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