SPIN CYCLE~ sand separators

Part 2 in a series on water filtration

 

Sometimes, wells have a lot of sediment and sand.  This material can really cause problems in a water system, and occasionally, cartridge filters just aren't sufficient to do the job.

In those cases, we will often install a sand separator, like the ones pictured in the photo.  

These filters literally spin the sand out of the water:

First,  unfiltered water is drawn through a side inlet, where it begins spinning down an inner chamber, creating a sort of vortex.  This spinning action causes the sand, which is heavier than water, to separate out of the central column of water.  The clean water is then pulled out of the center of the inner chamber, and sand falls out of the unit.

These filters do not address solutes or chemical contaminants in the water, only particles- and even then, not all of the particles.  Most systems require additional cartridge filters to remove smaller particles from the the client's water before it enters their water system, but these separators are a terrific first-line against particulates.  The thing that makes this filtration method really unique is that there are no moving parts, and nothing to replace-ever; so it could save a client a ton of money in cartridge replacements, not to mention if they have drip irrigation or spray nozzles in their systems.  

Sand Separators may not be the best solution for every case,  but it is truly dizzying just how effectively they can spin a solution for some!

"Reverse Osmosis?" You'll never learn ANYTHING that way!

Part one in a series on water filtration.

As a teenager, I remember laying my head on a stack of books when I should have been studying.

When questioned how that might improve my grades, I said I was learning through osmosis.

All that "studying" did not prepare me to understand how Reverse Osmosis works, though...

In osmosis,  a solvent passes through a membrane to try to achieve an equilibrium on both sides of the membrane.  This happens naturally when a red blood cell is submerged in water.  These contain a high concentration of solutes including salts and protein.  Water molecules pass through the cell membrane from an area of low solute concentration (outside the cell) to one of high solute concentration (inside the cell).  The cell membrane is selectively permeable, so only necessary materials are let into the cell.  

Osmotic pressure is the catalyst, and can be increased on the high-solute side of the membrane to force the equilibrium and stop osmosis. This is, apparently, represented in the following formula:

δPV = -RT ln(1-x₂) (2)

Presumably, if you continued to increase the pressure on that side, you will reverse that process, and that is how Reverse Osmosis works:  It actually pulls the water away from the solutes, through a semipermeable membrane, leaving pure, "distilled" water: H2O.  This is usually the last stage in a 2 or 3 stage filtration system, and because it takes a long time to pull water molecules through the membrane, small storage tanks are usually part of the system.  A typical home system will fit in a kitchen cabinet and provide about 10-15 gallons per day, delivered to a tap by the kitchen sink.   

Now, since it has been stripped of all the salts (electrolytes) and minerals the water has no flavor- and some folks say that "no flavor" tastes an awful lot like plastic.  But, if one is really concerned about the quality of your drinking water and is willing to pay the $250-$700 for the system, plus another $150 or so in yearly filter replacements, it is by far the best way to be assured of the quality of your drinking water.