How does turbidity affect dissolved oxygen?

Question

I have to do a EEI for school about turbiduty of water and finding the most cost effective method for purifying a sample of water. My group was planning to do a standard test where we use materials such as filter paper, cloth, sand, gravel, etc. and run the turbid water through it. As our school has no turbidometers we wanted a way to have some quantitative data. To do this we were planning on conducting a dissolved oxygen test (wrinklers method) as we found some sources linking turbidity to oxygen levels. Would this be a valid test? Would the filtered water need to sit overnight, for example, before we tested the DO?

And help is appreciated!!!

Answer 1

According to this document, turbidity and oxygen content can be correlated because the more microbes in the water, the more turbid the water is, and the less oxygen is left (because they breathe it).

But a correlation is no cause-effect relationship. Both are linked in the particular case of microbes because they affect both by their presence.

Not a reliable method at all. More oxygen in the water does not mean it is potable. If you let sit a bucket of water contaminated with microbes, the oxygen levels will drop over time, but if you stir the water, you re-dissolve some up to saturation levels, but you still have the microbes present.

You may want to evaluate the oxygen demand, or the biomass (absorption at 600nm), centrigugate and evaluate visually, etc.