Calcium Enhanced Precipitation Of Swine Manure: Supporting Concepts And Lab Scale Trial Findings

Can Solid and Liquid Manure Fractions Be Treated to Enhance Nutrient Management?

An important consideration of liquid manure solids separation is the fate and economic value of the resulting liquid and solids fractions. The desired properties of the separated fractions, operator preferences, regulatory considerations, and economics should determine the type and degree of treatment.

Research has shown that treatment with aluminum, iron, and calcium chemicals can concentrate phosphorus and manure solids into a lower moisture manure product. This research focuses on calcium to enhance phosphorous and solids precipitation. Concepts leading to this research were: creating calcium phosphorus compounds with liming and phosphorus fertilizer soil amendment value; retaining nitrogen for on farm use; enhancing/maintaining manure market value to offset treatment/transportation costs; reducing phosphate extraction from global mineral reserves; and investigating the impacts on energy and bio-char production from manure solids.

This research treated liquid swine manure with hydrated lime [Ca(OH)2] and agricultural lime [CaCO3]. The hydrated lime was added as both a liquid slurry and as a dry powder. The agricultural lime was added as dry granules. The 3 calcium sources were added to the manure at 3 treatment levels with 3 replicates. A non-treatment control for each chemical source and additional final non-treatment control were also processed. The resulting 31 mixtures were sampled prior to separation via filter bags. After separation, the filter bag contents and the leachate were also sampled. The filter bags and leachate were then stored under ambient conditions but protected from precipitation for 10 days before being sampled again.

The analysis of all 155 samples included % solids, TKN, NH4-N, NO3-N, P, WEP, K, and Ca. This manuscript presents an analysis of the results of the analytical tests performed. An associated provides an assessment of the separated solids as a feed stock for thermo energy conversion and bio-char production.


VanDevender, Karl                               Univ of Ark, Div of Ag, Extension, BAEG

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