Water purity indicator

Hi guys

Gr8 forum.. have been hooked onto it for the past hour. As for intros, i am an engineering student <electronics> from india, lookin fwd to hv some fun here

I want to design a water purity indicator. Any ideas???

Thnx for the trouble...

Apart from a simple conductivity test, is it possible to say whether the sample is microbe-free???

In my town, we face a lot of diseases due to contaminated water. The market is flooded with purification devices, but no reliable means to check whether they really work. Any sugg guys???

You should start by developing an understanding of the contaminents. I think, although the subject matter may be interesting, people are less concerned about detection than using a shotgun approach to removing every possible contaminent 50 times over. I also think electronics will be of little help in detecting biologicals which are probably the main sources of polution.

The usual method of detecting inorganic compounds is to precipitate them out of solution. I see little opportunity for electronics there. You might find interesting projects that will measure the pH, or the alkalinity, or the metalic content.

There is mass spectrometry which is expensive, but probably the most thourough way of analyzing an unknown sample.

I could be wrong on any of these points, this is not my area of expertise. Let us know what you find.

Thanks papabravo...

Guess u r rite abt the microbes. It was just a wild hope.

Cud i build a ckt to measure levels of other contaminants like iron, aluminium etc...?

You can certainly build circuits that will measure things, the problem is to find something to measure that is corellated with the presence of something you are interested in. I would start by learning about and measuring pH. The term is a chemical shorthand for the concentration of Hydrogen Ions, H+.
Pure water has a pH of 7. IIRC that means the concentration of Hydrogen Ions is 10^-7 moles/liter. A strong acid like 18M Sulphuric Acid
https://en.wikipedia.org/wiki/Sulphuric_acid
woud have a pH of 1, while a concentrated solution of Lye or Sodim Hydroxide would have a pH of 14.

This is a logarithmic scale similar to the Richter scale for measuring earthquakes and the decibel scale for measuring power and gain. You could find worse topics to spend some time on. Good luck and let us know what you find.

Thanks papabravo....

I do hv a chemistry bkground... had some fun at highschool with it. pH is related to conductivity and can be measured. But how do i identify the presence of individual elements like iron and more importantly their levels??? I wonder whether there are any cks available?

I will do a bit of digging... Thnx papabravo. But i think this is one area whr Chemistry beats electronics' ass!

Hi Hurricane,
The usual method of measuring purity is to measure the pH and conductivity.
The measure of pH is pretty straight forward; the pH probe outputs a small voltage with respect to pH. To measure conductivity, pass an AC signal through your solution and use a probe in a feedback loop to measure conductivity.
As for biologicals, I agree with Papabravo; they are best measured other ways.
Please keep us posted on your findings, this is a most interesting project.
Regards,
Robert

PS, both pH and conductivity are temperature dependent