Practical Guide To Odour Control In Sewage Transport Systems
Phillip Dack and Gary Finke
The Authors Phillip Dack is currently Director of Sulfide Control Pty Ltd. Gary Finke is currently Managing Director of Aromatrix Australia Pty Ltd.
Acknowledgements This practical guide is the first in a new series of publications produced by the Water Industry Operators Association of Australia (WIOA) and represents the considerable commitment of WIOA to improving the skills of operational staff in the water industry. WIOA has previously produced a set of Practical Guides to Water Treatment. The series includes:
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Practical Guide to Understanding and Managing Surface Water Catchments Practical Guide to the Optimisation of Chemical Dosing, Coagulation, Flocculation and Clarification Practical Guide to the Operation and Optimisation of Media Filters Practical Guide to the Operation and Optimisation of Chlorine and Chloramine Disinfection Practical Guide to the Operation and Optimisation of Distribution Systems
Collectively, these guides assist WIOA to meet an organisational goal of accumulating and disseminating information on the design, control, operation and maintenance of water and wastewater systems. The authors wish to particularly thank Peter Mosse from Hydrological and George Wall from the WIOA for editorial input and critical review of this practical guide. The authors also wish to thank Steven Nash from Goulburn Valley Water and Philippe Cussinet from Environmental Group Limited (EGL) for critical discussion and thoughtful review of the manuscript. WIOA would like to thank the sponsoring partner organisations:
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Australian Water Association (AWA) Government Skills Australia (GSA) International Centre for Excellence in Water Resources Management (ICE WaRM) National Water Commission (NWC) Water Directorate, New South Wales Pipes Wagga Wagga Queensland Water Directorate (qldwater) Water Industry Training Association Queensland (WITA) Water Services Association of Australia (WSAA)
Publications Details First Edition, September 2011.
Ordering More Copies An order form is availble from the WIOA website (www.wioa.org.au) for people wishing to order additional copies, any of the other guides in the wastewater series or any of the Practical Guides to Water Treatment.
General Introduction The Water Industry Operators Association of Australia (WIOA) has produced a successful series of Practical Guides to Water Treatment. These cover key control points from the catchment all the way through to the customers tap. In this new series of Practical Guides produced by WIOA, the key elements of the provision and operation of sewerage treatment systems are covered. The series includes: 1. Management of odours in sewage transport systems. 2. The operation and optimisation of lagoon treatment systems. 3. The operation and optimisation of activated sludge treatment systems. 4. The operation of reclaimed water systems. An underlying objective for each of the guides is that on each and every page operational staff should be able to make mental notes to themselves along the lines of: o That’s a good idea. o We should be doing that. o We can start on that immediately. The guides are not about identifying costly solutions but simply identifying ways to get the best out of what is available at any particular time. The aim is to provide suggestions and hints that can be implemented easily, cheaply and immediately in the field.
Feedback Requested These guides have been written to help operators perform their jobs effectively and to help operators understand the vitally important roles they fulfil within the water industry. The authors would be pleased to receive any feedback on this guide. Suggestions for further information or areas where additional explanation would have aided understanding can all help to make any second or subsequent editions stronger and more useful for operators in our industry. Any suggestions can be directed by e-mail to the Water Industry Operators Association of Australia (WIOA) at info@wioa.org.au or by post to PO Box 6012, Shepparton, Victoria, 3632.
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Contents General Introduction Chapter 1 Background • • • • •
The History Of Sewage Transport Systems And Odours................................................................5 The Cost Of Ignoring Odour And Corrosion....................................................................................7 Current Industry Knowledge............................................................................................................8 STS Definition.................................................................................................................................8 How STS Operators Should Use This Guide..................................................................................8
Chapter 2 Odour And Odour Chemistry
• What Are The Common Odorous Compounds In Sewage?...........................................................9 • Odour Versus Hydrogen Sulfide....................................................................................................10 • Safety And Sewer Gas..................................................................................................................10 • Gas Concentrations And Conversion Of Units..............................................................................11 • The Generation Of Hydrogen Sulfide In STS’s.............................................................................12 • How Much Hydrogen Sulfide Will Be Released From Sewage As A Gas?...................................13 • Estimating Worst Case Gas Levels...............................................................................................14 1. General Method For Odorants In Sewage At 250C................................................................14 2. Method For Hydrogen Sulfide At Different Temperatures.......................................................15 • Estimation Of Sulfide Generation In Pipelines..............................................................................16 • Trade Wastes................................................................................................................................17 1. Trade Waste Quality...............................................................................................................17 2. Trade Waste Flow Management.............................................................................................18 • Hydrogen Sulfide And Corrosion...................................................................................................19
Chapter 3 Measuring Odorous Compounds Odour And Gas Flows
• Liquid Phase Measurements Including Safety Aspects................................................................20 Safety Aspects......................................................................................................................20 Sampling...............................................................................................................................21 On Site Liquid Phase Oxidation Reduction Potential (ORP) Measurements........................21 On Site Liquid Phase Soluble Sulfide Measurements..........................................................21 Laboratory Based, Liquid Phase Soluble Sulfide Measurements.........................................22 Continuous Liquid Phase Measurements.............................................................................22 • Gas Phase Measurements Including Safety Aspects...................................................................24 Safety Aspects......................................................................................................................24 Laboratory Based Measurement Of Odour And Odour Related Compounds.......................24 On Site Gas Phase Measurements .....................................................................................24 • Gas Flow Rate Testing And Estimation Of Downwind Odour Levels............................................26 • Smoke / Leak Testing ...................................................................................................................27 • Site Sampling And Testing Kit Checklist For Operators ...............................................................28
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Chapter 4 Sewage Transport System Components And Odour Issues
• STS Components..........................................................................................................................29 Household Boundary Traps..................................................................................................29 Gravity Reticulation Collection Mains...................................................................................30 Pump Stations And Wet Wells..............................................................................................30 Rising Mains.........................................................................................................................31 Manholes..............................................................................................................................31 Hydraulic Drops ...................................................................................................................32 Sewage Treatment Plant Inlet Works....................................................................................32 Vents ....................................................................................................................................32 Ventilation Fans ...................................................................................................................33 • Principles Of Ventilation................................................................................................................34 Septicity And Venting............................................................................................................34 Ventilation Air Flow Rates.....................................................................................................34 • Gravity Mains And Reticulation Pipework Venting........................................................................34 • Pump Station Venting....................................................................................................................35 • Part Full Branch And Trunk Sewer Venting...................................................................................36 • Air Valves Versus Vent Stacks......................................................................................................36 • Pressure Sewers...........................................................................................................................37 • Vacuum Sewers............................................................................................................................37
Chapter 5 Targets For Achieving Low Odour
• Targets For Sewage Quality Including Trade Wastes...................................................................38 • Targets For Vents And Ambient Air...............................................................................................40 EPA Odour Legislation And Standards.................................................................................40
Chapter 6 Control Of Sulfide Levels In Sewage
• General Principles.........................................................................................................................41 • Treatments That Prevent Sulfide Formation.................................................................................41 Air And Oxygen.....................................................................................................................41 Chlorine................................................................................................................................43 Nitrates.................................................................................................................................43 Nitrites...................................................................................................................................45 Anthraquinone......................................................................................................................45 Bacterial Mixtures.................................................................................................................45 Nutrient or Bacterial Stimulant Mixtures................................................................................45 Alkalis...................................................................................................................................46 Other Biocides......................................................................................................................46 • Treatments To Prevent Sulfides Leaving The Liquid Phase..........................................................46 Caustic Soda (Sodium Hydroxide) Solution..........................................................................46 Lime......................................................................................................................................47 Magnesium Hydroxide (MHL)...............................................................................................47 • Treatments To Remove Existing Sulfides......................................................................................47 Air And Oxygen.....................................................................................................................47 Hydrogen Peroxide...............................................................................................................48 Chlorine................................................................................................................................48 Nitrates.................................................................................................................................48 Nitrites...................................................................................................................................48 Ferric Chloride And Ferric Sulfate.........................................................................................49 Ferrous Chloride, Ferrous Sulfate and Pickle Liquors (Ferrous Salts)..................................49 Others...................................................................................................................................50 • Removing Other Odorous Compounds From Sewage..................................................................50 • Chemical Dosing: Dosing Point and Control Type .......................................................................50 • Comparison Of Liquid Dosing Options For Sulfide Control...........................................................52 3