Present State of Phosphorus Recovery Technology from Organic Wastes with High Water Content

Abstract

Although phosphorus is one of the most important resources for fertilizer and industrial materials, the amount of phosphorous ore production is decreasing year by year. For Japan, which is completely dependent on phosphorus ore imports from abroad, the recovery of phosphorus from wastes in Japan is becoming more and more important under the destabilized international situation. Phosphorus is recovered from sewage sludge as a raw materials of fertilizer through the following technologies: MAP production from digested sludge before dewatered or its filtrate; Recovery with a calcium silicate-based agent; Direct use of sewage sludge incineration ash; Calcium phosphate production by acid extraction/crystallization from the ash. Phosphorus is also recovered from livestock dung as a raw material through: Carbonization of compost; Direct use of incineration ash from compost or raw dung; Calcium phosphate production by acid extraction/crystallization from the ash. In order to develop future phosphorus recovery technologies, improvement in the collection systems of livestock dung and response to population decline will need to be taken into consideration.