What is the purpose of anthracite in sand filters 1

[cremora]

Hi all.
I,m new to this site as well as being new to the water treatment environment so please bear with me if my question/s seem stupid.
Can someone please tell me what the purpose of anthracite is for in swimming pool sand filters and also which other materials can be used in the place of anthracite.
Thanks
Regards cremora

 

[RWF7437]

Anthracite is "hard coal" which is almost pure carbon. Carbon filters are used widely in water treatment because they efficiently remove patricles including those as small as most bacteria. That's a very simple answer, but so am I.

good luck

 

[sbush]

Anthracite is a very hard coal. It weighs about half as much as filter sand and, therefore, it expands slightly more than sand when it is backwashed. The granules have irregular shapes so they don't tend to pack down as tightly as filter sand. This "loose web" is desireable when filtering larger particles and/or suspended matter that has been made "sticky" by coagulation. Anthracite can be used alone in a single media filter bed, or as a cap on top of a layer of sand as is the case in a dual media filter.

Although anthricite is coal and predominantly carbon, it is not activate carbon. Because it has not gone through the activation process, it is not porous and it will not perform adsorption. It does not filter bacterial size particles, like diatomaceous earth.

Anthracite is commonly used in industrial and municipal water filters. It is not as common in the swimming pool industry where silica sand is the predominant media.

If you are looking for a replacement for anthracite sand, the closest material I can think of are the light-weight sands that are processed from volcanic pumas. One of these products is a product sold under the trade name "Filter-AG" sand. Agiean sand and Zeolite sand are others. However, these products are a good deal more expensive than anthracite.

S. Bush

http://www.water-eg.com

 

[semo]

Sbush is right. Adding the anthracite allows the filter to capture the larger particles in the top section and finer particles further down in the sand layer. With sand only, the top few inches of the sand would capture everything and foul earlier. So, the anthracite reduces the fouling rate that would occur with sand only and gives a longer filter run.

The anthracite is not necessarily needed; but, it can help.

 

[orenda1168]

Cremora:

You can count on one hand the instances of anthracite coal usage as a topping for sand filtration in the swimming pool market......it's simply not needed given the routinely low level solids requiring removal from pool water, easily handled and disposed of by periodic backwashing of the filter to waste.

Orenda
orendatech@earthlink.net

 

[cremora]

Thanks all you guys for the valuable information, I am taking all the facts into consideration and I'm sure I'll be back to visit you all. Keep up the good site, I think it 's brilliant.

Regards to all who responded

Regards Cremora

 

[geotype]

I'm finding that submerged (in tap water) anthracite in a small beaker in a lab starts to degass considerably after left to sit for 24 hours.
Any ideas as to what might be going on?

 

[Peteypete]

We have looked this phenomenon and it appears to be carbon dioxide degassing. You can accelerate the degassing by using warm water (15-30 minutes @60°C) or an alcohol like methanol (as a wetting agent). You can inhibit the degassing by placing the anthracite in "carbonated water."