FDSC585 Lecture 5: Odor Treatment Technologies

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Questions and Answers

What is a primary feature of photoionization in odor control?

Treatment of odors as a whole (correct)

Dependency on chemical scrubbers

Elimination of specific chemical substances

Operation sensitivity to environmental conditions

Which of the following is NOT a requirement for photoionization operation?

Nutrients (correct)

Water (correct)

Electricity

Chemicals (correct)

What advantage does photoionization offer in terms of maintenance and operation?

Very low maintenance and operation demand (correct)

Monthly operational checks required

High maintenance demand

Frequent chemical replenishment necessary

Why is photoionization considered an effective technology for odor treatment?

It efficiently handles high and varying odor loads Signup and view all the answers

Which characteristic enhances the scalability of photoionization systems?

Easily expandable design Signup and view all the answers

What is one primary advantage of biological methods of odor treatment compared to physicochemical processes?

Reduced operating costs Signup and view all the answers

What is the main operational cost related to biofilters?

Replacement of biofilter media Signup and view all the answers

What happens to odor-causing compounds in a biofilter as they pass through the organic media?

They are adsorbed onto a film of water and microbes Signup and view all the answers

Which component is NOT part of a typical biofilter's construction?

Chemical reaction chamber Signup and view all the answers

What is the relationship between Empty Bed Residence Time (EBRT) and performance of biofilters?

Longer EBRT generally correlates with better performance Signup and view all the answers

How long is the required EBRT to effectively remove hydrogen sulfide (H2S) from air in a biofilter?

20 seconds Signup and view all the answers

Which of the following correctly states a function that biofilter microbes perform?

They oxidize adsorbed compounds to harmless byproducts Signup and view all the answers

What is a characteristic feature of biofilters that allows them to operate efficiently?

A self-regulating ecosystem Signup and view all the answers

What condition in wastewater treatment is primarily responsible for odor generation?

Anaerobic condition Signup and view all the answers

Which of the following bacteria thrive in anaerobic conditions and produce hydrogen sulfide?

Sulfate-reducing bacteria Signup and view all the answers

What is a common byproduct of sulfate-reducing bacteria that is associated with a strong odor?

Hydrogen sulfide (H2S) Signup and view all the answers

In which area of a wastewater treatment facility are odor issues most prominent?

Primary treatment facilities Signup and view all the answers

Which compound is NOT typically associated with odor issues in biosolids treatment?

Ethanol (C2H5OH) Signup and view all the answers

What type of treatment method is a bioscrubber classified as?

Biochemical Signup and view all the answers

What type of process is NOT used for odor removal according to the classification of treatment technologies?

Electrochemical Signup and view all the answers

What is a common characteristic of odor compounds released during biosolids dewatering?

High volatility Signup and view all the answers

What is the primary function of a biofilter?

To biologically treat odor-causing gases Signup and view all the answers

What is the perception threshold in relation to odor units?

The point at which 50% of panelists cannot smell the odor Signup and view all the answers

Which type of biofilter media typically has a long life and lower loading rates?

Soil media Signup and view all the answers

What is a key consideration when designing a biofilter?

Moisture control Signup and view all the answers

Why is an acidic scrubber utilized in an NH3 scrubber system?

To neutralize ammonia before biological treatment Signup and view all the answers

What temperature range is considered optimal for effective odor elimination in biofilters?

28-35 C Signup and view all the answers

What is one method of odor elimination mentioned in the content?

Photoionization Signup and view all the answers

Which characteristic best describes organic media used in biofilters?

Higher loading rates and a replacement cycle every 2 to 5 years Signup and view all the answers

Study Notes

Lecture 5 - FDSC585: Food Waste/Odor Treatment Technologies

The control of odor removal and air pollution in the food industry and wastewater treatment plants has become crucial. Negative impacts of invasive pollutants now extend to residential areas, not just the treatment plant work environments.
Sources of odors in food waste: Waste treatment plants, MSW plants, biogas plants, and food industries.

Background

Municipal wastewater treatment typically uses the activated sludge process.
Odor problems often arise in collection systems, primary treatment facilities, and solids handling facilities.
Anaerobic (septic) conditions cause odors, resulting from limited oxygen transfer in wastewater.
Hydrogen sulfide (H₂S) is a byproduct of sulfate-reducing bacteria in an anaerobic environment, responsible for the strong rotten-egg smell.
Solids handling creates another significant odor problem due to extreme turbulence, pH adjustment, and/or thermal treatment of biosolids. The odor compounds released can include ammonia (NH₃), hydrogen sulfide, amines, organic sulfides and mercaptans; in varying concentrations.

Background: Technologies for Odor Treatment

Technologies are available for treating odorous air from confined areas of food plants, wastewater treatment plants, and sludge handling facilities.
- These can be categorized based on the removal process:
  - Biochemical: biofilters, bioscrubbers
  - Chemical: scrubbers, catalytic oxidation, ozonation
  - Physical: adsorption (activated carbon), absorption (clean water scrubbers)
Waste gases from industry have traditionally been treated using physicochemical processes.
Biofilters are a biological odor treatment method that offers simpler operation and maintenance. Costs related to biofilter media replacement.

Biofilter

A biofilter is a bed of organic material (media) allowing for air passage, humidity trapping and biomass growth.
Odor-causing compounds are adsorbed by the microbes/film of water on the organic material.
Microbes convert adsorbed compounds into carbon dioxide, water, and inorganic salts.
Biofilters are a self-regulating ecosystem.
Components of a biofilter: containment, biofilter media, humidifier/wetting systems, air diffusion system, air ducts, fans.
Inflow is contaminated air and out flow is treated air(Odors and VOCs are converted to organisms + CO2 + H2O).
Design of Biofilter-Sizing: Empty Bed Residence Time (EBRT) is required depending on the type of media and odor compound.

Biofilter Media Selection

Soil media has longer life and lower loading rates.
Organic media has a replacement cycle of 2-5 years and higher loading rates.
Synthetic media is often component of a mix and is site-specific.
Successful biofilters require careful media selection, moisture control, and airflow distribution.

Biotrickling Filter

Biotrickling filters biologically treat odor-causing gases.
Examples of odor causing gases include Ammonia (NH₃), H₂S, other volatile organic compounds (VOC's).
Biotrickling filter method is a more thorough method than chemical methods.
- NH₃ Scrubber System: The base material is neutralized with an acidic scrubber (like H₂SO₄) to remove it. The material is then saturated with water (increased humidity) to prolong the life of the packing.
Components include: nutrients make-up tank, recycle pump, structured packing material, and acid make-up tank.
Biofilter vs. Biotrickling Filter: A comparison of differences (see page 25)

Photoionization

Photoionization is an effective odor elimination method.
Primarily used for wastewater treatment, sewage, wastewater sludge, and food processing plants.
Process relies on UV-light and catalysts.
Environmentally stable method.
Treats odors as a whole, not a single compound.
- Advantages:Effective treatment, high efficiency, incorporated redundancy, low maintenance, no water/chemicals/nutrients, expandable, reduced installation costs.
- Operations: Only electricity is required; switch ON/OFF operation, easy to handle, reliable, low maintenance demand
- Technical specifications: off gas flow rate, dimensions, plant footprint, filter class, material of housing, location of fans, external ductwork, number of control cabinets, voltage, protection, operation power demands.

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Description

Explore the technologies used in odor removal and air pollution control in the food industry and wastewater treatment plants. This lecture discusses the sources of food waste odors and the processes involved in municipal wastewater treatment. Understand the role of anaerobic conditions and their contribution to odor issues.