Natural Organic - WaterRA

CRC for Water Quality and Treatment

Private Mail Bag 3

Salisbury SOUTH AUSTRALIA 5108

Tel: (08) 8259 0211

Fax: (08) 8259 0228

E-mail: [email protected]

Web: www.waterquality.crc.org.au

The Cooperative Research Centre (CRC) for Water Quality and Treatment is Australia’s national drinking water research centre. An unincorporated joint venture between 30 different organisations from the Australian water industry, major universities, CSIRO, and local and state governments, the CRC combines expertise in water quality and public health.

The CRC for Water Quality and Treatment is established and supported under the Federal Government’s Cooperative Research Centres Program.

The Cooperative Research Centre for Water

Quality and Treatment is an unincorporated

joint venture between:

• ACTEW Corporation

• Australian Water Quality Centre

• Australian Water Services Pty Ltd

• Brisbane City Council

• Centre for Appropriate Technology Inc

• City West Water Ltd

• CSIRO

• Curtin University of Technology

• Department of Human Services Victoria

• Environmental Protection Agency Queensland

• Griffith University

• Melbourne Water Corporation

• Monash University

• Orica Australia Pty Ltd

• Power and Water Corporation

• Queensland Health Pathology & Scientific

Services

• RMIT University

• South Australian Water Corporation

• South East Water Ltd

• Sydney Catchment Authority

• Sydney Water Corporation

• The University of Adelaide

• The University of New South Wales

• The University of Queensland

• United Water International Pty Ltd

• University of South Australia

• University of Technology, Sydney

• Water Corporation

• Water Services Association of Australia

• Yarra Valley Water Ltd

Natural Organic Matter

Understanding and Controlling the Impact on Water Quality and Water Treatment Processes

Management implications from the Research Programs of the Cooperative Research Centre for Water Quality and Treatment

The Cooperative Research Centre for Water Quality and Treatment

CRC NOM COVER FINAL 5.indd 1-2 26/7/05 10:21:22 AM

TableofContents

FS1 NOMCharacter-ToolstoAssistOperators Page 2

FS2 ManagingNOMintheCatchment/Reservoirs Page 7

FS3 OptimisingNOMRemovalinConventionalTreatmentPlants Page 9

FS4 OtherProcessestoRemoveNOM Page 11

FS5 TheEffectofNOMontheApplicationofActivatedCarbon Page 13

FS6 FoulingofLowPressureMembranes Page 15

FS7 EffectofNOMonManagingDistributionSystems Page 17

Acknowledgements Page 20

ADWGFrameworkElementsInsideBackCover

Factsheetobjective

ThenewAustralianDrinkingWaterFrameworkoutlinesthemethodologyforprovidingsafedrinkingwaterbymanagingthewatersupplysystemfromthecatchmenttothetap.UnderstandingthelevelofriskinourwatersuppliesandtreatmentsystemsisfundamentaltotheFramework.Thisallowsmanagersofcatchmentsandwaterutilitiestofocustheireffortsonpolicies,worksandoperationalpracticestonotonlylowerriskstopublichealthbutalsoimprovetheenvironmentalhealthofthesewaters.

These fact sheets present the findings of research carried out by the Cooperative Research Centre (CRC) for Water Quality and Treatment into understanding the character of natural organic matter (NOM) in Australian watersuppliesandassessingitsimpactonwaterqualitysuchasincreasingdisinfectantdemandandformationof byproducts which adversely affect health. NOM also impacts on water treatment processes by increasing requiredcoagulantdoses,reducingtheeffectivenessofadsorptionprocessesandfoulingmembranesystems.Arange of treatment options have been evaluated to remove NOM to reduce its impact on the described treatment processes and produce water which requires less disinfectant but also minimises biofilm growth in distribution systems.

Factsheetcontents

These fact sheets are derived from the following CRC for Water Quality and Treatment research projects:

• Microbial Degradation and Remineralisation of Dissolved Organic Carbon in the Warren Reservoir

• Impacts of Destratification of Reservoir Waters on the Character of NOM and on the removal of NOM by Water

TreatmentProcesses

• Impact of NOM on the Movement of Phosphorus in Soils

• Characterisation of NOM

• Development of Treatment Systems for Removal of NOM

• Hybrid Membrane Processes in Water Treatment

• Optimisation of Adsorption Processes – Stages 1 and 2

• Modelling Coagulation to Maximise Removal of Organic Matter – a Pilot Plant and Laboratory Based Study

• Development of Combined Treatment Processes for the Removal of Recalcitrant Organic Matter

• Biological Removal of UV Pretreated NOM from Potable Water

• Factors affecting Biofilm Development under Controlled Conditions

• Development of Tools for Improved Disinfection Control within Distribution Systems

ADWGFrameworkElements Key research findings and reference to Fact sheet No.

Assessmentof the Drinking WaterSupplySystem

WaterSupplySystemAnalysis

FS 2 Soil and vegetation impact on release of natural organic matter (NOM). The lowest dissolved organic carbon (DOC) concentrations were from soils with grass or pasture cover.

AssessmentofWaterQualityData

FS1 Understandingtheorganiccharacterofthewaterallowspredictionoftreatability,disinfectiondemandandby-productformation.

FS 1 DOC is not a sufficient measure of NOM character to determine the impact on water treatment.

FS 1 There are a range of simple analytical techniques that provide more information on NOM character.Theusefulnessofeachtechniquedependsontheapplication.

Hazard Identification and RiskAssessment

FS 2 Water from recent rainfall events with high DOC may short circuit through reservoirs during thecoolerseasons.

PreventativeMeasuresfor Drinking WaterQualityManagement

PreventiveMeasures and MultipleBarriers

FS 2 Gypsum application may provide a means of minimising the transport of NOM in catchments.

FS4 Theselectionoftreatmentprocesstoremoveorganicswillbedependantonthecharacterof the organics and the extent of removal required.

OperationalProcedures and Process Control

OperationalProcedures

FS 3 DOC removal can be optimised in conventional treatment by increasing applied coagulant dose,changingcoagulantandmanipulatingpH.Softwareisavailabletoassistwiththis.

FS 3 Coagulation preferentially removes higher molecular weight UV absorbing compounds.

FS 3 The charged and hydrophobic fractions (CHA, VHA and SHA) are the most amenable to removalbycoagulation.Thehighertheproportionofthesefractionspresent,thegreatertheamount of DOC that will be removed by coagulation.

FS 4 There is a portion of the organic matter (recalcitrant NOM) which cannot be removed by coagulationprocesses.

FS 4 If there is a need to remove NOM to improve water quality beyond that achievable by coagulationalone,additionaltreatmentwillbeneeded.

FS 7 Removal of biodegradable organics will reduce disinfectant decay and biofilm growth in distributionsystems.

FS 4 Adding MIEX®tothetreatmentprocesseitheraloneorcombinedwithlowalumdoseswillimprove DOC removal when compared with alum alone, resulting in decreased chlorine decay and lower trihalomethane formation potential (THMFP).

FS 5 An increase in DOC concentration in the inlet to the plant, such as might occur during an algal bloom, will result in an increased requirement for powdered activated carbon (PAC), or a reduced life expectancy for granular activated carbon (GAC).

FS 5 For optimum application of activated carbon the aim should be maximum prior removal of NOM. With the application of PAC, the effect of competing NOM can be at least partially offset by an increase in the PAC contact time, and avoiding dosing PAC with other chemicals suchaschlorineormetalcoagulant.

FS 6 The membrane type as well as the NOM composition and concentration influence the rate of foulingoflowpressuremembranes,withhydrophilicmembraneshavinglowerfoulingratesthanmorehydrophobicmembranes.

FS 6 Coagulants almost always lower the rate of membrane fouling. Aluminium chlorohydrate is therecommendedcoagulantforusewithmembranes.

OperationalMonitoring

FS 3 Monitoring NOM character by measuring the very hydrophobic (VHA) fraction will allow operators to better control coagulant dose to optimise DOC removal.

FS 3 Software is available to predict coagulant doses, pH control reagents and residual DOC in treatedwater.

FS 7 Monitoring UV254

will allow operators to predict chlorine demand and THMFP and optimise chlorineresidualsindistributionsystems.

Verification of Drinking Water Quality

Drinking Water Quality Monitoring

FS 7 On-line UV spectrophotometry may be used to optimise chlorine residuals.

Research and Development

Investigative Studies and ResearchMonitoring

FS 4 There is potential for the application of UV at higher irradiation doses for removal of NOM either alone or to increase biodegradability prior to a granular activated carbon filter.

FS 4 A 3-stage MIEX®/Powdered activated carbon/Coagulant treatment was found to improve the amount of DOC removed, decrease chlorine demand and significantly decrease THMFP. However bacterial regrowth was increased.

FS 6 A range of processes are being trialled to remove NOM prior to membrane filtration.

In Australia, drinking water quality management is undertaken in the context of the Australian Drinking Water Guidelines Framework. In the table below the salient research findings are presented within the Framework to aid in their implementation by the Australian WaterIndustry.


The CRC research has identified that NOM is impacted by the soil and vegetation surrounding catchments and reservoirs and is also affected by seasonal variations. However characterising the NOM using a range of techniques, in addition to the quantitative measure of dissolved organic carbon (DOC), allows understanding and prediction of a waters susceptibility to coagulation, disinfection and formation of disinfection by-products. For example, monitoring NOM character by measuring the very hydrophobic (VHA) fraction will allow operators to better control coagulant dose to optimise DOC removal.

The optimum selection of treatment processes to remove organics will depend on the character of the organics present and the final treated water quality required. Conditions for optimum removal of organics in conventional treatment have been identified and software developed to assist operators to implement this more effectively within treatment plants.

However, there is a portion of the organic matter that cannot be removed by coagulation processes and will require additional treatment if more NOM removal is required. Processes to remove NOM that may be implemented together with conventional treatment that were investigated in this research included MIEX® and powdered activated carbon. Application of these processes will result in significant decrease in chlorine demand and trihalomethane formation potential (THMFP).

The residual NOM after treatment impacts on the disinfectant demand, formation of disinfection by-products and biofilm formation in the distribution system. Removal of biodegradable organics will reduce disinfectant decay and biofilm growth in distribution systems. Characterising the remaining NOM using UV254 will allow operators to predict chlorine demand and THMFP and optimise chlorine residuals in distribution systems.

Increasing DOC concentrations in the source water impacts the effectiveness of powdered activated carbon for removal of problem contaminants and necessitates an increased carbon dose. Some measures to decrease the fouling of low pressure membranes by NOM were also identified.

Page 1

Summary of key points

FS 1

Page 2

FS 1 NOM Character - Tools to Assist Operators

The IssuesNOM impacts on the efficiency and effectiveness of water treatment processes and on the final water quality reaching the customer tap.

Raw Water QualitySeasonal VariationImpact of Rain or Bush FireUV Irradiation – Prolong Storage

Treatment Plant

Treatment PerformanceRemoval of OrganicsTreated Water Quality

Reservoir Disinfection Distribution System Customer Tap

Disinfectant DemandDBP

Biofilm FormationBacterial RegrowthDiscoloured Water

Available Tools for OperatorsA range of analytical techniques offer more information on NOM character. The usefulness of each technique varies depending on the application.

Parameters Analytical Tools

Colour Visible SpectrophotometryVisual Comparators

Aromaticity (UV absorbance) UV SpectrophotometryTotal Organic Carbon

DOC AnalyserDissolved Organic Carbon (DOC)Biodegradable Organic Carbon (BDOC)Assimilable Organic Carbon (AOC) Bacterial Regrowth Potential (BRP)Bacterial Regrowth

Molecular Weight Distribution High Performance Size Exclusion Chromatography (HPSEC)

Hydrophobicity/Hydrophilicity Rapid Fractionation (RF)Trihalomethane Formation Potential (THMFP) Gas Chromatography (GC)

Functional Groups(Aliphatic, Aromatic, Nitrogen Containing)

Gas Chromatography-Mass Spectroscopy (GC-MS)Infrared Spectroscopy (FTIR)Nuclear Magnetic Resonance (NMR)

Research FindingsDissolved organic carbon (DOC) is the most commonly used parameter to quantify NOM. The DOC concentrations of waters from around Australia were quite diverse – ranging from very low in eastern states (NSW and VIC) and NT to very high in SA and WA. The difference after treatment is demonstrated in the graph opposite - the SA/WA supplies with high DOC have optimised treatment to obtain significant removal whereas the NSW treatment plants with lower DOC values are not optimised to remove DOC to the same extent.

DOC levels in Australia - Snap shot from early 2003

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FS 1

• The results of the survey of nine water samples including river, reservoir and ground water sources from around Australia over a 24-month period indicated that all water sources experienced seasonal variation in DOC concentration. In extreme situations where both the percentage variation and DOC concentration are high, this could have a significant impact on water treatment plant operation.

• DOC is not a sufficient measure of NOM character to determine the impact on water treatment. Generally the higher the DOC, the higher the coagulant and disinfectant doses required to treat the water, however, there are exceptions (Chow et al, 2004a).

Simple Organic Characterisation• UV absorbance at 254nm (UV254) is a useful surrogate measure for DOC although it tends

to include only the more complex NOM character. This technique only requires very simple instrumentation and can be performed by the operators in the treatment plant.

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Treated Water

Raw Water

Correlation between DOC and UV254 for both raw and treated waters

• Care must be taken when using UV254 as a DOC surrogate. Good correlation can only be obtained with similar water quality. The above example indicates that this raw water has higher UV absorbance (UV254) per DOC than the treated water.

• UV254 correlates well with the chlorine demand and disinfection by-product (DBP) formation (refer FS 7).

• The ratio of UV254 to DOC (specific UV absorbance – SUVA) or colour to DOC (specific colour) is also often used to characterise organics. To date, SUVA and specific colour have not provided useful measures to assist plant operation.

• Trihalomethane formation potential (THMFP) is a useful technique to compare the potential of waters to form DBPs. Extra information can be obtained by using THMFP per DOC. The THMFP/DOC value in treated water is generally lower than in raw water, indicating that the treatment process selectively removes THM precursors.

High Performance Size Exclusion Chromatography (HPSEC)• HPSEC separates NOM constituents according to molecular weight (MW) (size) by a differential

permeation process, using a high performance liquid chromatography system with UV detector. This technique is simple and informative.

FS 1

Page 4

• The HPSEC chromatogram can be used to distinguish water sources (eg, river, ground water and reservoir water).

For example, the post-rainfall (August 2004) chromatogram below shows significant increases in NOM concentration and in particular an increase in higher MW fractions, characteristic of catchment source water. Furthermore, a high MW peak (likely to be colloidal organic matter) is observed.

• This HPSEC system is limited as it does not detect NOM which contains little or no UV activity (coagulated or chlorinated water). To overcome this problem, the CRC for Water Quality and Treatment is currently developing a new detector system for HPSEC based on direct measurement of DOC.

Rapid Fractionation (RF)• Rapid Fractionation (RF) describes the NOM as a mixture of four organic fractions, very

hydrophobic acids (VHA), slightly hydrophobic acids (SHA), hydrophilic charged (CHA) and hydrophilic neutral (NEU), by using adsorption on various resins (Chow et al, 2004d).

• RF of supplies from around Australia indicated that waters with higher DOC tended to have a higher proportion (percentage) of hydrophobic fractions (VHA/SHA) whereas supplies with lower DOC tended to have higher proportions of the hydrophilic neutral (NEU) fractions. Most waters surveyed in Australia tended to have very low concentration of CHA and NEU fractions with the greatest concentration of the DOC present as hydrophobic fractions (VHA/SHA).

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FS 1

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DOC: 1 - 6 mg/LVHA: 35 - 58 %SHA: 12 - 24 %CHA: 6 - 8 %NEU: 19 - 26 %

DOC: 1 - 3 mg/LVHA: 19 - 38 %SHA: 14 - 25 %CHA: 6 - 7 %NEU: 33 - 50%





Snap ShotSnap Shotin 2003in 2003

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• Coagulation with increasing alum dose results in increased removal of the VHA and SHA fractions and to a lesser extent the CHA fraction but little or no removal of the NEU fraction, which results in the character of the treated water differing significantly from that of the raw water.

• RF can quantify the proportion of DOC that will definitely not be removed by conventional treatment (most of NEU fraction).

• The amount of VHA present correlates very well with both coagulant and chlorine demands (refer FS 3 and 7).

Biodegradable Organics• Bacterial regrowth potential (BRP) is a technique developed to measure the ability of water to

support microbiological growth. The growth of bacteria is measured after filtering the sample and re-inoculating with bacteria from the original sample. Growth is measured over 3-5 days by automatically measuring turbidity changes (12o forward scatter) (Withers and Drikas, 1998).

• Generally, after oxidation with either chlorine or ozone, BRP increases. This is a result of larger compounds being oxidised and/or broken down to more assimilable compounds. Waters with higher BRP have a higher potential for regrowth in distribution systems.

• In studies to date, an increase in BRP appears to occur when high molecular weight compounds are removed from water. This could be due to the release of more assimilable organics which were previously complexed and unavailable.

• Biodegradable Dissolved Organic Carbon (BDOC) is defined as the fraction of dissolved organic carbon (DOC) that can be mineralised by bacteria on a fixed support media.

• The reduction of BDOC in drinking water is an important part of the water treatment process as even low concentrations are sufficient to support bacterial growth in the distribution system.

• Conventional treatment consisting of coagulation/filtration reduces BDOC. The higher the applied alum dose the lower the BDOC in the treated water.

Implementation• Understanding the organic character of the water allows operators to predict the applicability of

coagulation to remove the organics and to predict the required chlorine demand.

• Treatment plant operators can use BDOC and BRP to optimise water treatment processes for removal of biodegradable organic carbon to minimise disinfection requirements and reduce disinfection by-products.

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FS 1

More InformationChow CWK, Fabris R, Drikas M and Holmes M (in press) A Case Study of Treatment Performance and Organic Character. J Water SRT – Aqua.

Chow CWK, van Leeuwen JA, Drikas M, Fabris R, Spark KM and Page DW (1999) The Impact of the Character of Natural Organic Matter in Conventional Treatment with Alum. Wat. Sci. Tech. 40(9) 97-104.

Chow C, Cook D and Drikas M (2002) Evaluation of Magnetic Ion Exchange Resin (MIEX®) and Alum Treatment for Formation of Disinfection By-Products and Bacterial Regrowth. Wat. Sci. Tech.: Water Supply 2(3) 267–274.

Chow CWK, Fabris R, Drikas M and Holmes M (2004a) The Impact of Organic Character on Water Treatment Plant Performance. NOM research: Innovations and Applications for Drinking Water Treatment, Victor Harbor, Australia.

Chow CWK, Favier M and Drikas M (2004b) Evaluation of Dissolved Organic Carbon Detector for High Performance Size Exclusion Chromatography as a Tool to Study Water Treatment Processes. NOM research: Innovations and Applications for Drinking Water Treatment, Victor Harbor, Australia.

Chow CWK, Fitzgerald F and Holmes M (2004c) The Impact of Natural Organic Matter on Disinfection Demand - A Tool to Improve Disinfection Control. AWA Enviro, Sydney.

Chow CWK, Fabris R and Drikas M (2004d) A Rapid Fractionation Technique to Characterise Natural Organic Matter for the Optimisation of Water Treatment Processes. J Water SRT – Aqua 53(2): 85-92.

Drikas M, Chow CWK and Cook D (2003) The Impact of Recalcitrant Organic Character on Disinfection Stability, Trihalomethane Formation and Bacterial Regrowth - An Evaluation of Magnetic Ion Exchange Resin (MIEX®) and Alum Coagulation. J Water SRT - Aqua 52 (7) 475-487.

Fabris R, Chow C and Drikas M (2004) The Link of Organic Character and Coagulation Performance – A Practical Experience. AWA Enviro, Sydney.

Fitzgerald F, Chow C and Holmes H (2005) Development of a Disinfectant Demand Sensor – An Attempt to Predict Disinfectant Demand. AWA Ozwater Convention, Brisbane.

Fitzgerald F, Chow CWK, Holmes M (2004) Link between Organic Character and Disinfection - Australian Experience. NOM research: Innovations and Applications for Drinking Water Treatment, Victor Harbor, Australia.

Wilkinson K, Chow C, Fabris R and Drikas M (2005) Organic Characterisation Tools for Drinking Water Treatment: A Summary of Applicability. AWA Ozwater Convention, Brisbane.

Withers N and Drikas M (1998) Bacterial Regrowth Potential: Quantitative Measure by Acetate Carbon Equivalents. Water, 25 (5) 19-23.

FS 2

Research Findings• Surveys in Victoria and South Australia revealed there is large variation in aqueous extractable

DOC in soils with different vegetation covers. The lowest DOC concentrations were from soils with grass or pasture cover.

• The application of gypsum as a soil ameliorant can retard the transport of DOC through the soil profile and limit transport of DOC in subsurface flows.

• Gypsum application at 15 T/ha caused a reduction in anion adsorption capacity in the upper 10 cm of soils studied, with an increase in anion adsorption capacity below 10 cm.

• The increase in anion adsorption capacity below 10 cm with gypsum treatment enhanced the overall anion adsorption capacity resulting in soil leachates having reduced concentrations in both NOM and Phosphorous concentrations.

• A relatively high minimum dose of gypsum appears to be required (≈ 10 T/ha).• DOC leached from soil treated with gypsum was found to be harder to remove with

conventional water treatment using alum, compared with DOC from soils not treated with gypsum.

• In soils, exchangeable cations with ameliorant sourced calcium, such as manganese may reach high concentrations in leachates.

• In cooler autumn and winter months riverine inflow containing freshly leached NOM travels along the bottom of the reservoir and can rapidly reach reservoir offtakes. This could lead to poorer quality water reaching the water treatment plants.

Implementation• Gypsum application may provide a means of minimising the transport of NOM and phosphorus

in catchments although the potential for deleterious water quality effects such as increased manganese release needs further investigation.

• Offtake of reservoir water to a water treatment plant should be based upon knowledge of reservoir hydrodynamics and the consequential changes in water quality due to river inflows.

• When possible water should not be harvested from within a riverine intrusion as this water generally has poorer water quality including higher concentrations of DOC and higher turbidity.

• A simple model called INFLOW is available to predict the depth of a riverine intrusion,

and how quickly it will travel from the inflow to the offtake. The model is available online at http://www2.cwr.uwa.edu.au/~ttfadmin/model/inflow/

More InformationLinden LG, Brookes JD, Hipsey M, Ganf GG and van Leeuwen JA (2004) Natural Organic Matter and Water Quality during Inflow Events: Linking Reservoir Processes and Water Treatment. NOM Research: Innovation and Applications for Drinking Water Treatment, Victor Harbor, Australia.

Page DW, van Leeuwen JA, Spark KM and Mulcahy DE (2001) Tracing Terrestrial Compounds Leaching from Two Reservoirs Catchments as Input to Dissolved Organic Matter. Mar. Freshwater Res., 52, 223-233.

Page DW, van Leeuwen JA, Spark KM and Mulcahy DE (2001) Reservoir Catchments and the Influence on Terrestrial Dissolved Organic Matter. AWA 19th Federal Convention, Canberra, April.

Page DW, van Leeuwen JA, Spark KM, Mulcahy DE (2002) Pyrolysis Characterisation of Plant, Humus and Soil Extracts from Australian Catchments. Journal of Analytical and Applied Pyrolysis, 65(2), 269-285.

FS 2 Managing NOM in the Catchment/Reservoirs

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FS 2

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Page DW, van Leeuwen JA, Spark KM and Anstis ST (2001) A Comparison of Degradative Techniques for the Determination of Water Soluble Lignin Derived Methoxyphenols in a Reservoir Catchment. Proceedings of the 9th International conference of the IHSS, 415-420.

Varcoe J, Chittleborough D, Cox J and van Leeuwen J (2000) Phosphate and NOM Adsorption with Soil Minerals as Influenced by Calcium. NZSSS/ASSSI Soil 2000 Conference.

Varcoe J, Chittleborough D, Cox J and van Leeuwen J (2000) The Effect of Gypsum on P and NOM Movement- A Field Trial. NZSSS/ASSSI Soil 2000 Conference.

Varcoe J, Chittleborough D, Cox J and van Leeuwen J (2001) The Effect of Ca Soil Amendments on P (& DOM) Mobility. International Phosphorus Transfer Workshop, Plymouth University, Devon.

FS 3

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Research Findings• Optimisation of coagulation conditions can yield significant improvements in DOC removal and

this is most effectively achieved by pH manipulation.

• The results of NOM characterisation techniques such as HPSEC indicate that coagulation preferentially removes higher molecular weight UV absorbing compounds, leaving lower molecular weight, less UV adsorbing material in the treated water.

• Sequential coagulation treatment, using repetitive doses of alum, has identified that there is a portion of the organic material which cannot be removed by coagulation processes, regardless of dose and conditions. This portion of organic matter is known as recalcitrant NOM.

• The CHA, VHA and SHA fractions are the most amenable to removal by coagulation. The higher the proportion of these fractions present in the water, the greater the amount of DOC that will be removed by coagulation. Most of the NEU fraction of DOC will not be removed by conventional treatment.

• Generally alum is the best performing inorganic coagulant for NOM, colour and turbidity removal under conventional pH conditions (6-7) as these conditions are closer to the optimum operating range of alum of pH 5-6.

• Generally ferric salts are the best performing inorganic coagulants for enhanced coagulation (higher doses, depressed pH) as these more acidic pH conditions are closer to the optimum operating range of ferric salts of pH 4-5.

Comparison of %DOC removal for alum and ferric chloride treatment of Myponga Reservoir water.

• A model called mEnCo, has been established that enables the following two functions, relevant to conventional water treatment,

• rapid determination of coagulant dose (alum and ferric chloride) and pH control reagents for enhanced coagulation

• prediction of residual DOC in treated water over wide ranges of coagulant doses and coagulation pH conditions from limited jar test data.

• Poly-aluminium chloride (PACl), also known as aluminium chlorohydrate (ACH), is an effective coagulant for low alkalinity waters in situations where pH control can not be used and acidic coagulants such as alum and ferric salts depress the pH below the effective coagulation range. The advantage of pre-formed coagulation products is also apparent in low temperature situations where coagulation with other inorganic coagulants can be too slow for the hydraulic flow of the treatment plant.

FS 3 Optimising NOM Removal in Conventional Treatment Plants

FS 3

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• Advanced coagulants (such as poly-ferric sulphate (PFS)) can remove more DOC over a wider range of operating conditions as they are less pH and dose dependant. However, they do not necessarily target significantly more organic components of concern such as recalcitrant neutral hydrophilics. The increased DOC removal was found to result in only marginal changes in secondary water quality parameters (chlorine demand, THMFP) and failed to show benefits to bacterial regrowth in the treated water.

Implementation • DOC removal can be optimised in conventional treatment by increasing applied coagulant dose,

changing coagulant and manipulating pH.

• Monitoring NOM character by measuring the VHA fraction will allow operators to better control coagulant dose to optimise DOC removal.

• Software for implementation of mEnCo to predict coagulant doses, pH control reagents and residual DOC in treated water is available through the CRC for Water Quality and Treatment. This software is currently being applied by several Australian water utilities.

More Information Chow CWK, van Leeuwen JA, Drikas M, Fabris R, Spark KM and Page DW (1999) The Impact of the Character of Natural Organic Matter in Conventional Treatment with Alum. Water Science and Technology 40(9) 97-104.

Fabris R, Chow C and Drikas M (2003) The Impact of Coagulant Type on NOM Removal. AWA Ozwater Convention, Perth.

Fabris R, Chow C and Drikas M (2004) The Link of Organic Character and Coagulation Performance – A Practical Experience, AWA Enviro, Sydney.

Fabris R, Chow C and Drikas M (2005) Evaluation of Alternative Coagulants for Removal of Problematic Natural Organic Matter in Drinking Water Treatment. AWA Ozwater Convention, Brisbane.

Kastl, G, Fisher I, Sathasivan A and van Leeuwen J (2004) Modelling DOC Removal by Enhanced Coagulation. Journal of the American Water Works Association, 96(2), 79-89.

van Leeuwen J, Chow C, Fabris R, Drikas M and Spark K (1999) Enhanced Coagulation for Dissolved Organic Carbon Removal in Conventional Treatment with Alum. AWWA 18th Federal Convention, Adelaide.

van Leeuwen, J, Daly R and Holmes M (2005) Modelling the Treatment of Drinking Water to Maximize Dissolved Organic Matter Removal and Minimize Disinfection By-Product Formation. Desalination, 177, 81-89.

FS 4

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FS 4 Other Processes to Remove NOM

Research Findings • There is a portion of the organic matter, known as recalcitrant NOM, which cannot be removed

by coagulation processes. Coagulants alone were incapable of producing required reductions in chlorine reactivity, DBP formation and bacterial regrowth.

• For the treatment of water for potable use, there are a number of advanced treatment techniques that have been developed worldwide. These generally fall into three categories: oxidative processes, adsorbents and membrane filtration.

• UV treatment of NOM leads to progressive reduction in its molecular weight, DOC and eventual mineralisation. The reduction in molecular weight is correlated with increased biodegradability, and the UV dosage for maximum biodegradability can be optimised to maximise NOM removal in a sequential UV/biologically activated carbon (BAC) process. VUV (vacuum ultraviolet) pre-treatment was shown to be five to six times faster and lead to greater NOM biodegradability than UV254 pre-treatment.

• The product water from the VUV/BAC process was shown to present low potential health risks in terms of THMFP, haloacetic acid formation potential, nitrite, hydrogen peroxide, bromate, cytotoxicity and mutagenicity.

• RF was used to demonstrate which fractions of the NOM were degraded by the UV and biological processes and was shown to be useful in predicting the applicability of the developed process for different NOM sources.

• The MIEX® process was designed specifically for the removal of DOC from drinking water. It is a polymer adsorption resin incorporating iron to enhance aggregation and settling (via magnetic interaction) (Morran et al, 1996).

• MIEX® significantly decreases required chemical dosing for effective treatment including reduced coagulant dosing and ultimately disinfectant dosing through improved DOC removal.

• Adding MIEX® to the treatment process either alone or combined with alum improved DOC removal when compared with alum alone resulting in decreased chlorine decay and lower THM formation.

• A three-stage MIEX®/powdered activated carbon (PAC) coagulant treatment was found to improve the amount of DOC removed by between 82-96%, decrease chlorine demand, and significantly decrease THMFP. Bacterial regrowth was increased, however, highlighting the critical difference between using treatment to reduce NOM concentration, and changing NOM character.

Effect on (a) DOC removal and (b) THMFP of PAC and alum treatment of Myponga Reservoir MIEX® treated water.

FS 4

Page 12

• PAC had a greater effect on DOC and THMFP removal than alum on the organics remaining after MIEX® treatment.

Implementation • The selection of treatment process to remove organics will be dependant on the character of the

organics and the extent of removal required.

• The need to remove NOM to improve water quality beyond that achievable by coagulation alone will require additional treatment.

• There is potential for the application of UV at higher irradiation doses for removal of NOM either alone or to increase biodegradability prior to a granular activated carbon (GAC) filter, similar to the current application of ozone/GAC.

• MIEX® has been applied to increase NOM removal and provide improved water quality in three Australian operating treatment plants.

• Data obtained from MIEX® and alum evaluations have been used to aid optimisation of treatment conditions at selected Australian water treatment plants including Mt. Pleasant WTP, South Australia.

More Information Buchanan W, Roddick F and Porter N (2004) Enhanced Biodegradability of UV and VUV Pretreated Natural Organic Matter. Water Science and Technology: Water Supply, 4(4), 103-111.

Buchanan W, Roddick F, Porter N, and Drikas M (2005) Fractionation of UV and VUV Pretreated Natural Organic Matter from Drinking Water. Environ. Sci. Technol., ASAP Web Release Date: 11 May; vol. 39(12), pp 4647-4654.

Cook D, Chow C and Drikas M (2001) A Laboratory Study of Conventional Alum Treatment versus MIEX® Treatment for the Removal of Natural Organic Matter, AWA 19th Federal Convention, Canberra.

Chow C, Cook D and Drikas M (2002) Evaluation of Magnetic Ion Exchange Resin (MIEX) and Alum Treatment for Formation of Disinfection By-Products and Bacterial Regrowth. Water Science and Technology: Water Supply 2(3) 267–274.

Drikas M, Chow CWK and Cook D (2003) The Impact of Recalcitrant Organic Character on Disinfection Stability, Trihalomethane Formation and Bacterial Regrowth - An Evaluation of Magnetic Ion Exchange Resin (MIEX®) and Alum Coagulation. J Water SRT - Aqua 52(7) 475-487.

Fabris R, Chow C and Drikas M (2004) Practical Application of a Combined Treatment Process for Removal of Recalcitrant NOM – Alum and PAC, Water Science and Technology: Water Supply 4(4) 89–94.

Morran JY, Bursill DB, Drikas M and Nguyen H (1996) A New Technique for the Removal of Natural Organic Matter. Proceedings of the Australian Water & Wastewater Association WaterTECH Conference, Sydney, 428-432.

Parkinson A, Roddick FA and Hobday MD (2003) UV Photooxidation of NOM: Issues Related to Drinking Water Treatment. J Water SRT - Aqua, 52, 577-586.

Thomson J, Parkinson A and Roddick FA (2004) Depolymerization of Chromophoric Natural Organic Matter. Environmental Science and Technology, 38(12), 3360-3369.

Thomson J, Roddick FA and Drikas M (2004) Vacuum Ultraviolet Irradiation for Natural Organic Matter Removal. J Water SRT – Aqua, 53(4), 193-205.

FS 5

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Research Findings• When activated carbon is applied for the removal of problem microcontaminants, such as

taste and odour compounds, algal toxins or pesticides, NOM has a significant impact on its effectiveness.

• While these problem compounds in drinking water are typically found in concentrations of nanograms or micrograms per litre, NOM is virtually always three to six orders of magnitude higher in concentration, and always offers significant competition for adsorption sites.

• Strong competition for adsorption sites results in higher dose requirements for powdered activated carbon (PAC) and shorter lifetimes for granular activated carbon (GAC) filters.

For example, the figure shows the PAC dose required to reduce the taste and odour compound, methyl iso-borneol (MIB), by 50% in waters of different DOC concentration (contact time 60 mins).

0 5 120

5

10

15

20

25

30

Car

bon

dose

(mg

L-1)

DOC concentration (mg L-1)

• NOM character also plays a role in the competitive effect, with the NOM in the molecular weight range similar to the target compound causing the greatest competition, and therefore the greatest effect on adsorption.

• Pre-adsorption, or preloading of GAC by NOM is the most important factor controlling the lifetime of filters for the removal of microcontaminants. NOM is constantly present in the water, utilising adsorption sites that are no longer available for the microcontaminant. Once again, the most detrimental NOM to the lifetime of GAC is the molecular weight range similar to the microcontaminant.

Implementation• An increase in DOC concentration in the inlet to the plant, such as might occur during an algal

bloom, will result in an increased requirement for PAC, or a reduced life expectancy for GAC.

• For optimum application of either form of activated carbon the aim should be maximum prior removal of NOM.

• As prior removal of NOM is not always possible with the application of PAC, the effect can be at least partially offset by an increase in the PAC contact time, and avoiding dosing PAC with other chemicals such as chlorine or metal coagulant.

FS 5 The Effect of NOM on the Application of Activated Carbon

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FS 5

More informationCook D and Newcombe G (2002) Removal of Microcystin Variants with Powdered Activated Carbon. Journal of Water Science and Technology: Water Supply 2(5-6), 201-208.

Cook D and Newcombe G (2004) Can we Predict the Removal of MIB and Geosmin by Using Water Quality Parameters? Water Science and Technology 4(4), 221-226.

Hepplewhite C, Newcombe G and Knappe DRU (2004) NOM and MIB, Who Wins in the Competition for Activated Carbon Adsorption Sites? Water Science and Technology 49(9), 257-265.

Newcombe G and Cook D (2002) Influences on the Removal of Tastes and Odours by PAC. Aqua, 51(8), 463-474.

Newcombe G, Morrison J, Hepplewhite C and Knappe DRU (2002) In the (Adsorption) Competition between NOM and MIB, Who is the Winner, and Why? Journal of Water Science and Technology: Water Supply 2(2), 59-67.

Newcombe G, Morrison J and Hepplewhite C (2002) Simultaneous Adsorption of MIB and NOM onto Activated Carbon: I Characterisation of the System and NOM Adsorption. Carbon 40(12), 2135-2146.

Newcombe G, Morrison J, Hepplewhite C and Knappe DRU (2002) Simultaneous Adsorption of MIB and NOM onto Activated Carbon: II Competitive Effects. Carbon 40(12), 2147-2156.

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FS 6

Understanding Fouling

Membrane System

Trans Membrane Pressure

(kPa)

Turbidity Removal

(%)

NOM Removal(%)

Water Loss(%)

Microfiltration <100 >97 <2 5-10Ultrafiltration <100 >99 <10 10-15Nanofiltration <500 >99 >90 15-30

Microfiltration (MF)/Ultrafiltration (UF) membranes remove little NOM as the NOM is smaller than the pore size of MF or UF. However, NOM fouls low pressure membranes and chemical cleaning is required to restore the flux. Fouling rate does not correspond to the traditional water quality parameters of colour and DOC.

Research Findings

• Composition of NOM has a strong impact on the rate of fouling, with the high molecular weight, hydrophilic neutral compounds appearing to have a large influence over the fouling rate in studies using surface waters.

• Interactions between NOM fractions and inorganic components can also influence the fouling characteristics.

• The membrane type as well as the NOM composition and concentration influence the rate of membrane fouling, with hydrophilic membranes having lower fouling rates than more hydrophobic membranes.

• Filtration does not remove all membrane foulants from the water, so the organic components will be available to foul subsequent membrane processes eg. when using microfiltration as pre-treatment for reverse osmosis.

• Coagulants almost always lower the rate of membrane fouling. Aluminium chlorohydrate is the recommended coagulant for use with membranes.

• Addition of particles, such as magnetite, with a coagulant may improve membrane performance by increasing the porosity of the filter cake.

• Adsorbents (PAC, MIEX® etc) generally require extended contact times or high concentrations to be effective. Recycling of the adsorbent may make the use of high concentrations economic. Adsorbents are unlikely to be used effectively by in-line dosing and direct filtration onto the membranes because of the subsequent slow kinetics.

• To date there have been conflicting reports and results on the performance of MIEX® and membranes. Some reports indicate improved performance and others indicate increased fouling rates.

• New advancements being tested for NOM control or removal are: • Ultra fine PAC that increases the kinetics of adsorption (dose in line and direct

filtration)• Novel coagulant, poly silicate iron, for reduced membrane fouling – particularly with

hydrophilic membranes• UV degradation of NOM prior to membranes to lower the fouling rate of

membranes.• Tailored membrane materials and coagulants/adsorbents for low fouling operation

(ie. MIEX® and positively charged polyacrylonitrile membranes).

FS 6 Fouling of Low Pressure Membranes

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FS 6

Implementation• Prediction of fouling rates still requires pilot plant trials for accurate results.

• Coagulant addition should be planned, even if its use is not anticipated.

More InformationCRC Water Quality and Treatment (2003) Occasional Paper 6 - Natural Organic Matter in Drinking Water: Problems and Solutions.

Fan L, Harris JL, Roddick FA and Booker NA (2001) Influence of Natural Organic Matter Characteristics on the Fouling of Microfiltration Membranes. Water Research, 35(18), 4455–4463.

Farahbakhsh K, Svrcek C, Guest RK, Smith DW (2004) A Review of the Impact of Chemical Pre-Treatment on Low-Pressure Water Treatment Membranes. J. Environ. Eng. Sci. 3, 237-253.

Gray S, Tran T, Bolto B and Johnson W (2005) Natural Organic Matter and Low Pressure Membranes – A Review. AWA Ozwater Convention, Brisbane.

Schaefer AI, Fane AG and Waite TD (2001) Cost Factors and Chemical Pre-Treatment Effects in Membrane Filtration of Natural Waters. Wat. Res. 35(6), 1509-1517.

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FS 7

Research Findings Surrogate Parameter to Predict Disinfectant Demand

• There is a strong relationship between chlorine demand and NOM. Parameters such as UV254, DOC, colour or VHA fraction can be used to predict chlorine demand.

• A 24-month laboratory study with samples every 3 months from water sources, including rivers, reservoirs and ground waters, confirmed that a generic equation using UV254 can predict chlorine demand. This also confirmed that the relationship between UV254 and chlorine demand is not affected by water sources and seasonal variation.

• The use of the VHA fraction to predict chlorine demand is slightly more time consuming. However, it may be superior for certain waters to produce a more accurate demand prediction.

• Only a weak correlation between NOM and chloramine demand was observed. No surrogate parameter was identified which correlated well enough to be used to predict chloramine demand. At this stage it appears that whilst NOM impacts on chloramination, it may not be the major component contributing to chloramine demand.

R2 = 0.94

0

5

10

15

20

25

30

0 0.2 0.4 0.6 0.8

UV254 (cm-1)3-

day

Chl

orin

e D

eman

d (m

g/L)

The relationship between 3-day chlorine demand and UV254.

Impact of Disinfection• HPSEC can be used to compare the change in organics after disinfection. After chlorination,

there is a general reduction of the UV absorbing components over the molecular weight range (100 to 10,000 Da) with higher reduction in the high molecular weight portion. This implies that it is very likely that the precursors are higher molecular weight compounds. However, chlorination did not reduce the colloidal organics peak (100,000 Da), indicating that the organic matter which appears after heavy rain may not contribute to the formation of DBPs.

• Chloramine is a weaker oxidant compared with chlorine and it has less impact on the organic character.

• DOC and UV254 correlate well with THMFP and can be used as surrogate parameters to predict THM formation.

FS 7 Effect of NOM on Managing Distribution Systems

0.000

0.005

0.010

0.015

0.020

0.025

0.030

10 100 1000 10000 100000

Molecular Weight (Da)

UV

abs@

260n

m (c

m-1) Prior to Disinfection

After 7 days Chloramination

After 7 days Chlorination

Colloid Organics

Larege reudction of highmolecular weight portion

Myponga Raw Water

0.000

0.005

0.010

0.015

0.020

0.025

0.030

10 100 1000 10000 100000

Molecular Weight (Da)

UV

abs@

260n

m (c

m-1) Prior to Disinfection

After 7 days Chloramination

After 7 days Chlorination

Colloid Organics

Larege reudction of highmolecular weight portion

Myponga Raw Water

Large reduction of highmolecular weight portion

Colloidal Organics

Page 18

FS 7

Biofilm and NOM• Biodegradable organic carbon is the primary driver of biofilm regrowth in chlorinated systems.

• Removal of biodegradable organic carbon causes a decrease both in biofilm biomass and the impact of biofilms on disinfectant decay.

• An increase in biodegradable organic carbon causes an increase in biofilm development, biofilm mediated disinfectant decay and release of cells to the aqueous phase.

• Disinfection decay by biofilms is dependant on the presence of biodegradable organic carbon.

• Biofilms convert non-reactive biodegradable organic carbon into fractions that readily react with disinfectants.

• HPSEC is a potential tool to study biofilm activity. Biofilms in distribution systems can be considered as a bioreactor; the change in organic character due to biofilm activity can be used as an indirect tool to assess biofilms. Preliminary results indicate that this technique can be used to characterise organics in different sections of the distribution system.

Implementation • Monitoring UV254 will allow operators to predict chlorine demand and THMFP and optimise

chlorine residuals in distribution systems.

• A trial using on-line UV spectrophotometry at the Myponga WTP demonstrated the feasibility of monitoring UV absorbance to predict chlorine demand. This can be further implemented to optimise chlorine residuals in distribution systems.

• Removal of biodegradable organics will reduce disinfectant decay and biofilm growth in distribution systems.

More InformationAngles ML, Chandy J, Kastl G, Jegatheesan V, Cox P and Fisher I (1999) Biofilms in drinking water: influence of organic carbon and disinfection. Water 26:30-33.

Chandy JC and Angles ML (2005) Physical and Chemical Effects on Distribution System Biofilms and Incorporated Pathogens. CRC for WaterQuality and Treatment Research Report - in preparation.

Chandy JC and Angles ML (2004) Factors Influencing the Development of Biofilms under Controlled Conditions. CRC for Water Quality and Treatment Research Report No. 20, Sydney Australia.

Chow CWK, Fabris R, Drikas M and Holmes M (in press) A Case Study of Treatment Performance and Organic Character. J Water SRT – Aqua.

Chow C, Cook D and Drikas M (2002) Evaluation of Magnetic Ion Exchange Resin (MIEX) and Alum Treatment for Formation of Disinfection By-Products and Bacterial Regrowth. Wat. Sci. Tech.: Water Supply 2(3) 267–274.

Chow, CWK, Fitzgerald F and Holmes M (2004) The Impact of Natural Organic Matter on Disinfection Demand - A Tool to Improve Disinfection Control, AWA Enviro, Sydney.

Drikas M, Chow CWK and Cook D (2003) The Impact of Recalcitrant Organic Character on Disinfection Stability, Trihalomethane Formation and Bacterial Regrowth - An Evaluation of Magnetic Ion Exchange Resin (MIEX®) and Alum Coagulation. J Water SRT - Aqua 52(7) 475-487.

Fitzgerald F, Chow C and Holmes H (2005) Development of a Disinfectant Demand Sensor – An Attempt to Predict Disinfectant Demand, AWA Ozwater Convention, Brisbane.

Fitzgerald F, Chow CWK, Holmes M (2004) Link between Organic Character and Disinfection - Australian Experience. NOM research: Innovations and Applications for Drinking Water Treatment, Victor Harbor, Australia.

Holmes M, Chow C, Dandy G, May R, Fitzgerald F, Maier H, Badalyan A and Nixon J (2005) DrCT®: Developing Tools for Improved Disinfection Control within Water Distribution Systems, WEF/AWWA/IWA Disinfection Specialty Conference in Mesa, Arizona.

Wilkinson K, Chow C, Fabris R and Drikas M (2005) Organic Characterisation Tools for Drinking Water Treatment: A Summary of Applicability, AWA Ozwater Convention, Brisbane.

Page 19

FS 7

Page 20

Acknowledgements

Microbial Degradation and Remineralisation of Dissolved Organic Carbon in the Warren Reservoir Project ParticipantsJohn van Leeuwen, Tanja Jankovic-Karasoulos, David Chittleborough, Steve Rogers, Ron Smernik, Friedrich Recknagel.

Impacts of Destratification of Reservoir Waters on the Character of NOM and on the removal of NOM by Water Treatment Processes Project ParticipantsJohn van Leeuwen, Justin Brookes, Mike Burch, Kliti Grice, Nira Jayasuriya, Alan Wade, Leon Linden, Jonathon Yeow, Chong Soh, Felicity Roddick.

Impact of NOM on the Movement of Phosphorus in SoilsProject ParticipantsFriedrich Recknagel, Jon Varcoe, John van Leeuwen, David Chittleborough, Jim Cox.

Characterisation of NOMProject ParticipantsKaye Spark, John van Leeuwen, Lidia Sledz, Rolando Fabris, Declan Page, Simon Anstis.

Development of Treatment Systems for Removal of NOM Project ParticipantsMary Drikas, Chris Chow, Rolando Fabris, Uwe Kaeding, Jim Morran, Kaye Spark, Brian Bolto, David Dixon, Rob Eldridge, Simon King, Felicity Roddick, Malcolm Hobday, Adele Parkinson, James Thomson, Dennis Mulcahy, David Davey, Shaun Thomas.

Hybrid Membrane Processes in Water TreatmentProject ParticipantsNic Booker, Tim Carroll, Stephen Gray, Tony Fane, Andrea Schafer, Felicity Roddick, John Harris, Cunli Xiang, Linhua Fan.

Optimisation of Adsorption Processes – Stage 1 and 2Project ParticipantsPascale Sztajnbok, Darren Oemke, Uwe Kaeding, Mike Holmes, Keith Craig, Gunter Klass, Phillip Pendleton, Felicity Roddick, Rebecca McCallum, Vern Snoeyink, Lionel Ho, Sam Brooke, David Cook, Chris Hepplewhite, Janina Morrison, Mick Bjelopavlic.

Modelling Coagulation to Maximise Removal of Organic Matter – a Pilot Plant and Laboratory Based StudyProject ParticipantsJohn van Leeuwen, Rob Daly, Don Bursill, Mary Drikas, Tung Nguyen, Ian Fisher, George Kastl, Arumugam Sathasivan, Phil Duker, Mike Holmes, Craig Heindenreich, Bronwyn Walsh, Uwe Kaeding.

Development of Combined Treatment Processes for the Removal of Recalcitrant Organic MatterProject ParticipantsMary Drikas, Chris Chow, Rolando Fabris, Stephen Gray, Colin Ritchie, Thuy Tran, Tony Fane, Vicki Chen, Eun Kyung Lee, Felicity Roddick, John Harris, Farhana Malek, Anna Heitz, Rob Kagi,

Page 21

Brad Allpike, David Masters, Steve Capewell, Keith Craig, Michael Holmes, Kym Wallent, Adam Lovell, Phil Duker.

Biological Removal of UV Pretreated NOM from Potable WaterProject ParticipantsMary Drikas, Felicity Roddick, Nichola Porter, Will Buchanan.

Factors affecting Biofilm Development under Controlled ConditionsProject ParticipantsMark Angles, Joseph Chandy, Hopi Yip, Alice Gilyou, Malcolm Warneke, George Kastl, Raj Shanker, Mary Drikas, Naomi Withers.

Development of Tools for Improved Disinfection Control within Distribution SystemsProject ParticipantsChris Chow, Fiona Fitzgerald, Mike Holmes, John Nixon, Graeme Dandy, Holger Maier, Robert May, Alex Badalyan, Terry Dermis, Sebastian Brunner, Philipp Kunkte, Paola Duartes Romeras, Joachim Buff, Karyn Jarvis, Karim Ghaoui, John Missikos, Ralf Mueller, Kathryn Clarkson, Alex Donald, Ken Turner, Steve Healy, Vince Sweet, David Smith, Richard Friend, Shane Hayden, Noel Miles, Robert Considine and Caroline Hussey, Dammika Vitanage, Corinna Doolan, Tony Venturino, Phil Duker, Richard Walker, Kevin Xanthis.

Organisations involved in these projects:

General support in the collation and development of these fact sheets was provided by:Chris Chow, Mary Drikas, Rolando Fabris, Stephen Gray, Uwe Kaeding, John van Leeuwen, Gayle Newcombe and Fiona Wellby.

The University of AdelaideRMIT UniversityAustralian Water Quality CentreCurtin University of TechnologyACTEW AGLUnited Water InternationalSydney WaterCSIROUNSWUniversity of South Australia

Melbourne WaterSA WaterPower and Water CorporationWater CorporationGippsland WaterGold Coast WaterMelbourne Water CorporationUniversity of IllinoisAwwaRFVeolia Water

• The Cooperative Research Centre for Water Quality and Treatment and individual contributors are not responsible for the outcomes of any actions taken on the basis of information in this document, nor for any errors and omissions.

• The Cooperative Research Centre for Water Quality and Treatment and individual contributors disclaim all and any liability to any person in respect of anything, and the consequences

of anything, done or omitted to be done by a person in reliance upon the whole or any part of this document.

• The document does not purport to be a comprehensive statement and analysis of its subject matter, and if further expert advice is required, the services of a competent professional should be sought.

© CRC for Water Quality and Treatment 2005

Natural Organic Matter: Understanding and Controlling the Impact on Water Quality and Water Treatment Processes. Management implications from the Research Programs of the Cooperative Research Centre for Water Quality and Treatment.

ISBN 187661644X

Disclaimer

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TableofContents

FS1 NOMCharacter-ToolstoAssistOperators Page 2

FS2 ManagingNOMintheCatchment/Reservoirs Page 7

FS3 OptimisingNOMRemovalinConventionalTreatmentPlants Page 9

FS4 OtherProcessestoRemoveNOM Page 11

FS5 TheEffectofNOMontheApplicationofActivatedCarbon Page 13

FS6 FoulingofLowPressureMembranes Page 15

FS7 EffectofNOMonManagingDistributionSystems Page 17

Acknowledgements Page 20

ADWGFrameworkElementsInsideBackCover

Factsheetobjective

ThenewAustralianDrinkingWaterFrameworkoutlinesthemethodologyforprovidingsafedrinkingwaterbymanagingthewatersupplysystemfromthecatchmenttothetap.UnderstandingthelevelofriskinourwatersuppliesandtreatmentsystemsisfundamentaltotheFramework.Thisallowsmanagersofcatchmentsandwaterutilitiestofocustheireffortsonpolicies,worksandoperationalpracticestonotonlylowerriskstopublichealthbutalsoimprovetheenvironmentalhealthofthesewaters.

These fact sheets present the findings of research carried out by the Cooperative Research Centre (CRC) for Water Quality and Treatment into understanding the character of natural organic matter (NOM) in Australian watersuppliesandassessingitsimpactonwaterqualitysuchasincreasingdisinfectantdemandandformationof byproducts which adversely affect health. NOM also impacts on water treatment processes by increasing requiredcoagulantdoses,reducingtheeffectivenessofadsorptionprocessesandfoulingmembranesystems.Arange of treatment options have been evaluated to remove NOM to reduce its impact on the described treatment processes and produce water which requires less disinfectant but also minimises biofilm growth in distribution systems.

Factsheetcontents

These fact sheets are derived from the following CRC for Water Quality and Treatment research projects:

• Microbial Degradation and Remineralisation of Dissolved Organic Carbon in the Warren Reservoir

• Impacts of Destratification of Reservoir Waters on the Character of NOM and on the removal of NOM by Water

TreatmentProcesses

• Impact of NOM on the Movement of Phosphorus in Soils

• Characterisation of NOM

• Development of Treatment Systems for Removal of NOM

• Hybrid Membrane Processes in Water Treatment

• Optimisation of Adsorption Processes – Stages 1 and 2

• Modelling Coagulation to Maximise Removal of Organic Matter – a Pilot Plant and Laboratory Based Study

• Development of Combined Treatment Processes for the Removal of Recalcitrant Organic Matter

• Biological Removal of UV Pretreated NOM from Potable Water

• Factors affecting Biofilm Development under Controlled Conditions

• Development of Tools for Improved Disinfection Control within Distribution Systems

ADWGFrameworkElements Key research findings and reference to Fact sheet No.

Assessmentof the Drinking WaterSupplySystem

WaterSupplySystemAnalysis

FS 2 Soil and vegetation impact on release of natural organic matter (NOM). The lowest dissolved organic carbon (DOC) concentrations were from soils with grass or pasture cover.

AssessmentofWaterQualityData

FS1 Understandingtheorganiccharacterofthewaterallowspredictionoftreatability,disinfectiondemandandby-productformation.

FS 1 DOC is not a sufficient measure of NOM character to determine the impact on water treatment.

FS 1 There are a range of simple analytical techniques that provide more information on NOM character.Theusefulnessofeachtechniquedependsontheapplication.

Hazard Identification and RiskAssessment

FS 2 Water from recent rainfall events with high DOC may short circuit through reservoirs during thecoolerseasons.

PreventativeMeasuresfor Drinking WaterQualityManagement

PreventiveMeasures and MultipleBarriers

FS 2 Gypsum application may provide a means of minimising the transport of NOM in catchments.

FS4 Theselectionoftreatmentprocesstoremoveorganicswillbedependantonthecharacterof the organics and the extent of removal required.

OperationalProcedures and Process Control

OperationalProcedures

FS 3 DOC removal can be optimised in conventional treatment by increasing applied coagulant dose,changingcoagulantandmanipulatingpH.Softwareisavailabletoassistwiththis.

FS 3 Coagulation preferentially removes higher molecular weight UV absorbing compounds.

FS 3 The charged and hydrophobic fractions (CHA, VHA and SHA) are the most amenable to removalbycoagulation.Thehighertheproportionofthesefractionspresent,thegreatertheamount of DOC that will be removed by coagulation.

FS 4 There is a portion of the organic matter (recalcitrant NOM) which cannot be removed by coagulationprocesses.

FS 4 If there is a need to remove NOM to improve water quality beyond that achievable by coagulationalone,additionaltreatmentwillbeneeded.

FS 7 Removal of biodegradable organics will reduce disinfectant decay and biofilm growth in distributionsystems.

FS 4 Adding MIEX®tothetreatmentprocesseitheraloneorcombinedwithlowalumdoseswillimprove DOC removal when compared with alum alone, resulting in decreased chlorine decay and lower trihalomethane formation potential (THMFP).

FS 5 An increase in DOC concentration in the inlet to the plant, such as might occur during an algal bloom, will result in an increased requirement for powdered activated carbon (PAC), or a reduced life expectancy for granular activated carbon (GAC).

FS 5 For optimum application of activated carbon the aim should be maximum prior removal of NOM. With the application of PAC, the effect of competing NOM can be at least partially offset by an increase in the PAC contact time, and avoiding dosing PAC with other chemicals suchaschlorineormetalcoagulant.

FS 6 The membrane type as well as the NOM composition and concentration influence the rate of foulingoflowpressuremembranes,withhydrophilicmembraneshavinglowerfoulingratesthanmorehydrophobicmembranes.

FS 6 Coagulants almost always lower the rate of membrane fouling. Aluminium chlorohydrate is therecommendedcoagulantforusewithmembranes.

OperationalMonitoring

FS 3 Monitoring NOM character by measuring the very hydrophobic (VHA) fraction will allow operators to better control coagulant dose to optimise DOC removal.

FS 3 Software is available to predict coagulant doses, pH control reagents and residual DOC in treatedwater.

FS 7 Monitoring UV254

will allow operators to predict chlorine demand and THMFP and optimise chlorineresidualsindistributionsystems.

Verification of Drinking Water Quality

Drinking Water Quality Monitoring

FS 7 On-line UV spectrophotometry may be used to optimise chlorine residuals.

Research and Development

Investigative Studies and ResearchMonitoring

FS 4 There is potential for the application of UV at higher irradiation doses for removal of NOM either alone or to increase biodegradability prior to a granular activated carbon filter.

FS 4 A 3-stage MIEX®/Powdered activated carbon/Coagulant treatment was found to improve the amount of DOC removed, decrease chlorine demand and significantly decrease THMFP. However bacterial regrowth was increased.

FS 6 A range of processes are being trialled to remove NOM prior to membrane filtration.

In Australia, drinking water quality management is undertaken in the context of the Australian Drinking Water Guidelines Framework. In the table below the salient research findings are presented within the Framework to aid in their implementation by the Australian WaterIndustry.


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The Cooperative Research Centre (CRC) for Water Quality and Treatment is Australia’s national drinking water research centre. An unincorporated joint venture between 30 different organisations from the Australian water industry, major universities, CSIRO, and local and state governments, the CRC combines expertise in water quality and public health.

The CRC for Water Quality and Treatment is established and supported under the Federal Government’s Cooperative Research Centres Program.

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joint venture between:

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Natural Organic Matter

Understanding and Controlling the Impact on Water Quality and Water Treatment Processes

Management implications from the Research Programs of the Cooperative Research Centre for Water Quality and Treatment

The Cooperative Research Centre for Water Quality and Treatment


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