Choosing the right fit

SIOUX FALLS, S.D. — Using the correct kind of sand is key for farms looking to implement high sand reclamation systems, especially if a digester is involved.

“Start off with something that you know you’re going have success with,” said Renee Schrift, business line director for McLanahan Corporation.

Schrift presented “High Sand Reclamation: What Types of Sand Work Best” March 20 at the Central Plains Dairy Expo in Sioux Falls. Schrift discussed sand types and tips for starting with a sand reclamation unit.

Using sand reclamation can help keep sand out of a manure pit and off fields. It frees up land for manure application and could limit the distance manure must be pumped because the removed sand is not adding bulk to manure systems. For farms with manure digesters, a sand reclamation unit can help keep sand out of the digester.

Systems differ, but Schrift said with a good reclamation sand type, systems could recover 87%-90%, and even up to 98%, of sand depending on what is used.

Schrift said that dairy producers looking to do sand reclamation should avoid fine sands. These sands are difficult to reclaim because they do not settle.

“We want to try to stay away from this type of sand, not only from the separation standpoint but also in your whole stall management and the work that it takes to make sure your stalls stay clean and dry,” Schrift said.

Fine sands can be packed in stalls and require raking. Schrift said producers like fine sand because they do not have to use as much of it. However, Schrift said this defeats the purpose of sand being used and then removed. Producers also like it because it is easy to work with and is cheaper.

“You want something that is going to be a little loose in the stall that drains well,” Schrift said. “It has a little more density to it so it packs less.”

Schrift recommends sand that is neither filled with fines nor coarse as optimal for sand separation while promoting cow comfort.

“If we get rocks, then we have really great recovery, but it’s not so good for the cows,” Schrift said.

Schrift said washed concrete sand has good recovery and is a good medium between fine and coarse. Dairy farms located near glass factories can use manufactured sand. Schrift said this sand is also uniform and good for sand separation.

Schrift said pit sand can contain a lot of organics and be packed in stalls. Over time, it can cause problems.

Fracking refusal sand, called utility sand, separates well and is a uniform, natural sand that is more available in Wisconsin and Texas.

Sand shape for cow comfort is another factor. Schrift recommends sand with round or softened edges to keep the cows comfortable.

Before purchasing sand, Schrift said to have it tested for sand reclamation using a sieve analysis test. The test uses sieves with progressively smaller mesh. Sometimes content at the bottom ends up being not sand at all but rather silt and clay, which is also unwelcome in a digester, Schrift said.

“You want to make sure that you do these kinds of tests first and make sure you know what your gradation is,” Schrift said.

For farms planning to put in a sand reclamation system with a digester, Schrift recommended switching to high-reclamation sand.

“Make sure that you leave yourself ample time to get that switched out,” Schrift said. “Don’t try to do it the week before you’re trying to start ... a digester, because that’s just a recipe for disaster.”

After a sand type has been purchased, Schrift said producers need to continue to check their sand. Because high sand reclamation requires less purchasing of sand, any new sand coming onto the farm may not be of the same initial caliber.

“Make sure you have a plan to at least look at that and make sure your quality and your consistency is there,” Schrift said.

Water quality can affect sand reclamation. The products that Schrift works with use reclaimed water from manure as well as fresh water for washing.

“If you have the right sand, you can have really, really, thick ... water, and it’s just going to take forever for that sand to settle,” Schrift said. “You can have cleaner water and a good quality sand that separates well and that’s going to separate easier.”

Schrift said for every cow, on average, the systems she works with will use about 1 gallon of fresh water to wash the sand. The rest of the water used is recycled from the manure. Usage varies by farm, but Schrift has seen as low as a half-gallon of fresh water and as much as 2 gallons.

“Every system is different,” Schrift said. “Every demand is different. ... They’re not going to be cookie cutter.”

Water usage is not the only thing that varies. Schrift said every sand reclamation system must be customized to the farm’s goals and scaled.