Investigation of the Critical Parameters in the Production of Ceramic Water Filters Isabelle Gensburger October 2011 A research executed by:
Contents 1. Introduction – Review and Problem Description – Research Objectives – Project Scope 2. Summary of Methods — Filter making process — Filter testing 3. Experimental Results & Discussion – Rice Husk Quantity Variations – Maximum Firing Temperature Variations – Rice Husk Particle Size Variation – Two-month Clogging Test – Strength Test 4. Conclusions & Recommendations
Project Objectives 1.To better understand the production components and variables and move towards an international certification programme 2.To investigate ways to increase the flow rate without compromising the water quality and strength of the filter
Research Scope Set up and test the research production line Test reproducibility of RDI filters by mimicking RDI processes from mixing to firing Experiment with variations 1. Rice husk quantity (9.7, 11, 12, 13 and 14 kg) 2. Maximum firing temperature (685, 800, 885 and 950 deg. C.) 3. Rice husk particle size (<1 and 0.5<mm<1)
Research Production Line • Water supply • Electricity supply • Raw materials • Equipment • Machinery: • Mixer • Hydraulic press
Research Scope Set up and test the research production line Test reproducibility of RDI filters by mimicking RDI processes from mixing to firing Experiment with variations 1. Rice husk quantity (9.7, 11, 12, 13 and 14 kg) 2. Maximum firing temperature (685, 800, 885 and 950 deg. C.) 3. Rice husk particle size (<1 and 0.5<mm<1)
Research Kiln
Research Scope Set up and test the research production line Test reproducibility of RDI filters by mimicking RDI processes from mixing to firing Experiment with variations 1. Rice husk quantity (9.7, 11, 12, 13 and 14 kg) 2. Maximum firing temperature (685, 800, 885 and 950 deg. C.) 3. Rice husk particle size (<1 and 0.5<mm<1)
Methods : Filter Making Process 1 . Preparation of raw materials (sieving < 1 mm) 2. Mixing of clay components (10 mins dry and 15 mins wet) 3. Forming of clay cubes for pressing 4. Pressing of clay cubes into ceramic filter form 5. Surface finishing and labeling of pressed filters 6. Drying of pressed filter elements (dry versus wet season) 7. Firing and cooling in kiln
Methods : Filter Making Process 1 . Preparation of raw materials (sieving < 1 mm) 2. Mixing of clay components (10 mins dry and 15 mins wet) 3. Forming of clay cubes for pressing 4. Pressing of clay cubes into ceramic filter form 5. Surface finishing and labeling of pressed filters 6. Drying of pressed filter elements (dry versus wet season) 7. Firing and cooling in kiln
Methods : Filter Making Process 1 . Preparation of raw materials (sieving < 1 mm) 2. Mixing of clay components (10 mins dry and 15 mins wet) 3. Forming of clay cubes for pressing 4. Pressing of clay cubes into ceramic filter form 5. Surface finishing and labeling of pressed filters 6. Drying of pressed filter elements (dry versus wet season) 7. Firing and cooling in kiln
Methods : Filter Making Process 1 . Preparation of raw materials (sieving < 1 mm) 2. Mixing of clay components (10 mins dry and 15 mins wet) 3. Forming of clay cubes for pressing 4. Pressing of clay cubes into ceramic filter form 5. Surface finishing and labeling of pressed filters 6. Drying of pressed filter elements (dry versus wet season) 7. Firing and cooling in kiln
Methods : Filter Making Process 1. Preparation of raw materials (sieving < 1 mm) 2. Mixing of clay components (10 mins dry and 15 mins 3. Forming of clay cubes for wet) pressing 4. Pressing of clay cubes into ceramic filter form 5. Surface finishing and labeling of pressed filters 6. Drying of pressed filter elements (dry versus wet season) 7. Firing and cooling in kiln
Methods : Filter Making Process 1. Preparation of raw materials (sieving < 1 mm) 2. Mixing of clay components (10 mins dry and 15 mins 3. Forming of clay cubes for wet) pressing 4. Pressing of clay cubes into ceramic filter form 5. Surface finishing and labeling of pressed filters 6. Drying of pressed filter elements (dry versus wet season) 7. Firing and cooling in kiln
Methods : Filter Making Process 1. Preparation of raw materials (sieving < 1 mm) 2. Mixing of clay components (10 mins dry and 15 mins 3. Forming of clay cubes for wet) pressing 4. Pressing of clay cubes into ceramic filter form 5. Surface finishing and labeling of pressed filters 6. Drying of pressed filter elements (dry versus wet season) 7. Firing and cooling in kiln
Methods : Filter Testing • Flow rate – constant head method – long-term testing • E. coli – indicator of bacteria – membrane filtration method – spiked influent water: • 10 3 CFU/ml without silver • 10 6 CFU/ml with silver • Strength – discs cut from the bottom of the filters – modulus of rupture (MOR) • Pore size (to be done at TU Delft) – mercury intrusion porosimetry
Variable: Rice Husk Quantity Comparison: Flow Rate and Rice Husk Quantity 25 20 n = 12 Flow Rate (LPH) 15 n = 12 n = 12 n = 12 n = 12 10 5 r = 0.867 strong correlation 0 9 10 11 12 13 14 15 Quantity of Rice Husk per Batch of 6 Pots (kg)
Variable: Rice Husk Quantity Comparison : LRV and Rice Husk Quantity WITHOUT SILVER: Average LRV = 2.9 6 n = 11 5 n = 10 n = 8 n = 13 n = 9 4 LRV (E. Coli) 3 2 1 Min Outlier r = 0.056 no correlation Max Outlier 0 9,7 11 12 13 14 Quantity of Rice Husk per Batch of 6 Pots (kg)
Variable: Rice Husk Quantity + Silver Nitrate Comparison : LRV and Rice Husk Quantity WITH SILVER: Average LRV = 6.8 8 7 6 n = 3 n = 3 n = 3 n = 3 5 n = 3 LRV (E. Coli) 4 3 2 1 Min Outlier Max Outlier 0 9,7 11 12 13 14 Quantity of Rice Husk per Batch of 6 Pots (kg)
Variable: Maximum Firing Temperature Comparison : Flow Rate and Max. Firing Temperature 10 685 deg. C 9 800 deg. C 8 885 deg. C 7 950 deg. C 6 Flow Rate (LPH) 5 4 3 2 strong 1 correlation 0 600 700 800 900 1.000 1.100 Maximun Firing Temperature (deg. C)
Variable: Maximum Firing Temperature Comparison : LRV and Max. Firing Temp. 12 10 weak correlation r = -0.454 8 LRV (E. Coli) n = 6 n = 9 n = 11 6 4 2 Min Outlier Max Outlier 0 800 885 950 Maximum Firing Temperature (degrees C.)
Variable: Rice Husk Particle Size Comparison : LRV and Rice Husk Size 4 3,5 3 strong 2,5 LRV (E. Coli) correlation 2 1,5 n = 16 1 0,5 n = 7 0 [0 - 1] [0.5 - 1] Rice Husk Particle Size (mm)
RESULTS Strength Test
Variable : Rice Husk Quantity Comparison : MOR and Rice Husk Quantity 4 n=16 3,5 r(kg rice husk, MOR) = 0.951 3 strong correlation MOR (MPa) 2,5 n=10 n=12 2 n=4 n=17 1,5 1 Min Outlier 0,5 Max Outlier 0 9,7 11 12 13 14 Quantity of rice husk per batch of 6 pots (kg)
Variable : Maximum Firing Temperature Comparison : MOR and Max. Firing Temp. n=7 4 n=16 3,5 3 MOR (MPa) n=3 2,5 2 n=6 1,5 1 0,5 r = 0.999 strong correlation 0 685 800 885 950 Maximum Firing Temperature (degrees C.)
Variable : Rice Husk Particle Size Comparison : MOR and Rice Husk Size 4 n=16 3,5 3 MOR (MPa) n=7 2,5 2 1,5 1 Min Outlier 0,5 Max Outlier 0 < 1 mm [0.5 - 1] mm Rice Husk Particle Size
RESULTS Long-Term Flow Rate Test
Long-Term Flow Rate Test using turbid pond water (12.9<NTU<199) 300 Flow Rate < 1 LPH Scrubbing 250 Throughput (L) 1st scrub 200 2nd scrub 150 3rd scrub 4th scrub 100 5th scrub 50 6th scrub 0 9,7 11 12 13 14 Quantity of Rice Husk per Batch of 6 Pots (kg) When using less turbid well water (2.7<NTU<27.1): - Pots (9.7 – 11 kg) already < 2 LPH - Pots (12 – 13 kg) maintained flow rates > 2 LPH and only had to be scrubbed 2 times in the month - Pots (14 kg) always maintained flow rates > 2 LPH throughout the whole month
Conclusions & Recommendations The flow rate can be increased by: 1. increasing the porosity of the filter, by increasing the quantity of burn-out material in the clay mix; and 2. increasing the pore size , either by – changing the particle size distribution of the burnout material, or by – changing the maximum firing temperature. The bacteria removal effectiveness is only compromised when increasing the pore size
Thanks Everybody at RDIC My EWB colleagues The Dutch Research Group
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