Grantee Research Project Results
Final Report: Virus Removal in Biosand Filters for Rural Mayan Communities
EPA Grant Number: SU834754Title: Virus Removal in Biosand Filters for Rural Mayan Communities
Investigators: Nguyen, Thanh (Helen) H.
Institution: University of Illinois Urbana-Champaign
EPA Project Officer: Page, Angela
Phase: II
Project Period: August 15, 2010 through August 14, 2012
Project Amount: $75,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2010) Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Chemical Safety , P3 Challenge Area - Safe and Sustainable Water Resources , P3 Awards , Sustainable and Healthy Communities
Objective:
Our Phase I findings show that amending the BSF's sand media with iron particles of similar size results in effective MS2 bacteriophage removal. Before applying this technology to Socorro's biosand filters, the research team proposed testing the filters on-site using the community's typical practices. This required establishing an on-site laboratory in the community for the analysis of microbial reductions by biosand filters charged daily with the community's tap water seeded with pathogen surrogates. The tap water was distributed from a contaminated river, so the proposed studies gave insight into surface water quality fluctuations and the biosand filter's buffering capacity. Also, the team wanted to test to see if the different sand and iron media used in Socorro would affect microbial removal. It was imperative that the final design of an ironamended filter included rigorous testing of actual scenarios. This research was the first to evaluate the removal capabilities of a biosand filter packed with a mixture of sand and low-cost iron oxide materials in the developing world. The filter construction materials and source iron were available locally.
At UIUC, the research was focused on long-term virus removal experiments using the Centre for Affordable Water and Sanitation Technology's (CAWST) newly designed Version 10 (V10) BSF. It was predicted that the efficacy of removal would increase due to a larger sand column and a smaller maximum fill volume of the filter. Promising results pushed the team to construct another V10 BSF with sampling ports throughout the depth of the filter. The filter was used to test the effects of residence time and depth on virus removal.
Summary/Accomplishments (Outputs/Outcomes):
Long Term Removal of MS2 Bacteriophage in Version 10 BSF
In 2009, the Centre for Affordable Water and Sanitation Technology (CAWST) designed the new V10 BSF that had a larger sand column and a smaller maximum fill volume than the previous Version 9 (V9) BSF. These changes were hypothesized to increase the efficacy of virus and bacteria removal due to decreased flow rate and increased contact time between the microbefilled water and the sand particles. Previous research studies at UIUC showed that a sand-only V9 BSF removed MS2 bacteriophage at less than the EPA standard of 4-log removal for drinking water. At UIUC, the research team has focused on improving the effectiveness virus removal in the BSF. A V10 sand-only BSF was constructed and our results show that V10 BSF can achieve up to 7-log10 (99.99999%) removal of MS2, which is significantly higher than the removal achieved by the V9 sand-only BSF (Figure 1).
Figure 1. Comparison of long term removal of MS2 by V9 and V10 concrete BSFs.
Effects of Residence Time and Depth on Removal of MS2 in V10 BSF
Because of the high removal of MS2 we saw, the UIUC research team wanted to determine the causes of high removal of MS2 in the V10 BSF. Another V10 BSF was constructed with seven ports inserted down the depth of the filter so samples could be taken from each depth and tested for virus removal (Figure 2). Results from this filter show that virus removal increases with depth and with residence time (Figure 3). The more contact the water has with sand, the higher the removal of viruses.
Figure 2: Picture of the depth of the filter with and without residence time. Figure 3. Average removal of MS2 throughout V10 BSF with ports.
Research in Guatemala
In March, 2011, UIUC installed four experimental (two sand-only and two iron-amended) V9 BSF in Socorro. These filters were strictly for experimental use, and the water from the filter was not consumed by anyone. A Wuqu' Kawoq social worker was in charge of running waterthrough the filter daily. When the UIUC team traveled to Socorro, the filters were spiked with MS2 bacteriophage and tested for efficacy of removal.
Our results show two crucial points:
1. The sand-only BSF removed 3-log10 of MS2 bacteriophage in Guatemala, showing that the filters remove viruses, but not to USEPA drinking water standards.
2. The two iron-amended BSF removed 5-6log10 of MS2 bacteriophage in Guatemala, proving that the addition of ironoxide increases the efficacy of virus removal significantly.
Figure 4. Comparison of sand-only and iron-amended experimental biosand filters in Socorro.
Although our results are promising, iron-amended BSF have not been implemented in Socorro yet. It was imperative that we collect consistent data from the experimental BSF before implementing any filters. Furthermore, we needed to consider how the community would react to the addition iron into the filters. After implementation in 2010, some BSF showed weakness in the base due to incorrect concrete mix. This led another NGO in the area, Servants 4 Him, to strengthen the base by using chicken wire. Unfortunately, iron leached into the filter and left the effluent water with an iron taste. Users were reluctant to continue using the filters until they were replaced.
In early 2012, the UIUC engineering team began collaborating with the UIUC School of Social Work. Biannual house-to-house visits are made together to monitor implemented BSFs and educate community members on safe storage. A pilot health study on water use, safety, and sanitation will be conducted in individual households in the Socorro region in early 2013.
Conclusions:
Since January, 2010, there has been a 50% reduction in severe diarrheal illness and severe child malnutrition, leading to Prosperity of the People in the communities. 85% of BSF users around the world continue to use them after 8 years, making BSFs a sustainable technology to protect the Planet. Overall, the People affected by the project have an improved level of Prosperity. When Socorro's population receives water, their subsequently improved health now allows them to live more comfortable and productive lives. The student team gained experience and life lessons by working on this project, and the public that they reached out to became more aware of water issues. This project reduced the release of harmful human waste without the production of toxic byproducts, pollution caused by long distance transportation of materials, or a large input of energy, and thereby promoted the wellbeing of the Planet altogether.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 10 publications | 1 publications in selected types | All 1 journal articles |
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Type | Citation | ||
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Bradley I, Straub A, Maraccini P, Markazi S, Nguyen TH. Iron oxide amended biosand filters for virus removal. Water Research 2011;45(15):4501-4510. |
SU834754 (Final) SU834296 (2010) SU834296 (Final) |
Exit Exit |
Supplemental Keywords:
Water treatment, virus removal, pathogen disinfection, human health, electrostatic adsorption, zero-valent iron, biosand filtration, slow sand filtration
Progress and Final Reports:
Original AbstractP3 Phase I:
Undergraduate Project on Virus Removal in Slow Sand Filters for Rural Mayan Communities | 2010 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.