Alum

[vacek]

As you all probably know,making up a strong solution of alum and then adding some of that to a jub of cloudy wate will create coagulaton/flocculation resulting in the particles settling out.  While supermarkets sell alum in the spice section it is actually kinda expensive for laying back a supply.  So as an fyi, if you are near an Asian supermarket you can buy lit blocks/crystals of alum for pennies what it costs in the spice section of your Safeway store.  You can always grind up what you need to make your alum solution if and when the time comes.

[HAMMERHEAD]

to a jub of cloudy wate will create coagulaton/flocculation

OK, I understood about two words there.
Could you expand a bit on the purpose of the end product?

[vacek]

Sorry.  Jug of Water.

Here is the skinny.  Mineral particles that we find in water pretty much divide up into Sand Silt and Clay.  Sands average size is 0.05 mm to 2.0 mm.  Silt is 0.002 mm to 0.05.  Clay is <0.002 mm.  A mm is about the width of a fine pencil lead as a reference.  All three being minerals that have essentially the same specific gravity, but they settle at different rates in water.  Shake up a jug of water and then set it down and the sand will settle out in less than 40 seconds.  That is followed by silt with the smaller silt particles settling out in 2 hours.  Much of the clay will not settle out and stay in supension.  So in short, the smaller the particle the longer it takes for that particle to settle out of suspension.

So your water treatment plant, if its source of water is surface, will bring the water into the plant and slow down the flow.  The larger particles will settle out.  To speed up the settling of the small silt and largely the clay particles a chemical is added so that the particles cling together (coagulation) and form a structure (floc).  Now the particles readily settle out.  There is a lot of colloidal and ionic chemistry behind this, but the above information is enough.  So the primary coagulant used by plans is aluminum sulfate AKA alum.  They add alum to the resource water, mixed it hard and fast then allow the coagulation/flocculaton take place followed by settlig.


So if you are having to purify water that is cloudy, you add alum.  Alum is expensive when purchased as a spice, but again in the Asian stores it is cheap.

[srussell]

why not use aluminum sulfate ?GET AT THE FARM STORE

[HAMMERHEAD]

Thanks for the explanation.

[vacek]

Alum is aluminum sulfate.  What is the cost at the farm store.

[clodbuster]

vacek  You have exposed yourself as a fellow soil scientist.  Even with my senior memory I thought I'd gone
back to school.  They had to work pretty hard to pound all that stuff through my thick skull.  Around here
(missouri river valley) they've used these concepts for decades to clarify creek and river water before sending
it on the Mighty MO and at the same time drop the sand, silt and clay on low laying farm land improving it too.
They built "settling basins" in a low 80 or 160 acre field by putting up a levee and running the stream in one
side and out the other through an overflow.  These basins turned in to some hellashus good duck and goose
hunting.  Always snapped up by rich duck hunting clubs from Omaha though.

[vacek]

Well Clodbuster, now that I am exposed can you say Cation Exchange Capacity....Isomorphic Substitution....Bulk Density....Particle Density......   Giving you nightmares??

[srussell]

sorry that was ammonium sulfate i saw

[vacek]

That's ok SRussle,

Ammonium Sulfate is another good topic.  If you live west of the Missisip, odds are that your soil is a little alkaline (pH > 7.5).  Localized ammonium sulfate can help bring that down.  Also, sandy soils especially during cold wet springs often respond well to ammonium sulfate (21% N and 24% S) since the organic matter is naturally low (source of N and S) and what there is is slow to breakdown and release N and S.

Also, applied sparingly it will give your grass a good mid-summer greenup and boost if you are needing to mow to get out of the house.