Canada - Centrifuge Based Solid Liquid Separation Offers Manure Nutrient Management Option
Published: September 3, 2007
Source : Farmscape
The use of centrifuge-based solid-liquid manure separation was pioneered in France about 20 years ago and the technology is now being used extensively in Europe. The process uses a centrifuge which turns at about 4500 RPM to separate liquid manure into two parts, a liquid fraction which includes most of the nitrogen and a solid fraction which includes most of the phosphorus.
The technology was imported into Quebec about seven years ago to help hog producers in that province comply with strict new phosphorus application limits. The process attracted the attention of a committee formed by Puratone to seek options for addressing new phosphorus based fertilizer application regulations due to take effect in Manitoba in the fall of 2008.
Manure Solids Create Most Concern
“The major cause of our problem, and any hog producer’s problem, is the solids in the manure,” says Puratone project engineer Dr. Shokry Rashwan.
He estimates removing the solids from the manure will cut the problem by at least half. With that in mind, Puratone, in partnership with Manitoba Agriculture, Food and Rural Initiatives (MAFRI) and Manitoba Conservation, secured the use of a mobile centrifuge unit this summer which had been used in a number of research projects in Quebec.
“The intent was to bring equipment out for demonstration and testing in Manitoba to show Manitoba hog producers some of the new technology that could possibly be used to help them remove phosphorus from manure and meet the requirements of the new amendments to the regulations,” says MAFRI technical review coordinator Gary Plohman.
He explains the phosphorus component of the regulation is making it difficult for some producers to continue to apply manure at the same rates as in the past which means they must either get more land or look at some alternate technology to treat the manure to take the phosphorus out.
Research Unit Evaluated in Manitoba
The research unit was set up at Heritage Hog Farm, a 6400 head finisher farm, located near Niverville. The unit was evaluated over a two month period.
Marc Trudelle, a soil specialist with Manitoba Conservation, points out the centrifuge tested near Niverville is an experimental unit designed to generate field data and demonstrate how the technology works. It is not commercial scale but it can be used on a commercial farm. He says in Quebec they have been able to achieve about 70 percent removal of phosphorus.
Dr. Rashwan notes that for Puratone to consider the process viable it would need to be capable of removing 50 percent or more of the solids and 60 to 70 percent or more of the phosphorus and the technology offers that. The Heritage Hog Farm trial achieved an average of 50 to 55 percent separation of solids and about 60 to 65 percent removal of phosphorus.
Solid Content Variable
Plohman points out the solid content of the manure that goes through the machine will vary somewhat from time to time based on the age of pigs in the finishing barn and whether the manure is taken from the beginning of a flush or at the end so proper adjustments are important.
“The testing has been done on solids that have ranged from anywhere from close to two and a half percent all the way up to probably nine percent solids. It covers the full range of manure that is typical for hog facilities all the way from farrowing to nursery to dry sow to finishing units.”
Dr. Rashwan says the focus of Puratone’s evaluation was to determine if this technology is technically viable or not and the answer is yes. He says the remaining question is is it capable of handling the average manure production of an average farm.
He acknowledges, “With this machine we can not do that. It is just a small machine so we know it can not handle a full farm production so obviously we have to get a larger unit.”
Larger Units Necessary to Accommodate Average Size Farm
Alfa Laval technical sales manager for western Canada Farah Salaria agrees the mobile research unit would not provide adequate capacity for any farm even a small one. Alfa Laval is a major supplier of centrifuge technology.
Salaria says what’s commercially available is mostly double the size of the trial unit and can be as large as three times or four times the capacity. She says what is needed is to find what is viable for a standard size farm – and estimates that a unit with a capacity between 10 and 15 cubic metres per hour would be sufficient for a typical Canadian farm.
Plohman estimates a unit capable of serving a typical four thousand head finishing barn would range in cost from $75,000 to $100,000 for the centrifuge and that there would be additional costs.
“In addition to that they would have to put in an agitation tank of some kind and conceivably that could add another $30,000 to $50,000. They may need to put in a storage building for the solids so there’s an additional cost there.”
He cautions that when producers do a budget they should consider the total system cost rather than just the cost of the centrifuge.
Solid Liquid Separation Part of Overall Strategy
Trudelle stresses that what Manitoba Conservation wants is to provide farmers with options to comply with the regulations. He is convinced that by combining options, such as reducing the amount of phosphorus added to the feed as well as manure separation systems like the centrifuge, farmers will be able to comply.
He points out that Quebec producers have decreased the phosphorus output per head sold by 50 percent in the last ten years.
Trudelle says all of the tests have been completed but there are still some lab reports that need to come back. He says once all of the results are in something will be published and it will be made public, likely this fall.
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