Innovative, Low-Cost, Water Purification Method by Leveraging the Synergetic Effect of UV and IR Radiation from the Sun
Sujay M. Swain Montgomery Blair High School, MD Typical source of drinking water
About 1 Billion people lack access to safe water (WHO) The water crisis is the #1 problem in the world (World Economic Forum) In developing countries, up to 80% of diseases are water related (The Water Project)
I saw first hand during my trip to India how poverty and lack of resources was forcing people, especially kids to drink contaminated water.
Contaminated water Purified water
My GOAL is to Make clean drinking water accessible to everyone!! Physical (P) Sediments Stones Fish and other organic materials
Chemical (C) Heavy metals (Lead, chromium) Human and animal drugs Pesticides
Biological (B) Contaminated water with impurities Pathogens (E. Coli, Salmonella, Rotavirus, etc.) Purification Methods Chlorination Ozonation Reverse Activated SODIS Osmosis Carbon
Parameters
Holistic No No No No No Residue-Free No No Yes Yes Yes Easy to Operation No No Yes? Yes Yes Easy to Maintain No No No Yes Yes Economical No No No Maybe Yes Removes Chemical Yes Yes Yes Yes No Removes Biological Yes Yes Yes? No Yes Time to Purify Quick Quick Quick Quick Long Effective for turbid water Yes Yes Yes Yes No
Table 1: Comparison of Purification Methods The proposed solution should addresses all three aspects of purification – Physical, Chemical and Biological in a quick, easy and cost effective manner
Water from Swamp Purification used as Contaminated Water Source
Contaminated water Purified water
The aim is to purify contaminated water from a stagnant water source (swamp area) to clean drinking water Abundance of sugarcane in areas with Local sugarcane juice shortage of clean drinking water. store – bagasse Sugarcane bagasse – For Physical produced in abundance separation Sugar Cane Juice – Chemical separation by converting to activated carbon
Filtration using Abundant Sunlight – Biological Purification activated with Solar Disinfection (SODIS) carbon
Other materials that may be used – Coconut coir (for Physical separation) Water Coconut shell (for generating bottles treated using activated carbon) SODIS • Water can be disinfected and in this way made drinkable using the rays of the sun • Important points to consider: • Material, color and shape of the bottle • Turbidity of water • Cloudiness • Preventing recontamination
SODIS Pros SODIS Cons Very Economical Takes a long time to purify water ( 2-4 days)
Easy to Use Does not remove chemical impurities Reasonably Not effective on water with high turbidity Effective Sugarcane bagasse (for filter) with different packing density
Filtration through loosely packed bagasse
Bagasse Packed Bagasse Filtered water Water from Water filtration (Turbidity – 840 NTU) Swamp Sugarcane bagasse (for filter) with different packing density
Filtration through densely packed bagasse
Bagasse Filtered water Water from Water filtration (Turbidity – 12 NTU) Packed Bagasse Swamp Designed and fabricated a turbidity meter using a Secchi disk turbidity tube Filled water into the tube while looking into the filled water column from the top until the black-and-white pattern on the disc cannot be seen anymore Height of that water column shows a measure of turbidity (using a calibration table)
900 Designed and 800 fabricated a 700 turbidity 600 meter using a 500 After filtration Secchi disk 400 300 200 100
Measured Turbidity (NTU) Turbidity Measured 0 0 1 2 3 4 5 6 7 Density of Sugarcane Bagasse Used sugarcane juice that is extracted from sugarcane as a starting material Heated the juice in open flame to obtain solid carbon
Treated in an laboratory oven at 650C with CaCl2 and 30% steam to activate (activated carbon) Crushed and packed the activated carbon between two sugarcane bagasse filters for water to flow through
Activated Sugarcane juice on Fully burnt juice Carbon from Sugarcane juice carbon open fire juice Water after Physical and Activated Chemical Packed Carbon bagasse Filtration
Water after Physical purification Measured three main chemical impurities: Lead concentration Chromium concentration
pH Palintest Scanning Lead test strip5 pH strips used analyzer used for measuring lead5
Contaminations As obtained First Filtration Second Filtration Comments (parts/billion) (parts/billion) (parts/billion) Lead > 15 < 15 < 15 Measured with instant lead strip 32 8 3 Measured with Palintest scanning Analyzer Chromium 122 88 53 Absorption at 540nm pH 6.5 (Acidic) 7.0 7.5 (Alkaline) pH Strip (Extrapolated)
EPA Limit for lead : 15 ppb Table 2: Chemical testing Results EPA Limit for Chromium : 100 ppb Traditional SODIS (Solar water disinfection) Method Makes use of natural sun light (only UV-A radiation) Not effective on turbid water
Modified conventional SODIS method (Enhanced SODIS – e-SODIS) Leveraged “Synergetic Effect” Synergetic effect of UV-A and temperature
20oC When water is heated to 55oC, the required UV-A radiation to Coli Density) Density) Coli purify water drops significantly - (E
(Synergetic effect of UV-A and 55oC temperature) (UV Exposure) Proposed a linear curved reflector design to concentrate sunlight (like a solar cooker) on the water target (at the focal point) to expedite heating of water to 55oC Since this water is already treated for physical and chemical purification, it has Linear Curved Reflector designed to concentrate sunlight on water bottle much lower turbidity which makes SODIS very effective Parameters chosen: Solar intensity on earth’s surface of 700 Watt.hr/m2 - a conservative number Using this value, performed optical modeling using LightToolTM to determine the irradiance (both for Infrared and UV) at the water bottle
Secondary reflector ( Water
Opened up Soda can to make reflector
Secondary reflector improves efficiency (by 30%) Goal : 15 Gallons of water to be purified per day. This will be adequate for 4-5 families (~ 3 gallons per family)
Design parameters: About 6 hrs. of strong sun light per day Calculated total amount of solar energy that would be delivered (to heat 15 gallons of waters to 55oC) Adjusted the reflector shape and size until results were acceptable Added secondary reflector that increased light concentration by 30% From this, estimated that a solar panel of area 1.4 m2 will be needed. This will be ~ 1.2 meter x 1.2 meter Fabricated a smaller version of the solar concentrator using scrap materials (Soda can + Al foil) to treat 1 liter of water to prove my concept (as building a 1.2 meter x 1.2 meter was not practical)
Used the same reflector shape, but adjusted the size (area) to heat 1 liter water to 55oC in 6 hrs
Experimented for 6 hrs. on 3 different days
Measured water temperature as a function of exposure time Water temperature of 55oC can be obtained after 6 hours of treatment using the proposed concentrator design
Stand Water under holding exposure bottle Linear curved reflector
Water heated by sunlight using linear solar concentrator. In one hour one can see water vapor on the wall! 700
600
500
1 2 3 400 Control
E. Count(CFU) E. Coli 300
4 5 6 200 100
0 0 1 2 3 4 5 6 UV Exposure Time (Hours) E-coli count with various UV exposures – from 1 hr to 6 hrs
Significant reduction in E-Coli count (580 to 9) after 6 hours of UV exposure Physical: Longevity of sugarcane bagasse, effectiveness of filtration (clogging), impact on water taste Chemical: Effectiveness of filtration (clogging) and ability to bind heavy metals Biological: Impact of dust deposition on solar reflector surface (reduced reflection), change in shape due to heat stress, cleanliness of bottles
GOAL: 15 gallons of purified water per day (For 5 families) Physical Purification – Free (bagasse) Chemical Purification - $12 (CaCl2 - $6, Activated carbon processing - $6) Biological purification - $6 (Reflector accessories) Maintenance cost = $12 Total Cost – $30 (per year) Total cost per year per family = $6 Based on insights gained from this work, developing a LED based water purification system using UV-A LEDs UV-C LEDs are typically used for purifying water Leveraging synergetic effect, UV-A LEDs may be used, in combination with heat, instead of UV-C Use water to be purified to cool LEDs during operation If the water temperature is not adequate, use additional heating mechanism Flow heated water through the tube and irradiate with UV-A Cross-sectional View Top View Parameters Measured Water Sample
Separation Parameters As collected from After Physical After Physical (P) After P, C and Method swamp purification (P) and Chemical (C) Biological (B)
Physical Turbidity (NTU) > 840 15 2 2 Chemical Lead (ppb) 32 32 3 3 Chromium 122 122 53 53 (ppb) pH 6.5 6.5 7.5 7.5 Biological E-Coli (#/uL)
OK to Drink!! 1. http://www.alamy.com/stock-photo-sugar-cane-juice-stall-132224992.html 2. Coconut Shell Activated Carbon, OSMOSIA, Water Technology and Water Filtration Process manual 3. Solar water disinfection, A guide for the application of SODIS, Swiss Federal Institute of Environmental Science and Technology and Dept. of Science and Sanitation in Developing Countries, SANDEC Report No 06/02 4. http://www.palintest.com/en/support/research-insight/lead-drinking-water-testing 5. Wegelin M., Canonica S., Mechsner K., Fleischmann T., Pesaro F., Metzler A. (1994): Solar Water Disinfection: Scope of the Process and Analysis of Radiation Experiments, J Water SRT – Aqua No. 4 6. http://www.itacanet.org/the-sun-as-a-source-of-energy/part-2-solar-energy- reaching-the-earths-surface 1. http://www.alamy.com/stock-photo-sugar-cane-juice-stall-132224992.html 2. Coconut Shell Activated Carbon, OSMOSIA, Water Technology and Water Filtration Process manual 3. Solar water disinfection, A guide for the application of SODIS, Swiss Federal Institute of Environmental Science and Technology and Dept. of Science and Sanitation in Developing Countries, SANDEC Report No 06/02 4. http://www.palintest.com/en/support/research-insight/lead-drinking-water-testing 5. Wegelin M., Canonica S., Mechsner K., Fleischmann T., Pesaro F., Metzler A. (1994): Solar Water Disinfection: Scope of the Process and Analysis of Radiation Experiments, J Water SRT – Aqua No. 4 6. http://www.itacanet.org/the-sun-as-a-source-of-energy/part-2-solar-energy- reaching-the-earths-surface