BIO-FILTRATIONA 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.

Air pollution Statistics

020406080

3010 2 10 10 16

5 5

90

2 2 2

40

5 321

415

2 8 2

60

8 11

Voc's Ammonia Nitrogen Oxides Sulphur Oxides

Perc

en

tage %

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 •Biological methods were proposed to treat odorous emissions.

1955 •Biological methods were applied to treat odorous emissions in low concentrations in Germany.

1960’s •Bio filtration was used for the treatment of gaseous pollutants both in Germany and US.

1970’s •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.

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.

WHY IS BIO-FILTRATION IMPORTANT

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 )*

Microbes’ life cycle –they breed, feed, eat, die. Their diet is based primarily on carbon-based compounds, water, oxygen (for aerobic reactions) and macronutrients.

HOW DO BIO-REACTORS WORK ?

Mass flow diagram of a bio-reactor

SCHEMATIC DIAGRAM OF A BIOFILTER UNITRef. 4

• Horizontal Flat Bed Bio Filter

• Vertical Bio FilterRef.5

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.

COMPONENTS OF A BIO-FILTER UNIT

Design and Performance Parameters

Contact Time and Air Flow

Moisture Content

Temperature

Siting

Media

Microorganism Seeding

Construction

Weeds

Rodents

Health and Safety Concerns

Costs

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.

DESIGN AND PERFORMANCE PARAMETERS

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 pelleteCompost + ACTIVETED CarbonPerlite

BenzeneEthanolHydrogen Sulphide

pseudomanas sp. Sugarcane BagasseWood BarkPig Manure

Methyl AcetateMethyl Ethyl KetoneMethyl Tert Butyl EtherNitrogen oxides

rhodococcus Sp.bacteria

Compost +activated carbon

Styrene exophiala yeanselmei Yard Wasteperlite

Toluene pseudomonas putida Peat

Xylene bacteria + yeast Cellulose

Ref.7

Bio-filteration Thermal Process Chemical Oxidation-Only By-product is waste biomass.

-Ambient Temperature and pressure process.

-investment and operation cost are lower than other two.

-By-Product is nitrogen oxides which causes ozone depletion and smog formation.

-requires additional natural gas for achieving high tempt hence increases CO2.

-operation and handling cost is high.

-Produce chlorine and chlorinated products.

-require precise temperature and pressure conditions.

-In chemical oxidations chemicals have to stored and handled.

Differentiation Between

BIOFILTERSA 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

5000 10000 150000

5000

10000

15000

20000

25000

30000

35000

40000

45000

CAPITAL COST

INCINERATION ABSORPTION CARBON ADSORPTION BIOFILTER

Ref.2

5000 10000 150000

50000

100000

150000

200000

250000

300000

350000

400000

OPERATING COST ($/YR)

ABSORPTION CARBON ADSORPTION INCINERATION BIOFILTER

GAS FLOW RATE (in cfm)

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, TXAt 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”.