Abstract
As a phosphorus recovering method, investigation of phosphorus recovering conditions from carbonized sewage sludge was carried out using sodium hydroxide. Carbonized sewage sludge was mixed with an aqueous solution of sodium hydroxide, and treated at 120°C . After this treatment, phosphorus was extracted by a hot-water extraction processes and cooled to 5 °C . for crystallization of sodium phosphate. In order to concentrate the phosphorus in the extracted water for crystallization, introduction of the low S/L ratioextraction processe was investigated. The phosphorus recovery rate was estimated to be about 60% to 70%. Recovered phosphorus was considered Na3PO4, from X-Ray analysis and the recovering condition. NaOH remaining in the processes water was identified to be reused as alkali of phosphorus extraction.
