Recycling of phosphorus from unused resources in Japan

Abstract

The apparent utilization rates of nitrogen and potassium as fertilizer have been thought to be 66% and 69%, respectively, for the Japanese food and feed production system. However, that of phosphorus, a strategic resource, has been thought to be only 17% in Japan. Phosphorus surplus calculated as the difference between input and output is the largest among OECD countries. Japan imports phosphorus as food and feed, and as iron ore, as well as the form of ore, ammonium phosphate, and various kinds of salts. An increase of the phosphorus utilization rate and recovery of hidden phosphorus in food and feed refuse (food waste, sewage, livestock wastes waste, etc.) and the like, as well as reuse as a secondly phosphorus resource, is important for reducing phosphorus imports and for increasing self-sufficiency in phosphorus as much as possible. In Japan, there are full-scale phosphorus recovery plants as components of municipal sewage sludge treatment plants, and both full-scale livestock waste treatment plants and a laboratory-scale system for phosphorus separation from iron-making slag. If these systems are fully adopted in Japan, most of phosphorus demand for fertilizer in Japan will be filled by the recovered phosphorus and livestock waste, although the required initial investment, maintenance, and renewing of phosphorus recovery and/or separation systems, as well as the negative image of “sewage born” fertilizer, make promoting these systems difficult. However, a sustainable and robust food and feed production back up resource supply is necessary for realizing SDGs 12 and 15with a circular economy and a society based on self-production and self-consumption.