Review Biox Acqua water treatment drops.

[daved]

Following on from the helpful advice I received about water treatment for an upcoming trip to Africa ("Water purification - African hotels" - sorry couldn't get it to link to the thread), I looked further at chemical treatments.

I had used traditional chlorine based tablets in the past and found the taste unbearably foul (how I imagine the contents of the footbath at a public swimming pool might taste) and also inconvenient to treat smaller amounts of water since the tablets are too small to break. After a bit of searching of old threads and the web, I came across Aquamira drops, which claim to be more effective than Iodine or Chlorine and with little flavour, which sounded good. Biox Acqua is a British made product using the same chemical (Chlorine Dioxide) as Aquamira but generally seems to be priced about 30% cheaper.

This system uses two chemicals: chlorine dioxide and phosphoric acid, which come in separate bottles and need to be mixed together before use. According to the instructions, to treat 1 litre of water, you mix 12 drops of each solution in the cap from one of the bottles and then wait 10 minutes for them to react before adding to your water. During this time, the mixture turns yellow. After adding to the water you leave it for a further 10 minutes for it to do its stuff before you can drink the water.

I decided to give it a try last night and to do a taste test.

Firstly, the outer packaging for the product does not give you any instructions for use and does not tell you how much water the pack will treat (a bit of a defect in my opinion). The instructions on the side of the bottles tell you to mix the drops in one of the caps but don't say which - not sure if it matters but I chose the activator bottle cap.

Measuring out the dose is easy with the plastic dropper bottles. The bottle caps are not entirely flat however, so I am not sure how well the mixing cap would stand up on a rough surface. After ten minutes I added the drops to the water. Another minor sticking point here - how do you get the last of the drops out of the cap? Don't fancy rinsing out the lid with untreated water.

After a further ten minutes wait, we did a taste test of the water against ordinary tap water that had been standing in a similar plastic bottle for the same time. I gave a glass of each to my wife (the guinea pig for the evening!) without telling her which was which. Result - She couldn't tell which had been treated.
I could notice a bit of a chlorine wiff to the treated water in the bottle but no effect on the taste. In fact, I have tasted worse water out of the tap in this country (My parents live in Liverpool and their water seems to have a strong chlorine taste).

After leaving overnight, the water in the bottle smelled a bit more strongly of chlorine but again the flavour was unaffected.

Plus points:

• Taste - excellent
• Flexibility - can treat smaller volumes by adjusting the number of drops used

Minus points:

• Bulk - two 30ml bottles
• Messy - the pre-mixing stage is a bit of a pain and might be difficult outdoors.
• Packaging - would be nice to know how much it will treat before you buy
• Cost - more expensive than iodine - £7 pack treats 60 litres of water.

Manufacturers claim that it is more effective than chlorine or iodine, but I was not able to test this out (there are limits to what my wife will tolerate!)

It would be worth adding a small container to mix the solutions in rather than using the lid. Instructions say to add the mixture to the water rather than the other way round - not sure if this is critical

Overall, I am pretty impressed but it is not the most convenient system for outdoor use

 

[hedgepig]

I used to work with a company that produced a chlorine dioxide products and having seen actual test results I can confirm that it is a highly effective biocide because of its nature and mode of action.

Can you check what the constituents in the kit actually are. You say one of the bottles already contains ClO2, which can not be the case - are you sure it doesn't contain Sodium chlorite (NaClO2). Mixing this with an acid forces the dissociation of NaClO2 to produce ClO2.

ClO2 is a yellow/green gas, which is why the solution changes colour.

Is there any information about how many parts per million are produced in the reaction and what the final ppm is in the 1 litre of treated water? Have they published any actual micro test results for water with various industrial organic compounds? I'm interested in this because ClO2 is a very strong oxidant (much stronger than chlorine) and there is data to show that it oxidises pesticide, cyanides, penols and such like.

 

[daved]

Hi Hedgepig,

There is minimal information on the bottles - it is marked as "stabilised chlorine dioxide 2%" and "Ortho-phosporic acid <10%". There is no other technical information with the pack (one of my criticisms in fact)

The aquamira website does give some technical information that might help (I believe their product is the same composition and concentration):
http://aquamira.com/consumer/aquamira-water-treatment-drops/product-description

(have a giggle at some of the pseudo-science in their FAQ - Dumbing down a little too far I think)

Would be interested to hear what you might find out.

 

[hedgepig]

Yeah, that sounds about right - "stabilised chlorine dixoxide" is just sodium chlorite with some other things (like sodium hypochlorite) added. The idea is not to stabilise the "chlorine dioxide" (which doesn't exist at this stage), but to stabilise the sodium chlorite. Addition of the phosphoric acid causes the dissociation to ClO2. However, this method of generation produces low yield of ClO2 and high residuals of chlorites and chlorates at a low pH. The 2&#37; figure doesn't mean very much as it is the actual yield of ClO2 that is important - different formulations of "stabilised" ClO2 produce different yields. The other thing is that the actual yield of ClO2 is often measured with the iodometric titration method. This is fine when the generation method was the analytical chemistry method that produces pure ClO2, however it can't be used to accurately measure ClO2 yield from "stabilised" preparations as it also measures the residual chlorates and chlorites (thus overstating the actual amount of ClO2 present).

Although I rate ClO2 very highly, I know too much about the limitations of the "stabilised" generation methods to trust the products without actual test data to back up their efficacy.

I know of a method that produces high yield of pure ClO2 that could be easily (from a technological standpoint) made into a highly portable field based kit, however, the cost would almost certainly be too high (and I'm not going to start advertising for the company involved!)