All life forms require phosphorus (P), which has no substitute in food production. The risk of phosphorus loss from soil and limited P rock reserves has led to the development of recycling P from industrial residues. This study investigates the potential of phosphorus recovery from sewage sludge and manure ash by thermochemical treatment (ASH DEC) in Finland. An ASH DEC plant could receive 46 to 76 kt/a of sewage sludge ash to produce 51 to 85 kt/a of a P-rich product with a P2O5 content of 13% to 18%, while 320 to 750 kt/a of manure ash could be supplied to produce 350 to 830 kt/a of a P-rich product with a P content of 4% to 5%. The P2O5 potential in the total P-rich product from the ASH DEC process using sewage sludge and manure ash is estimated at 25 to 47 kt/a, which is significantly more than the P fertilizer demand in Finland’s agricultural industries. The energy efficiency of integrated incineration and the ASH DEC process is more dependent on the total solid content and subsequent need for mechanical dewatering and thermal drying than on the energy required by the ASH DEC process. According to the results of this study, treated sewage sludge and manure ash using the ASH DEC process represent significant potential phosphorus sources for P fertilizer production.
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