A Novel Treatment System to Remove Phosphorus from Liquid Wastes

Animal Manure Management March 18, 2015 Print Friendly and PDF

Lowering the total phosphorus (P) content of animal manures is one means of addressing concerns over P runoff following land application of animal manure. We developed a treatment system for liquid manures that conserves the manure nitrogen (N) content while removing most of the manure P content. Initial evaluation of a treatment system involving manure solid separation and precipitation of dissolved P with an alkaline salt (calcium hydroxide) resulted in poor liquid/solid separation and poor dissolved P removal and created conditions promoting ammonia-N volatilization. As a result, we developed a three step system with iterative solid removal and acid salt (ferric sulfate) precipitation of dissolved P: (1) removal of bulk and intermediate sized solids (>25 μm); (2) chemical treatment to convert dissolved P; and (3) final removal of fine solids and chemically precipitated P. When tested on manure slurries from 150 and 2700 cow dairies, 96 and 99% total P was removed respectively, resulting in liquid manure filtrates with up to 400:1 N:P ratio. While costs of treatment were roughly $38 per kg P removed, equivalent to $750 per cow annually, we anticipate that refinement of the process and beneficial uses of the solid materials (bedding, compost, etc.) will improve cost-efficacy considerably.

Author

Church,  Clinton  Clinton.Church@ars.usda.gov     USDA-ARS 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.