To reduce treating cost and improve versatility of waste by treating the waste using waste acid or waste alkali, without using chemicals of high purity as acid or alkali.
Waste acid A is added as acid to phosphorus-containing waste W containing at least phosphorus to dissolve or partly dissolve the waste to obtain a primary dissolved liquid L1, then waste alkali B is added as alkali to the primary dissolved liquid L1 that forms precipitate by reacting with metal elements of one or more kinds contained in the primary dissolved liquid L1, to obtain a secondary dissolved liquid 2 containing phosphorus by solid-liquid separation. The metal element forming the precipitate is a carrier element allowing coprecipitation of unnecessary other element that hardly precipitates in a single state. Carrier element-containing waste J containing the carrier element is added as a coprecipitant into the primary dissolved liquid L1.
SUGAWARA TAKIE
SATO YOSHIYUKI
SAITO HIROYUKI
NAMISAKI YASUHARU
ABE TAKASHI
