Quantifying the Impact of Reused Plastic Materials on the Quality of Drinking Water
Supervisor: Dr Marta Vignola and Dr Caroline Gauchotte-Lindsay
School: Engineering
Description:
Unsafe drinking water is responsible for over 829,000 deaths annually (WHO data). Safe and affordable drinking water for all remains out of reach, especially in rural areas. As of 2020, only 88% of the world's rural population had access to improved water sources, compared to 98% in urban areas. Sub-Saharan Africa has a more significant divide, with only 66% of the rural population having access and just 28% relying on piped water.
In areas without access to piped water, light and durable plastic containers are often used for its transport and storage. However, when these plastic bottles come into contact with drinking water, a significant amount of organic matter can be released. These compounds are often biodegradable, providing microorganisms with assimilable organic carbon (AOC) source, which can promote microbial growth and biofilm formation (1). This can ultimately compromise the safety of the drinking water itself. Factors such as storage temperature and cleaning strategies can affect the process of carbon migration into the drinking water and ultimately impact its quality.
Kware is a peri-urban community located on the outskirts of Nairobi, Kenya, where local vendors are relied upon for drinking water, and repurposed plastic bottles are used to collect and store it. Thanks to an interdisciplinary project funded by GCFID, numerous water bottles that are used for this purpose have already been collected, along with information on the common practices for their usage, cleaning, and storage.
The goal of this project is to measure the impact of these plastic bottles on the overall quality of the stored drinking water. To achieve this goal, the project will pursue the following two objectives:
- Quantify and characterise the amount of organic matter that migrates from the bottle into the drinking water at different storage temperatures and after multiple cleaning cycles;
- Assess and quantify the microbial growth supported by the organic carbon released.
Bottles will undergo multiple cleaning cycles; the effect of each cycle on carbon migration will be assessed by quantifying and characterizing the leaked organic matter. Microbial growth will be assessed through flow cytometry (FCM).
Additionally, coupons of the bottles' plastic material will be created, immersed in ultrapure water, and incubated for several days at different temperatures. The organic carbon released will be quantified and characterized using analytical chemistry techniques such as FEEM and LC-OCD. Microbial growth will be assessed using the standardized BioMig method (2).
1: Neu, L. et al. npj Biofilms Microbiomes 4, (2018)
2: Wen, G. et al. Environ. Sci. Technol. 49, 11659–11669 (2015)