Why did a Canadian town’s water supply turn pink?

Pink water. Image: Magic Momentz/Flickr/creative commons.

Most of us take it for granted that the taps in our homes will deliver safe and clean water for drinking, cooking, showering and cleaning. This means there is usually little interest from the public in how the water gets there. However, it took less than a day for a story from Onoway, a small town in Alberta, Canada, with just over 1,000 residents, to make it from social media to global newsfeeds. “Bright pink water comes out of taps in Canada!” – suddenly we are all interested in water treatment methods. The Conversation

To enjoy the benefits of clear and safe water, a hidden but valuable infrastructure of water treatment exists in our cities and villages. These are operated and maintained by engineers and scientists, and among them are water chemists. These chemists have been investigating the use of neat chemical reactions to remove undesired chemicals and potential pathogens from naturally sourced water and to prepare the water for its safe journey through distribution systems.

The local drinking water treatment plant of Onoway treats its water using potassium permanganate. This is an almost black looking solid which forms a bright purple solution in water and also removes dissolved iron and another metal called manganese.

Iron and manganese are not harmful to human health, but if these metals are present at high concentrations it can lead to deposits in the water distribution system and discolouration of the water. However, the auburn tints of iron seem boring compared to the spectacular pink that has raised global interest and lively social media discussions.

Customers are very sensitive to the colour, taste and odour of drinking water – these are the human senses used to assess water quality – so this incident has understandably caused alarm. The pink colour stems from some potassium permanganate that escaped through a failed valve and into the drinking water distribution system, eventually ending up with the customers.

Potassium permanganate has been used in drinking water treatment for more than 100 years. In addition to iron and manganese removal, it is used to remove taste and odour as well as to control undesired algal or mussel growth in treatment works. It also has disinfecting properties. Permanganate forms solid, black manganese dioxide when it reacts with the water contaminants – and this can then be filtered out of the water.


A little goes a long way

Potassium permanganate has the chemical structure KMnO4 and is a compound that is electron deficient – that is, it doesn’t have enough electrons. This lack of electrons makes it a strong oxidant that readily reacts with a wide range of unwanted compounds in water. It belongs to an established group of water treatment chemicals that can be summarised under the term “conventional chemical oxidants”, which also include oxygen, chlorine, chlorine dioxide, ozone, hydrogen peroxide and, in the wider sense, UV light.

Water is typically treated with a dose of 1-3mg of potassium permanganate per litre of water, which is quite a small amount. But only unreacted potassium permanganate has a visible pink colour in water and is visible even at very low concentrations – as low as 0.05 mg per litre of water – so it doesn’t take much to add colour.

Since only small quantities of permanganate can change the colour of water, customer complaints relating to residual permanganate are known to occur . This means treatment works usually take care to remove any unreacted, coloured permanganate before the water reaches consumers.

The pink water does not pose a threat to human health but skin irritation related to potassium permanganate is known at a certain concentration. Onoway’s mayor claimed that customers were not at risk. However, these concentrations seemed to vary – some had water merely tinted pink whereas some water was bright purple. Regardless of what shade of pink they receive, customers are advised to rely on alternative drinking water sources until the permanganate is flushed out of the distribution system.

Water treatment isn’t simple

For water treatment, there is no one-size fits all approach. Drinking water treatment processes vary due to different local water resources and what the traditional and established technologies are. Iron and manganese can be removed by alternative methods, such as aeration, which uses the oxygen present in the air, or by running the water over catalytic granules consisting of manganese dioxide. But every method has its specific advantages and disadvantages.

Many parameters need to be evaluated before making an informed decision on which method to use to treat a water supply – but there’s no doubt that potassium permanganate is one of the more colourful methods.

Jannis Wenk is a lecturer in water science and engineering at the University of Bath.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

The smartphone app placing virtual statues of women on the map

A virtual Edith Wharton in Central Park, New York City. Image: The Whole Story Project.

If you’re a woman, then in order for you to be immortalised in stone, bronze or whatever once you’ve shuffled off this mortal coil, you should either have royal blood or be willing to be sculpted naked. That is the rule of thumb.

A statue that actually celebrates a woman’s achievements is a rare sight. Writing in the New Statesman last year, equality campaigner Caroline Criado-Perez found that out of 925 statues in Britain, as listed by the Public Monuments and Sculpture Association, only 158 are of solo women. Of these, 46 are of royalty, including 29 of Queen Victoria. Fourteen depict the Virgin Mary.

There are signs of change, albeit slow. The suffragist Millicent Fawcett is set to be honoured with a statue in Parliament Square, where currently all 11 of the statues are of men. (They include Nelson Mandela and a nine-foot Gandhi.) The monument is to be unveiled next year to celebrate the centenary of British women receiving the right to vote.

Elsewhere, the late comedian Victoria Wood is being honoured with a statue that’ll be erected in Bury, Greater Manchester. In the Moss Side area of the city, a statue of Emmeline Pankhurst will be unveiled in 2019. Unlike the Fawcett one, neither of these is expected to receive public money, relying on crowdfunding and other sources instead.

So how many more statues of women, regardless of how they’re funded, would we need to build in order to reduce the gender gap? Well, according to Jonathan Jones, art critic at the Guardian, the magic number is: zero.

Jones’s argument, back in March, was that building statues doesn’t advance feminism, but simply traps us in the past. He wrote:

Statues don’t hold public memory. They politely bury it. These well-meaning images melt into the background scenery of our lives.

Whether this is empirically true is questionable, but it’s true that we tend not to erect them as often as we used to anyway. This is partly because there is less space available for such monuments – a noticeable disadvantage cities of the present have compared to those of the past. In order to reduce the imbalance, statues of men would probably have to be removed; many would no doubt be okay with that, but it would mean erasing history.

One partial answer to the problem is augmented reality. It can’t close the gender gap, but it could shine a spotlight on it.

To that end, an advertising agency in New York launched an app at the beginning of May. The Whole Story allows users to place virtual statues of women on a map; other uses can then view and find out more about the individuals depicted at their real-world locations, using their smartphone cameras.


Currently, users have to upload their own virtual statues using 3D-modelling software. But going forward, the project aims for an open collaboration between designers, developers and organisations, which it hopes will lead to more people getting involved.

Contributions submitted so far include a few dozen in New York, several in Washington and one of Jane Austen in Hyde Park. There are others in Italy and the Czech Republic.

Okay, it’s an app created by a marketing firm, but there are legitimate arguments for it. First, the agency’s chief creative office has herself said that it’s important to address the gender imbalance in a visual way in order to inspire current and future generations: you can’t be what you can’t see, as the saying going.

Second, if the physical presence of statues really is diminishing and they don’t hold public memory, as Jones argues, then smartphones could bridge the gap. We live our lives through our devices, capturing, snapping and storing moments, only to forget about them but then return to and share them at a later date. These memories may melt away, but they’ll always be there, backed up to the cloud even. If smartphones can be used to capture and share the message that a gender imbalance exists then that’s arguably a positive thing.  

Third, with the success of Pokemon Go, augmented reality has shown that it can encourage us to explore public spaces and heighten our appreciation for architectural landmarks. It can also prove useful as a tool for learning about historical monuments.

Of course no app will replace statues altogether. But at the very least it could highlight the fact that women’s achievements are more than just sitting on a throne or giving birth to the son of God.

Rich McEachran tweets as @richmceachran.

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