Production of technical grade phosphoric acid from incinerator sewage sludge ash (ISSA).
The recovery of phosphorus from sewage sludge ash samples obtained from 7 operating sludge incinerators in the UK using a sulfuric acid washing procedure to produce a technical grade phosphoric acid product has been investigated. The influences of reaction time, sulfuric acid concentration, liquid to solid ratio and source of ISSA on P recovery have been examined. The optimised conditions were the minimum stoichiometric acid requirement, a reaction time of 120 min and a liquid to solid ratio of 20. Under these conditions, average recoveries of between 72% and 91% of total phosphorus were obtained. Product filtrate was purified by passing through a cation exchange column, concentrated to 80% H(3)PO(4) and compared with technical grade H(3)PO(4) specifications. The economics of phosphate recovery by this method are briefly discussed.
Donatello
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S
Department of Civil and Environmental Engineering, Imperial College London SW7 2AZ, UK.
Tong
D
D
Cheeseman
C R
CR
D002244:Carbon / Q000737:chemistry*; D005374:Filtration; D017745:Incineration; D010756:Phosphoric Acids / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry; D012722:Sewage / Q000737:chemistry*; D013464:Sulfuric Acids / Q000737:chemistry; D018505:Waste Management / Q000379:methods*
D010756:Phosphoric Acids; D012722:Sewage; D013464:Sulfuric Acids; D010758:Phosphorus; D002244:Carbon; C030242:phosphoric acid; C033158:sulfuric acid