Treating Liquid Swine and Dairy Manure with Aluminum Chloride

Authors: Moore Jr, Philip

Submitted to: SERA-IEG 17 Bulletin
Publication Type: Other
Publication Acceptance Date: 10/2/2024
Publication Date: 12/1/2024
Citation: Moore Jr, P.A. 2024. Treating Liquid Swine and Dairy Manure with Aluminum Chloride. SERA-IEG 17 Bulletin. SERA-17 Website, (https://sera17.wordpress.ncsu.edu/).

Interpretive Summary:

Technical Abstract: Liquid aluminum chloride is added to liquid swine or dairy manure to reduce soluble phosphorus. Liquid manures, such as liquid swine or dairy manure, contain relatively high concentrations of soluble phosphorus. Research has shown that phosphorus runoff and leaching from manure is correlated to the soluble phosphorus content of manure. Aluminum chloride can be added to liquid swine or dairy manure to reduce soluble phosphorus, resulting in less phosphorus runoff and leaching. Liquid manure may be treated in the pits inside swine production facilities or in retention ponds, holding ponds and/or lagoons on swine or dairy farms. In addition to reducing phosphorus runoff, aluminum chloride additions reduce ammonia volatilization from liquid manure, which improves air quality. It also facilitates flocculation to help remove solids from liquid manure. Aluminum chloride additions to liquid manure reduce non-point source phosphorus pollution by reducing soluble phosphorus via precipitation of aluminum phosphate and/or adsorption of phosphorus onto aluminum hydroxide. Once phosphorus is bound with aluminum it is less mobile, hence, phosphorus runoff and leaching are greatly reduced. Aluminum chloride can be applied to liquid manure in almost any location from inside production facilities to holding ponds or even in liquid manure spreaders immediately prior to land application. Reducing phosphorus runoff and leaching improves water quality by decreasing eutrophication, since phosphorus is normally the limiting nutrient for primary productivity, at least in freshwater systems. Reducing soluble phosphorus also reduces struvite mineral formation, which can cause clogging of pipes in liquid manure systems.Aluminum chloride additions also reduce ammonia emissions from manure by lowering the pH of the manure, which shifts the ammonia/ammonium equilibria towards ammonium, which is not volatile. When utilized inside production facilities, such as treating pits in swine houses, lower atmospheric ammonia levels can result in improved animal performance such as better weight gains, feed conversion and reduced susceptibility to diseases, particularly airborne viral diseases. Improved air quality in animal rearing facilities is also beneficial to the health of agricultural workers.