Simple sand filter construction

My water quality students in ENVH 568 built these sand  filters for a class requirement. They are now up and running in the LLU Environmental Microbiology Research Laboratory. We will use them for some class activities in the ENVH 569 sampling class. 

We started with a design and then a trip to the hardware store

We dry-fit the pieces together in the hardware store. This is where the students realized that there are many possible combinations.

Students discovered that there were a few possible combinations of diffuser pipes and spout exit styles. Our class built five filters with varying construction.

All filters had about 2 inches of 3/4" gravel around the pipes with another 2 inches of pea gravel on top of that (1/4" gravel). Those were separated by a cloth to minimize sand going into the gravel and then the bottom diffuser pipe.

Sand was added on top of that until it was about 2" below the spout. Our filters tested varying heights.

There were 5 filters built and are now hooked up to a recirculating water system. They will be tested for arsenic and E.coli removal in our ENVH 569 class.