odor & corrosion - cip update

ODOR & CORROSION -CIP UPDATE

WASTEWATER MANAGEMENT SPECIALISTS, LLC

JULY 13, 2020

Sewer Authority Mid-Coastside

Odor and Corrosion Control – Usually Defined by Both

Multiple Causes/Contributors:

Long “Detention Time”

Settlement of Solids

Slime Layer

Turbulence

Somewhat the Natural Characteristic of Wastewater

High Nutrient Content (BOD)

Low Oxygen Content (DO) (Sulfate)

High Water Temperature

Anaerobic Processes in the Treatment Facility (Digesters)

Wastewater Odor Compounds

Mercaptans Amines Sulfur Dioxide

Hydrogen Sulfide

(H2S)

Ammonia Skatole Organic Sulfides Diamines


ODOROUS COMPOUNDS•SULFIDES, ORGANICS (REDUCED) AND AMINES:

• H2S gas is most predominate in collection systems

• Exists in equilibrium with liquid phase HS- and S=

(sulfides)

• Amines are derivatives of ammonia (NH3) with the amine being

C-C-NH2.

• Reduced organics are mercaptans, disulfides, (C-C-C-HS, C-S-C)

• All are very odorous.

Sulfur Cycle

Biological Activity Diagram

Sewer Authority

Mid-Coastside Montara Forcemain Section

Winzler and Kelly EngineeringReport of 2009

Deposit Corrosion on bottom of pipe

“The microscopic penetration and the scale layers in the photomicrographs indicate that a corrosion mechanism other than erosion corrosion or impingement was operating. The most likely cause is deposit attack, with the possibility of a contribution from microbiologically induced corrosion” (M&M/W&K 2009)


Treatment Alternatives

Liquid Phase

Precipators

Oxidants

pH Shifters

Nitrates

Atmospheric Phase (Odor Control Only)

Adsorption

BioFilters

Wet Air Scrubbing

Iron Salts

Ferrous Salts

Ferrous Chloride - FeCl2

Very Corrosive, Aggressive, Hazardous

Rarely Used

Ferrous Sulfate - FeSO4 (Odophos)

Mildly Corrosive

0.5 - 0.7 lb Fe per gallon

Green to Brownish Green Liquid

“Pickle Liquor” or Co-Product of Titanium Oxide Pigment Production

Iron Salts

Ferric Salts

Ferric Chloride - FeCl3

Very Corrosive, Aggressive, Hazardous

Rarely Used

Ferric Sulfate - Fe2(SO4)3

Moderately Corrosive - Higher Acid Content Than Ferrous Sulfate

1.0 lb Fe per gallon

Brown Liquid

Iron Salts - Summary

Quick Reaction - Good for Short Detention Times

Specific to Sulfide - Economical to 0.5 mg/l

Moderately Safe

Produces Solids

Can Cause Scaling/Plugging of Lines

Cost To Treat Solids

Iron Salts Permanently Tie Up Sulfides Into a Solid Form

Oxidizers

Typical Municipal Applications

Peroxide

Potassium Permanganate

Chlorine Gas

Sodium Hypochlorite – Bleach

Mostly Industrial Use but Sometimes Used in Municipal

Chlorine Dioxide

Chlorite

Ozone

Oxidizers

Hydrogen Peroxide

Colorless, Aqueous Solution - 50%

Requires SS Piping, Pressure Relief, and Other Precautionary Devices for Storage and Feed

Potassium Permanganate

Typically Solid

Purple Crystals

Storage and Feed Equipment Includes Dry Material Feeders

Difficult/Messy to Handle

Oxidizers

Chlorine Gas

Colorless, Gas

Requires Pressure Relief, and Other Precautionary Devices for Storage and Feed

Requires Emergency Scrubbing Device

Requires Mixing System

Sodium Hypochlorite

Liquid - 12.5% Solution

Requires Double Containment

Precautionary Devices for Storage and Feed

Oxidizers - Summary

Quick Reaction

Not Specific to Sulfide

Will React With Other Odor Compounds

Will React With Non-Odor Compounds

Cannot Maintain Downstream Residual

Great for Short Detention Times or Point-Source Only

Economic in Short Detention Times

Hazardous

Difficult to Handle

Oxidizers Remove Sulfides From Solution

pH Shifters

➢ CAUSTIC SODA - SODIUM HYDROXIDE

➢ MAGNESIUM HYDROXIDE

➢ LIME - CALCIUM HYDROXIDE

pH Shifters - The Science

pH Shifters - Caustic Soda

Total H2S Control Requires the pH to be over 9.0

Relatively Inexpensive

Handling

Very Aggressive and Hazardous

Requires Double Containment

Precautionary Devices for Storage and Feed

Treatment Plant Concerns

Accidental Overdose can Severely Upset Treatment Plant

pH Shifters

Magnesium Hydroxide

Does Not Totally Control Hydrogen Sulfide

Reasonable Control to pH as low as 8.3

Relatively Expensive

Handling

Relatively Safe

Difficult to store and deliver

Special Mixing and Feed Equipment

pH Shifters - Summary

Contains the Hydrogen Sulfide in the Liquid

Moves the Hydrogen Sulfide Downstream

Releases Downstream where it joins other flow

Releases at the Headworks

If All Flow is Treated It Oxidizes in Secondary

pH Shift Cost is the Same Regardless of the Level of Hydrogen Sulfide

Economic in Very High Sulfide Cases

pH Shift Does Not Treat Hydrogen Sulfide - It Holds it in Solution as

Long as the pH is High

Alternative Oxygen Supply

Air Injection (Very Short-term effect)

Liquid Oxygen (Expensive and

Hazardous)

Nitrates

Nitrates

Typically Calcium Nitrate or Sodium Nitrate

Both Clear to Brownish-Clear Solution

Calcium Nitrate (Bioxide) = 3.5 lb. NO3-O per gal.

Sodium Nitrate = 2.0 lb. NO3-O per gal.

VERY SAFE - Not CERCLA Listed

Prevents and Removes Sulfide and Other Odors

Sulfide Prevention via Nitrate

Sulfide Removal via Nitrate


Nitrate Summary

Requires Moderate to Long Detention Time

Natural Process

Wide Range of Compounds Treated

Residual Maintained Downstream

Can Be Used for Removal and Prevention with One

Application Point

VERY SAFE

Nitrate Remove Sulfides From Solution


Liquid Phase Treatment - Summary

Precipitants - Permanently Tie Up Sulfides

Can be Economic in Less Demanding Applications

Solids Generation is a concern

Safety is a Concern

Oxidizers - Permanently Remove Sulfides

Can be Economic in Short Detention Times

Safety is a Concern


Liquid Phase Treatment - Summary pH Shift - Holds Sulfides in Solution

Can be Economic in Very High Sulfide Concentration Applications

Downstream Effect is a Concern

Safety is a Concern for Caustic

Treatment Plant Impacts are a Concern

Nitrate - Permanently Remove Sulfides

Economic in Most Applications

Not for Short Detention Times - Feed Location is Very Important

Safety is a Strong Positive


Questions and Discussion


Credits

Odor Control Presentation - Lamb Technical Services, Inc. | Brown & Caldwell | 2002

Odor and Corrosion Control Presentation - AH Water (Vince Marano)


THANK YOU

odor & corrosion - cip update

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