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United States Department of Agriculture

Agricultural Research Service

Title: Polymer Type and Aluminum Chloride Affect Solids and Phosphorus Removal from Dairy Slurry

Authors
item Timby, G - UNIV OF ARKANSAS
item Daniel, T - UNIV OF ARKANSAS
item Moore, Philip
item Mcnew, R - UNIV OF ARKANSAS

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 15, 2003
Publication Date: January 1, 2004
Citation: Timby, G.G., Daniel, T.C., Moore Jr, P.A., McNew, R.W. 2004. Polymer type and aluminum chloride affect solids and phosphorus removal from dairy slurry. Applied Engineering in Agriculture. 20:57-64.

Interpretive Summary: Most dairy farms in the use have manure collection systems that are called flush systems because a large amount of water is used to flush the manure from a large concrete feeding area into a lagoon or holding pond. If the solids are not removed from this liquid slurry that results from flushing, then the holding ponds will rapidly fill up with solids, resulting in management problems. Hence, dairy farmers try to separate the solids out of the slurry using solid separators. These do not work well (less than 20% efficient). Hence, the objective of this study was to determine if the additions of polymers and/or aluminum in combination or alone would increase solid separation. The polymers evaluated are called polyacrylamides or PAMS. Eight different PAMs ranging in charge (-, 0, and +) and charge density (high, medium, and low) were tested in combination with different levels of aluminum choride. The cationic (+) PAMs significantly increased solids removal by almost two times and reduced the amount of total P (TP) in the filtrate by one quarter. The addition of Al in combination with both anionic (-) and cationic (+) PAMs increased both the solids and TP removal efficiencies; however, the concentration range over which the cationic PAMs exhibited an increas in solids and TP removal was wider and more consistent than the anionic PAMs. The combination of Al and PAM also decreased the TP retained in the filtrate by as much as three times as compared to the control. Treatment concentration of Al was the only factor affecting soluble reactive P (SRP) removal and resulted in an approximately 99.9% removal rate.

Technical Abstract: Solids removal in flushed dairy systems by solid separators is about twenty percent efficient, resulting in several management problems. Due to the daily solids influx, liquid storage capacity is continually reduced requiring frequent pumping of the lagoon to maintain storage capacity. Since the liquid portion of the waste is consistently applied to the same areas, soil test phosphorus (P) levels rapidly increase above crop needs. A more sustainable system smust be developed that dramatically reduces the solids and P content in the slurry. This project evaluated the effectiveness of different polyacrylamides (PAMs or polymers) and aluminum (Al), alone or in combination, for removing solids and P from dairy slurry. The eight different PAMs evaluated ranged in charge (-, 0, and +) and charge density (high, medium, and low). After testing the PAMS alone and in comparison to the control, the cationic (+) PAMs significantly increased solids removal by almost two times and reduced the amount of total P (TP) in the filtrate by one quarter. The addition of Al in combination with both anionic (-) and cationic (+) PAMs increased both the solids and TP removal efficiencies; however, the concentration range over which the cationic PAMs exhibited an increas in solids and TP removal was wider and more consistent than the anionic PAMs. The combination of Al and PAM also decreased the TP retained in the filtrate by as much as three times as compared to the control. Treatment concentration of Al was the only factor affecting soluble reactive P (SRP) removal and resulted in an approximately 99.9% removal rate.

Last Modified: 10/21/2014
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