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