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Livestock Nutrient Management The Mobile Struvite Project

A farm scale mobile technology that can cost effectively transport manure nutrients from regions of dense populations of animal agriculture to areas that have a demand for manure nutrients.

Washington State University (WSU) is using a farm scale mobile struvite crystallizer unit at 30 dairies in the State of Washington to demonstrate this technology’s ability to protect the environment by removing excess phosphorus from dairy wastewater.  Phosphorus continues to accumulate in soils associated with the use of dairy manure. In addition, the price of commercial P based fertilizers recently soared to record high prices, and are likely to do so again as diminishing reserves struggle to accommodate increasing demand.  A viable solution is the adoption of technology to capture P from liquid manure in the form of struvite, a slow release form of P based fertilizer. The struvite that is formed is easy to handle and transport, and is low in moisture (looks much like sand). Each farm has a unique need for P removal to reach a whole farm nutrient balance. The Mobile Struvite Project demonstrates the farm-scale deployment of a mobile system for economical and efficient means of capture and subsequent transport of nutrients from a region or P density to an area of forage production that needs supplemental P.

Struvite technology, already in use in large municipal wastewater plants, has been limited in its adoption in liquid livestock manure due to two factors: (1) the relatively small and numerous units that would need to be installed and operated at dairy farms; and (2) the need to transport the small quantities of raw struvite from the numerous locations to a product center for drying and preparation for distribution to the areas that need additional P.  The purpose of this project is to break these two barriers by assembling a mobile, trailer-mounted unit and demonstrating it at separate farm locations.  The unit removes and captures P from liquid manure at those locations, converting it to raw struvite.  The raw struvite, being very rich in P (29% P2O5 equivalent), will be sufficiently compact that it can be easily transported by the mobile unit to the product center, and shipped from there to the grower industry (crops and horticulture) in the region.

This video is part of the Mobile Struvite Project at Washington State University’s Livestock Management Program. This effort was supported by a NRCS Conservation Innovation Grant and by the Washington State Dairy Products Commission.