Range <1 to 187,000 cfu/l Legionella spp.jan2014 Assigned value 2957 cfu/l 135 cfu/l Z = -2.4; 190,000 cfu/l Z = +4.4 Range ND to 800,000 cfu/l (nd, 10, 0 and 0 cfu/l results)

36 Issue of Standard Methods Should CEN/ISO international standards be compulsory, if available, as in some parts of mainland Europe? Or is the UK approach of using any fit for purpose fully validated (NS30 approach) nonempirical method acceptable? Disadvantages of standard methods Written by committee over 4 5 years Many method options (not all are validated) Follow the manufacturer s instructions Sometimes lack of convincing validation data ICP-MS water standard first appeared in ALcontrol were using this technique from 1996

37 KCT comments on CEN soil/sludge/biowaste draft PAH method validation data for phenanthrene The following is cited in Annex E: - The reproducibility limit was calculated using the relationship: R = f 2 sr with the critical range factor f = 2. For instance, the reproducibility limit around a measurement result 1000 ug Phenanthrene/kg is ± 941 ug Phenanthrene /kg (i.e. ± 94 % of 1000) Surely a result (95% confidence) that can range from 59 to 1941 ug/kg is of little value to the standard user or the regulator. Defence lawyers will relish this type of information.

38 KCT comments on CEN soil/sludge/biowaste draft PAH method validation data for benzo-[a]-pyrene The benzo-[a]-pyrene accepted mean results for each lab for sludge 1 ranged from 0.23 to 1.28 mg/kg with a mean of 0.82 mg/kg and an SR of 37% for the 16 participating labs. (There was one outlier lab.) The above individual sludge 1 mean lab results (across the 16 participating labs) correspond to: ; 0.29; 0.51; 0.56; 0.75; 0.77; 0.80; 0.85; 0.89; 0.90; 0.91; 1.03; 1.11; 1.12; 1.14; 1.28 mg/kg benzo-[a]-pyrene It is felt that regulators should understand this typical wide range of results for this key PAH carcinogen indicator parameter obtained for a best case homogeneous sludge samples with high quality labs at this potentially critical level

39 Example of the Draft Horizontal CEN Mercury Standard Validation Data The individual mean accepted lab results for one of the two sludge samples (across the 5 accepted participating labs) were: ; 0.90; 1.07; 1.31; 1.44 mg/kg. There were two outlier labs. Thus the data from 2 out of 7 (29%) participating labs were outliers. The mean was 1.2 mg/kg. This was the only sample with a mean mercury level above 1 mg/kg There were 48 method options

40 Three Example of Prescriptive Standards ISO 6060:1989 Water quality -- Determination of the chemical oxygen demand ISO :2003 Water quality -- Determination of biochemical oxygen demand after n days (BODn) -- Part 1: Dilution and seeding method with allylthiourea addition BS EN :2002 Characterisation of waste Leaching Compliance test for leaching of granular waste materials and sludges Part 3: Two stage batch test at a liquid to solid ratio of 2 l/kg and 8 l/kg for materials with a high solid content and with a particle size below 4 mm (without or with size reduction)

41 Summary of Results for CONTEST Round 69 Leaching Test (1) Parameter Median result (mg/litre) Low (mg/litre) High (mg/litre) Standard Deviation (mg/litre) Chromium (total) Chromium (VI) Potassium Sodium Sulphate Chloride Nitrate Ammonia Phenol Index Conductivity (us/cm) TOC Note: - Typically results for each parameter

42 Summary of Results for CONTEST Round 69 Leaching Test (2) Parameter Median result (mg/litre) Lower satis 2z limit Upper satis 2z Limit % Satisfactory results Z = 0-2 % Unsatisfactory results Z <3 or >3 Chromium (total) Chromium (VI) Potassium Sodium Sulphate Chloride Nitrate Ammonia Phenol Index Conductivity (us/cm) TOC ph Greater than 20% Notes: - Best case dried and ground homogeneous sample Most highly toxic substances close to LOD. Therefore not shown above Except for chromium, only simple parameters with levels well above LOD shown above

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46 Commonly perceived acceptable risks??? Smoking (Approx. 20% of UK adults smoke) Unknown provenance of illicit drugs Alcohol abuse Obesity Car and motorcycle journeys Traffic fumes Bonfire nights and fireworks (Ba, Sr, Cu, Cl and a carbon source and hence dioxins) Recycling of (untreated) animal manure, (but not fully treated sewage sludge to land)

47 Commonly perceived unacceptable risks??? Chlorine and disinfection by-products in drinking water Pesticides and pharmaceuticals in drinking water Fluoride in drinking water Recycling of treated sewage sludges to land Building residential houses on remediated brownfield sites Preservatives in foods such as benzoic acid

48 ents/wntd/2006/report_v8_4may06.pdf 210 Po

49 A possible way forward? 1. Adopt an ongoing continuous improvement performance based approach such as MCERTS or DWTS) Precision targets Bias targets Detection limit targets (regulatory limits must not be cited in ISO/CEN standards (NOTE: -Method validation is a once every five years event) 2. Provision of lower-cost reference materials 3. Blind proficiency testing across the EU 4. Production of ISO good practice documents

50 Thank you for listening