Assessment of disinfecting contaminated water bottles for reuse within potable water requirements in Tanzania.

Friis, Line Møller

3. term

Water and Environmental Engineering , Master

2020

2020-12-31

103 pages

Tanzania er et udviklingsland, hvori fattigdom og konsekvenserne af klima forandringer præger størstedelen af befolkning, hvilket resulterer i store risikoer for vandbårne sygdomme og dertilhørende dødsfald som følge af utilgængeligheden af rent vand. Både nationale og internationale intiativer har fokuseret på at øge tilgængeligheden af rent vand, hvilket angiver en risiko i forurende beholdere, som benyttes til at transportere vandet i. Dette studie har undersøgt muligheden for at lave en renseenhed, der kan rense en flaske, således at det genopfyldte vand i flasken kan overhold krave for sikkert drikkevand, angivet i Tanzanias standarder. ECA vand er et disinfektionsmiddel baseret på natriumklorid, som bruger oxidations potentiale til at deaktivere bakterier, hvor efterskylning af flaske er unødvendigt. Ved at justere på parametrene rensetid, koncentration of vandtryk, benyttes kimtal til at vurdere hvorvidt kravene for drikkevand kan opnåes. Sideløbende er dysen til rengøring blevet modificeret. Ved en koncentration på 30 ppm og en rensetid på 5 sekunder ved et vandttryk på 2,6 bar er det muligt for kimtal at overholde kravene til drikkevand. Hertil vil kimtallet reduceres med up til 99% sammenlignet med vandkvaliteten i en flaske, der ikke var rengjort. Der er testet for Coliforms og E. coli, hvor et komplet fravær var fundet, hvilket opfylder kravene til drikkevand. Ubetydelige mængder af ATP var fundet på overflade arealer af dysen, gevindet i proppen og på flaske hovedet, hvilket indikere begrænsede smitterisiko imellem brugere.

Tanzania is a developing country, where the majority of the population are suffering from poverty and experiencing the severe consequences of climate change, resulting in great risks of waterborne diseases and related deaths due to inaccessibility to clean water. Both national and international initiatives have focused on increasing access to clean water, however contaminated bottles and containers for transporting the water remain a risk. This thesis has investigated the possibility of a cleaning unit that allows for the criteria of potable water, following the standards in Tanzania, to be withheld for water refilled in a cleaned bottle. The unit disinfects the bottles using ECA water, a sodium chloride based solution that inactivates the bacteria by oxidation, and does not require a rinse of the bottle after use. Cleaning time, concentration and water pressure were adjusted until a steady results of viable counts within the criteria for potable water could be met, where as little water as possible was wasted for cleaning. Alongside, the nozzle underwent physical modifications. It was found that a concentration of 30 ppm for 5 seconds of cleaning time with a water pressure of 2,6 bar will allow for the criteria to be met, and decrease the amount of viable counts of up to 99% from initial state of water in an uncleaned bottle. Furthermore an absence of Coliforms and E. coli is found, and insignificant levels of ATP is found on cap and mouth piece of bottle, and surface area of cleaning unit, indicating limited risks of transmitting diseases between users.

Disinfektionsmiddel ; ECA vand

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