1. Damitha Abeynayaka (st109642)
Methanotrophic Biofilter using Inorganic Filter Media: Optimization of Loading Rate and Inlet Gas Humidity
Damitha Abeynayaka (st109642)
Good Afternoon, Dear Teachers and dear friends, This is my master thesis final presentation. The topic of this study is BIOFITERS FOR MITIGATION OF GHG EMISSIONS FROM WASTE SECTOR
16th May 2011

2. Outline of the Presentation
Introduction
Background
MBFs
Objectives
Methodology
Results and Discussion
Conclusion & Recommendation
Today presentation will be consisted with INTRODUCTION, OBJECTIVES and SCOPE OF STUDY, LITERATURE REVIEW, METHODOLOGY, RESULTS AND DISSCUSSUION FINALLY CONCLUSION AND RECCOMMENDATIONS.
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3. Global Warming & Waste Sector CH4
Global warming and climate change are leading environmental issues
Increase of atmospheric GHGs concentration
Global Warming Potential (GWP) of CH4
100 years time horizon – 23
20 years time horizon – 62 relatively to CO2 (Wilshusen, 2004)
Waste Sector contribution:
From WWTP/ SWM
Total contribution ~ 5% (IPCC, 2001)
At the present global warming and climate change are considered as the leading environmental issues. Increase of the concentrations of green house gases such as carbon dioxide, Methane are the main reason for that.
Methane is one of the important GHGS with the GWP alone 100 year time horizon is 23 and along 20 time horizon is 62 times relatively to carbon dioxide.
Mitigation of CH4 Emission
Incineration
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4. Night soil treatment plant (Nothaburi)
Why it is Difficult?
landfill (Saraburi)
Johkasou
Night soil treatment plant (Nothaburi)
Anaerobic reactor,
EEM lab
Small Scale WWTP, Landfills
Onsite Treatment Systems (septic tanks, Johkasou)
Lab scale Experiments
Many of the methane emissions from small scale wwtp and solid waste landfills and onsite treatment process such as septic lank or johkasu are directly emitted to the atmosphere with out any treatment. These picture shows the direct methane emissions from night soil treatment plant in Nothaburi and industrial landfill site in saraburi. Methane concentration and flow are low in these causes then conventiamnal mitigation measures like incineration is not econamically feasible. Not only that some causes it is difficult to use incineration to treat methane emissions as an example lab scale experiment. Most of lab and pilot scale anaerobic wwt experiments release methane to the atmosphere. In AIT EEM ambient lab 150l/d and research station 4m3/d.
EEM Ambient lab : 4 Anaerobic reactors ≈ 150 L/d
Research station: Anaerobic Digester ≈ 4 m3/d
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5. Methanotrophic Biofilters
To 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
Combustion is not the only method of destroying Methane. It can also be oxidized through microbiological activity. Therefore, many of investigating are conducted the practical application of microbiological processes to convert the methane in extracted landfill gas to carbon dioxide.
Biofilter Research Cells at Betton Abbotts Landfill, UK
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6. Objectives Main Objective Specific Objectives
To develop, operate and evaluate an appropriate MBF system using inorganic filter media at lab scale
Specific Objectives
To compare the CH4 removal performances at different loading rates
To investigate optimum CH4 loading rate
To investigate the effect of inlet stream humidity and bed moisture content for removal of CH4
To select the optimum inlet humidity
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7. Methodology Literature Review Biofilter Setup
Phase 1
Loading Rate Optimization
Phase 2
Lab Analysis
Inlet Humidity Optimization
Phase 3
Performance Evaluation
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8. Filter Media Mechanically Sieving (select proper size) Dry
Wash with tap water (eliminate impurities)
Filter Media Preparation
Property
Value
Filter media
Sand
Average Particle Size (mm) 2
Bulk Density (kg/m3)
1400
Void Fraction
0.42
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9. Experimental Set-up Water Pumps Gas Outlets Timer Humidifier
Nutrient Storage
Biofilter
Digital Pumps
Compressed Ambient Air
Leachate Collection
Tedlar Bag with Biogas
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10. Methodology Phase 2: VLR Optimization Biofilter 1 Biofilter 2
Operating with VLR 45 g/m3.h & inlet humidity > 85%
Operating with VLR 25 g/m3.h & inlet humidity > 85%
Operating with VLR 55 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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11. VLR= (Ci x Q)/ Vf EBRT= Vf/Q
Operating Parameters
VLR= (Ci x Q)/ Vf
EBRT= Vf/Q Vf
Ci, Q
Outlet
Inlet
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
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12. Different Loading Rates
Test run
Loading rate (g CH4/m3/h)
Biofilter.1
Biofilter.2 1 45 25 2 55 35
VLR (g/m3.h)
Biogas flow rate
(mL/min)
Air flow rate
Inlet flow rate
EBRT
(min) 25 20
119
139
111 35 28
166
194 79 45 36
214
250 62 55 44
262
306 50
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13. Methodology Phase 3: Inlet Humidity Optimization Biofilter 1
Operating with VLR 55 g/m3.h & 80%>inlet humidity > 60%
Operating 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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14. How to Select Optimum Conditions?
RE = (Ci –Co)/Ci x 100
EC = (Ci –Co)Q/Vf Vf
Ci, Q
Outlet
Inlet Co
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)
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15. Results and Discussion
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16. Removal Efficiency for VLR 25 & 35 g/m3.h
Maximum RE = 100% with both VLRs
RE was reduced by 20% with respect to the increase of VLR from 25 to 35 g/m3.h
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17. Elimination Capacity for VLR 25 & 35 g/m3.h
Removal Efficiency
VLR=25 g/m3.h
VLR=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
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18. Removal Efficiency for VLR 45 & 55 g/m3.h
Maximum RE 80% and 52 % with VLR 45 and 55 g/m3.h respectively
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19. 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 EBRT
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20. Removal Performances Vs. VLR Optimum VLR range for Maximum EC
100% conversion
Optimum VLR range for Maximum EC
The optimum VLR = 35 g/m3.h
(EBRT= 79 min)
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21. 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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22. 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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23. 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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24. 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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25. Discussion
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
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 35
194 79 45
250 62 78 55
306 50 52 28
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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26. Removal Efficiency with Different Humidity (VLR 35 g/m3.h)
80% >Inlet humidity>60% & Bed moisture content 10%-15%
60% >Inlet humidity>40% & Bed moisture content 5%-10%
Inlet humidity >85% & Bed moisture content 10%-15%
When inlet humidity > 60 % RE was 100 %
RE was dropped by 20 % when inlet humidity was lower than 60%
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27. Removal Efficiency with Different Humidity (VLR 55 g/m3.h)
Inlet humidity >85% & Bed moisture content 10%-15%
80% >Inlet humidity>60% & Bed moisture content 5%-10%
When inlet humidity > 85 % RE was 52 %
RE was dropped to 38 % when inlet humidity was lower than 80%
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28. Influence of Inlet Humidity
VLR (g/m3.h)
Inlet flow rate
(mL/min)
Average Inlet Humidity (%)
Bed moisture content (%)
Maximum RE
(%) 35
194 90
100 75 55
10 - 5 78
306 52 28
When the VLR increases inlet gas humidity plays an important role
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.
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29. Conclusions
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 = % )
Optimal EBRT is 78 min for this study
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30. Recommendations
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
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31. Thank you