Cod Methods, Locations, References, Relationships - 07 December 2015

Country

SPAIN

ITALY

METHODS FOR COD (Title)

NOMENCLATURE

Water quality. Determination of the chemical oxygen demand (COD). Dichromate method

UNE 77004:2002

IRSA-CNR NUMERO 5130. Potassium Dichromate Method

IRSA-CNR 5130

Chemical oxygen demand (COD)

APAT-IRSA 5130

Method 5135. Chemical oxygen demand (COD) in aqueous matrix by cell tests.

5135 Method

Link to The Institute for COD-Cr(VI) method http://www.isprambiente.gov.it/files/pubblicazioni/manuali-lineeguida/MLG_117_14.pdf Environmental Protection and Research (ISPRA)

Water analysis Determination of the chemical oxygen demand (dichromate method)

DS 217:1991

https://webshop.ds.dk/Files/Files/Products/14916_attachPV.pdf Link to Danish Standard

LINK

TYPE

COMMENT

ALTERNATIVE METHODS (Title)

Water analysis. Guidelines for Link to AENOR (Asociación the determination of Total http://www.aenor.es/aenor/normas/normas/fichanorma.asp?tipo=N&codigo=N0026986&PDF=Si#.VK5rhNKXGDQ Española de Normalización y Equivalent to ISO 6060:1989 organic carbon (TOC) amd Certificación) dissolved organic carbon (DOC).

COD-Cr(VI) method Link to Water Research http://www.irsa.cnr.it/Docs/Capitoli/5130.pdf Institute (IRSA)

NOMENCLATURE

UNE-EN 1484:1998

LINK

TYPE

COMMENT

Link to AENOR Equivalent to EN 1484:1997 http://www.aenor.es/aenor/normas/normas/fichanorma.asp?tipo=N&codigo=N0009787&PDF=Si#.VK5lldKXGDR

Determination of total organic carbon

Link to National Institute of TOC method for non-waste http://www.iss.it/binary/aqua/cont/TOC_14aprile2005.1161254593.pdf Health water using UV-persulphate

A novel and quick method to avoid H O2 interference on COD measurement in Fenton system by Na2SO3 reduction and O2 oxidation

http://www.ncbi.nlm.nih.gov/pubmed/24135101

COD-Cr(VI) method

Method described for using Fenton reaction for COD measurements, not specifically Danish

2

Denmark 5 works 3 weeks COD vs NVOC, 2.46-3.23 SD10%. Ref to similar results for Norway & http://www.reference-lab.dk/media/2792874/cod-toc_rapport_2004.pdf Link to Eurofins Germany. Recommend 10 measurements and taking median value. Factor needs to be determined for each site

NVOC/TOC

Member States of the European Union

Poland

Water Quality - Determination Of The Chemical Oxygen Demand

PN ISO 6060:2006

Link to SAI GLOBAL http://infostore.saiglobal.com/EMEA/Details.aspx?ProductID=408076

Water Analysis - Guidelines For The Determination Of Total Organic Carbon (toc) And Dissolved Organic Carbon (doc)

Water Quality - Determination Of The Chemical Oxygen Demand Index (st-cod) - Smallscale Sealed-tube Method

PN ISO 15705:2005

http://infostore.saiglobal.com/EMEA/Details.aspx?ProductID=408254 Link to SAI GLOBAL

BOD

Water and wastes. Study of the carbon content. Determination of the total organic carbon (TOC)

PN-EN 1484:1999

Link to SAI GLOBAL http://infostore.saiglobal.com/EMEA/Details.aspx?ProductID=406690

PN-EN 1899-1:2002 and PN- http://infostore.saiglobal.com/EMEA/results2.aspx?searchType=simple&publisher=All&keyword=%20PN-EN%201899-1% Link to SAI GLOBAL EN 1899-2:2002

PN-C- 04633-3

Link to SAI GLOBAL http://infostore.saiglobal.com/EMEA/Details.aspx?ProductID=406690

Dichromate Potassium French Standard AFNOR 90101

NF T90-101

A novel and quick method to avoid H O2 interference on Link to L’Agence de l'eau COD measurement in Fenton ISO 15705 http://www.eau-seine-normandie.fr/fileadmin/mediatheque/Entreprise/REDEVANCES/GUIDE_VALIDATION_AUTOSURVEILLANCE/RIF400_01_annexe_3_REFERENCES_NORMATIVES.pdf Seine-Normandie (references http://www.ncbi.nlm.nih.gov/pubmed/24135101 system by Na2SO3 reduction normatives) and O2 oxidation

Water quality - Determination of chemical oxygen demand (COD)

NF T90-101

Link to French Standard COD-Cr(VI) method http://www.boutique.afnor.org/norme/nf-t90-101/qualite-de-l-eau-determination-de-la-demande-chimique-en-oxygene-dco/article/778836/fa111555

Method described for using Fenton reaction for COD measurements, not specifically French

2

France

Similar to ISO 6060 COD-Cr(VI) method. Unclear what SERES monitor is.

SERES monitor

Portugal

Scandinavian

Potassium dichromate method

ISO 6060:1989

Pulps (dried market pulps) AOX, COD and TOC removable by washing

ISO 6060

Scandinavian pulp, paper and board Testing Committee referencing ISO 6060, SS 02 81 Link to Paper and Fibre http://www.pfi.no/Documents/Scan_test_methods/C_CM_M/CM_44-97.pdf 42 (Swedish standard), SFS research Institute 5504 (Finnish standard and NS4748-2 (Norwegian standard)

Determination of chemical oxygen demand in water CODCr oxidation with dichromate

SS 28142

Lint to Swedish Standards http://www.sis.se/milj%C3%B6-och-h%C3%A4lsoskydd-s%C3%A4kerhet/vattenkvalitet/avloppsvatten/ss-28142 Institute

Potassium dichromate method with closed tube

SF 5504

http://www.pfi.no/Documents /Scan_test_methods/C_CM_ M/CM_44-97.pdf

Potassium dichromate method

NS 4748-2 replaced by ISO 6060

ISO 8245

https://www.ecn.nl/docs/society/horizontal/hor_desk_17_TOC.pdf Ways to determine DOC

http://www.standard.no/no/Nettbutikk/produktkatalogen/Produktpresentasjon/?ProductID=146579 Link to Standards Norway

Link to Marmara University, BOD/TOC of untreated http://mimoza.marmara.edu.tr/~bilge.alpaslan/ENVE%20302/Chp1.pdf background information to domestic wastewater 1.2-2 mg measurements 02/mg C

TOC

Titration method with Ferrous Ammonium Sulphate

http://www.iso.org/iso/catalogue_detail.htm?csnumber=29920 Link to ISO

Lint to Paper and Fibre research Institute

Potassium dichromate method

Turkey

TOC

Link to Turkish Journal of http://www.trjfas.org/pdf/issue_5_1/35_42.pdf Fisheries and Aquatic Sciences

Link not working

Prediction of Chemical Oxygen Demand (COD) Based on Link to Research gate http://www.researchgate.net/publication/227723921_Prediction_of_Chemical_Oxygen_Demand_(COD)_Based_on_Wavelet_Decomposition_and_Neural_Networks Wavelet Decomposition and Neural Networks

Wavelet decomposition and neural networks

Modelling of chemical oxygen demand by using ANNs, Link to Research gate http://www.researchgate.net/publication/260189455_Modelling_of_chemical_oxygen_demand_by_using_ANNs_ANFIS_and_k-means_clustering_techniques ANFISand k-means clustering techniques

ANNs, ANFIS and K-means clustering techniques

Link to LAR Process Analysers On-line instrumentation for http://www.lar.com/products/cod-analysis/cod-chemical-oxygen-demand.html AG TOD measurements

TOD

TOC

DIN EN 1484:1997-08 ISO 8245:1999-03 EPA 415,1

Link to LAR Process Analysers http://www.lar.com/products/toc-analysis/toc.html AG

Measurement Range: 0.1-100 mg/l, 2-400 mg/l, 5-2,000 mg/l, 100-15,000 mg/l, 10050,000 mg/l Highest combustion temperature available (1,200 ºC)

Germany

Potassium dichromate method

ISO 15705

Reference to German standard methods for the examination Link to MACHEREY-NAGEL of water, waste water and ftp://ftp.mn-net.com/english/Instruction_leaflets/NANOCOLOR/985027en.pdf GmbH & Co. KG sludge (DIN 38 409 - H41-1 and DIN ISO 15705-H45) ISO 15 705 - H45)

Malta

Potassium dichromate method

Romania

Potassium dichromate method

SR ISO 6060/96

Country

METHODS FOR COD (Title)

NOMENCLATURE

LINK

Titrimetric

EPA-NERL 410.1

USA

Link to Innovative Romanian http://www.bioaliment.ugal.ro/revista/2/paper2pfit.pdf Food Biotechnology

Link to German waste water In reference to Appendix 1 on http://www.bmub.bund.de/fileadmin/bmu-import/files/pdfs/allgemein/application/pdf/wastewater_ordinance.pdf urban waste water, see ordinance especially Article 6 (3))

http://www.nipne.ro/rjp/2013_58_1-2/0211_0219.pdf

Validation procedure for assessing TOC

Link not working

TOC

ISO 8245:2000

TYPE

COMMENT

ALTERNATIVE METHODS (Title)

NOMENCLATURE

https://www.nemi.gov/metho ds/method_summary/5261/

Link to NEMI (National Environmental Methods Index)

COD, titrimetry (detection level > 50 mg/L)

TOC

USGS-NWQL (O-3100)

Link to NEMI (National https://www.nemi.gov/methods/method_summary/5566/ Environmental Methods Index)

EPA-NERL 410.2

https://www.nemi.gov/metho ds/method_summary/5262/

Link to NEMI (National Environmental Methods Index)

COD, titrimetry (detection level 5- 50 mg/L)

TOC

Standard method 5310

Link to Standard Methods http://standardmethods.org/store/ProductView.cfm?ProductID=409

Standar methods 5520C

https://www.nemi.gov/metho ds/method_summary/7613/

Link to NEMI (National Environmental Methods Index)

COD by Closed Reflux, Titration (detection level 40 mg/L)

TOC

Colorimetric TOC

LINK

TYPE

COMMENT

Applicable concentration range > 0.1 mg/L

Link to wef (Water Close correlation between http://www.ingentaconnect.com/content/wef/wefproc/2004/00002004/00000009/art00043 Environment Federation) TOC and COD

Standard method 5520D

Link to NEMI (National https://www.nemi.gov/methods/method_summary/5716/ Environmental Methods Index)

Standard method 5520

http://standardmethods.org/store/ProductView.cfm?ProductID=408 Link to Standard Methods

USA

Bolivia

Member States out of the European Union

Mexico

Link to NEMI (National https://www.nemi.gov/methods/method_summary/4747/ Environmental Methods Index)

COD, Micro, by Sealed Digestion and Spectrometry (Test Method B), (detection level 5-800 mg/L)

EPA-ORD/EPA-OST 410.4

Link to NEMI (National https://www.nemi.gov/methods/method_summary/9627/ Environmental Methods Index)

COD in water by colorimetry (detection level 3-900 mg/L)

Japan

Electrochemical oxidation using OH-radicals

Fenton system by Na(2)SO(3) reduction and O(2) oxidation

Closed reflux method

NMX-AA-030-SCFI-2001

Link to Diario Oficial de la Closed Reflux /Open Reflux http://dof.gob.mx/nota_detalle_popup.php?codigo=5184479 Federación (SEGOB)

NMX-AA-030-SCFI-2001

http://www.agua.org.mx/inde x.php/bibliotecatematica/marco-juridico-delagua/1466-normasmexicanas/15232-nmx-aa030-scfi-2001-analisis-deagua-determinacion-de-lademanda-quimica-deoxigeno-en-aguas-naturalesresiduales-y-residualestratadas-metodo-de-prueba

Dichromate by flow injection analysis

Electrochemical COD measurements?

ASTM D6238

ASTM D1252B

Standard method 5520C Potassium dichromate method

COD by Closed Reflux, Colorimetric method (detection level 50 mg/L)

Link to Centro Virtual de Información del agua

Link to Science Direct precision: 5 mg/l http://www.sciencedirect.com/science/article/pii/S0003267001953346

Flow Injection Analysis Using Potassium Permanganate: An Link to Taylor Francis Online http://www.tandfonline.com/doi/pdf/10.1080/00032718008078020#.VLUz7dKXEbp Approach for Measuring Chemical Oxygen Demand in Organic Wastes and Waters

Potassium permanganate

JIS K 0400-20-10:1999

Water Quality - Determination http://infostore.saiglobal.com/EMEA/Details.aspx?ProductID=815170 Link to SAI GLOBAL Of The Chemical Oxygen Demand

Standard dichromate method (COD Cr)

GB 11914-89, 1990

applicable to various kinds of water samples with COD level Link to Ministry of higher than 30mg/L. The http://english.mep.gov.cn/standards_reports/standards/water_environment/method_standard2/200807/t20080710_125434.htm environmental protection of maximum determination limit the people's Republic of China for undiluted water sample is 700mg/L

Permanganate method (COD Mn)

GB 11892-89, 1990) ISO 8467-1986

applicable to the determination of drinking Link to Ministry of http://english.mep.gov.cn/standards_reports/standards/water_environment/method_standard2/200807/t20080710_125438.htm environmental protection of water, water at drinking water source areas and surface the people's Republic of China water with determination range of 0,5-4,5 mg/l

Potassium dichromate method

GB/T 22597-2008

Brazil

Potassium dichromate method

Standar methods 5520C

Panama

Potassium dichromate method

Method 8000 (HACH DR/2400)

China

Potassium dichromate method

Link to http://www.tratamentodeagua.com.br/r10/Biblioteca_Detalhe.aspx?codigo=401 www.tratamientodeagua.com. There is no rule or legislation br Link to Technological http://www.utp.ac.pa/sites/default/files/PCUTP-CIHH-LSA-201-2006.pdf University of Panamá

https://www.google.es/url? sa=t&rct=j&q=&esrc=s&sourc e=web&cd=1&cad=rja&uact= 8&ved=0CCEQFjAA&url=http %3A%2F%2Ffaolex.fao.org %2Fdocs%2Ftexts %2Fpar48153.doc&ei=Sf7ZVLy bJoryUIWTgJgF&usg=AFQjCNH YHRHhlotgLxA4y66S1_36Grn_ 8A&sig2=pOh87ZYj0FT_ULzdjT8Vw&bv m=bv.85464276,d.d24

Link to resolution

Closed reflux method with spectrometric detection and volumetric > 0,71 mg/L

Potassium dichromate method

Link to Analytical Laboratory http://ojs.uo.edu.cu/index.php/cq/article/view/1936 of the Industrial Biotechnology Center (CEBI)

Potassium dichromate method

Link to Alcaldia de Bogota (D http://www.alcaldiabogota.gov.co/sisjur/normas/Norma1.jsp?i=18617 1594/1984)

http://www.academia.edu/76 97466/VALIDACI %C3%93N_DE_LOS_M %C3%89TODOS_DE_AN %C3%81LISIS_DQO_REFLUJO_ CERRADO_SULFATOS_Y_NITRA Link to document of University TOS_EN_AGUAS_EN_EL_LABO Pontificia Bolivariana. RATORIO_DE_AN Bucaramanga %C3%81LISIS_QU %C3%8DMICO_DE_AGUAS_RE SIDUALES_DE_LA_UNIVERSID AD_PONTIFICIA_BOLIVARIANA _SECCIONAL_BUCARAMANGA

Colombia

Chile

Link to SAI GLOBAL

ISO (International Standartization Organization) Estándar Methods for the http://www.matus-dubarry.com/v2/index.php/resoluciones-seam/319-resolucion-22202-por-la-cual-se-establece-el-padron-de-calidad-de Link to resolution There is no rule or legislation Examination of Water and Wastewater- APHA-AWWAWPCF)

Paraguay

Cuba

http://infostore.saiglobal.com /EMEA/Details.aspx? ProductID=1143348

Reacción Digestión/ Titulación Redox FAS

NCh 2313/24 Of.97

Russia

GOST R 52708-2007

South Africa

SANS 6048 Ed.2.02 (2010)

http://www.siss.cl/577/w3propertyvalue-3481.html

Link to Standards national Institute of Standardization. Government of Chile

http://runorm.com/product/vi Link to Russian Standards and ew/2/31436 Technical regulations http://infostore.saiglobal.com /EMEA/Details.aspx? productID=1106423

Link to SAI GLOBAL

28 days

OH-radicals have a significantly higher oxidation potential. The OH-radicals are directly related to the COD. This method offers a fast, simple, accurate and pollution-free alternative to the common dichromate method (wet chemical method).

http://www.astm.org/Standards/D6238.htm Link to ASTM INTERNATIONAL

TOD can be correlated to both COD and BOD, providing effective on-line control

A novel and quick method to avoid H2O2 interference on http://wst.iwaponline.com/content/68/7/1529 COD measurement in Fenton system by Na2SO3 reduction and O2 oxidation

Independent of pH in the range 2,50-11,95

There is no rule or legislation

Method

Usage

Type of test

COD-CrVI

Widespread, plant operations, regulator

Chemical

COD-MnIII

Limited

Chemical

COD-MnVII

Obsolete?

Chemical

TOD

Developing in USA

Chemical (combustion)

PeCOD

Patented, TiO2 / UV

Advanced oxidation

BOD

Widespread, regulatory

Biological

Suspended solids

Widespread, regulatory, operation

Mass

TOC / NVOC Turbidity UV absorbance

Some operational & regulatory, including online Online site operations Online site operations

Electrochemical COD Online site operations

Chemical (combustion) Light scatter Photometric Electrochemical

Glossary COD-CrVI – dichromate COD method COD-MnIII – manganese III method COD-MnVII – permanganate method TOD – Total Oxygen Demand BOD – Biochemical Oxygen Demand SS – Suspended Solids TOC / NVOC – Total Organic Carbon, or Non-Volatile Organic Carbon UV – Ultra-violet

Determinand : COD-CrVI ratio

Analysis kit

Issues and relevance

1

Site or analytical lab

Complete oxygen load, rapid information (2-3 hours);

0.8

Site or analytical lab

Subject to salinity interference

Site or analytical lab Analytical lab instrument

Incomplete, variable organic oxidation Quick analysis (minutes)

0.7

Per sample cost, € 3

2.5

NA

15 minutes analysis 0.4

Analytical lab

0.6

Site or analytical lab

Site or analytical lab Site Site Site or analytical lab

Varies with composition; 7 day to reporting

Not suitable for high COD

3.5

Equipment cost Hach DR3900 £3000

A set of 25 TNT vials (20-1000 mg/l O2) costs approximately £40 (€55, 2015-10-28), with a sample cost of approximately £1.6 (€2.2, 2015-10-28). The cost for 25 CRC was £28 (€39) or £1.1 (€1.6) per sample. The cost for COD-CrVI is approximately €3 per sample.

£16,800 for PeCOD L100, £587 for battery, £679 for carrier case, electrolyte from £42/l, calibration solution £355/l.

Bottles, DO probe, incubator or pressure test cells The laboratory method is straightforward and readily implemented but the drying of the filter delays the results. A pack of 100 GF/C filters costs in the order of £60 (€85) or £0.60 (€0.85) per sample. On-line and handheld instruments are considerably more expensive but will provide results faster.

MW acetate ethanol

per gram COD TOC TOC/COD 60 1.07 0.4 0.38 46 2.09 0.52 0.25

Method

COD

COD MnIII

COD MnVII

TOD

PeCOD

BOD

SS

TOC

Turbidity

UV

Electrochemical COD

Description

The sanitary measurements of COD, total nitrogen, and or ammoniacal-N, Chlorine, and a variety of the inorganic determinand reagent and colorimeter systems. WRc is familiar with the Hach-Lange system (e.g. http://www.hach-lange.co.uk/view/content/wastewater), and the similar Palintest system (http://www.palintest.com/pro demand-cod/). Figure 4.3 Hach Lange DR3900 colorimeter plus test cuvettes Both systems require: • Colorimeter, designed for each supplier, with programmed analytical correlations (£2500 - £4000); • Heater block for COD tests; • Pipettes to dispense sub-samples into pre-prepared cuvettes (see Figure 4.3). • Pre-prepared cuvettes, supplied by the manufacturer (typical single determinand cost, £2.50 to £4.00 per sample). The systems are widely used and highly reliable. They can be readily used by a trained operator.

The patent for COD measurement using Mn(III) was filed by Hach Company in June 1995. The patent describes the method in d Mn(III) is generally poorly soluble in water but is stabilised by concentrated (14-20 N or 7-10 M) sulphuric acid (H2SO4), formin disproportionate to Mn(II) and Mn(IV) and Mn(II) is added to the test solution in a ration of Mn(II):Mn(III) of approximately 3:1 The reaction between organic matter and Mn(III) was summarised by Hach Company using potassium acid phthalate (KHP) as: KC8H5O4 + 15 Mn2(SO4)3 + 12 H2O → 8 CO2 + 30 MnSO4 + 14 H2SO4 + KHSO4 The equivalent reaction using oxygen as the oxidant, the reaction can be written as: KC8H5O4 + 7.5 O2 → 8 CO2 + 2 H2O + KOH The Mn(III) ion (free or in complex) is purple in colour. As Mn(III) is reduced it forms Mn(II), which is colourless. The intensity of spectrophotometer and the concentration determined using suitable calibration solutions. The concentration can also be deter recommended by Hach Company. A standard operating procedure has been developed by Hach Company (Method 10067) using Test ‘N TubeTM (TNT) vials, whic company. A 0.5 ml homogenised sample is added to a test vial, the vial is inverted several times to mix the sample and then dig treated in the same way. When the sample and blank vials have cooled to room temperature, they are inverted several time to instrument. Chloride ions (Cl-) are known to interfere with the reaction, causing an overestimate of the COD. A method for chloride remova CrVI method. For the analysis, 9 ml of homogenised sample is acidified with 1 ml concentrated H2SO4 and mixed. A blank (usin per sample is placed in a Vacuum Pretreatment Device (VPD), a Chloride Removal Cartridge (CRC) is placed above the vial and 0 suction. Once filtering is complete, the glass fibre filter (which has no oxygen demand) from the top of the CRC is transferred to vial is capped and inverted, digested and analysed as above. The VPD has, however, been withdrawn and the recommendation from Hach was to dilute the sample to assess the effect of ch provided by Hach state that the concentration at which chloride interference can be seen is unknown. Ammonia in the presence of chloride also interferes with the measurement and the interference is quoted as “severe” at high not defined.

The method used prior to the Cr(VI) method for COD measurements was the Kubel’s method, where the sample is boiled with sulphuric acid. In permanganate the manganese ion is in oxidation state +VII and in Kubel’s method, permanganate is reduced MnO4- + 5 e- + 8 H+ → Mn2+ + 4 H2O The excess of permanganate is determined by back titration with oxalate: 2 MnO42- + 5 C2O42- + 16 H+ → 2 Mn2+ + 10 CO2 + 8 H2O No manufacturer of test kits or instrumentation for this method was been found. There has been research into the use of Mn( spectroscopy (FAAS) based on flow injection analysis (FIA) with ultrasound-assisted digestion and Mn speciation separation and laboratories.

For the determination of TOD, the sample is thermally oxidized at high temperature in a reactor of high-purity alumina and the in the gas phase. Until this point, the sample is fed into a combustion furnace, similar to TOC analysis. The furnace has to be co in a “closed” system. During the sample injection, a gas exchange with the environment has to be prevented to avoid measurem oxygen content is measured directly with a zirconiumoxide-based detector, and the reduction of the oxygen content is directly Within the furnace, the water of the injected sample will evaporate immediately and all organic compounds contained will be o C. The used reactor is filled with inert ceramic material, which is not affected by ingredients of the sample water. No catalyst is process, and thus the risk of poisoning of the catalyst that may cause a malfunction of the oxidation process is avoided. The pr the measurement frequency to be three to five minutes, depending on the application. A standard test method has been developed by ASTM (ASTM D6238 - 98(2011)) where it is stated that “This test method is pa industrial effluents and process streams. Its application for monitoring secondary sewage effluents is not established. Its use fo interferences defined in Section 6.”

PeCODTM is a patented method that uses titanium dioxide (TiO2) catalyst which is activated by UV light. The instrument measu of organic species. The reaction time quoted is 15 minutes. A AgNO3 doping agent in the sensor allegedly removes interferenc The Ontario Ministry of the Environment has developed a method (see link below). The procedure and comments below are ta ml is required for analysis. Samples are to be stored at 5±3°C for a maximum of 7 days if not preserved. Samples may be preser acid per 100 ml of sample). Preserved samples have a maximum storage time of 21 days from preservation. The PeCOD measurement is not affected by the presence of chloride at concentrations lower than 400 mg/l. If the sample is su sample should be diluted. The central sensor element appears black in colour. If the sensor becomes white, it indicates that ch The suitable pH range for samples is from pH 4-10. Samples having a pH>10 will have results biased low. PeCOD measures tota macromolecules or cellulose. Cr(VI)-COD provides total COD, so differences may be observed for some samples (mainly influen The manufacturer states that the PeCOD has a good correlation with BOD. The method quoted suggests centrifuging samples if the solids concentration is high. This would, however, have a significant im solids concentration is not reduced.

The method consists of filling with diluted and seeded sample, to overflowing, an airtight bottle of specified size and incubatin Dissolved oxygen is measured initially and after incubation, and the BOD is computed from the difference between initial and fi the dilution is made, all oxygen uptake occurring after this measurement is included in the BOD measurement. The BOD will always be lower than COD as some refractory material will not be degraded by microorganisms but can be degrad and more time-consuming than the Cr(VI)-COD method. Instruments using tryptophan-like fluorescence with turbidity and temperature corrections have been developed for a quick on

Total suspended solids (TSS) is a laboratory gravimetric procedure where the solids from the water sample are filtered through the residue of the sample reported as mg/l. If the sample contains significant quantities of dissolved solids (such as seawater), drying, otherwise the TSS concentration will be overestimated. In addition to the laboratory method, on-line instruments are available that are based on either an optical method or the atten are also available. It is, however, likely that there will be a (variable) difference between the gravimetric procedure and the me composition and nature of samples changes.

Total Organic Carbon (TOC) is the amount of carbon left in a sample after it has been acidified and sparged with an inter gas to oxidised to CO2 using one of several methods, e.g. high-temperature combustion, catalytic oxidation or photo(chemical) oxidati infrared (IR) detector. TOC is a well-established method and can be used on-line. No simple test kit is, however, available and samples would have to depends on the composition of samples as a high portion of oxygen-containing organic compounds will have a lower COD than compounds, but the TOC could still be the same. In addition, any compounds consuming oxygen but not containing carbon wil A Danish investigation found that TOC did correlate well with COD-Cr(VI) but the correlation needed to be established for each

A range of turbidimeters are available, including handheld, bench top and on-line instruments. The majority of turbidimeters u type. In some flowcells the sample is in direct contact with optical surfaces whereas others are partly or fully non-contact. Good correlation can sometimes be seen between suspended solids and turbidity but the correlation should be seen as site sp generally be expected to be a good correlation between COD and turbidity as turbidity includes inorganic solids (e.g. clay partic

UV absorbance of organic compounds relates to the aromatic groups present, i.e. the higher UV absorbance, the more aromati typically measured at 254 nm on a 0.45 µm filtered sample and is then referred to as true UV254 absorbance and reported in m A range of UV absorbance instruments are available, including handheld, bench top and on-line instruments. As with TOC, the samples.

Researchers have investigated the use various electrode materials (e.g. copper-based or polystyrene based with catalytic mater instrument is commercially available (COD Analyser Elox100 from LAR Process Analyser AG). The instrument is of on-line type b auto-sampler for laboratory analysis. The manufacturer claim a good correlation with the standard COD-Cr(VI) method but no independent studies have been found minutes, making it significantly faster than the >2 h for the standard COD-Cr(VI) method.