16th May 2011

Damitha Abeynayaka (st109642)

Methanotrophic Biofilter using Inorganic Filter Media:

Optimization of Loading Rate and Inlet Gas Humidity

Outline of the Presentation

IntroductionBackgroundMBFs

ObjectivesMethodologyResults and DiscussionConclusion & Recommendation

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Mitigation of CH4 EmissionIncineration

Waste Sector contribution:From WWTP/ SWM Total contribution ~ 5% (IPCC, 2001)

Global Warming Potential (GWP) of CH4 100 years time horizon – 2320 years time horizon – 62 relatively to CO2 (Wilshusen,

2004)

Global Warming & Waste Sector CH4

Global warming and climate change are leading environmental issues

Increase of atmospheric GHGs concentration

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Why it is Difficult?

Small Scale WWTP, Landfills Onsite Treatment Systems (septic tanks, Johkasou)Lab scale Experiments

EEM Ambient lab : 4 Anaerobic reactors ≈ 150 L/dResearch station: Anaerobic Digester ≈ 4 m3/d

Anaerobic reactor, EEM lab

landfill (Saraburi)

JohkasouNight soil treatment

plant (Nothaburi)

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Methanotrophic BiofiltersTo treat waste gas streams using a culture of immobilized micro

organisms called “METHANOTROPHS”CH4 + 2O2 CO2 + 2 H2O + biomass

(source: Nikiema et al,2005)

Methane is converted to CO2, H2O and organic biomass through biological oxidation

It is more effective and economical

Biofilter Research Cells at Betton Abbotts Landfill, UK5/30

ObjectivesMain Objective

To develop, operate and evaluate an appropriate MBF system using inorganic filter media at lab scale

Specific Objectives1. To compare the CH4 removal performances at different loading

rates

2. To investigate optimum CH4 loading rate

3. To investigate the effect of inlet stream humidity and bed moisture content for removal of CH4

4. To select the optimum inlet humidity

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Methodology

Loading Rate Optimization

Performance Evaluation

Inlet Humidity Optimization

Biofilter Setup

Literature Review

Lab Analysis

Phase 1

Phase 2

Phase 3

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Filter Media

Property ValueFilter media Sand

Average Particle Size (mm) 2

Bulk Density (kg/m3) 1400

Void Fraction 0.42

Mechanically Sieving (select proper size)

Dry

Wash with tap water (eliminate impurities)

Filter Media Preparation

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Experimental Set-up

Tedlar Bag with Biogas

Compressed Ambient AirLeachate

Collection

Nutrient Storage

HumidifierBiofilter

Gas Outlets

Digital Pumps

Water Pumps

Timer

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MethodologyPhase 2: VLR Optimization

Biofilter 1Operating with VLR 45 g/m3.h &

inlet humidity > 85%

Operating with VLR 55 g/m3.h & inlet humidity > 85%

Biofilter 2Operating with VLR 25 g/m3.h &

inlet humidity > 85%

Operating with VLR 35 g/m3.h & inlet humidity > 85%

Lab Analysis

Data Analysis

Selection of optimal VLR

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Operating Parameters

VLR= (Ci x Q)/ Vf

VLR = Volumetric loading rate (g/m3/h)

Ci = Inlet CH4 concentration (g/m3)

Q = Inlet flow rate (m3/h)

Vf = Empty bed volume

EBRT = Empty bed residence time

EBRT= Vf/Q

Vf

Ci, Q

Outlet

Inlet

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Different Loading Rates

Test runLoading rate (g CH4/m3/h)

Biofilter.1 Biofilter.21 45 25

2 55 35

VLR (g/m3.h)

Biogas flow rate

(mL/min)

Air flow rate

(mL/min)

Inlet flow rate

(mL/min)EBRT(min)

25 20 119 139 11135 28 166 194 7945 36 214 250 6255 44 262 306 50

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MethodologyPhase 3: Inlet Humidity Optimization

Biofilter 1Operating with VLR 55 g/m3.h &

80%>inlet humidity > 60%

Biofilter 2Operating with VLR 35 g/m3.h &

80%>inlet humidity > 60%

Operating with VLR 35 g/m3.h & 60%>inlet humidity > 40%

Lab Analysis

Data Analysis

Selection of optimal Humidity

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How to Select Optimum Conditions?

RE =Removal efficiency (%)

EC = Elimination capacity(g/m3/h)

Ci = Inlet CH4 concentration (g/m3)

Co = Outlet CH4 concentration (g/m3)

Q = inlet flow rate (m3/h)

Vf = filter bed volume (m3)

RE = (Ci –Co)/Ci x 100

EC = (Ci –Co)Q/Vf

Vf

Ci, Q

Outlet

Inlet

Co

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Results and Discussion

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Removal Efficiency for VLR 25 & 35 g/m3.h

VLR=25 g/m3.h VLR=35 g/m3.h

Maximum RE = 100% with both VLRsRE was reduced by 20% with respect to the increase of VLR from 25

to 35 g/m3.h

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Elimination Capacity for VLR 25 & 35 g/m3.h

Maximum EC was increased with the increase of VLR from 25 g/m3.h to 35 g/m3.h

Elimination capacity increases even the Removal Efficiency decreases

VLR=25 g/m3.h VLR=35 g/m3.h

Removal Efficiency

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Maximum RE 80% and 52 % with VLR 45 and 55 g/m3.h respectively

VLR=45 g/m3.h VLR=55 g/m3.h

Removal Efficiency for VLR 45 & 55 g/m3.h

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VLR=45 g/m3.h VLR=55 g/m3.h

Elimination Capacity for VLR 45 & 55g/m3.h

Maximum EC 29 and 35 g/m3.h with VLR 55 and 45 g/m3.h respectively

The reduction of EC is due to the reduction of EBRT19/30

Removal Performances Vs. VLR

The optimum VLR = 35 g/m3.h(EBRT= 79 min)

100% conversion Optimum VLR range for Maximum EC

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Gas Concentration Profiles with VLR of 25 g/m3.h

Inlet CH4 concentration was 8.6%At 75 cm height CH4 concentration was zero%

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Gas Concentration Profiles with VLR of 35 g/m3.h

Inlet CH4 concentration was 8.6%Outlet CH4 concentration was achieved to zero

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Gas Concentration Profiles with VLR of 45 g/m3.h

Inlet CH4 concentration was 8.6%Outlet CH4 concentration was 2%

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Gas Concentration Profiles with VLR of 55 g/m3.h

Inlet CH4 concentration was 8.6%Outlet CH4 concentration was 4%

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Discussion

CH4 + 2O2 CO2 + 2 H2O + biomass (source: Nikiema et al,2005)

VLR (g/m3.h)

Inlet flow rate

(mL/min)EBRT(min)

Maximum RE(%)

Maximum EC(g/m3.h)

25 139 111 100 25

35 194 79 100 35

45 250 62 78 35

55 306 50 52 28

Increase of CO2 concentration and decrease of O2 concentration with height is an indicator of the microbial oxidation of CH4 in side the filter column

Lower EBRT restrict the contact time between filter media and CH4 therefore removal performances were reduced with the increase of the VLRs

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Inlet humidity >85% & Bed moisture content 10%-15%

80% >Inlet humidity>60% & Bed moisture content 10%-15%

60% >Inlet humidity>40% & Bed moisture content 5%-10%

Removal Efficiency with Different Humidity (VLR 35 g/m3.h)

When inlet humidity > 60 % RE was 100 %RE was dropped by 20 % when inlet humidity was lower

than 60% 26/30

Inlet humidity >85% & Bed moisture content 10%-15%

80% >Inlet humidity>60% & Bed moisture content 5%-10%

Removal Efficiency with Different Humidity (VLR 55 g/m3.h)

When inlet humidity > 85 % RE was 52 %RE was dropped to 38 % when inlet humidity was lower

than 80% 27/30

Influence of Inlet HumidityVLR (g/m3.h) Inlet flow rate

(mL/min)Average Inlet Humidity (%)

Bed moisture content (%)

Maximum RE(%)

35 194

90 15 - 10 10075 15 - 10 10055 10 - 5 78

55 306 90 15 - 10 5275 10 - 5 28

Suitable bed moisture content was 10-15% . This result was similar to former study which found optimum moisture content of 13% with loamy sand soil (Park et al, 2002).

To get suitable bed moisture content … Optimum inlet gas humidity Filter bed watering frequency by nutrient solution Inlet flow rate Temperature ……..….. are important.

When the VLR increases inlet gas humidity plays an important role

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Maximum RE with VLR of 25 and 35 g/m3.h was 100%, while maximum ECs with those VLRs were 25g/m3.h and 35 g/m3.h respectively.

Maximum RE and EC were 78% and 35 g/m3.h for VLR of 45 g/m3.h

Maximum RE and EC were 52% and 28 g.m3.h for VLR of 55 g/m3.h

Optimum Humidity value for VLR of 35 g/m3.h is more than 60% and bed moisture content 10% – 15%

Optimal Humidity value for 55g/m3.h is more than 80% for keep bed moisture content between 10% - 15%

Optimal VLR is 35g/m3.h for coarse sand filter media (Tem.= 30 0C, pH= 6.8 – 7 and bed moisture content = 10 -15% )

Optimal EBRT is 78 min for this study

Conclusions

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Studies with different low cost inorganic media

and different size media

Implementations of MBF with inorganic media

Analysis of microbial community variations

with VLR and different moisture content

Studies with possible inoculation sources

Recommendations

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Thank you