Assessment of disinfecting contaminated water bottles for reuse within potable water requirements in Tanzania.
Author
Friis, Line Møller
Term
3. term
Publication year
2020
Pages
103
Abstract
Tanzania is a developing country where a large share of the population lives in poverty and experiences severe effects of climate change. Lack of safe water creates high risks of waterborne disease and death, and even when clean sources are available, dirty bottles and containers used for transport can re-contaminate the water. This thesis evaluates a bottle-cleaning unit designed to ensure that water refilled into a cleaned bottle continues to meet Tanzania's potable water standards. The unit disinfects with ECA water, a sodium-chloride-based solution that inactivates bacteria through oxidation and does not require rinsing. During testing, disinfectant concentration, water pressure, and cleaning time were adjusted, and the nozzle was physically modified, aiming for consistent microbiological results while minimizing water waste. Under the tested conditions, a concentration of 30 ppm for 5 seconds at 2.6 bar met the criteria and reduced counts of living bacteria (viable counts) by up to 99% compared with water in an uncleaned bottle. Coliform bacteria and E. coli were not detected, and ATP levels (an indicator of biological material) on the bottle cap and mouthpiece and on the unit’s surfaces were negligible, suggesting a limited risk of disease transmission between users.
Tanzania er et udviklingsland, hvor en stor del af befolkningen lever i fattigdom og mærker de alvorlige følger af klimaforandringer. Manglende adgang til rent vand giver høj risiko for vandbårne sygdomme og dødsfald, og selv når rent vand er tilgængeligt, kan snavsede flasker og beholdere til transport forurene vandet igen. Dette speciale undersøger en flaske-renseenhed, der skal sikre, at vand påfyldt i en rengjort flaske fortsat opfylder Tanzanias drikkevandsstandarder. Enheden desinficerer med ECA-vand, en natriumklorid-baseret opløsning, som inaktiverer bakterier ved oxidation og ikke kræver efterskyl. Under forsøgene blev koncentration, vandtryk og rengøringstid justeret, og mundstykket blev fysisk ændret, for at opnå stabile resultater inden for de mikrobiologiske kriterier og samtidig minimere vandspild. Resultaterne viser, at 30 ppm (dele pr. million) i 5 sekunder ved et vandtryk på 2,6 bar opfylder kriterierne og reducerer antallet af levende bakterier (viable counts) med op til 99% sammenlignet med vand i en urengjort flaske. Coliforme bakterier og E. coli blev ikke påvist, og ATP-niveauer (en indikator for biologisk materiale) på flaskeprop, mundstykke og enhedens overflader var ubetydelige. Dette tyder på en begrænset risiko for smittespredning mellem brugere under de testede betingelser.
[This apstract has been rewritten with the help of AI based on the project's original abstract]
Keywords