The tests were done with very diluted manure reconstituted with the mix of solid manure with water to obtain 1% total solids. Polymers (natural or synthetic) can be used for flocculation as these macromolecules attach themselves (by their electric charges in the case of livestock and poultry treatment this charge has to be positive)) to several particles in suspension, flocculation thus occurs followed by settling. The most cost effective is a synthetic polymer which removed 42% of the volatile solids at a concentration of 1,0 mg/L and the cost would be 108.46 U.S.$ per year for 1000 hogs. The synthetic polymers are also nontoxic and more easy to handle and apply than the ferric chloride which is a corrosive liquid.
The use of such chemical has to be integrated with other manure treatment or could be considered if it presents an advantage to handle the liquids and solids separately.