SEWER CORROSION & ODOUR RESEARCH (SCORe) PROJECT. NEW INSIGHTS INTO SEWER ODOUR AND CORROSION November 2010

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1 SEWER CORROSION & ODOUR RESEARCH (SCORe) PROJECT NEW INSIGHTS INTO SEWER ODOUR AND CORROSION November 2010

2 A LITTLE HISTORY 1890 First Modern Sewers Paris & London Fundamental Science 1946 Pomeroy 1972 Thistlethwayte Applied Knowledge 1989 Hydrogen Sulphide Control Manual 1989 ASCE Sulphide in WW & Treatment Fundamental Science 25 years Applied Knowledge 25 years 10 years

3 INDUSTRY KNOWLEDGE

4 INDUSTRY KNOWLEDGE

5 NEW DRIVERS 1. Increased Population - Urbanisation - Fringe Areas Larger Sewer Networks More Pumping Stations Higher HRT 2. Water Restrictions / Demand Management Reduced Flows More Concentrated Sewage Higher HRT Build-up of Sediments Sewer Blockages 3. Global Warming Reduced DO Greater Bacterial Activity Anaerobic Conditions Promoted SRB promoted 4. Trade Waste Regulations / Reduced Heavy Metals Reduced Precipitation of metal sulfides Reduced Inhibitory effect on SRB 5. Lower Public Tolerance to Odours More complaints Closing of Sewer Vents & Increased Corrosion

6 CONTROL METHODS Corrosion Processes & Control (Theme 1) Sewer Pipe Gas Phase Technologies (Theme 2) Close Vent, Odour Abatement, Dispersion UNDESIRABLE ODOUR Escape to Atmosphere Lining, Sacrificial Coating. Sulfuric Acid on headspace wall (Corrosion) SOB H2SO4 H2S + O2 Pigging or Cleaning of Sewers. Hydrogen sulfide gas (Odour, OH&S) Ventilation (natural or forced) Return to Liquid Sulfate, Protein, Amino acids in wastewater Wastewater Inhibitors, Biocides (nitrite, ferric). SO4-2 +C+H2O H2S+CO2 SRB Liquid-air mass transfer Sulfide in wastewater ph elevation (Mg(OH) 2 ), No Turbulence. Oxidants (O 2, nitrate), Precipitant (ferric). Liquid Phase Technologies (Theme 3)

7 KNOWLEDGE GAPS CORROSION PROCESSES & CONTROL The rate of corrosion for various H 2 S concentration How factors such as temperature and humidity affect the rate of corrosion. How the rate of corrosion varies over time with various stages of corrosion. How production rate of H 2 SO 4 and other corrosives change over time. How fluctuations in H 2 S conc affect the rate of corrosion. How strength of concrete pipe changes at different stages of corrosion. The spatial variability of such changes around the sewer circumference. Stability requirements for coatings to protect concrete pipes from corrosion.

8 KNOWLEDGE GAPS cont. GAS PHASE TECHNOLOGIES Reliable way to correlate the chemical composition of a gas with its odour intensity and character. Composition of the main odorants in sewers and how this composition varies through the sewerage system. The chemical and biochemical transformation processes of odorous gases that occur in sewers. Reliability of sampling, transport and storage for analysis of sewer gases. Predicting life expectancy of adsorption odour abatement technologies or the time left before odour breakthrough will occur. Effective removal rates of biological odour abatement systems for removal of odorants other than H 2 S. Predicting air movement in sewer headspace under both natural and forced ventilation conditions to determine H 2 S in sewer networks.

9 KNOWLEDGE GAPS cont. LIQUID PHASE TECHNOLOGIES Composition and spatial variation of biofilm microbiology in a sewer and how this functions in the production of H 2 S & other odorous compounds. A complete understanding of the chemical and biochemical transformations that occur in wastewater & the impact of variables such as flow velocity, sediments, industrial discharges, etc. The impact on the biofilm of chemicals commonly used to control H 2 S in sewers such as O 2, NO 3, Mg(OH) 2, Fe 2 Cl 3, etc and other chemical and biochemical side reactions that may occur. An understanding of the processes which emerging biomaterials claim to use to control odours in sewers.

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11 INDUSTRY PARTNERS 6 of Australia s 7 largest cities > 60% Australia s Population Allconnex Water Water Corp, WA Hunter Water SA Water United Water Int. CH2M Hill Sydney Water W Q R A Barwon Water Melbourne Water South East Water

12 Cash: $8.1m PROJECT BUDGET ARC: $4.7m Industry: $3.5m In-kind: $11.7m Total: ~ $20m Universities $7.4m (37%) Other partners $0.7m (3%) ARC $4.7m (24%) Industry $7.1m (36%)

13 BACKGROUND Nov

14 METHODOLOGY RESEARCHERS + INDUSTRY = OUTCOMES (fundamental scientific knowledge) (field expertise) (practical outcomes) integrating & supporting Field Conditions Laboratory Conditions Mathematical Modelling Laboratory System Studies METHODOLOGYH2S concentrations Liquid Temperature Field Studies identifying revealing & confirming

15 PROPOSED PROJECT OUTCOMES The lifetime prediction will allow making trade-offs between corrosion rate and mitigation costs Gas treatment Theme 2 (SP3): odor measurement, abatement technology assessment and optimisation Transport Theme1 (SP1&2): Corrosion processes Dependency of corrosion rate on key factors Model predicting corrosion rate Remaining service time estimation Theme 2 (SP4): ventilation technology Target levels of H 2 S and other compounds in sewer gas Sewer wall Biofilms on wall causing corrosion Sewer gas phase Theme 3 (SP8): Models to predict the production, emission and transport of the compounds Emission Production Theme 3 (SP5, 6&7): liquid phase technologies to minimize production/emission of H 2 S and other odorous compounds Sewer liquid phase Biofilms on wall producing sulfide and other compounds Sewer wall Theme 4 (SP9): Capture all knowledge and transfer to industry through a web-based system

16 OUTCOMES TO-DATE 1. Analytical tools & protocols: Laboratory corrosion chambers. Concrete coupons installed in sewers. Laboratory reactors mimicking rising main. Standard protocols for corrosion assessment. 2. Decision Support & Knowledge Management: Survey of Industry odour monitoring and OAT s used. Develop and field test new ventilation model. Survey of Industry chemical dosing systems. Literature review of new biochemical odour control products. Enhanced SeweX model for carbon, trade waste & velocity. Web-based knowledge management system established. 3. New Technologies: Proof of concept of electrochemical sulfide control. SeweX sulfide model to optimise chemical dosing. Inhibition of SRB with ferric and nitrite.

17 OUTCOMES TO-DATE Laboratory Corrosion Chambers Allow testing of concrete corrosion under controlled conditions Before After

18 SYDNEY WATER CORPORATION

19 MELBOURNE WATER CORPORATION

20 WATER CORPORATION, PERTH

21 OUTCOMES TO-DATE Laboratory Reactors Mimicking Rising Main Verified & validated to mimic UC09 at Gold Coast for H 2 S Fed with real wastewater using Real pumping patterns

22 Laboratory Reactors Mimicking Rising Main Verified & validated to mimic UC09 at Gold Coast for H 2 S Regulation of biofilm Experimental line Weak biofilm removed by shear Different Shear conditions applied Storage Tank 4ºC Chemical Methodology specially designed to monitor relevant parameters RME1 RME2 Heating unit Pump Pump Control line e.g. Sulfur species, Methane, VFA, solids content in reactor and effluent RMC1 RMC2

23 OUTCOMES TO-DATE 100% Proof of Concept of Electrochemical Control of Sulfide Demonstrated first with synthetic and then real wastewater Removal efficiency 90% 80% removal efficiency (%) 70% 60% 50% 40% 30% 20% 10% 0% (1) domestic wastewater, (2) (2) 5 g L -1 NaHCO 3- buffer solution with the addition of acetate, chloride and trace elements and (3) (3) 5 g L -1 NaHCO 3- buffer solution with the addition of trace elements.

24 OUTCOMES TO-DATE Survey of Industry Chemical Dosing Systems Used to select chemicals for optimisation of dosing Dosage in 117 sites Number of sites applied O2 Mg(OH)2 NO3 FeCl3 Odour neutralizer NaOH Bioproduct Survey of chemicals consolidate the list of products used and identify opportunities for collaboration with utilities

25 OUTCOMES TO-DATE Literature Review of New Biochemical Products Used to select products for laboratory testing ACTIVE MECHANISM CLAIMED No. PRODUCTS Enzymatic enhancement 4 Bioaugmentation 9 Bioaugmentation + enzymatic enhancement 11 Bacteria stimulant by trace chemicals 4 Bacteria inhibition by trace chemicals 1 Masking agents or other mechanism 4 TOTAL 33

26 OUTCOMES TO-DATE Web-based Knowledge Management System Outcomes from SP1-SP8 readily available to Industry PROJECT INFORMATION with Version Control RESEARCH PLAN PROJECT SCHEDULES PROJECT BUDGET PROGRESS REPORTS SUBPROJECT WORKING DOCUMENTS THEME BASED FORUMS KNOWLEDGE BASE SUBPROJECT OUTPUTS ODOUR & CORROSION DECISION SUPPORT TREE UPDATED SULFIDE MANUAL REFERENCE DATA BASE

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29 APPLYING KNOWLEDGE Fundamental Science 25 years Applied Knowledge 25 years 10 years CYCLE to 1989 (43 years) CYCLE to 2014 (5 years) Putting Science into Sewers

30 ACKNOWLEDGEMENTS Australian Research Council The SCORe project industry partners: Research collaborators Advanced Water Management Centre, University of Queensland The University of New South Wales Sydney University Newcastle University Curtin University of Technology