BIO-FILTRATION
A Detailed Study of Methodology of Bio filtration In Controlling Air Pollution.
Shreyash Gupta
Avichal Sharma
OVERVIEW-:
 Industries, agriculture transport many more modern socio-economic
practices pollute our environment.
 Gas Biofiltration is a relatively new technology used to purify
contaminated air from volatile organic and inorganic compounds VOC’S
and VIC’S, aromatic compounds and other toxic and odorous compounds.
 Our main aim is to study use of bio filters for controlling air pollution in
industries having above mentioned pollutants.
 The experience gained from monitoring exercise carried out during the
last 25 years and adoption of appropriate strategy for air quality control
have been discussed in this paper presentation.
Percentage %
Air pollution Statistics
90
80
70
60
50
40
30
20
10
0
90
60
40
30
21
5
2
Road
Transport
10
5 5 8
Industrial
Process
Voc's
2
3 2
Agriculture
Ammonia
10
2
10
8
2 4
16
2
15 11
Energy
Solvent and Commercial
Production
other
Industrial
Nd
Product Use
And
Distrubition
household
Nitrogen Oxides
Sulphur Oxides
Ref. 1
INTRODUCTION
 Bio filtration is air pollution control technique
 Involves bio degradation of contaminants under the action of microorganisms
diffused in a thin layer of moisture known as “BIOFILM”
 Mainly used for elimination of malodorous gas emissions and low
concentrations of Volatile Organic Compounds (VOCs).
The process of Bio Degradation is :
Organic Pollutant + O2
CO2 + H2O + Heat + Biomass
BRIEF TIMELINE OF DEVELOPMENT OF BIO
FILTERS
1923
1955
1960’s
1970’s
• Biological methods were proposed to treat odorous emissions.
• Biological methods were applied to treat odorous emissions in low
concentrations in Germany.
• Bio filtration was used for the treatment of gaseous pollutants both in
Germany and US.
• Biofiltration is used with high success in Germany.
1980’s
• Biofiltration is used for the treatment of toxic emissions and volatile
organic compounds (VOCs) from industry.
1990’s
• Today, there are more than 500 biofilters operating both in Germany and
Netherlands and it is widely spreaded in US.
WHY IS BIO-FILTRATION IMPORTANT
 Bioreaction 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.
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 )*
HOW DO BIO-REACTORS WORK ?
 Microbes’ life cycle –they breed, feed, eat, die. Their diet is based primarily on carbon-based
compounds, water, oxygen (for aerobic reactions) and macronutrients.
Mass flow diagram of a bio-reactor
SCHEMATIC DIAGRAM OF A BIOFILTER UNIT
Ref. 4
• Horizontal Flat Bed Bio Filter
• Vertical Bio Filter
Ref.5
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, CO2 and water.
 Material that is indigestible is left over and becomes residue.
Design and Performance Parameters
 Contact Time and Air Flow
 Moisture Content
 Temperature
 Siting
 Media
 Microorganism Seeding
 Construction
 Weeds
 Rodents
 Health and Safety Concerns
 Costs
DESIGN AND PERFORMANCE PARAMETERS
 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.
 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.
Ref. 6
BIOFILTERS EFFECTIVENESS
 Odor and hydrogen sulfide reductions up to 95%.
 Ammonia reductions up to 80%.
 Uses Microorganisms
 Absorbs And Oxidizes
 VOC’s
 VIC’s
 Oxidisable Inorganic Gases and Vapors
 Produces

Water, Carbon di oxide, Salts

Microbial Biomass
Air Waste/Component
Microorganism
Support
Ammonia
bacteria
Celine pellete
Compost + ACTIVETED
Carbon
Perlite
Benzene
Ethanol
Hydrogen Sulphide
pseudomanas sp.
Sugarcane Bagasse
Wood Bark
Pig Manure
Methyl Acetate
Methyl Ethyl Ketone
Methyl Tert Butyl Ether
Nitrogen oxides
rhodococcus Sp.
bacteria
Compost +activated carbon
Styrene
exophiala yeanselmei
Yard Waste
perlite
Toluene
pseudomonas putida
Peat
Xylene
bacteria + yeast
Cellulose
Ref.7
Differentiation Between
Bio-filteration Thermal Process Chemical Oxidation
-By-Product is
nitrogen oxides which
causes ozone
depletion and smog
formation.
-Produce chlorine and
chlorinated products.
-Ambient Temperature
and pressure process.
-requires additional
natural gas for
achieving high tempt
hence increases CO2.
-require precise
temperature and
pressure conditions.
-investment and operation
cost are lower than other
two.
-operation and
handling cost is high.
-In chemical oxidations
chemicals have to
stored and handled.
-Only By-product is
waste biomass.
BIOFILTERS
A Viable Option
 Effective at emission reduction.
 Low-cost
 Biological system requiring management.
 Design, installation and operation will impact building
ventilation and bio-filters effectiveness.
COMPARISON OF BIOFILTERS AND OTHER
TREATMENT PROCESSES
CAPITAL COST
45000
40000
35000
30000
25000
20000
15000
10000
5000
0
5000
INCINERATION
10000
ABSORPTION
CARBON ADSORPTION
15000
BIOFILTER
Ref.2
OPERATING COST ($/YR)
400000
350000
300000
250000
200000
150000
100000
50000
0
5000
10000
15000
GAS FLOW RATE (in cfm)
ABSORPTION
CARBON ADSORPTION
INCINERATION
BIOFILTER
Ref.3
Review of RESEARCHES
 In research on Transient Behavior of Biofilter , Marc A.
Deshusses describes the aerobic biodegradation of VOC mixtures from
effluent air streams in laboratory scale compost based biofilters.
 Bio filters had degraded and absorbed Hexane , Acetone , MIBK , propane
and MEK in different proportions.
 Established a fundamental description of pollutant removal in biofilters.
BIOFILTRATION-AN INNOVATIVE TECHNOLGY FOR THE FUTURE
-by Dr. Rakesh Govind, Prof. Chemical Engg. Department
University of Cincinnati, OH
 different types of biofilters’ support media
 the various biofilters operations adopted in industry.
 waste compounds treatable by biofiltration
 commercial potential of biofiltration.
 The paper concludes that when compared to other available technologies, biofilters
have significant technical and economical advantages.
Photograph of four Biofilters being installed in Arlington, TX
At Central Regional Wastewater System Plant
A FEW EXISTING BIO FILTERS
 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.
 Long Sault, Ontario: Although a small (1500 cfm), indoor, container-type
system, this installation demonstrates several key aspects that are relevant to
any installation.
 Sarnia, Ontario: This biofilter was installed in 2001 and treats 12,500 cfm of air
coming from a sludge liming and drying operation.
 Brookfield, P.E.I. : This biofilter was installed in 2002, at a composting plant in
P.E.I., that treats 60,000 cfm of air from the composting process.
 Toronto, Ontario: This biofilter was installed in 2002 in the north end of Toronto
at the Toronto Mixed Waste Recycling and Organics Processing Facility.
REFERENCES:
Review Paper on Biofiltration 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);
ref. 4

Magazine paper on Biofiltration: an innovative technology by Dr. Rakesh Govind, chemical engg.,
University Of Cincinnati, OH 45221-0171 (2000)
ref. 2, ref. 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
ref. 6, ref.7

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
ref.5

Pollution statistics from Indian Journal Of Biotechnology vol. 2, july 2003 case study of effluent in
Industries of Delhi-NCR region.
ref.1

Frederickson, J.; Boardman, C. P.; Gladding, T. L.; Simpson, A. E.; Howell, G. and Sgouridis, F. (2013).
Evidence: Biofilter performance and operation as related to commercial composting. Environment Agency,
Bristol.

EPA handout Environmental Protection Agency “What is Biofilter?”; “Using bio-filters to control air pollution”.