Water treatment

What is the purpose of a flocculant? How does it remove small particles form water?

• traps small particles into large aggregates that will settle to the bottom

What happens during filtration through sand beds?

• matter stick to the sand grains

• activated charcoal used to remove chemicals

• bacteria used to catch particles in biofilms

• inexpensive/ easy to maintain

How are membranes better or worse?

• completely removes large particles like Giardia 

• expensive and hard to maintain 

What are the 3 common methods of disinfection of filtered water? 

1. Chlorine: 

• effective/ inexpensive 

• leaves residual taster/health concerns 

2., Ozone ( reactive oxygen)

• no residual taste/ health concerns

• expensive/ hard to maintain

3. Ultraviolet:

• no residual taste/ health concerns

• must pass through special tubes ot give good exposure

What is an indicator organisim? Why do we test for it instead of directly testing for pathogens? 

• indicate the presence of conditions which potentially can cause illness in people

• can’t test for pathogens