Science Buddies: "Ask an Expert"

I am trying to conduct a science fair project on purifying floodwater.
Do you know where I can get any floodwater from?
What are the top items I should be testing the floodwater for to prove I have purified it once the experiment is done?
What types of contaminants should I make sure are in the floodwater?
Any other important information I should include or research?

I'm having problems narrowing it down.
I'm also having issues finding Guidelines for Drinking Water as set by the World Health Organization.

Thanks for any help you can give.

Hi,
Flood water could contain many different things depending on where the flood occurred. If it was a flooded farm there would be fertilizer, pesticides and maybe waste from animals. Flood water from a city like New Orleans might contain gasoline or oil, human waste, dirt, rotting garbage—almost anything. In Fukushima, Japan, water from the tsunami flood contained radioactive waste. All I am try ing to say is that there is no single list of pollutants in ‘flood water’.

What is your purpose in purifying flood water? To make it drinkable? To remove a specific pollutant? Do you have a hypothesis? What method were you planning to use to purify the water? Distillation removes just about everything but it requires a lot of energy. Filtration and deionization as with a Berkey water purification system can make water drinkable, but these units are quite expensive and could not produce enough water for a flooded community if that is your purpose.

As to where to get flood water, I would think collecting runoff from a street gutter during a heavy rain would be about as close as you could get without traveling to a flooded area. Here again what is in the water will depend on where you collect it. It will always have some dirt, insect parts, trash and soil particles that have to be filtered out and there will probably be nitrates from fertilizer used on people’s lawns, maybe some herbicides such as RoundUp and metals from rusty pipes, buildings and automobiles.

Repost on this thread with some specific description of your purpose and plans and we can try to help you design a project.

Regards,

Sybee

Purpose:

The purpose of this experiment is to determine and demonstrate how the boling point of water collections of its water vapour can create drinkable water from highly contaminated simulated floodwater by the pre and post testing of Total Dissolved Solids (TDS), Bacteria, arsenic, chlorides, metals, flouride, hardness, manganese, nitrates and nitrites sodium, pH, and uranium. This is in relation to the Federal-Provincial-Territorial Committee on Drinking Waters' (CDW) Guidelines for Canadian Drinking Water Quality.

Hypothesis:

I predict that boiling of water and collection of its water vapour will remove the harmful contaminants from the simulated flood water. This includes microbiological, chemical and physical, and radiological contaminants that flood water may contain. I believe that for all twelve test factors, the created clean drinkable water will be within the range of what is considered "quality drinkable water" by the Federal-Provincial-Territorial Committee on Drinking Waters' (CDW) Guidelines for Canadian Drinking Water Quality.


Basically, I wanted to take run-off water from a nearby river and add certain amounts of specific contaminants to pointedly demonstrate different contaminants within it. I haven't decided what that will all include. Amongst my ideas are: dry wall, water paint, oil paint, gravel, sand, tar, asphalt, gas, salt, detritus, fertilizer, and manure.

From there, I was going to simply make up 4 separate 10L pots of this simulated flood water. I was going to test all 4 prior to the experiment to show how dirty they were. Then, I was going to boil 3 of them for 5 minutes each at a constant temperature between 100 and 105 degrees. The idea is that the water will evaporate, hit the upside down lid of the pot and slide into the cup in the middle, creating clean drinking water.

Thoughts on how I was planning on running this experiment? Foreseeable issues? What kind of contaminants should I make sure are in it?

Distillation has been used to purify water probably since the Middles Ages. It works for particulates, microbes, metal and other salts. Some volatile compounds like oils and other hydrocarbons ('oil paint, asphalt, gas') will distill over with the steam, however, so if these are present the water may still not be drinkable. Flood water would likely have some volatile compounds that distill with the water vapor phase and condense into the receiver. You might want to run your water through an activated carbon filter to remove VOCs before distillation.

Sybee

I am conducting this experiment and am adding some mixed gas in the ratio of 1:50 to 1 litre of floodwater.
How much gas should I add?
I was thinking around 1 mL mixed gas to 1 litre of floodwater, but am now thinking that may be too much.
Thoughts?

Hi,

When you say you are adding 'mixed gas', what exactly do you mean? Gasoline? If you add gasoline to water and then heat it to boiling you are creating a potentially explosive situation that could be dangerous. Please explain your method better. As i said in my previous post, water distillation is only good for removing solids, not volatile compounds like gas. If you want to remove gasoline or oil, you need to filter the water through activated charcoal.

Maybe i am misunderstanding what you are doing, so please try to give more details of your procedure so we can help you better.

Sybee