Bio Filtration for Air Pollution Control

BIO-FILTRATION FOR AIR POLLUTION CONTROL

By

I D NO: 15E 15E N8 N81 15: PATE L K AUSHALK AUSHALK UMAR ASHOKBHA I

P r of. R eshma shma L. Pate Patel

D r . J ayeshkum yeshkuma ar R . Pi trod troda

Associate Professor Civil Engineering Department BVM Engineering College Vallabh Vidyanagar, Gujarat

Assistant Professor Civil Engineering Department BVM Engineering College Vallabh Vidyanagar, Gujarat

A Report Submitted to Birla Vishvakarma Mahavidyalaya (Engineering College), An Autonomous Institution affiliated to Gujarat Technological Universit y in Partial Fulfillment of the ngineering ri ng ) Specialization in Requirements for The Master of Technology (Ci vil E nginee

E nvi nvi r onme nmental ntal E ngine ngi nee er i ng

May, May, 201 2017 7

BIRLA VISHVAKARMA MAHAVIDYALAYA (ENGINEERING COLLEGE) AN AUTONOMOUS INSTITUTION

Vallabh Vidyanagar – 388120 388120 GUJARAT, INDIA

CERTIFICATE

This is to certify that work embodied in this seminar-II report was Pollution Control”

entitled “Bio-F iltration

for Ai r

carried out by I D N o:15EN815: Patel Kaushalkumar Ashokbhai at Birla

Vishvakarma Mahavidyalaya (Engineering College) An Autonomous Institution for partial fulfillment of Master of Technology (Ci vil E ngineering) with Specialization in E nvironmental

E ngineeri ng degree to be awarded by Gujarat Technological University. This work has been carried out under our supervision meets the requirement of Gujarat Technological University.

Date: Place:

(Prof. Reshma L. Patel )

(Dr. Jayeshkumar R. Pitroda )

Head, Civil Engineering (Dr . L. B . Zala)

Principal (Dr. I. N. Patel)

BIRLA VISHVAKARMA MAHAVIDYALAY (ENGINEERING COLLEGE) AN AUTONOMOUS INSTITUTION

Vallabh Vidyanagar – 388120 GUJARAT, INDIA II

TABLE OF CONTENTS

Title Page

I

Certificate

II

Table of Contents

III

List of Figures

IV

List of Tables

V

1

Introduction

1

2

Background

1

3

Why is Bio-filtration Important

2

4

Types of Bio-filters

3

5

How Do Bio-reactors Work

3

5.1

Components of a Bio-filter Unit

7

6

Design Parameters

7

7

Bio-filters Effectiveness

10

8

Advantages and Disadvantages of Bio-filtration

11

8.1

Advantages of Bio-filtration

11

8.2

Disadvantages of Bio-filtration

11

9

Commercial Application

12

10

Bio filters – A Viable Option

12

11

A Few Exiting Bio-Filters

13

References

14

LIST OF FIGURES

Figure No.

Figure Name

Page No.

Figure 2.1

Air Pollution Statistics

2

Figure 5.1

Mass Flow Diagram of a Bio-reactor

4

Figure 5.2

Bio-reactors

4

Figure 5.3

Multi-Layer Bio-filters

5

Figure 5.4

Components of a Bio-filter Unit

7

LIST OF TABLES

Table No.

Table 7.1

Table Name

Differentiation

between

Bio

oxidation & Thermal Processes

Page No.

Filtration,

Chemical

10

BIO-FILTRATION FOR AIR POLLUTION CONTROL 1. INTRODUCTION?

Bio-filtration is a relatively new pollution control technology. It is an attractive technique for the elimination of malodorous gas emissions and of low concentrations of volatile organic compounds (VOCs). The most common style bio filter is just a big box. Some can be as big as a basketball court or as small as one cubic yard. A bio filter’s main function is to bring microorganisms into contact with pollutants contained in an air stream. The box that makes up this bio filter contains a filter material, which is the breeding ground for the microorganisms. The microorganisms live in a thin layer of moisture, the "biofilm", which surrounds the particles that make up the filter media. During the bio filtration process, the polluted air stream is slowly pumped through the bio filter and the pollutants are absorbed into the filter media. The contaminated gas is diffused in the bio filter and adsorbed onto the biofilm. This gives microorganisms the opportunity to degrade the pollutants and to produce energy and metabolic byproducts in the form of CO2 and H2O. This biological degradation process occurs by oxidation, and can be written as follows: Organic Pollutant + O2

=

CO2 + H2O + Heat + Biomass

2. BACKGROUND

Bio filters have been designed primarily for odor control at wastewater treatment plants, rendering plants, and composting operations. However, bio filters are becoming more popular in the treatment of VOCs and other organic compounds. The following is a brief timeline of the development of bio filters: 1923 -- Biological methods were proposed to treat odorous emissions. 1955 -- Biological methods were applied to treat odorous emissions in low concentrations in Germany.

B.V.M. Engineering College / Gujarat Technological University (An Autonomous Institution) 1


1960’s -- Bio filtration was used for the treatment of gaseous pollutants both in Germany and US. 1970’s -- Bio filtration is used with high success in Germany. 1980’s -- Bio filtration is used for the treatment of toxic emissions and volatile organic compounds (VOCs) from industry. 1990’s -- Today, there are more than 500 bio filters operating both in Germany and Netherlands and it is widely spreading in US.

Figure 2.1 Air Pollution Statistics

Applications for odor control have occurred since the 1950s and ranged from soil filters to large biological trickling filter plants. Odorous air emissi ons generally can be characterized as having relatively low pollutant concentrations that include hydrogen sulfide, mercaptons, and other reduced sulfur compounds. In addition, applications for VOC control have just become popular in the past decade and are still being researched extensively. For example, research has shown that bio filters can be used to remove a variety of airborne contaminants, including aliphatic and aromatic hydrocarbons, alcohols, aldehydes, organic acids, acrylate, carbolic acids, a mines and ammonia. 3. WHY IS BIO-FILTRATION IMPORTANT 

Bio reaction is a green process.



Thermal and catalytic control units consume large volumes of expensive fuel.



Bioreactors only use small amounts of electrical power to drive two or three small motors.



Normally, bioreactors do not require full-time labor and the only operating



supplies needed are small quantities of macronutrients.

4. TYPES OF BIO-FILTERS

On The Basis of Layout 

Open Bed : Uncovered and Exposed to all Weather conditions.



Closed Bed : Enclosed with a small exhaust port for venting of cleaned air

On The Basis of Shape Horizontal:







With Larger footprints Relatively inexpensive Easy maintenance

Vertical:



Designed to reduce the footprint required.



Use less surface area compared to Horizontal



Expensive



Not easy to Maintain

On the Basis of Support Media 

Compost Bio Filter : Soil , Peat, Compost material is used



Synthetic Bio Filter : Ceramic , Plastic ( BTX )

5. HOW DO BIO-REACTORS WORK

Bio filtration utilizes a supported media for microbial growth to remove odors and organic contaminants from air streams. The filter consists of a closed chamber containing contaminant degrading microbes and absorbed water suspended in a filter medium. The filter medial is designed to provide a high capacity for water uptake, have a long working life, and provide a low pressure drop for the gases passing through the B.V.M. Engineering College / Gujarat Technological University (An Autonomous Institution) 3


media.

Figure 5.1 Mass Flow Diagram of a Bio-reactor

Figure 5.2 Bio-reactors B.V.M. Engineering College / Gujarat Technological University (An Autonomous Institution) 4


Smaller and more popular multi-layer bio filters are shown below:

Figure 5.3 Multi-Layer Bio-filters

In the bio filtration process, contaminated air is moistened by a humidifier and is pumped into the bio filter through a chamber below the filter medium. While the air slowly flows upward through the filter media, the contaminants in the air stream are absorbed and metabolized. The purified air passes out of the top of the bio filter and into the atmosphere. Most bio filters that are in operation today can treat odor and VOCs add efficiencies greater that 90%. However, the drawback to this technology is that it B.V.M. Engineering College / Gujarat Technological University (An Autonomous Institution) 5


can only handle low concentrations of pollutants (<1000 ppm) and loading rates between 300-500 ft3/ft2-hr. Bio filter media:

The moist filter medium provides physical and chemical conditions appropriate for the transfer of contaminants from the air to the liquid phase and the biodegradation of the contaminants in the biofilm layer. The mechanism of the bio filtration process includes a combination of adsorption, absorption and microbial degradation. Microorganisms contained in the biofilm layer continually metabolize the contaminants, as they are absorbed, converting them ultimately to water, car bon dioxide and salts. Typical bio filter media material includes compost-based materials, earth, heather, plastic, or wood-product based material. The purpose of the bio filter media is to provide a large surface area for the absorption and adsorption of contaminants. The media also serves as a nutrient source for the microbial population. In fact, s ome types of media lack proper nutrients and will require the manual addition nutrients (e.g. nitrogen and phosphorous compounds) in order to sustain microbial life. Most bio filters will operate for 5-7 years before it is necessary to renew the filter media. Major considerations when determining the appropriate filter material include: 

Ability to retain moisture to sustain biofilm layer;



Large surface area, both for contaminant absorption and microbial growth;



Ability to retain nutrients and supply them to microbes as required;



Low resistance to air flow (minimizes pressure drop and blower power requirements);



Physical characteristics, such as physical stability and ease of handling


BIO-FILTRATION FOR AIR POLLUTION CONTROL 5.1. Components of a Bio-Filter Unit:

Figure 5.4 Components of a Bio-filter Unit 

Materials used for bed media – peat, composted yard waste, bark, coarse soil, gravel or plastic shapes (Reference 2 from EPA PDF)



Oyster shells (for neutralizing acid build-up) and fertilizer (for macronutrients) are mixed with bed media.



Support Rack -perforated – allow air from the plenum to move into the bed media -to contact microbes that live in the bed. Perforations also permit excess, condensed moisture to drain out of the bed to the plenum.



Fan – used to collect contaminated air, as the emissions flow through the bed media, the pollutants are absorbed by moisture on the bed media. Microbes reduce pollutant concentrations by consuming and metabolizing pollutants. During the digestion process, enzymes in convert compounds into energy, CO 2 and water. Material that is indigestible is left over and becomes residue.

6. DESIGN PARAMETERS Space Constraints:

Space at a site is the greatest concern during design of a bio filtration system. A small bio filtration unit can be designed to handle approximately 30 cubic-feet-perminute in as little space as 25 square feet, similarly, a bio filtration system designed to treat large air volumes and require space as large as a basketball court. Chemical Constituents and Concentrations:

Analysis of chemical constituents and their concentrations are required to determine if bio filtration is a plausible alternative. Bio filters performed best when B.V.M. Engineering College / Gujarat Technological University (An Autonomous Institution) 7


treating hydrophilic compounds in low concentrations (<1000 ppm). Some chemicals biologically degrade at low rates, such as chlorinated compounds, which require units to be oversized. Residence Time:

Residence Time represents the amount of time the microbes are in contact with the contaminated air stream, and is defined by (Void Volume/Volumetric Flow Rate). Consequently, longer residence times produce higher efficiencies; however, a design must minimize residence time to allow the bio filter to accommodate larger flow rates. For most bio filters, residence times range between 30 seconds to 1 minute. Humidity:

The humidity of gas stream is important for maintaining the moisture content of the bio filter media. Gas streams introduced to the bio filtration system are usually pumped through a humidifier prior to entering the bio filter. The gas entering the bio filter should be humidified to greater than 95% relative humidity. Ph.-Control:

The by-products of microbial degradation are organic acids. In order to maintain the pH of the vessel around neutral, or a pH of 7, buffering material may be added to the organic media. Bio filter Media:

The media used in bio filters can include peat, heather, bark, composted sewage sludge, granular carbon or other suitable materials. Generally, the media should be capable of providing nutrients to the microorganisms and minimizing pressure drop. In addition, the moisture content of the bio filter media must be maintained between 30% and 60% in order to support the microbial population. In addition to humidifying the airflow, sprinkler systems are frequently installed inside the bio filter that can be controlled to maintain a suitable bed moisture. Pressure Drop:

Pressure drop across the bio filter reactor vessel should be minimized since an increase in pressure drop requires more blower power and can result in air channeling B.V.M. Engineering College / Gujarat Technological University (An Autonomous Institution) 8


through the media. Pressure drop is directly related to the moisture content in the media and the media pore size. Increased moisture and decreased pore size result in increased pressure drop. Consequently, media filter selection and watering is critic al to bio filter performance and energy efficiency. For a typical bio filter pressure drops range between 1 and 10 hope. Maintenance:

The operation and maintenance of the bio filtration system would require weekly site visits during initiation of operations for amiss. However, after acclimation and all system problems are resolved the frequency of site visits could be reduced to the biweekly or monthly. Temperature:

Most microbes can survive and flourish in a temperature range of 60 to 105 /F (30 to 41/C) (Ref. 3 of EPA PDF). When emissions are too hot, humidifiers are used which cools gases down by evaporative cooling. Moisture:

Moisture creates the bio-film that removes (absorbs) pollutants from an air stream so that they can be assimilated by microbes. Humidifiers made from an old FRP (fiber reinforced plastic) tank are used to increase moisture. Care and Feeding:

Microbes need a diet of balanced nutrients to survive and propagate. Pollutants provide the main source of food and energy, but microbes also require macronutrients to sustain life. Microbes use nitrogen to build cell walls. Some nitrogen products form water-soluble compounds and are leached out of the system with condensing water. Nitrogen, phosphorus, potassium added by incorporating agricultural fertilizer into bed media. Acidity:

Most bioreactors perform best when the bed pH is near 7, or neutral. Hydrogen sulfide, organic sulfur compounds, and halogens (chlorine, fluoride, bromine and iodine) are acidic in nature and lower the ph. B.V.M. Engineering College / Gujarat Technological University (An Autonomous Institution) 9

BIO-FILTRATION FOR AIR POLLUTION CONTROL Oyster Shells:

May be added to neutralize the ph. a Dilute solution of soda ash (sodium carbonate, Na2 CO3) may be introduced by a garden hose periodically.

7. BIO FILTERS EFFECTIVENESS 

Odor and hydrogen sulfide reductions up to 95%.



Ammonia reductions up to 80%.



Uses Microorganisms



Absorbs And Oxidizes



VOC’s



VIC’s



Ox disable Inorganic Gases and Vapors



Produces



Water, Carbon di oxide, Salts



Microbial Biomass

Table 7.1 Differentiation between Bio Filtration, Chemical oxidation & Thermal Processes Bio-filtration

Thermal Process

- Only by-product is waste

- By-product is nitrogen

biomass

oxides

which

ozone

depletion

Chemical Oxidation

causes

-Produce

chlorine

and

chlorinated products.

and

smog formation - Ambient

temperature - Requires

and pressure process

additional - Require

precise

natural gas for achieving

temperature and pressure

high

conditions.

temp.

Hence

increases Co2. - Investment

and

operation cost are lower than other two

- Operation and handing cost is high.

- In chemical oxidations chemical have to stored and handled.


BIO-FILTRATION FOR AIR POLLUTION CONTROL 8. ADVANTAGES AND DISADVATAGES OF BIOFILTRATION 8.1.Advantages of Bio filtration:

1. The main advantage of using bio filtration over other more convention control methods are lower capital costs, lower operating costs, low chemical usage, and no combustion source. 2. Bio filtration units can be designed to physically fit into any industrial setting. A bio filtration unit can be designed as any shape, size or as an open field with the piping and delivery system underground. In addition, bio filters can be designed with stacked beds to minimize space requirements and multiple units can be run in parallel. 3. Bio filtration is versatile enough to treat odors, toxic compounds, and VOCs. The treatment efficiencies of these constituents are above 90% for low concentrations of contaminants (<1000 ppm). 4. Different media, microbes and operating conditions can be used to tailor a bio filter system for many emission points. 8.2.Disadvantages of Bio filtration:

1. Bio filtration cannot successfully treat some organic compounds, which have low adsorption or degradation rates. This is especially true for chlorinated VOCs. 2. Contaminant sources with high chemical emissions would require large bio filter units or open areas to install a bio filtration system. 3. Sources with emissions that fluctuate severely or produce large spikes can be detrimental to the of a bio filter’s microbial population and overall performance. 4. Acclimation periods for the microbial population may take weeks or even months, especially for VOC treatment.


BIO-FILTRATION FOR AIR POLLUTION CONTROL 9. COMMERCIAL APPLICATIONS

There have been over 50 commercial bio filters using compost-type material installed in Europe and the United States over the past 15 years. VOC applications to date have included the following industries:



Chemical and petrochemical industry



Oil and gas industry



Synthetic resins



Paint and ink



Pharmaceutical industry



Waste and wastewater treatment



Soil and Groundwater remediation

Odor abatement applications to date have included the following industries. 

Sewage treatment



Slaughter houses



Rendering



Gelatin and glue plants



Agricultural and meat processing



Tobacco, cocoa and sugar industry



Flavor and fragrance

10. BIOFILTERS – A Viable Option 

Effective at emission reduction.



Low-cost



Biological system requiring management.



Design, installation and operation will impact building ventilation and biofilters effectiveness. Bio filtration-an Innovative Technology for the Future:



different types of bio filters’ support media





The various bio filters operations adopted in industry.



waste compounds treatable by bio filtration



Commercial potential of bio filtration.



The paper concludes that when compared to other available technologies, bio filters have significant technical and economic advantages.

11. A Few Existing Bio Filters:

1. McMinnville, Oregon: The installation in McMinnville, Oregon perhaps best

demonstrates the capabilities as the levels of odorous compounds to be treated were among the highest ever reported from the wastewater treatment environment. 2. Long Sault, Ontario: Although a small (1500 cms), indoor, container-type

system, this installation demonstrates several key aspects that are relevant to any installation. 3. Sarnia, Ontario: This bio filter was installed in 2001 and treats 12,500 cms of

air coming from a sludge liming and drying operation. 4. Brookfield, P.E.I.: This bio filter was installed in 2002, at a composting plant

in P.E.I. that treats 60,000 cms of air from the composting process. 5. Toronto, Ontario: This bio filter was installed in 2002 in the north end of

Toronto at the Toronto Mixed Waste Recycling and Organics Processing Facility.


BIO-FILTRATION FOR AIR POLLUTION CONTROL REFERENCES 1

Review Paper on Bio filtration of Volatile Organic Compounds (VOCs) – An Overview by Thakur Prabhat Kumar, Rahul, Mathur Anil Kumar and Balomajumder Research Journal of Chemical Sciences ISSN 2231-606X Vol. 1(8), 83-92, Nov. (2011)

2

Magazine paper on Biofiltration: an innovative technology by Dr. Rakesh Govind, chemical engg., University Of Cincinnati, OH 45221-0171 (2000)

3

Journal on Environmental Progress vol. 24 no.23 (october 2005) by American Society of Chemical Engineers Project No. 98-CTS-4 Bureau of Sanitation, LA

4

Indian Journal Of Biotechnology vol. 2, july 2003, Biofiltration-an emerging technology by Soccol, Woicieschowski, Vedanberghe, Soares and Neto UFPR, Federal university of Parana, Curtiba-PR, Brazil CEP 81531-970

5

Pollution statistics from Indian Journal of Biotechnology vol. 2, July 2003 case study of effluent in Industries of Delhi-NCR region.

6

Frederickson, J.; Boardman, C. P.; Gladding, T. L.; Simpson, A. E.; Howell, G. and Sgouridis, F. (2013). Evidence: Bio filter performance and operation as related to commercial composting. Environment Agency, Bristol.

7

EPA handout Environmental Protection Agency “What is Bio filter?”; “Using biofilters to

8

Head, I. M., Singleton, I., and Milner, M. (2003). Bioremediation: A critical review horizon scientific press Norfolk.

9

Devinny, J. S.; Deshusses, M. A., & Webster, T. S.Biofiltration for air pollution control. Lewis publishers London.

10

Sincero, A. P. and Sincero, G. A. Environmental engineering. PHI learning Private Limited. N. Delhi.

11

Evans, G. M. and Furlong, J. C. Environmental Biotechnology. Wiley & Sons.

12

Liu, D. H. F. and Liptak, B. G. Environmental engineer’s handbook. (2nd Ed.).

13

Nathonson, J.A. Basic Environmental Technology.4th Ed.

14

Brown, C. A., Karl, B. Air pollution control technology handbook.

15

http://www.mega.cz/electrodialysis.html.

16

www.globalspec.com/../air bio filter

17

www.gnest.org/journal/vol 11_no2/218.

18

www.ambio.ca/operation.php


Bio Filtration for Air Pollution Control

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