Reducing Potential Leaching of Phosphorus, Heavy Metals, and Fecal Coliform From Animal Wastes Using Bauxite Residues

Long-term applications of animal manures to agricultural fields have caused serious environmental concerns over release of excessive nutrients, heavy metals, and fecal coliforms into waterbodies. An alternative is to control nutrient bioavailability of animal manures before their land application. In this study, two types of bauxite residues (red mud and brown mud) were evaluated for their potential use in reducing leachability of phosphorus (P), copper (Cu), and zinc (Zn) as well as fecal coliform and NH3 release from animal manures. Poultry litter and cattle manures collected from production farms were mixed with bauxite residues at mixing rates of 11%, 22%, and 50%. Bauxite residues were effective in suppressing the leaching of water-soluble P, As, Cu, and Zn from animal manures. At 22% mixing rate, brown mud reduced water-extractable P by 40% and 70% from chicken litter and cattle manure, whereas red mud reduced water-extractable P by 27% and 55%, respectively, in five successive extractions. Amending manures with bauxite residues also decreased populations of fecal coliform. Bauxite residues did not increase NH3 release despite its relatively high pH. The results suggest that bauxite residues could be used as a potential amendment for reducing P and other contaminant leaching in animal manures and improve the application of both wastes for beneficial use.