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Michigan dairy invests in manure separation equipment

Melissa Hart Published on 30 June 2014
Chad Minnis

Dairy producers from New York to Wisconsin met in central Michigan recently at the Car-Min-Vu Dairy Farm to check out the latest technology in manure management.Owner Chad Minnis, the next generation of the family, adopted a new generation of manure handling with the McLanahan Nutrient Separation System.

This new technology begins with manure and ends with recycled sand, concentrated nutrients and clean water.



Carl Minnis raised his family on their 60-cow registered Holstein dairy farm known as Car-Min-Vu Dairy in Webberville, Michigan. When his son, Chad, graduated from nearby Michigan State University, he had a hunger to expand and adopt new technology on the farm. They grew from 60 to 90 cows and then made the leap to 300 when they built a double-12, rapid-exit parlor and a freestall barn.

“When we expanded in 1997, we put mattresses in our freestall barn, and from 1997 to 2000 we struggled with production, burned hocks, leg problems and skinny cows, and that’s when we made the decision to pull the mattresses and put in sand bedding,” Chad explained.

After the decision to use sand bedding he decided to install a sand separation system. “The question was: Do I lay a ton of concrete for a bigger lagoon or invest in stuff like this? Well, I decided to invest in stuff like this,” Chad explained as he points to the sand separator.

With 950 cows now on the farm, the manure is picked up by a vacuum truck and is then dumped into the separating unit and combined with recycled water and milking parlor wastewater. When the manure travels through the closed-loop system, the sand is separated from the liquid and the liquid is then pumped into a lagoon.

The sand is conveyed out of the barn and dumped into a pile to be re-used in the freestall barns on the dry cows and lower-producing cows. The solids that are separated from the liquid and sand are then composted and used to spread on the fields.


Chad has found several advantages to the separating system. He explained, “My manure storage is better in that I don’t have to worry about filling the lagoons so quickly.”

He also realized the application is faster because he’s not having to pump sand out of the lagoon and apply it to the fields. Another benefit is the wear on equipment; Chad simply said, “Sand is hard on manure-handling equipment.”

Sand usage has also decreased. “We used to haul in five loads of sand a week; now we haul in about one to two loads per week and use it on our fresh cows and high-producing cows,” Chad said.

pre treatment tank

When asked about how much time is needed to man the separator, Chad explained, “For the most part, it runs on its own. We spend about a half-hour in the morning getting it started, and then it runs all day on a timer according to how much manure is in there.

When it gets to a certain level, it shuts off automatically.” He added, “I check it a couple of times a day just to make sure everything is working properly.”


But the sand separator is just half of the new technology adopted by Car-Min-Vu Dairy. They are now a test site for a nutrient separation system that takes the liquid from the sand separator and refines it even more to capture the organic nitrogen, ammonia-nitrogen, phosphorus and potassium and end up with clean water.

Because Car-Min-Vu is a test site, the manure from about 100 cows is used in the system where the liquid is pumped into a pre-treatment tank which will produce effluent that goes through the system and biogas that can be used for heat and electricity.

The effluent then enters the ultrafiltration system that separates according to particle size. The solids are rejected and the water is allowed to flow through the membrane. This water, called “tea water,” contains the dissolved constituents found in manure, most notably ammonia and potassium but very little phosphorus and organic nitrogen.

From there the tea water flows through the air-stripping absorption process. This process takes out the ammonia-nitrogen as ammonium sulfate, and then the water goes through the reverse osmosis system with a much tighter membrane that separates based on molecular size.

Through this process, concentrated potassium is separated out, resulting in clean water that is suitable for direct discharge or land irrigation.

Andrew Wedel, general manager of McLanahan’s Agricultural Systems Division, elaborated on the system. “The system takes manure after the sand and solids are removed, pre-treats it, perhaps in an anaerobic digester, and captures 95 percent of the phosphorus in 30 percent of the volume.”

filtration unit

Wedel continued, “Do you know of anybody that has distant fields that have never seen manure and are deficient in phosphorus? This concentrated phosphorus can be in a liquid or solid form.

The system also produces concentrated liquid ammonium sulfate that can be used to perhaps side-dress corn. This represents only 1 percent of the volume, but it is very concentrated. Approximately 15 percent is concentrated potassium in a liquid form.

“We might all agree spreading manure on alfalfa ground for the most part is manure disposal,” Wedel added. “What if we could apply concentrated liquid potassium to alfalfa ground? Would that be helpful? The system can produce separated and concentrated nitrogen, phosphorus and potassium – the technology exists and the solution is at our fingertips.”

Besides separating nutrients, the system, as well as some others in today’s marketplace, produces clean, dischargeable water.

Wedel concluded with these questions to producers: “What if you didn’t have to haul half of your manure and still had all the nutrients? Would that have some cost benefit? How would that affect relationships with your neighbors? How about plans for expansion and growth?” PD

Melissa Hart is a freelance writer based in North Adams, Michigan.

PHOTO 1:Chad Minnis has adopted sand separation and manure nutrient capture new technology on his family’s farm, Car-Min-Vu Dairy.

PHOTO 2:The liquid is first put in the pre-treatment tank where solids and biogas are separated from the liquid.

PHOTO 3:Liquid is pumped through the filtration unit to separate out nutrients from water. Photos courtesy of Melissa Hart.