Grantee Research Project Results
2019 Progress Report: Ultra-Low-Cost Reusable Solar Disinfection Sensor
EPA Grant Number: SV839487Title: Ultra-Low-Cost Reusable Solar Disinfection Sensor
Investigators: Lacks, Daniel J , Mesiano, Sam , Tippareddy, Charit , Maatouk, Chris , Stanley, Sam , Kang, Lei , Lu, Elaine , MacDougall, Gordon , Augustine, Ashley , Ahorukomeye, Peter , Meyers, Abigail , Salomon, Eric , Jella, Tarun , Hanumanthu, Anu , Sangani, Jay , Sinha, Annika , Pfau, David , Datta, Sanjit , Al-Serhaid, Sarah , Carr, Daniel
Current Investigators: Lacks, Daniel J , Tippareddy, Charit , Maatouk, Chris , Stanley, Sam , Kang, Lei , Lu, Elaine , MacDougall, Gordon , Augustine, Ashley , Sinha, Annika , Pfau, David , Datta, Sanjit , Al-Serhaid, Sarah , Lundgren, Katherine
Institution: Case Western Reserve University
EPA Project Officer: Page, Angela
Phase: II
Project Period: April 1, 2019 through March 31, 2021 (Extended to March 31, 2022)
Project Period Covered by this Report: April 1, 2019 through March 31,2020
Project Amount: $75,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2019) Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources
Objective:
The goal of this project is to prevent waterborne illnesses by improving a process known as solar disinfection, the most cost-effective household drinking water disinfection technique in the developing world. During a solar disinfection treatment, the user places a clear plastic bottle filled with source water in sunlight; there is typically sufficient ultraviolet radiation in six hours of direct sunlight to kill bacteria and other pathogens in the water. While the process is extremely simple, a wide range of factors from cloud cover to water turbidity drastically affect the treatment time. These factors can reduce the reliability of solar disinfection, eroding end user confidence in the technique and thereby preventing practical use of a method that is otherwise extremely accessible, affordable, and effective.
We propose the development of ultra-low-cost, reusable UV dosimeters called OSPRI and SANTE that change color to notify the user that the water is safe to drink. OSPRI is a submersible sensor that incorporates a UV-sensitive dye-based indicator formulation that changes color reversibly so that the sensor can be reused daily. SANTE is an even lower-cost embodiment that uses a similar dye-based indicator, but is affixed to the outside of the disinfection bottle. Such sensors would add very little to the long-term cost of solar disinfection but would drastically simplify the technique, thereby making it usable for far more people. The sensor’s design enables it to offer the highest accuracy at low cost while minimizing end-user training. We aim to develop OSPRI with cost below $1 USD and reusability for at least one year.
Progress Summary:
Approximately one year of the Phase II project term has elapsed. In that time, we have developed an indicator formulation that slowly changes color in response to ultraviolet exposure and is reusable for at least 90 cycles without significant decay or degradation. We have developed an additional device that is more lightweight than OSPRI, called SANTE. SANTE is a sticker-based sensor that is placed on the outside of the water bottle. Raw production costs for SANTE are significantly less than OSPRI, but it is less durable and likely has less reusability. Nonetheless, it provides a simpler platform for testing the underlying color-changing chemical formulation while we continue to refine the design of OSPRI's housing.
Since our last report, there have been three major developments in our effort.
1) The development of SANTE gives users an alternative to OSPRI that is significantly cheaper to manufacture and distribute. SANTE includes the same color-changing chemical formulation as OSPRI, but is incorporated into a vinyl sticker that can be placed on the outside of a water bottle during disinfection.
2) Two pilot field tests in Brazil and Kenya demonstrated the appropriate color changes of our chemical formulations (in the form of SANTE prototypes) with direct sunlight in the six-hour time frame known to be effective for solar disinfection. Disinfection tests using local drinking water sources demonstrated more rapid disinfection than traditional SODIS guidelines, suggesting that use of OSPRI or SANTE has the potential to significantly speed disinfection.
3) A modified formulation has demonstrated 90 cycles of reusability without significant change in the UV dose required to trigger the color change. These cycling tests are ongoing as we seek to characterize the upper limit of reusability with our existing design. The color intensity does diminish with time, however, and this is the subject of further design effort.
4) Two low-cost standardized protocols were tested that enable consistent and accurate testing of bacterial inactivation using our device. This testing protocol is much cheaper than the methods used in our previous field tests and will enable us to pursue field testing in locations with more limited laboratory resources. Our work was largely halted from March-June 2020 due to the COVID pandemic, as our laboratory facility was closed and a statewide shelter-in-place order was enforced. In addition to a halt in laboratory testing, our planned field testing in Uganda, Kenya, and Zambia has been postponed indefinitely due to restrictions on international travel.
Future Activities:
We have undergone development of a closely-linked device called SANTE that offers a cheaper alternative than our prior OSPRI at the cost of reusability. Preliminary field testing shows proper conversion times that correlate to the time for water disinfection. We have successfully demonstrated 90 cycles of our formulation without significant decay or degradation. A standardized protocol has been developed to cheaply, uniformly, and accurately undergo field testing in various sites. We anticipate successful completion of the specific aims during the project period.
Journal Articles:
No journal articles submitted with this report: View all 7 publications for this projectSupplemental Keywords:
Ultraviolet dosimeter, WASH, diarrheal disease, sustainable water management, drinking water treatment, water purification, water filtration, solar water treatment, water disinfection, pathogen removal, SODISRelevant Websites:
The Billion Bottle Project Exit
Progress and Final Reports:
Original AbstractP3 Phase I:
Ultra-Low-Cost Reusable Solar Disinfection Sensor | 2018 Progress Report | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
- Final Report
- 2020 Progress Report
- Original Abstract
- P3 Phase I | 2018 Progress Report | Final Report