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Algae make fertilizer…

May 7, 2010

Algae growing in tracks using waste runoff from a feedlot.

Here’s a nice article ( LINK ) describing some work showing how algae can “clean up” livestock waste, taking up the nitrogen and phosphorus in their cells and holding onto it before it can enter streams, lakes, and oceans.  The algae can then be collected and readily turned into a “slow release” fertilizer, returning the N and the P to agriculture (where it belongs).  Certainly seems we need a lot more of this and it needs to be studied for how it can be scaled up.

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2 Comments leave one →
  1. Rob Mikkelsen permalink
    May 13, 2010 4:40 am

    Jim,

    This is a great way to clean up waste water from fairly concentrated nutrient sources. The technology has been demonstrated in many applications. Constructed wetlands have been successfully used for many years for water quality benefits (both chemical and biological processes).

    It may be difficult to convince most farmers to use this algae-based material. The USDA-ARS authors state that the cost of algae-derived N will be $5 to $6/lb of N. This compares with $0.30/lb with commercial fertilizer. The authors state the cost of recovering P will be $25/lb (I’m not sure if this is P or P2O5). This contrasts with less than $1/lb for commercial P.

    Then consider that the volume of material to be handled may be up to 25 times greater with the algae than fertilizer. That requires considerably more hauling and spreading expense too.

    These logistical problems are always problematic with low-analysis organic nutrient sources. In some regions, the transportation expenses are subsidized with public funds (poultry litter for example). It gets complicated!

    If the water quality benefits are sufficiently valuable to make the operation feasible, that may be enough to make the system justified. Any minor value obtained from the recovered nutrients would be a nice addition.

  2. May 16, 2010 9:50 pm

    Thanks Rob. You are correct to point out the price differentials between “industrial” fertilizer and “bio”-fertilizer like that described in the web site. Of course, such differentials might start to shrink if mined P becomes more scarce and/or as economies of scale are achieved on the bio-based fertilizer side. It’s also interesting to begin to think about what kind of incentive systems might be deployed that could bring the price of fertilizer closer into line with all of its distributed (“downstream”) costs that are born by others (such as those in the seafood industry).

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