VAPOR PHASE ODOR CONTROL FOR COLLECTIONS SYSTEMS AND LIFT STATIONS - - PowerPoint PPT Presentation

13135 Danielson Street, Suite 204 Poway, CA 92064

VAPOR PHASE ODOR CONTROL FOR COLLECTIONS SYSTEMS AND LIFT STATIONS KHALED ROUEIHEB, IMS 2017 SCAP Collection Systems Committee Meeting January 24, 2017

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• What is Odor Control?
• Types of Odors
• Sources of Odors
• Conditions for Odors
• Treatment Options
• Gas Phase Odor Control Systems
• Design Considerations/Applications
• Technology Selection

Outline

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COMPANY CONFIDENTIAL

What is Odor?

The term “odor” refers to the perception experienced when one or more chemical substances in the air come in contact with human sensory

• system. Therefore “odor” is a human response.

“Odor Control” treats chemical compounds in the air that are perceived as

• ffensive odors. Different reagent chemicals, bacteria, adsorbents are

needed to target different odorous chemical compounds. It is necessary to know what chemical compounds are causing the

• dor, and then determine the best chemical, physical or biological

means to eliminate those chemicals or render them “odorless”.

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COMPANY CONFIDENTIAL

Serious Eye Injury

Odor Threshold Offensive Odor Headache, Nausea Throat and Eye Irritation Eye Injury Conjunctivitis, Respiratory Tract Irritation, Olfactory Paralysis Pulmonary Edema Strong Nervous System Stimulation Apnea Death ppm 3 10 50 100 300 500 1,000 2,000

Rotten Egg Odor Alarm Loss of Sense

• f Smell

Imminent Life Threat Immediate Collapse

.001 -0.1 H2S Odor Profile

Odor Control is Necessary Mitigate Health Hazards, Neighbor Complaints and Prevent Corrosion Damage

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4 IDLH OSHA PEL (8‐hr avg.)

How Are Odors Produced?

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Conditions Promoting Hydrogen Sulfide Release

High Temperature

• Solubility of H2S is temperature

dependent

• Increased biological activity

Low pH

• Three species of sulfides exist: H2S,

HS‐, S= (Only H2S is volatile)

• Low pH favors H2S

High Turbulence

• High velocities induce turbulence,

which in turn increase the liquid/vapor mass transfer area

Long Force Mains/Long Detention Times

• More time, more sulfate uptake,

more sulfide

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Liquid Phase – Prevent Atmospheric Sulfide – Effective Corrosion Control for pipes and structures – Treat Multiple Downstream Locations Gas Phase or Vapor Phase – Provide Point‐Source Solution – Treat Wider Range of Compounds – Provide Area Ventilation

Treatment Options

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Chemical Reaction – Nitrates – Iron salts – Oxidizers – Peroxide, Hypochlorite, Permanganate pH Adjustment – Sodium or potassium hydroxide Oxygen injection Others – ozone, etc.

Liquid Phase Options

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Vapor Phase Options

Vapor Phase Treatment is technology to control odors in the air or gas stream:

Absorption (Chemical Reaction)

• Wet Chemical Scrubbers

Adsorption (Physical Process)

• Carbon Adsorbers

Biological Systems (Biological Process)

• Biotrickling filters (inorganic media)
• Biofilters (organic media)

COMPANY CONFIDENTIAL

Collection Systems

Characterized by:

• 99% H2S odors, 1% organic sulfides, low ammonia & amines
• H2S can range from < 1ppm to > 500 ppm, with wide daily and

seasonal variations

• Smaller air flow requirements: 100 to 3000 cfm typical. Unoccupied

with 3‐6 ACPH typical

• Residential locations, aesthetics and noise are equally important
• Remote, un‐manned locations

– Low maintenance – Reliable operation – Simple process – Safety/vandal resistant

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Vapor Phase Odor Control Systems

13135 Danielson Street, Suite 204 Poway, CA 92064

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Carbon Odor Control Systems

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How Does It Work?

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Activated Carbon is Most Commonly Made from Bituminous/Anthracite Coal or Coconut Shells

• COCONUT SHELL CARBON
• ANTHRACITE COAL
• BITUMINOUS COAL
• ORGANIC POLYMERS
• SUB‐BITUMINOUS COAL
• LIGNITE
• PEAT
• WOOD

Increasing Microporosity (20 - 40 Angstrom in diameter)

1 Angstrom = 1 x 10-10 meters

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Carbon Capacity Comparison

0.04 0.25

Virgin Activated Caustic Treated Water Regenerated High Capacity

0.65 0.18 0.12 0.06 15

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How Odor Control Carbons Differ With Respect to H2S Reaction Products?

Products From H2S Reaction pH of Spent Carbon Coconut Shell & Coal Carbons Both Sulfur and Sulfuric Acid Acidic pH <2 Impregnated (Caustic Treated) Carbons Both Sulfur and Sulfuric Acid Acidic pH <2 Water Regenerable Catalytic Carbon >95% Sulfuric Acid Acidic pH <1 High H2S Capacity Carbon >95% Elemental Sulfur Neutral or Slightly Acidic pH >5

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Where Does Carbon Odor Control Fit?

Advantages:

• Simplest odor control technology
• Reliable and effective until breakthrough
• Low operator attention/Low maintenance
• Lower capital cost
• Treat H2S and many organic odors
• Moderate air flow capacity (~60‐70

cfm/ft2)

• Good response to odor spikes

Disadvantages:

• Limited H2S/odor capacity and life
• Can be high operating cost because media

replacement/regeneration can be expensive

• Limited capacity for some organics odors
• Some carbons are hazardous/flammable

Best Application:

• Low odor levels (< ~1‐10 ppm)
• Polishing stage behind chemical or

biological systems 17

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Biological Odor Control Systems

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Three (3) Steps are involved in Biological Odor Control

• Absorption [H2S and other compounds

are dissolved into the water film on surface of media]

• Oxidation [Bacteria that reside in the

water film biologically degrade the dissolved compounds]

• Removal of sulfates (byproduct)

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Biological odor control systems are designed to promote the growth of sulfur‐oxidizing bacteria which under proper conditions will biologically oxidize H2S and other sulfur compounds to soluble sulfates

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Biofiltration – Technology Advantages

• No hazardous chemicals
• No regular media change‐out‐ Long

media life

• Media promote bacteria growth
• “Green”
• Low Maintenance / Operating cost

Requirements

• Need regular load of H2S
• Acclimation
• No intermittent use

Requirements of Sulfur‐Oxidizing Bacteria

• Energy source:

– H2S and other sulfur compounds

• Carbon source:

– Organic matter (heterotrophic bacteria) – Carbon dioxide (autotrophic bacteria)

• Nutrients: nitrate, phosphate, potassium
• Water
• Oxygen (H2S + O2 → H2SO4)
• Temperature (10 to 50oC)
• Time (for absorption and reaction)

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• Organic media – typically

dirt, compost, wood chips

• In‐ground most common
• Very large footprint, low flow

rate (30 to 60 second contact times)

• Good removal of organic

sulfides and VOC’s

• Good removal of low H2S

concentrations

• Limited media life
• Sensitive to compaction and

drying out

Biofilters (Organic Media)

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• Inorganic media – typically

plastic or mineral

• Smaller footprint, higher flow

rate (8 to 20 second contact times)

• Some proprietary media
• Very good removal of H2S,

not as good for organic sulfides

• Long media life

Biotrickling Filters (Inorganic Media)

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Process Flow (Example)

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Biological Odor Control Systems

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Packaged Systems

Chemical Scrubber Systems

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Wet chemical scrubbers are defined as devices which utilize a liquid to separate gaseous or particulate contaminants from a gas stream – utilizing mass transfer and chemical reactions

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COMPANY CONFIDENTIAL

Chemical Odor Control Systems

Chemical Reactions

Chemical reagents selected based on odorous compounds:

– Ammonia/Amines ‐ removed by Sulfuric Acid (H2SO4)

• 2NH3 + H2SO4  (NH4)2SO4

– Hydrogen Sulfide ‐ solubilization with Sodium Hydroxide (NaOH) or oxidation with Sodium Hydroxide and Sodium Hypochlorite (NaOCl)

• H2S + 2NaOH  Na2S + 2H2O
• H2S + 2NaOH + 4NaOCl  Na2SO4 + 4NaCl + 2H2O

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Chemical Scrubber System

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Chemical Odor Control Scrubbers

Packaged Multistage Systems

Benefits: Most reliable and flexible vapor phase treatment technology High removal efficiency (99.5%+) Can respond instantly to changing H2S loads Small footprint required ( up to 500 ft/min velocity) Can remove any water soluble compound Can run intermittently Drawbacks : Chemical requirements Higher operating cost Maintenance requirements

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Where do Chemical Scrubbers Fit?

Applications

Information needed to select appropriate technology

• Air Flow Rate or Ventilation Rate (cfm)
• H2S Concentration (average and peak)
• Required level of odor removal (H2S removal efficiency, others?)
• Concentration of other odorous compounds present
• Site location
• Temperatures (ambient air and odor stream)
• Need freeze protection?
• Indoor or Outdoor location?
• Hazardous area classification?

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COMPANY CONFIDENTIAL

Applications‐ Air Flow Rate

Standard Engineering Practice Occupied spaces use 12 ACPH+

Headworks building Dewatering building Pump Stations

Unoccupied spaces use 3‐6 ACPH

Storage Tanks Clarifiers Wet wells 32

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Airflow rate (ft3/min)= [Air space Volume (ft3) x ACPH]/60

Hydrogen Sulfide (H2S) typically used as indicator of odor level Grab Samples (w/ or w/o data loggers) OR Continuous Monitors

Odor Measurement

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Vapor Phase Odor Control Technology Selection

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Odor Control Factors to Consider

For any given application, the selection of the best technology may be based on many factors, including:

• Capital cost for Equipment
• Installed cost
• Operating cost
• Maintenance requirements
• Reliability
• Safety
• Performance (% removal)
• Size (footprint, height)

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• Biological Systems
• Activated Carbon Systems
• Wet Chemical Scrubbers

COMPANY CONFIDENTIAL

Each Technology has its Niche

Biological Systems:

• Have very low operating and maintenance costs
• Do not require handling of hazardous chemicals
• Operating cost is not proportional to H2S concentration (hence

they are well suited to high H2S applications) 36

COMPANY CONFIDENTIAL

There is no one technology that is best in every application. Each technology has its niche.

Each Technology has its Niche

Activated Carbon Systems:

• Are the simplest and lowest maintenance systems (unless you need

to change out the carbon frequently)

• Require only electrical power to operate (no water, no chemicals)
• Are efficient for a wide range of compounds

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Each Technology has its Niche

Wet Chemical Scrubbers:

• Can treat larger air flows in a single vessel
• Have more compact footprint
• Are less sensitive to variations in actual vs. design H2S loadings
• Respond effectively and quickly to concentration spikes
• Are effective for a wider range of odorous compounds (H2S, NH3,

amines, organic sulfides) with high removal efficiencies 38

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Odor Control Summary

a. Odor Control is becoming an important issue b. There are a wide range of treatment options for vapor phase odor control c. Define the problem d. Pick the right technology for your particular application

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Contact

Khaled Roueiheb Integrity Municipal Systems, LLC Director of Sales 13135 Danielson St. Suite 204 Poway, CA 92064 USA Phone: (+01) 858‐486‐1620 Mobile: (+01) 858‐248‐7834 Email: Khaled@integrityms.net

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