Age 15 | London, Ontario
Canada-Wide Science Fair 2018 Finalist
Clean water is a basic human right, yet not all Canadian residents have equal access. A 2015 investigation by the Canadian Broadcasting Corporation showed that there are “third world” water conditions on First Nations reserves1. The investigation revealed that two-thirds of all Canadian First Nations communities have been under at least one drinking water advisory during the last decade1. The Neskantaga community in Ontario has been under a boil water advisory for over 20 years1. Waterborne diseases are more common in Indigenous communities and as a result have poorer health outcomes and more commonly suffer from cancers and chronic conditions2. Lack of access to clean water could be due to the high expense of building and maintaining large water decontamination systems, which proves the need for effective low-cost and simple filtration systems.
Banana peels were chosen as a filtration material as they are widely accessible, produced in 135 different countries3, and one of the cheapest fruits on the market. The porous nature of the peel was the primary reason to use these as a filter to trap particles4. Oregano was chosen because its primary compounds, carvacrol and thymol, both have antibacterial properties5. Oregano is also widely accessible, grows quickly, and inexpensive.
In Canada, drinking water is tested in two ways; a turbidity test and a bacterial test. Turbidity is a measure of the cloudiness of a water sample. It is an indicator of the effectiveness of disinfection methods6. Increased turbidity increases the potential risk of pathogens in the water sample. Health Canada guidelines state that drinking water must be under 1 NTU6. Municipalities also test for three different bacteria; total coliform, E.coli, and background bacteria6. E.coli is an indicator of the microbiological safety of drinking water and was used in this study to examine oregano’s effects on bacterial growth. Health Canada guidelines dictate that the bacteria count must be zero6. These two tests were used in this investigation to study the effectiveness of the filtration system.
The purpose of this experiment was to create a simple low-cost filter that uses common materials, is easily replicable, and produces water that is safe to consume by eliminating bacteria and particle contaminants through the use of banana peels and oregano.
The first hypothesis was that the banana peels would cause the turbidity of the water to decrease by a minimum of 50%. The fresh peels were predicted to be more effective as ground dried peels are less porous than cut up pieces of fresh banana peels. The second hypothesis was that oregano would decrease the growth of the E.coli bacteria by a minimum of 50%. The dried oregano was expected to be more effective as the compounds carvacrol and thymol would be more concentrated.
To construct the final filtration system, a series of experiments were initially performed to test the effects of the materials on the cleanliness of water after filtration. The materials tested were fresh and dry banana, fresh and dry oregano, sand, and cotton. Potability was measured by turbidity and bacteria growth.
The materials used were 80 grams of oregano, peels of 6 bananas, 5 plastic water bottles, wine rack (6 large holes), 5L of distilled water, E.coli bacteria (strain ATCC 25922) , 50 mL of sludge solution, pipette, clean sand, measuring cup, 30 coffee filters, rubber bands, hot glue gun and glue, knife, oven, 6 sterile collection bottles, one 1L and two 500 mL bottles, petri dishes filled with media, turbidity machine, 10 mL turbidity tubes, pure white vinegar, staples, and used cotton towel.
1. Create a stand using the wine rack.
2. Cut the bottoms off of three 1L plastic bottles and place them upside down. Wrap a piece of used cotton around the bottom of each of the filters.
3. Dry the peels of 2 bananas in a convection oven at 300 degrees Celsius for 2 hours. Cut peels into 1 cm by 1 cm pieces. Soak in water for 24 hours. Spray with 50% vinegar solution and let air dry. When dry, place in a plastic bottle.
4. Fill remaining two bottles with ½ cup of sand.
5. Wash 20 grams of oregano, spray with a 50% vinegar solution, then air dry. Construct 3 teabags out of coffee filters and distribute oregano evenly among them.
6. In a licensed water analysis laboratory, create a suspension of contaminated water using E. coli and 0.5 grams of SPCA media powder. Record turbidity and colony forming units (CFU) of this sample. Pour the contaminated water through a sand filter, then the banana peel filter, expose to oregano teabags for 20 minutes, then pour through the last sand filter. Measure and record turbidity and CFU of final water sample.
When the sample of contaminated water was exposed to fresh oregano at concentration of 1 gram of oregano to 25 mL of water, there were significant changes in bacterial growth between the positive control, fresh oregano, and dried oregano. Twenty minutes of exposure to fresh oregano decreased bacterial growth by 100% (Figure 4). Dried banana peels were able to decrease turbidity by 98% (Figure 5). Exposure to fresh oregano at a lower concentration of oregano was not effective in eliminating E. coli bacteria.
This filtration system can be highly useful to many Canadians and people around the world who lack continuous access to clean drinking water. It is easily replicable as it uses common and low-cost natural materials that can be stored. Within only 20 minutes of exposure in a concentration of 1 gram of oregano to 25 mL of water, the oregano was able to decrease bacterial growth by 100%. The dried banana peels used in this experiment were able to decrease turbidity by 98%, and therefore together, these two water purification methods are capable of producing potable water according to Health Canada’s standards. It was already known that the compounds in oregano have antibacterial effects, however this study proves the extent of these effects. With the knowledge gained from the use of oregano in this experiment, future researchers may be able to conduct research on the two compounds carvacrol and thymol to develop a less elementary way to apply these in a low-cost way to current commercial water purification systems that only target the turbidity of water, to improve their efficacy.
Currently, large-scale water purification methods that are being employed by the government are not working well enough in underfunded areas of Canada. First Nations communities under water advisories could use this as an interim measure to improve water access. This could also be beneficial to communities with sudden outbreaks of waterborne diseases due to breakdown of infrastructure or natural disasters as recently seen in many parts of the world. This could prevent diseases and lead to better health outcomes. In the future, this prototype could be improved by adding materials or testing existing materials to remove heavy metals from the water. Further experiments can be done to determine how many times the filtration system can be effectively reused.
The final filtration system consisting of sand, dried banana peels, fresh oregano, and cotton produced potable water according to Health Canada standards.
I would like to thank Mr. Dan Huggins from the Water Operations Division, City of London, Mr. Chris Walsh, Public Health Inspector of the Middlesex Health Unit, and Ms. Bronwyn Kelly-Seigh and Ms. Angela Stott of SGS Laboratories London for their support and guidance for this project.
1. Levasseur, J. (2015, October 15). Water advisories chronic reality in many First Nations communities | CBC News. Retrieved from http://www.cbc.ca/news/canada/manitoba/bad-water-third-world-conditions-on-first-nations-in-canada-1.3269500
2. Bradford, L. E., Bharadwaj, L. A., Okpalauwaekwe, U., & Waldner, C. L. (2016). Drinking water quality in Indigenous communities in Canada and health outcomes: A scoping review. International Journal of Circumpolar Health, 75(1), 32336. doi:10.3402/ijch.v75.32336
3. Randy, P., & Evans, E. (2015). Horticultural Reviews (Vol. 43) (J. Janick, Ed.). John Wiley & Sons. doi:10.1002/9781119107781.ch06
4. Al-Qahtani, K. M. (2016). Water purification using different waste fruit cortexes for the removal of heavy metals. Journal of Taibah University for Science, 10(5), 700-708. doi:10.1016/j.jtusci.2015.09.001
5. Xu, J., Zhou, F., Ji, B., Pei, R., & Xu, N. (2008). The antibacterial mechanism of carvacrol and thymol against Escherichia coli. Letters in Applied Microbiology, 47(3), 174-179. doi:10.1111/j.1472-765x.2008.02407.x
6. Guidelines for Canadian drinking water quality: Summary table. (2006). Ottawa: Health Canada.
Turbidity FAQ. (n.d.). Retrieved January 14, 2018, from https://www.kjwc.org/water_quality_alerts/turbidity_faq/
Choi, C. Q. (2011, March 16). Banana Peels May Help Filter Pollutants Out of Water. Retrieved December 19, 2017, from https://www.livescience.com/13276-banana-peels-filter-toxic-metals.html
2017 WHO Guidelines for Drinking Water Quality: First Addendum to the Fourth Edition. (2017). World Health Organization, 109, 44-51. doi:10.5942/jawwa.2017.109.0087
Al-Qahtani, K. M. (2016). Water purification using different waste fruit cortexes for the removal of heavy metals. Journal of Taibah University for Science, 10(5), 700-708. doi:10.1016/j.jtusci.2015.09.001
Clasen, T., Roberts, I., Rabie, T., & Cairncross, S. (2015). Interventions to improve water quality for preventing diarrhoea. Cochrane Database of Systematic Reviews. doi:10.1002/14651858.cd004794
Piaskowski, K., Świderska-Dąbrowska, R., & Zarzycki, P. K. (2018). Dye Removal from Water and Wastewater Using Various Physical, Chemical, and Biological Processes. Journal of AOAC International. doi:10.5740/jaoacint.18-0051
Dizer, H. (2018). Comparison of microbial removal between slow dead-end versus tangential sand filtration. Water Environment Research. doi:10.2175/106143017x15131012152933
Maurya, S., & Daverey, A. (2018). Evaluation of plant-based natural coagulants for municipal wastewater treatment. 3 Biotech, 8(1). doi:10.1007/s13205-018-1103-8
Chung, D., Cho, T. J., & Rhee, M. S. (2018, March 11). Citrus fruit extracts with carvacrol and thymol eliminated 7-log acid-adapted Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes : A potential of effective natural antibacterial agents. Food Research International, 107, 578-588. doi:10.1016/j.foodres.2018.03.011
Wijesundara, N. M., & Rupasinghe, H. (2018). Essential oils from Origanum vulgare and Salvia officinalis exhibit antibacterial and anti-biofilm activities against Streptococcus pyogenes. Microbial Pathogenesis, 117, 118-127. doi:10.1016/j.micpath.2018.02.026
Pelissari, F. M., Andrade-Mahecha, M. M., Sobral, P. J., & Menegalli, F. C. (2017). Nanocomposites based on banana starch reinforced with cellulose nanofibers isolated from banana peels. Journal of Colloid and Interface Science, 505, 154-167. doi:10.1016/j.jcis.2017.05.106
My name is Anika Garg and I am a grade 10 student at A.B. Lucas Secondary School in London, Ontario. At school I am involved in DECA, science olympics, Reach for the Top, Model UN, math contests, and the swim team. Until a few months ago, I used to swim competitively for the London Aquatic Club. I also enjoy music as I play piano, clarinet, and sing in the school’s choir. I have a strong interest in science and plan on pursuing a career in a STEM field. I love learning about new topics in science, especially about ecology and biology. I got the inspiration for my project while watching a documentary about the bad conditions of drinking water in other countries. After this I became curious and discovered water issues in our own country. This led me to think about innovative solutions to overcome this important issue.This is my second year participating in the science fair, and I really enjoyed working on a project that piqued my interest.