Technique of Phosphorus Recovery from Dehydrated Sludge by Incineration

Water sludge contains significant amounts of phosphorus, and in order to recover the phosphorus, some kinds of methods are investigated. One of the methods, phosphorus recovery from the dehydrated sludge by incineration is considered to be useful. The dehydrated sludge was mixed with the reagent of NaOH, KOH or Na2 CO3 , and incinerated at 750°C or 900°C. Phosphorus in the generated ash of the sludge was dissolved by the addition of the hot water, and recovered by the evaporation of the extract. The recovered phosphorus was confirmed to be an alkali metal phosphate, and the recovery rate reached about 75%.