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Control of Volatile Organic Compound

(VOC) and Odorous Emissions usingBiofilters

Dr. Suchismita Bhattacharya

SIES BRSI Workshop on Recent Advances inMedical, Plant and Enviro Biotechnologies

January 13-14, 2006


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Contents

Introduction to Biofiltration

Types of Biofilters and Configurations

Research at the New Jersey Institute ofTechnology

VOC removal methods and comparison

Practical Applications

Case Study

Conclusions


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The problem

Volatile Organic Compounds

Odors

Removal Methods Chemical Scrubbing

Activated Carbon Adsorption

Thermal Oxidation/incineration

Catalytic Oxidation Absorption on Activated Carbon


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Types of Biofiltration

Based on Operational mode Biofilters

Packing contains nutrients

Possibility of clogging of biomass

Accumulation of acidic products

Biotrickling filters Continuous nutrient recycle

Removal of dead biomass

pH control possible

Based on Packing material Organic media

Peat, wood chips, soil

Synthetic media


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Synthetic Packing Media

High Density polypropylene

media 132 ft2/ft3

PVC hollow polymeric spheres


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Biofilter Configurations


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Biotrickling Filter Configurations


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Biotrickling Filter Configurations


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Possible Substrates

Substrate Bio-degradibility

Aliphatic Hydrocarbons (Methane, Propane) Low-Moderate

Aromatic Hydrocarbons

(Benzene, Toluene, Xylene)

Moderate -Good

Chlorinated hydrocarbons

Carbon tetrachloride, Chloroform

Trichloroethylene (cometabolic)

O-Dichlorobenzene, monochlorobenzene

Low

Moderate

LowAldehydes, Esters, Ketones Good

Ammonia

Hydrogen Sulfide

Nitrogen oxide

Good

Good

Poor


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Schematic of BTF Unit at NJIT

S

S2

1

3

45

6

7

8 8

9

1110

MEDIUM WATER

AIR

S

1. Air pump, 2. Rotameter Assembly, 3. Humidification tower, 4. Ethanol tank, 5. o-DCB tank, 6.

Biotrickling Filter, 7. Tank for recirculating medium, 8. Peristaltic pump, 9. Flow meter, 10. pH

Meter, 11. pH Electrode, S=Sampling Port. (Not to scale)


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How it appears

Clean

Packing

Biomass on

Packing


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Biotrickling Filter Model

Assumptions

ED,i,

i

i

LiLi

Gi

G

m

CCK

dh

dCu

O

GO

LOLO

GO

G

m

CCK

dh

dCu

With boundary conditions

;GDiGD

CC

;GEiGE

CC

;GOiGO

CC at 0h

No axial concentration gradients in the gas and liquid filmsNegligible mass transfer resistance from the bulk liquid to thebiofilm.The liquid film is modeled as a CSTR.The density of the biofilm and biomass concentration.At equilibrium, the concentration at the air/liquid interface followsHenrys law.Diffusion and reaction in the biofilm can be described by using abiodegradation effectiveness factor;

Balances In the gas phase


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Model Equations

Balances In the liquid phase

)()0( HhChC LDLD , )()0( HhChC LELE , )()0( HhChC LOLO

)(),(

)(),(

LOLELDE

OE

S

LVLVOE

LOLELDD

OD

S

LVLVODLO

O

GO

LO

LO

L

CfCCY

AXX

CfCCY

AXXC

m

CK

dh

dCu

)(),()(),( LOLDLEEE

SVELOLDLEE

E

SVLLLE

e

GELC

LEL CfCC

Y

AXCfCC

Y

AXC

m

CK

dh

dCu

)(),()(),( LOLDLEDD

SVDLOLDLED

D

SVLLLD

D

GDLD

LDL CfCC

Y

AXCfCC

Y

AXC

m

CK

dh

dCu

Mass Transfer Reaction in liquid Reaction in biofilm

With boundary conditions


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Validation of the Model

Percent Removal Removal Rate

(gm-3

-reactor h-1

)

Inlet

Concentration

(gm-3

) Experimental predicted Experimental Predicted

Error %

(Rpred-

Rexp)/Rexp

t = 4.2 min ; QL = 8.7 Lh-1

o-DCB 0.91 95.88 92.57 12.46 12.14 -2.60

Ethanol 2.51 95.38 98.32 34.20 35.38 3.46

o-DCB 3.35 90.25 90.19 43.19 43.37 0.43

Ethanol 2.35 97.35 98.35 32.68 33.13 1.38

o-DCB 2.11 95.24 91.47 28.71 27.77 -3.27

Ethanol 2.62 95.38 98.27 35.70 36.92 3.43

t = 4.00 min ; QL = 4.2 Lh-1

o-DCB 2.20 85.88 85.62 26.99 27.05 0.22

Ethanol 2.57 94.36 97.19 34.64 35.95 3.77

o-DCB 3.50 81.89 82.30 40.95 41.16 0.51

Ethanol 2.51 92.76 97.19 33.26 35.11 5.55


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VOC Removal Technologies

Technology Air Flow rate Concentration in ppmv

Condensation 200 20,000 m3/h

(120-12,000 SCFM)

50-200 g/m3

(2.8 % - 11.2% by volume)

Cyro-Condensation 30-600 m3/h

(20 -400 SCFM)

5-90 g/m3

(0.28 % - 5% by volume)

Scrubbing 200 20,000 m3/h

(120-12,000 SCFM)

10-40 g/m3

(0.56 % - 2.3% by volume)

Incineration 10,000 100,000 m3/h

(6000-60,000 SCFM)

8-140 g/m3

(0.5 % - 8% by volume)

Catalytic Oxidation 10,000 100,000 m3/h

(6000-60,000 SCFM)

1-10 g/m3

(500 ppmv 6000 ppmv)

Regenerative

Adsorption

100-10,000 m3/h

(60-6,000 SCFM)

1-10 g/m3

(500 ppmv 6000 ppmv)Non-RegenerativeAdsorption

10-60 m3/h

(6-40 SCFM)

0-5.0 g/m3

(


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Cost Comparison

Biofiltration Thermal treatment

with Concentrators

Thermal treatment

without

Concentrators

Capital Cost $1.4 million $1.8 million $0.9 million

Operating Cost for

ten years

$820,000 $7,100,000 $10,955,000

Natural gas Nil $0.65-$0.7 million/year

$1.05-$1.1 million/year

Electricity $42,500/ year

(2000 kWh/day)

$35,000/year (1700

kWh/day)

$20, 500/year (1000

kWh/day)

Water $12,500/year

(1,100 cu.ft./day)

Nil Nil

Bed Replacement $180,000/four years Nil Nil

Removal Efficiency 85% >95% >95%

Cost/Ton of VOC

removed over Ten

years

$5,800 $20,800 $27,700


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Technology Suppliers

Aromatrix Technologies Pte Ltd

Singapore

S&H GmbH (Zeestow/Germany)

PPC Biofilter: Airphase Biofilters & Bioscrubbers

Texas, USA

PRD Tech Inc.

Ohio, USA. Biospeedup

Biorem Technologies Inc

Ontario, Canada Biomix, Biosorbens


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Biotrickling Filter Applications

Air at Effluent, Waste Water Treatment Plants Odor, Hydrogen Sulfide, VOCs

Pseudomonas, Sphingomonas, Mycobacteria,Acetobacteriaceal

Thiobacillus

VOCs from Microelectronics Industry

Toluene, Acetone, Trichloroethylene Forest Products industry

-pinene (55 C), Methanol (70 C) Thermophillic bacteria

Vapors from Bathtub manufacturing facility Styrene

Flue gas from Coal based power Plant SO2 removal

Off-gases from Bakery plant Ethanol


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Biofilter Applications

Printed Circuit Board Manufacturing

Propylene Glycol, Monomethyl Ether Acetate

Vinyl Resin Production

MEK, Toluene

Animal Rendering Plant

H2S, VOC

Waste Water Pumping Station

H2S, Dimethyl Sulfide, Methyl Mercaptan, Dimethyl

Disulfide

Sludge Conditioning process

Odor Treatment


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Feasibility of Biofiltration

Gas Stream Specification VOC specification. Use of flame ionization detector (FID) or GC/MS

Temperature.

Relative humidity

Particulate loading, including condensables.

Air flow and volume to be treated

Applicability of Biofiltration Mixture or single substrate

Production of acid during biomass metabolism

Temperature: For mesophilic bacteria 10-40 C.

Humidity of Air should be close to saturation

If the particulate loading is water soluble and biodegradable, 0.034 g/std.m3

may be allowed. If the particulate loading is not water soluble and notbiodegradable, a maximum of 0.009 g/std.m3 is allowed.

Pretreatment may be required for warmer air or air containing particulates

Pilot Studies and Data analysis

Economic analysis


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Case Study: Conversion of ChemicalScrubber to Biotrickling Filter

Treatment of odorous emissions from waste water treatment plant Air flow rate 16,000m3h-1 (9,600cfm)

Inlet H2S concentration 5-35 ppm

Existing chemical scrubbers modified: Random Packing replaced by polyurethane foam packing 4 cm cubes

with 600m2m-3 specific surface area

Existing 7HP recycle pump replaced with 0.5 HP pump for tricklingrate of 77 Lmin-1

Secondary effluent instead of inorganic nutrients pH recycle liquid1.5-2.3

Dimensions/Operational Parameters

Internal Diameter 1.8 m Reactor height 9.7 m

Bed height 3.7m

Empty Bed residence time 2 sec

Start-up time 9 days


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Case Study: Conversion of ChemicalScrubber to Biotrickling Filter

Measurement of Process Variables Online H2S Concentrations at inlet/outlet

Inline pH sensor

Bed pressure drop with U-tube manometer

Gas chromatography of grab samples for Carbonyl sulfide,SO2, Methyl Mercaptan, etc

VOC using portable Scentograph

Water samples for CO2, NH3, foul airflow

Economic Analysis

Conversion cost $40,000-$60,000

Chemical costs for removing 3,000 kg of year H2S= $30,000.


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Conclusions

Biofilters and Biotrickling filters are anestablished technology in USA, Canada and inEurope

Biotrickling filters may be more suitable forrecalcitrant compound removal

Biofilters with synthetic packing media havesolved some of the problems with organic media

Both technologies have enormous odor/VOCcontrol potential

Can these work in India?