There’s nothing stinky about a plan to turn manure into cash. It might be a dirty business, but the results can be a boon to dairymen around the globe. A group of scientists led by Aicardo Roa Espinosa, founder of Madison, Wisconsin-based Soil Net LLC, is working on a $9 million research study that uses polymer to separate manure.
The study, funded federally and by the dairy industry, includes a partnership with Braun Electric Inc., of Saint Nazianz, Wisconsin, which makes equipment for the Trident nutrient management system that, with help from Roa’s polymers, separates fibers from manure and turns them into sellable products.
“We’re changing the way manure is managed,” said R.C. Ludke, development manager for Braun Electric. “We’re changing the view of manure in that, first of all, it’s not waste. There’s value in manure.”
The project was awarded $7 million by the U.S. Departments of Agriculture and Energy, while another $2 million in equipment and construction comes from Maple Leaf Dairy, where the project is under way.
The study is divided into three phases – renewable accelerated energy, extraction and purification of proteins from animal manure, and water retention capacity of natural fibers and fertilizers coated with polymers – ending in 2016.
“It will be a very intensive study over the next four years,” Ludke said.
The process
The project already has proven successful, said Roa. Much of the testing is being done at Maple Leaf Dairy, a 4,000-cow operation near Cleveland, Wisconsin. Eight other customers are on board, he said, noting that he has well more than $2 million worth of equipment in his 6,000-square-foot lab in Belleville.
All systems are promoted under the Trident moniker. “In this case,” Ludke said, “it will be the Trident water treatment system, the Trident arid bedding system and the Trident nutrient management system.”
Part of the lineup is a polymer hydration unit which, when manure is processed, separates the fibers. One type can then be used for animal bedding, another for fertilizer and another for biofuels. Separating the fibers is one continuous process, Roa said.
How does it work? In a nutshell, the system squeezes most of the moisture out of manure to separate the fiber.
Here’s an example from Maple Leaf Dairy: Wastewater from the barn – a mixture of manure, water and fiber – passes through rotating drums, separating the largest of the bedding fiber from liquid and manure.
The rinse water gathers in a large tank with water from the milking parlor; this water and manure mixture is then sent to a methane digester and onto a screw press, where smaller particles of bedding are separated from the wastewater. The solids separated here are dropped into a truck bed and taken back to the barn to be recycled.
The waste liquid continues on to the polymer hydration unit, where polymer is metered and mixed, coagulating the tiny particles that remain in this liquid-and-manure mixture. Large flecks separate the liquids and solids.
Dissolved air injected into the recycled water line forces these flecks to the surface, while a skimmer pushes them toward a screw press. Clean water, free of fibers and solids, flows underneath to an overflow loop. This clean, untreated water is sent back to tanks to be used to clean the barn.
“We apply polymer, which is where the proteins and nutrients are. Then it could be granulized,” Roa said. “The nutrient-depleted water you can use again and again and again.”
Waste solids skimmed toward the screw press are collected nearly dry and taken to fields to be used as value-added waste, which will not run off.
Roa, who’s been working on this system for seven years, said he came up with the idea when hearing how farmers wanted manure and water separated.
“OK,” he said. “That’s one part. Then it evolved into what we do with the fiber, then separating the fiber from the nutrients … We have fiber, we have protein, but what do we do with them? Then I decided to look at alternative methods.”
Without the polymers, very little separation happens. Treated solids, on the other hand, are easy to separate and transport.
To summarize, Ludke said: “The first step of our process is removal of bulk fiber. This material can be used as bedding or processed into a sellable mulch product. We will be testing this material to see if there is merit in extracting ethanol from the cellulosic fiber.
The granules are a concentrated form of the isolated nutrients and can be handled and stored much the same as commercial fertilizers. They can be dry applied and have a slow-release characteristic.”
Time to process the manure: About 90 minutes, Roa said.
“Nobody has seen this approach to manure,” he said. “Manure is a nuisance. Everybody says it’s gold, but nobody knows how to get the gold out.” Until now.
Phosphorus issue
For every 100 gallons of manure processed, Ludke said, 80 gallons are nutrient-depleted liquid that can be directly applied to crops. The remaining 20 gallons of material – basically a sludge – is handled by conventional methods, either through a sludge system or tankers.
What is left, he said, now contains high levels of phosphorous, nitrogen and sulfur – “so it’s highly concentrated, meaning farmers can start doing some precision ag applications.”
He shares this example – the phosphorous index of a field.
Because you can use only so many gallons of manure on a field, due to phosphorous limitations, chances are you likely have to purchase commercial nitrogen to also put on the field. But, Ludke said, by segregating these nutrients in the manure, farmers can use nitrogen on fields that need it without exceeding their phosphorous application limits.
“You’re better able to utilize the nutrients because they’re divided up,” he said.
And then there’s this: Every ton of manure processed yields about 200 liters of potential ethanol, Roa said.
“We expect the ethanol production aspect of this study to yield data that would substantiate the economic feasibility of on-farm production,” Ludke said. “Dr. Roa has already developed the process on a bench scale in his lab.”
Still another benefit: “We’re concentrating nutrients into a sludge, which is a much smaller fraction of the total waste stream,” he said. “What this does for dairymen is that it greatly reduces their cost to haul manure.”
At one time, 100 trucks might have been needed to haul away manure. But after it’s been processed, Ludke said, only one truck might be needed. That alone is a cost-saver to dairymen.
As for the investment cost, Ludke said that’s where another challenge lies.
“These are the hard questions to answer right now,” he said. “A big part of the study is to establish scalability and determine cut-off points as we are assessing the cost-effectiveness or ROI return on investment. This will largely be determined by actual throughput data of the equipment we will be using. It is our intent to keep the entry level at or below 500 cows, and we anticipate startup costs to be less than $500,000. The variables are a big factor here. Type of bedding being used, if a digester is in the system, if they buy feed or make their own, how they are currently managing their manure – all will affect the ROI.”
Future implications
Roa doesn’t get much sleep – “I work seven days a week, 12 hours a day,” he said.
It’s a small price to pay to help dairymen.
“They’ve been swindled so many times,” he said, noting he wants to help them find “gold” in their own farm’s manure. “They don’t trust anyone except other dairymen.”
If they hear good things about this project from fellow farmers, Roa said, they’re more likely to jump on board.
Word about the project is spreading, he said.
He already has nine customers, and envisions a time when it’ll spread across the country and, in some cases, to other parts of the globe. “Yes, yes,” he said, “in California, Idaho, Iowa, Texas.”
He’d like to one day see the technology used on small dairy farms as well as large ones, saying their investment would well pay off.
Ludke summed the benefits, saying this could be a significant advance in the industry’s ability to be compliant with the regulations governing application of nutrients, broaden application windows, reduce transportation costs and add value.
“The fiber aspect of it is going to be the next step in the project,” he continued. “We’re going to be taking that sludge and further reducing it to a granule.”
On the docket also is a comprehensive study to determine the impacts of land application of the nutrient-depleted water to various soil types and conditions, waterways and any contamination potential, Ludke said.
“We will also evaluate the potential of value-added benefits that can be derived from this renewable resource.”PD
Weeks is a freelance writer based in Twin Falls, Idaho.
