Effective use of livestock wastes as phosphorus resources

Abstract

Phosphorus recovery and reutilization are emphasized in Japan which is poor in phosphorus resources. Livestock wastes amounted to 80 million tons per year contain 110 to 190 thousand tons of phosphorus. Recovery methods of phosphorus from livestock wastes are described about compost, incineration ash, and insoluble phosphate salt from wastewater. Average contents of phosphorus as P₂O₅ in composts of dairy cattle, beef cattle, pig, layer, and broiler are 1.8, 2.5, 5.6, 6.2, and 4.2% dry basis, respectively. Phosphorus content in cattle waste compost is higher than the content in pig and poultry. Incineration ash of poultry waste contains around 9% phosphorus. The ash is bought by a fertilizer company. Insoluble phosphate salt (ammonium magnesium phosphate, MAP) is crystallized from aerated wastewater. Phosphorus contents of compost, incineration ash, and MAP are 160, 12, and 10 thousand tons, respectively. They are 172 thousand tons in total and within scope of 110 to 190 thousand tons. Phosphorus recovery and reutilization of livestock wastes will economize consumption of natural phosphorus resources mainly imported from foreign countries and lead to sustainable recycling of resources.