Phosphorus Recovery from Carbonized Sewage Sludge by Hydrothermal Processes

Abstract

Sewage sludge contains significant amounts of phosphorus, however, the best recovery method for them is not established.In order to establish the phosphorus recovery technique, investigation of phosphorus recovery from carbonized sewage sludge was investigated.Carbonized sewage sludge was mixed with a sodium hydroxide aqueous solution, and treated in hydrothermal conditionsfor2 to 6 hours.After this treatment, hot-water was added to the treated mixture, and phosphorus containing extract was recovered.Phosphorus was recovered as a form of sodium phosphate from phosphorus containing extract.Optimal recovery conditions were investigated in treatment temperature, amount of added NaOH and Solid-Liquid ratio of the charcoal and aq.NaOH solution.The recovered phosphorus was confirmed as sodium phosphate (Na 3 PO 4 ), and its recovering rate was estimated to be about 58%-71%.