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Collection System Odor Control Haluk Bafrali Anue Water Technologies November 19, 2015
Outline
•Collection Systems •Hydrogen Sulfide Formation •Various Types of Solutions •Oxygen and Ozone Odor Control •Case Studies
Collection System to the WWTP
Underground Pipeline (Sanitary Sewers) Sometimes they are combination sewers that include storm water also
Along the way…other components
• Wet Wells • Dry Wells
• Force Mains • Manholes • Gravity Interceptors
Hydrogen Sulfide • Other Names: Hydrogen Sulphide, Hydrosulfuric
Acid • Chemical Formula: H2S • Color: Colorless • Physical Form : Gas • Odor Characterization: Rotten Egg Odor • In solution: Weak acid • Relative Gas Density: 1.19
HYDROGEN SULFIDE
Hydrogen Sulfide – Health Effects
HYDROGEN SULFIDE
Revised IDLH =
100 ppmv
Hydrogen Sulfide is a…. • Nuisance Odor – Odor Control • Health Hazard – Odor Control
The above items take into consideration
the Infrastructure aspect. However, there is another aspect to consider:
HYDROGEN SULFIDE
? ? ? ? ? ? ? ? ? ?
When all the puzzle pieces combine…
OXYGEN
SULFUR OXIDIZING BACTERIA
WATER
HYDROGEN SULFIDE
SULFURIC ACID
…the combination forms Sulfuric Acid
Sulfuric Acid deteriorates Concrete
PVC liner peeling off the concrete
surface below the manhole frame.
Exposed aggregate beside a mortar covered
surface.
SULFURIC ACID
Sulfuric Acid corrodes Metallic Surfaces
Metallic sanitary sewer pipe crossing a storm
sewer.
Gate Valve with corroded surfaces.
SULFURIC ACID
Hydrogen Sulfide Generation
• H2S may be generated from the biological reduction of sulfate (SO4
-2) under anaerobic conditions by Sulfur Reducing Bacteria leading to Septic conditions.
• Septic conditions are present once the dissolved oxygen
(O2) and nitrate (NO3-) oxygen are depleted.
• SO4
-2 + 2C + 2H2O 2HCO3-2 + H2S Bacteria HYDROGEN
SULFIDE
Oxygen Uptake Declension
O2 NO3- SO4
-2 R-C-R'
Oxygen Type Dissolved Nitrate Sulfate Organic
Relative Uptake Time
Minutes Hours
Hours Days
Days Weeks
Weeks Months
Industry Jargon Aerobic Anaerobic
Anoxic Septic Anoxic Fermentation
O=
Oxygen Uptake Declension
O2 NO3- SO4
-2 R-C-R'
Oxygen Type Dissolved Nitrate Sulfate Organic
Relative Uptake Time
Minutes Hours
Hours Days
Days Weeks
Weeks Months
Industry Jargon Aerobic Anaerobic
Anoxic Septic Anoxic Fermentation
O=
Oxygen Uptake Declension
O2 NO3- SO4
-2 R-C-R'
Oxygen Type Dissolved Nitrate Sulfate Organic
Relative Uptake Time
Minutes Hours
Hours Days
Days Weeks
Weeks Months
Industry Jargon Aerobic Anaerobic
Anoxic Septic Anoxic Fermentation
O=
Evolution of H2S - Odor Control
Oxygen Uptake Declension
O2 NO3- SO4
-2 R-C-R'
Oxygen Type Dissolved Nitrate Sulfate Organic
Relative Uptake Time
Minutes Hours
Hours Days
Days Weeks
Weeks Months
Industry Jargon Aerobic Anaerobic
Anoxic Septic Anoxic Fermentation
O=
Biological Sulfide Production In Sewers
Biological Sulfur Transformation Summary • Sulfate Is Reduced to Sulfide in the Slime Layer • Sulfide Is Produced (Along With Alkalinity) and Is • Released As H2S Gas by Turbulence • H2S Gas Is Oxidized to Sulfuric Acid by Thiobacillus • Bacteria Living on Sewer Walls Above the Sewage • Sulfuric Acid Runs Back Down Into the Wastewater to • Destroy the Alkalinity Produced Earlier and Become • Sulfate • • Process Starts All Over Again With Sulfate Reduction
Solutions to H2S Production
•Chemical addition: • Iron salts •Nitrate solutions •Peroxide addition
•Ventilation •Difficult to get entire pipeline
Chemical Addition
Vapor Phase Treatment
Chemical Wet Scrubbers
Vapor Phase Treatment
Activated Carbon Systems
Vapor Phase Treatment
Biotrickling Filter
New Solution
•Oxygen and ozone addition •Keep pipeline aerobic •Stops the formation of H2S •Stops odors and corrosion
The oxidation of dissolved H2S in the presence of O3 is a thermodynamically favorable reaction with a theoretical ratio of 4:1.
S2- + 3O3 SO32- + 3O2
SO32- + O3 SO4
2- + O2
S2- + 4O3 SO42- + 4O2
Step 1
Step 2
Overall
The reaction rate with O3 is pH dependent as H2S is a diprotic acid.
H2S HS- + H+
HS- S2- + H+ pKa = 7.0 pKa = 19.0
In normal pH ranges though, hydrogen sulfide exits only in the form of H2S and HS- in water.
Ozone Oxidation Chemistry of Hydrogen Sulfide
Example of Calculating the Amount of Ozone to Oxidize H2S in a Process Stream
[H2S] O3 Demand (mg/L)
Molar Ratio
1.9 13.8 4.8:1 4.2 20.6 3.3:1 6.0 24.8 2.8:1
O3 Oxidation of H2S in a Well Water Sample Matrix
The actual molar oxidation ratio of O3 to S2- is less than the theoretical 4:1. This is due to possible side reactions with hydroxyl radicals and some contribution from the high concentration of dissolved oxygen.
Ozone Oxidation Chemistry of Hydrogen Sulfide Ozone Oxidation Chemistry of
Hydrogen Sulfide
Fast Action Infusion
Treatment <5 minutes
Treatment after two minutes
Untreated force main wastewater
Limited Access Infuser System
Single Tap Infuser
O2 / O3
Lift Station
• Grinder pump in lift station • Venturi with infuser • Treated wastewater infused through 2” tap
FORSe 5 O2 / O3
Generator Control
Grinder Pump
Treated Flow Return
Venturi Infuser
Untreated Flow to Infuser
System Packaging- High Flow
• Systems up to 1400 grams/hr ozone & 600 liters/minute oxygen
• Flows of up to 20 MGD
•Four cell ozone generator •High output oxygen system
SYSTEM COMPONENTS
Compressor
SYSTEM COMPONENTS
AirSep Unit with Oxygen Receiver
SYSTEM COMPONENTS
FloSpec Cabinet with HMI Display
SYSTEM COMPONENTS
Force Main Tap
FORSe 5/FORSe 2 System
FORSe 5 System (O3 + O2) • Treat odor and corrosion in force main, lift stations,
or combination of the two • Attack H2S at it source • Break sulfide production cycle • Sustainable technology • FORSe 2 System (O2 Only)
CASE STUDIES
•Equipment used •Locations •Monitoring of sites for H2S and DO
Test Equipment
Application Capacity:
Ozone: 300 grams/hour
Oxygen: 75 liters/ minute
Components:
Oxygen generator
Ozone Generator
Control with Cellular MODEM
Transformer
CASE STUDY
Lift Station Treatment: Lebanon, TN
Sulfides vs DO at Force Main Outfall
CASE STUDY
Lift Station Treatment: Lavergne, TN
Average of Daily Readings at Lift Station
0.0
10.0
20.0
30.0
40.0
50.0
60.0
6-Apr 7-Apr 8-Apr 9-Apr 10-Apr 11-Apr 12-Apr 13-Apr 14-Apr 15-Apr 16-Apr 17-Apr 18-Apr
WednesdayThursday Friday Saturday Sunday Monday TuesdayWednesdayThursday Friday Saturday Sunday Monday
H2S ppm- Vapor- OdaLog
H2S ppm- Vapor- OdaLog
Start Treatment
System Shut OFF
System Turned ON
End Treatment
System settings: 120 gph O3 20 lpm O2
Thank You - Questions