Phosphorus mineralization for resource recovery from wastewater using hydrothermal treatment

Abstract

We investigated the resource recovery of phosphorus from aqueous media containing various inorganic phosphorus compounds by hydrothermal mineralization treatment. The hydrothermal treatment was carried out for the model wastewaters containing 2000 mg/dm3 of phosphorus in forms of PVO43-, PIIIO33-, PIO23- or a mixed aqueous solution of PIIIO33- and PIO23- with mineralizer Ca(OH)2. The phosphorus concentration in the treated water, which contained PVO43-, was less than 0.1 mg/dm3. On the other hand, the hydrothermal mineralization treatments with solid-liquid separation under hydrothermal conditions were required for the treatment of PIIIO33- and PIO23-, in order to accomplish the national effluent standard of Japan (16 mg/dm3). In this case, the phosphorus concentration in the solution treated under the optimal conditions was 0.20 mg/dm3. Thus, the hydrothermal mineralization with Ca(OH)2 is recommended as one of the detoxification and recovery techniques of phosphorus in aqueous solution.