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

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. 2/30

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 3/30

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 4/30

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 5/30

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 6/30

Methodology Literature Review Biofilter Setup Phase 1 Loading Rate Optimization Phase 2 Lab Analysis Inlet Humidity Optimization Phase 3 Performance Evaluation 7/30

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 8/30

Experimental Set-up Water Pumps Gas Outlets Timer Humidifier Nutrient Storage Biofilter Digital Pumps Compressed Ambient Air Leachate Collection Tedlar Bag with Biogas 9/30

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 10/30

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 11/30

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 12/30

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 13/30

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) 14/30

Results and Discussion 15/30

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 16/30

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 17/30

Removal Efficiency for VLR 45 & 55 g/m3.h Maximum RE 80% and 52 % with VLR 45 and 55 g/m3.h respectively 18/30

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 19/30

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) 20/30

Gas Concentration Profiles with VLR of 25 g/m3.h Inlet CH4 concentration was 8.6% At 75 cm height CH4 concentration was zero% 21/30

Gas Concentration Profiles with VLR of 35 g/m3.h Inlet CH4 concentration was 8.6% Outlet CH4 concentration was achieved to zero 22/30

Gas Concentration Profiles with VLR of 45 g/m3.h Inlet CH4 concentration was 8.6% Outlet CH4 concentration was 2% 23/30

Gas Concentration Profiles with VLR of 55 g/m3.h Inlet CH4 concentration was 8.6% Outlet CH4 concentration was 4% 24/30

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 25/30

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% 26/30

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% 27/30

Influence of Inlet Humidity VLR (g/m3.h) Inlet flow rate (mL/min) Average Inlet Humidity (%) Bed moisture content (%) Maximum RE (%) 35 194 90 15 - 10 100 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. 28/30

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 = 10 -15% ) Optimal EBRT is 78 min for this study 29/30

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 30/30

Thank you