Science Buddies: "Ask an Expert"

1. I have done hours of research but cannot seem to find the particle size in microns of common water pollutants like zinc, copper, lead, manganese, iron, E coli, coliform,nitrites/nitrates, phosphates, and pharmaceuticals.

2. I cannot seem to identify a reasonably priced test kit or laboratory test for many of these pollutants. I do have a Reef aquarium test kit for calcium, phosphates, nitrates, and hardness. I can test for chlorine and pH using a pool test kit. For the rest I am looking for guidance.

Thank you

Hi schufoo,

1. Most of the water pollutants you mentioned are far smaller than 1 micron (1 Micron = 10^-6 Meters). The measurement you are looking for is called an Angstrom. 1 Angstrom = 10^-10 Meters. Any molecule (like zinc, copper, or lead) will be on the order of a few angstroms. The same is true for nitrites/nitrates, phosphates and pharmaceuticals. E. coli and other bacteria are on the order of 1 micron (approximately 1 x 5 microns).

2. Use Google to search for "coliform test kit", which can be used to test for bacteria like E. coli. You'll find many reasonably priced kits. The same is true for zinc and lead.

I hope this helps.

-Dave

I did find a coliform test kit. Thank you Dave.

I ran a trial test tonight using a 1900 3M Maximum Allergen air filter that is rated a MERV 13 so should filter out particles as small as 0.3 microns at an 80-95% rate. I used two layers of the air filter material and a thick layer of activated carbon suspended in pantyhose to keep it compact. When I tested for nitrates my filter accomplished almost nothing. My activated charcoal has sat around for a couple of years since I last did some testing, so could it be old? Could the water flowing through the air filter material have compromised it's filtering capabilities? I did flatten out the filter material from it's pleated state to make it easier to work with, but that shouldn't have decreased it's filtering capability as I thought a higher MERV rating was from a tighter weave of the filter material. I really thought I had a good idea here, but I failed miserably tonight. I had hoped to construct a filter for storm water outflow pipes in my area using the sandwiched carbon, air filter material and a layer of filter sock used on drainage pipes, but now I am not sure what to do. Does anyone have any thoughts?

I have solved the problems of the other night by purchasing a new test kit and new activated carbon. I have my model set up and I ran flow rate tests tonight successfully and am ready to test my filter when we get the next big rain after a dry spell. I am getting a turbidity meter from one of the teachers at schhol. I have my test kit for nitrates, ph etc. and am ready with easygel and an incubator for e coli and coliform. I haven't been able to find a way to test for heavy metals or pharmaceuticals in the water that doesn't require some high tech equipment that I don't have access to. Does anyone know of a kit I can purchase or any other ideas? Thank you.